USRE31781E - Isomerization of monocyclic alkyl aromatic hydrocarbons - Google Patents
Isomerization of monocyclic alkyl aromatic hydrocarbons Download PDFInfo
- Publication number
- USRE31781E USRE31781E US06/516,830 US51683083A USRE31781E US RE31781 E USRE31781 E US RE31781E US 51683083 A US51683083 A US 51683083A US RE31781 E USRE31781 E US RE31781E
- Authority
- US
- United States
- Prior art keywords
- zeolite
- zsm
- alumina
- weight percent
- binder
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000006317 isomerization reaction Methods 0.000 title claims abstract description 17
- -1 monocyclic alkyl aromatic hydrocarbons Chemical class 0.000 title abstract description 18
- 238000000034 method Methods 0.000 claims abstract description 38
- 239000012808 vapor phase Substances 0.000 claims abstract description 7
- 239000010457 zeolite Substances 0.000 claims description 70
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 claims description 62
- 229910021536 Zeolite Inorganic materials 0.000 claims description 51
- 239000003054 catalyst Substances 0.000 claims description 50
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 31
- 150000001768 cations Chemical class 0.000 claims description 25
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 24
- 239000000203 mixture Substances 0.000 claims description 23
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims description 18
- 239000000463 material Substances 0.000 claims description 17
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 claims description 16
- 239000001257 hydrogen Substances 0.000 claims description 14
- 229910052739 hydrogen Inorganic materials 0.000 claims description 14
- 239000000377 silicon dioxide Substances 0.000 claims description 14
- 239000008096 xylene Substances 0.000 claims description 14
- 239000011230 binding agent Substances 0.000 claims description 13
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 12
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 12
- 229910000323 aluminium silicate Inorganic materials 0.000 claims description 12
- 239000003085 diluting agent Substances 0.000 claims description 12
- 229930195733 hydrocarbon Natural products 0.000 claims description 8
- 150000002430 hydrocarbons Chemical class 0.000 claims description 8
- 150000003738 xylenes Chemical class 0.000 claims description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 6
- 239000004215 Carbon black (E152) Substances 0.000 claims description 5
- 230000003197 catalytic effect Effects 0.000 claims description 4
- 229910052759 nickel Inorganic materials 0.000 claims description 4
- 229910017052 cobalt Inorganic materials 0.000 claims description 3
- 239000010941 cobalt Substances 0.000 claims description 3
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 3
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 claims description 3
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 150000004682 monohydrates Chemical class 0.000 claims 1
- 238000006243 chemical reaction Methods 0.000 abstract description 12
- 239000013078 crystal Substances 0.000 description 21
- 239000000047 product Substances 0.000 description 18
- RWRDLPDLKQPQOW-UHFFFAOYSA-N Pyrrolidine Chemical compound C1CCNC1 RWRDLPDLKQPQOW-UHFFFAOYSA-N 0.000 description 12
- 239000000243 solution Substances 0.000 description 12
- 125000001477 organic nitrogen group Chemical group 0.000 description 9
- URLKBWYHVLBVBO-UHFFFAOYSA-N Para-Xylene Chemical group CC1=CC=C(C)C=C1 URLKBWYHVLBVBO-UHFFFAOYSA-N 0.000 description 8
- IVSZLXZYQVIEFR-UHFFFAOYSA-N m-xylene Chemical group CC1=CC=CC(C)=C1 IVSZLXZYQVIEFR-UHFFFAOYSA-N 0.000 description 8
- 239000011148 porous material Substances 0.000 description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 8
- 229910052783 alkali metal Inorganic materials 0.000 description 7
- 125000000217 alkyl group Chemical group 0.000 description 7
- 230000000737 periodic effect Effects 0.000 description 7
- 239000011734 sodium Substances 0.000 description 7
- FYGHSUNMUKGBRK-UHFFFAOYSA-N 1,2,3-trimethylbenzene Chemical compound CC1=CC=CC(C)=C1C FYGHSUNMUKGBRK-UHFFFAOYSA-N 0.000 description 6
- GWHJZXXIDMPWGX-UHFFFAOYSA-N 1,2,4-trimethylbenzene Chemical compound CC1=CC=C(C)C(C)=C1 GWHJZXXIDMPWGX-UHFFFAOYSA-N 0.000 description 6
- YNQLUTRBYVCPMQ-UHFFFAOYSA-N Ethylbenzene Chemical compound CCC1=CC=CC=C1 YNQLUTRBYVCPMQ-UHFFFAOYSA-N 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 6
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 239000010703 silicon Substances 0.000 description 5
- 229910052710 silicon Inorganic materials 0.000 description 5
- 229910052708 sodium Inorganic materials 0.000 description 5
- PIICEJLVQHRZGT-UHFFFAOYSA-N Ethylenediamine Chemical compound NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 description 4
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 4
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical group [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 description 4
- 239000002585 base Substances 0.000 description 4
- 239000000571 coke Substances 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 4
- 229910000510 noble metal Inorganic materials 0.000 description 4
- QUBBAXISAHIDNM-UHFFFAOYSA-N 1-ethyl-2,3-dimethylbenzene Chemical class CCC1=CC=CC(C)=C1C QUBBAXISAHIDNM-UHFFFAOYSA-N 0.000 description 3
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 3
- 238000002441 X-ray diffraction Methods 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-O ammonium group Chemical group [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 3
- 125000000129 anionic group Chemical group 0.000 description 3
- 238000001354 calcination Methods 0.000 description 3
- 125000004432 carbon atom Chemical group C* 0.000 description 3
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 3
- 239000001307 helium Substances 0.000 description 3
- 229910052734 helium Inorganic materials 0.000 description 3
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 3
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 3
- 150000002892 organic cations Chemical class 0.000 description 3
- 125000004430 oxygen atom Chemical group O* 0.000 description 3
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 3
- 239000000376 reactant Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 150000005199 trimethylbenzenes Chemical class 0.000 description 3
- PFEOZHBOMNWTJB-UHFFFAOYSA-N 3-methylpentane Chemical compound CCC(C)CC PFEOZHBOMNWTJB-UHFFFAOYSA-N 0.000 description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 2
- 239000004115 Sodium Silicate Substances 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- 230000004913 activation Effects 0.000 description 2
- 238000013019 agitation Methods 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 229910001413 alkali metal ion Inorganic materials 0.000 description 2
- 229910000272 alkali metal oxide Inorganic materials 0.000 description 2
- 150000001340 alkali metals Chemical class 0.000 description 2
- JYIBXUUINYLWLR-UHFFFAOYSA-N aluminum;calcium;potassium;silicon;sodium;trihydrate Chemical compound O.O.O.[Na].[Al].[Si].[K].[Ca] JYIBXUUINYLWLR-UHFFFAOYSA-N 0.000 description 2
- 150000003863 ammonium salts Chemical class 0.000 description 2
- 239000004927 clay Substances 0.000 description 2
- 229910001603 clinoptilolite Inorganic materials 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000006731 degradation reaction Methods 0.000 description 2
- 150000005195 diethylbenzenes Chemical class 0.000 description 2
- 230000029087 digestion Effects 0.000 description 2
- 229910052675 erionite Inorganic materials 0.000 description 2
- 229910001657 ferrierite group Inorganic materials 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 239000000499 gel Substances 0.000 description 2
- 239000007863 gel particle Substances 0.000 description 2
- 150000004820 halides Chemical class 0.000 description 2
- 229910052677 heulandite Inorganic materials 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 2
- 230000002209 hydrophobic effect Effects 0.000 description 2
- 229910052809 inorganic oxide Inorganic materials 0.000 description 2
- 238000005342 ion exchange Methods 0.000 description 2
- 239000012263 liquid product Substances 0.000 description 2
- 229940078552 o-xylene Drugs 0.000 description 2
- 150000007530 organic bases Chemical class 0.000 description 2
- 239000008188 pellet Substances 0.000 description 2
- 230000036619 pore blockages Effects 0.000 description 2
- 238000000634 powder X-ray diffraction Methods 0.000 description 2
- 239000002243 precursor Substances 0.000 description 2
- 239000012429 reaction media Substances 0.000 description 2
- 239000011541 reaction mixture Substances 0.000 description 2
- 230000008707 rearrangement Effects 0.000 description 2
- 230000008929 regeneration Effects 0.000 description 2
- 238000011069 regeneration method Methods 0.000 description 2
- 239000011780 sodium chloride Substances 0.000 description 2
- KKCBUQHMOMHUOY-UHFFFAOYSA-N sodium oxide Chemical compound [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 description 2
- 229910001948 sodium oxide Inorganic materials 0.000 description 2
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 2
- 229910052911 sodium silicate Inorganic materials 0.000 description 2
- 239000012265 solid product Substances 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- MEGFZVZIOCKTCS-UHFFFAOYSA-N 1,2,3,4-tetramethylbenzene Chemical compound CC1=CC=C(C)C(C)=C1C.CC1=CC=C(C)C(C)=C1C MEGFZVZIOCKTCS-UHFFFAOYSA-N 0.000 description 1
- WGSMMQXDEYYZTB-UHFFFAOYSA-N 1,2,4,5-tetramethylbenzene Chemical compound CC1=CC(C)=C(C)C=C1C.CC1=CC(C)=C(C)C=C1C WGSMMQXDEYYZTB-UHFFFAOYSA-N 0.000 description 1
- WJYMPXJVHNDZHD-UHFFFAOYSA-N 1,3,5-triethylbenzene Chemical compound CCC1=CC(CC)=CC(CC)=C1 WJYMPXJVHNDZHD-UHFFFAOYSA-N 0.000 description 1
- WZEYZMKZKQPXSX-UHFFFAOYSA-N 1,3,5-trimethylbenzene Chemical compound CC1=CC(C)=CC(C)=C1.CC1=CC(C)=CC(C)=C1 WZEYZMKZKQPXSX-UHFFFAOYSA-N 0.000 description 1
- CYNYIHKIEHGYOZ-UHFFFAOYSA-N 1-bromopropane Chemical compound CCCBr CYNYIHKIEHGYOZ-UHFFFAOYSA-N 0.000 description 1
- 229910018404 Al2 O3 Inorganic materials 0.000 description 1
- PRASOHMFFINPCQ-UHFFFAOYSA-N CC1=CC(C)=C(C)C(C)=C1.CC1=CC(C)=C(C)C(C)=C1 Chemical compound CC1=CC(C)=C(C)C(C)=C1.CC1=CC(C)=C(C)C(C)=C1 PRASOHMFFINPCQ-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910017897 NH4 NO3 Inorganic materials 0.000 description 1
- 101100386054 Saccharomyces cerevisiae (strain ATCC 204508 / S288c) CYS3 gene Proteins 0.000 description 1
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 150000004996 alkyl benzenes Chemical class 0.000 description 1
- 229940037003 alum Drugs 0.000 description 1
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 description 1
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 229910000278 bentonite Inorganic materials 0.000 description 1
- 239000000440 bentonite Substances 0.000 description 1
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 description 1
- UNYSKUBLZGJSLV-UHFFFAOYSA-L calcium;1,3,5,2,4,6$l^{2}-trioxadisilaluminane 2,4-dioxide;dihydroxide;hexahydrate Chemical compound O.O.O.O.O.O.[OH-].[OH-].[Ca+2].O=[Si]1O[Al]O[Si](=O)O1.O=[Si]1O[Al]O[Si](=O)O1 UNYSKUBLZGJSLV-UHFFFAOYSA-L 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 125000002091 cationic group Chemical group 0.000 description 1
- 229910052676 chabazite Inorganic materials 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 238000010908 decantation Methods 0.000 description 1
- 239000007857 degradation product Substances 0.000 description 1
- 230000002939 deleterious effect Effects 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 239000000975 dye Substances 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000004817 gas chromatography Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 229910001683 gmelinite Inorganic materials 0.000 description 1
- 239000002638 heterogeneous catalyst Substances 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 239000000543 intermediate Substances 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- 125000000959 isobutyl group Chemical group [H]C([H])([H])C([H])(C([H])([H])[H])C([H])([H])* 0.000 description 1
- 125000001449 isopropyl group Chemical group [H]C([H])([H])C([H])(*)C([H])([H])[H] 0.000 description 1
- 229910001711 laumontite Inorganic materials 0.000 description 1
- 239000000395 magnesium oxide Substances 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 239000002808 molecular sieve Substances 0.000 description 1
- 229910052680 mordenite Inorganic materials 0.000 description 1
- 125000004108 n-butyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])C([H])([H])* 0.000 description 1
- 125000004123 n-propyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])* 0.000 description 1
- KBJMLQFLOWQJNF-UHFFFAOYSA-N nickel(II) nitrate Inorganic materials [Ni+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O KBJMLQFLOWQJNF-UHFFFAOYSA-N 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
- 239000005060 rubber Substances 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000010561 standard procedure Methods 0.000 description 1
- 238000010025 steaming Methods 0.000 description 1
- 229910052678 stilbite Inorganic materials 0.000 description 1
- 101150035983 str1 gene Proteins 0.000 description 1
- 230000002459 sustained effect Effects 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- PUGUQINMNYINPK-UHFFFAOYSA-N tert-butyl 4-(2-chloroacetyl)piperazine-1-carboxylate Chemical compound CC(C)(C)OC(=O)N1CCN(C(=O)CCl)CC1 PUGUQINMNYINPK-UHFFFAOYSA-N 0.000 description 1
- 238000007669 thermal treatment Methods 0.000 description 1
- ZCUFMDLYAMJYST-UHFFFAOYSA-N thorium dioxide Chemical compound O=[Th]=O ZCUFMDLYAMJYST-UHFFFAOYSA-N 0.000 description 1
- 238000010555 transalkylation reaction Methods 0.000 description 1
- 238000011282 treatment Methods 0.000 description 1
- LEMQFBIYMVUIIG-UHFFFAOYSA-N trifluoroborane;hydrofluoride Chemical compound F.FB(F)F LEMQFBIYMVUIIG-UHFFFAOYSA-N 0.000 description 1
- YFTHZRPMJXBUME-UHFFFAOYSA-N tripropylamine Chemical compound CCCN(CCC)CCC YFTHZRPMJXBUME-UHFFFAOYSA-N 0.000 description 1
- 239000011800 void material Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J29/00—Catalysts comprising molecular sieves
- B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
- B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
- B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
- B01J29/42—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively containing iron group metals, noble metals or copper
- B01J29/46—Iron group metals or copper
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
- C07C5/22—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by isomerisation
- C07C5/27—Rearrangement of carbon atoms in the hydrocarbon skeleton
- C07C5/2702—Catalytic processes not covered by C07C5/2732 - C07C5/31; Catalytic processes covered by both C07C5/2732 and C07C5/277 simultaneously
- C07C5/2708—Catalytic processes not covered by C07C5/2732 - C07C5/31; Catalytic processes covered by both C07C5/2732 and C07C5/277 simultaneously with crystalline alumino-silicates, e.g. molecular sieves
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
- B01J2229/10—After treatment, characterised by the effect to be obtained
- B01J2229/26—After treatment, characterised by the effect to be obtained to stabilize the total catalyst structure
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
- B01J2229/30—After treatment, characterised by the means used
- B01J2229/42—Addition of matrix or binder particles
Definitions
- the present invention relates to the use of specific diluents, i.e. toluene and C 9 + recycle material, with the monocyclic alkyl aromatic hydrocarbon feed in a vapor phase isomerization process over a catalyst comprising a crystalline aluminosilicate zeolite characterized by a silica/alumina mole ratio of at least 12 and a constraint index, hereinafter defined, within the approximate range of 1 to 12.
- specific diluents i.e. toluene and C 9 + recycle material
- the catalytic rearrangement of alkyl groups present in alkyl aromatic hydrocarbons to provide one or more products suitable for use in the petroleum and chemical industries has heretofore been effected by a wide variety of catalysts.
- Acidic halides such as aluminum chloride, aluminum bromide, boron trifluoride--hydrogen fluoride mixtures, etc. have been used in the rearrangement of alkyl benzenes to provide valuable intermediates which find utility in the synthesis of rubber, plastic, fibers and dyes.
- Other catalysts which have been used include solid siliceous cracking-type catalysts such as silica-alumina and clays and platinum deposited on silica-alumina.
- catalysts heretofore employed suffer from several disadvantages.
- Acidic halides such as aluminum chloride, for example, are partially soluble in the feed material and are easily lost fromm the catalyst zone. Catalysts of this type are also uneconomical because of their extreme corrosiveness and requirement for recovery from the effluent products.
- Other catalysts of the heterogeneous type such as silica-alumina, platinum on alumina, etc., do not possess sufficient acidity to provide effective conversion and necessitate the use of relatively high temperatures above the order of 800° to 950° F. High temperatures frequently lead to coke formation which lowers the yield of desired product and necessitates frequent regeneration of the catalyst to remove coke.
- Heterogeneous catalyst such as the crystalline aluminosilicates, both natural and synthetic, possess sufficient acidity but suffer the disadvantage or poor selectivity and aging as evidenced by "coke” make and the excessive amounts of disproportionated product formed in isomerization reactions.
- This invention relates to the use of from about 3 to about 30 combined weight percent, preferably from about 5 to about 25 combined weight percent of toluene and C 9 + recycle material as diluents with the monocyclic alkyl aromatic hydrocarbon feed in vapor phase isomerization thereof.
- the isomerization reaction is carried out in the presence of a catalyst composition comprising a crystalline aluminosilicate zeolite characterized by a silica/alumina mole ratio of greater than 12 and a constraint index of from about 1 to about 12.
- the catalyst composition must contain, as replacement for at least a part of the original cations, cations of a metal of Group VIII of the Periodic Table of Elements, e.g. nickel, iron and/or cobalt. Further, it is preferred that the catalyst composition also contain, as replacement for at least a part of the original cations, hydrogen or hydrogen precursor cations.
- the crystalline aluminosilicate zeolites used in the catalyst composition of the process of this invention are referred to generally as ZSM-5 type or as behaving like ZSM-5 and are represented by the general formulas, expressed in terms of mole ratios of oxides in the anhydrous state, as follows: ##EQU1## wherein M is a cation, predominately non-noble metal of Group VIII of the Periodic Table and/or hydrogen, n is the valence of M and X is at least 5, ##EQU2## wherein M is a cation, predominately non-noble metal of Group VIII of the Periodic Table and/or hydrogen, n is the valence of M and y is from 20 to 90, ##EQU3## wherein M is a cation, predominately non-noble metal of Group VIII of the Periodic Table and/or hydrogen and n is the valence of M,
- R is an organic nitrogen-containing cation derived from ethylenediamine or pyrrolidine for ZSM-35 and from a 2-(hydroxyalkyl)trialkylammonium compound, wherein alkyl is methyl, ethyl or a combination thereof, for ZSM-38, and M is a cation, predominately non-noble metal of Group VIII of the Periodic Table and/or hydrogen.
- the catalyst composition useful in this invention comprises a crystalline aluminosilicate zeolite characterized by a silica/alumina mole ratio of at least 12 and a constraint index of from about 1 to about 12, non-limiting examples of which include ZSM-5, ZSM-11, ZSM-12, ZSM-35 and ZSM-38.
- the zeolite ZSM-5 for use in the catalyst composition useful in this invention has a formula, in terms of mole ratios of oxides in anhydrous state, as follows: ##EQU4## wherein M is selected from the group consisting of a mixture of alkali metal cations, especially sodium, and tetraalkylammonium cations, the alkyl groups of which preferably contain 2 to 5 carbon atoms, and x is at least 5. Particularly preferred is a zeolite having the formula in the anhydrous state as follows: ##EQU5## wherein Z is from greater than 30 to about 350 or higher.
- Zeolite ZSM-11 is taught by U.S. Pat. No. 3,709,979, issued January 9, 1973, the disclosure of which is incorporated herein by reference.
- the zeolite ZSM-11 for use in the catalyst composition useful in this invention has a formula, in terms of mole ratios of oxides in the anhydrous state, as follows: ##EQU6## wherein M is a mixture of at least one of the quaternary cations of a Group V-A element of the Periodic Table and alkali metal cations, especially sodium.
- the original cations can be present so that the amount of quaternary metal cations is between 10 and 90 percent of the total amount of the original cations.
- the zeolite can be expressed by the following formula in terms of mole ratios of oxides: ##EQU7## wherein R is an alkyl or aryl group having between 1 and 7 carbon atoms, M is an alkali metal cation, X is a group V-A element, especially a metal, and x is between 0.1 and 0.9.
- Zeolite ZSM-12 is taught by U.S. Pat. No. 3,832,449, issued Aug. 27, 1974, the disclosure of which is incorporated herein by reference.
- ZSM-35 is described in U.S. application Ser. No. 582,061, filed Nov. 29, 1974.
- This zeolite can be identified, in terms of mole ratios of oxides and in the anhydrous state, as follows:
- R is an organic nitrogen-containing cation derived from ethylenediamine or pyrrolidine
- M is an alkali metal cation and x is greater than 8, and is characterized by a specified X-ray powder diffraction pattern.
- zeolite ZSM-35 has a formula in terms of mole ratios of oxides and in the anhydrous state, as follows:
- R is an organic nitrogen-containing cation derived from ethylenediamine or pyrrolidine
- M is an alkali metal, especially sodium
- y is from greater than 8 to about 50.
- ZSM-38 is described in U.S. application Ser. No. 560,412, filed Mar. 20, 1975.
- This zeolite can be identified, in terms of mole ratios of oxides and in the anhydrous state, as follows:
- R is an organic nitrogen-containing cation derived from a 2-(hydroxyalkyl) trialkylammonium compound, x is greater than 8 and M is an alkali metal cation, and is characterized by a specified X-ray powder diffraction pattern.
- the zeolite has a formula, in terms of mole ratios of oxides and in the anhydrous state, as follows:
- R is an organic nitrogen-containing carbon derived from a 2-(hydroxyalkyl) trialkylammonium compound, wherein alkyl is methyl, ethyl or a combination thereof, M is an alkali metal, especially sodium, and y is from greater than 8 to about 50.
- the zeolites herein described have unusually low alumina contents, i.e. high silica to alumina ratios, they are very active even when the silica to alumina ratio exceeds 30.
- the activity is surprising since catalytic activity is generally attributed to framework aluminum atoms and cations associated with these aluminum atoms. These catalysts retain their crystallinity for long periods in spite of the presence of steam at high temperature which induces irreversible collapse of the framework of other zeolites, e.g. of the X and A type.
- carbonaceous deposits, when formed may be removed by burning at higher than usual temperatures to restore activity.
- the zeolites of this class exhibit very low coke forming capability, conducive to very long times on stream between burning regenerations.
- the crystal structure of the zeolites for use herein provides constrained access to, and egress from, the intracrystalline free space by virtue of having a pore dimension greater than about 5 Angstroms and pore windows of about a size such as would be provided by 10-membered rings of oxygen atoms. It is to be understood, of course, that these rings are those formed by the regular disposition of the tetrahedra making up the anionic framework of the crystalline aluminosilicate, the oxygen atoms themselves being bonded to the silicon or aluminum atoms at the centers of the tetrahedra.
- the preferred type catalysts useful in this invention possess, in combination: a silica to alumina ratio of at least about 12; and a structure providing constrained access to the crystalline free space.
- the silica to alumina ratio referred to may be determined by conventional analysis. This ratio is meant to represent, as closely as possible, the ratio in the rigid anionic framework of the zeolite crystal and to exclude aluminum in the binder or in cationic or other form within the channels.
- catalysts with a silica to alumina ratio of at least 12 are useful, it is preferred to use catalysts having higher ratios of at least about 30.
- Such catalysts after activation, acquire an intracrystalline sorption capacity for normal hexane which is greater than that for water, i.e. they exhibit "hydrophobic" properties. It is believed that this hydrophobic character is advantageous in the present invention.
- the present invention provides a highly effective vapor phase isomerization process with a catalyst, the crystalline aluminosilicate zeolite portion of which, as suggested above, has a smaller pore size than those crystalline aluminosilicates previously used for such purpose.
- zeolite ZSM-5 which has elliptical pores of approximately 4.8 ⁇ 7.1 Angstrom units.
- the type zeolites useful in this invention freely sorb normal hexane and have a pore dimension greater than about 5 Angstroms, or, if elliptical in pore shape, at least the size of the pores in ZSM-5.
- the structure must provide constrained access to larger molecules. It is sometimes possible to judge from a known crystal structure whether such constrained access exists. For example, if the only pore windows in a crystal are formed by 8-membered rings of oxygen atoms, then access to molecules of larger cross-section than normal hexane is excluded and the zeolite is not of the desired type. Windows of 10-membered rings are preferred, although, in some instances, excessive puckering or pore blockage may render these catalysts ineffective. Twelve-membered rings do not generally appear to offer sufficient constraint to produce the advantageous conversions. Also, structures can be conceived due to pore blockage or other cause, that may be operative.
- a simple determination of the "constraint index" may be made by passing continuously a mixture of an equal weight of normal hexane and 3-methylpentane over a small sample, approximately 1 gram or less, of catalyst at atmospheric pressure according to the following procedure.
- a sample of the catalyst, in the form of pellets or extrudate, is crushed to a particle size about that of coarse sand and mounted in a glass tube.
- the catalyst Prior to testing, the catalyst is treated with a stream of air at 1000° F. for at least 15 minutes. The catalyst is then flushed with helium and the temperature adjusted between 550° and 950° F. to give an overall conversion between 10% and 60%.
- the mixture of hydrocarbons is passed at 1 liquid hourly space velocity (i.e. 1 volume of liquid hydrocarbon per volume of catalyst per hour) over the catalyst with a helium dilution to give a helium to total hydrocarbon mole ratio of 4:1.
- a sample of the effluent is taken and analyzed, most conveniently by gas chromatography, to determine the fraction remaining unchanged for each of the two hydrocarbons.
- the constraint index approximates the ratio of the cracking rate constants for the two hydrocarbons.
- Catalysts suitable for the present invention are those having a constraint index in the approximate range of 1 to 12.
- Constraint Index (CI) values for some typical catalysts, including those useful herein, are:
- the above constraint index values typically characterize the specified zeolites but that such are the cumulative result of several variables used in determination and calculation thereof.
- the constraint index may vary within the indicated approximate range of 1 to 12.
- other variables such as the crystal size of the zeolite, the presence of possibly occluded contaminants and binders intimately combined with the zeolite may affect the constraint index.
- the constraint index while affording a highly useful means for characterizing the zeolites of interest is approximate, taking into consideration the manner of its determination, with the probability, in some instances, of compounding variable extremes. However, in all instances, at a temperature within the above-specified range of 550° to 950° F., the constraint index will have a value for any given zeolite of interest herein within the approximate range of 1 to 12.
- the specific zeolites described, when prepared in the presence of organic cations, are catalytically inactive, possibly because the intracrystalline free space is occupied by organic cations from the forming solution. They may be activated by heating, for example, in an inert atmosphere at 1000° F. for one hour, followed by base exchange with ammonium salts and by calcination at 1000° F. in air.
- the presence of organic cations in the forming solution may not be absolutely essential to the formation of this type zeolite; however, the presence of these cations does appear to favor the formation of this special type of zeolite. More generally, it is desirable to activate this type catalyst by base exchange with ammonium salts followed by calcination in air at about 1000° F. for from about 15 minutes to about 24 hours.
- Natural zeolites may sometimes be converted to this type zeolite catalyst by various activation procedures and other treatments such as base exchange, steaming, alumina extraction and calcination, in combinations.
- Natural minerals which may be so treated include ferrierite, brewsterite, stilbite, dachiardite, epistilbite, heulandite and clinoptilolite.
- the preferred crystalline aluminosilicates are ZSM-5, ZSM-11, ZSM-12, ZSM-35 and ZSM-38, with ZSM-5 particularly preferred.
- the catalysts hereof are selected as those having a crystal framework density, in the dry hydrogen form, of not substantially below about 1.6 grams per cubic centimeter. It has been found that zeolites which satisfy all three of these criteria are most desired for the present process. Therefore, the preferred catalysts of this invention are those having a constraint index as defined above of about 1 to about 12, a silica to alumina ratio of at least about 12 and a dried crystal density of not less than about 1.6 grams per cubic centimeter.
- the dry density for known structures may be calculated from the number of silicon plus aluminum atoms per 1000 cubic Angstroms, as given, e.g., on page 19 of the article on Zeolite Structure by W. M. Meir.
- the crystal framework density may be determined by classical pyknometer techniques. For example, it may be determined by immersing the dry hydrogen form of the zeolite in an organic solvent which is not sorbed by the crystal. It is possible that the unusual sustained activity and stability of this class of zeolite is associated with its high crystal anionic framework density of not less than about 16 grams per cubic centimeter. This high density of course must be associated with a relatively small amount of free space within the crystal, which might be expected to result in more stable structures. This free space, however, is important as the locus of catalytic activity.
- Crystal framework densities of some typical zeolites are:
- the synthetic ZSM-35 zeolite possesses a definite distinguishing crystalline structure whose X-ray diffraction pattern shows substantially the significant lines set forth in Table 1.
- the synthetic ZSM-38 zeolite possesses a definite distinguishing crystalline structure whose X-ray diffraction patterns shows substantially the significant lines set forth in Table 1A.
- Ion exchange of the sodium ion with cations reveals substantially the same pattern with some minor shifts in interplanar spacing and variation in relative intensity. Other minor variations can occur depending on the silicon to aluminum ratio of the particular sample, as well as if it has been subjected to thermal treatment.
- Zeolites ZSM-5, ZSM-11 and ZSM-12 for use in the process of this invention are prepared as indicated in their respective patents, incorporated herein by reference above.
- Zeolite ZSM-35 can be suitably prepared by preparing a solution containing sources of an alkali metal oxide, preferably sodium oxide, an organic nitrogen-containing oxide, an oxide of aluminum, an oxide of silicon and water and having a composition, in terms of mole ratios of oxides, falling within the following ranges:
- an alkali metal oxide preferably sodium oxide, an organic nitrogen-containing oxide, an oxide of aluminum, an oxide of silicon and water and having a composition, in terms of mole ratios of oxides, falling within the following ranges:
- R is an organic nitrogen-containing cation derived from pyrrolidine or ethylenediamine and M is an alkali metal ion, and maintaining the mixture until crystals of the zeolite are formed.
- the quantity of OH- is calculated only from the inorganic sources of alkali without any organic base contribution). Thereafter, the crystals are separated from the liquid and recovered.
- Typical reaction conditions consist of heating the foregoing reaction mixture to a temperature of from about 90° to about 400° F. for a period of time of from about 6 hours to about 100 days. A more preferred temperature range is from about 150° to about 400° F. with the amount of time at a temperature in such range being from about 6 hours to about 80 days.
- the digestion of the gel particles is carried out until crystals form.
- the solid product is separated from the reaction medium, as by cooling the whole to room temperature, filtering and water washing.
- the crystalline product is dried, e.g. at 230° F., for from about 8 to 24 hours.
- Zeolite ZSM-38 can be suitably prepared by preparing a solution containing sources of an alkali metal oxide, preferably sodium oxide, an organic nitrogen-containing oxide, an oxide of aluminum, an oxide of silicon and water and having a composition, in terms of mole ratios of oxides, falling within the following ranges:
- an alkali metal oxide preferably sodium oxide, an organic nitrogen-containing oxide, an oxide of aluminum, an oxide of silicon and water and having a composition, in terms of mole ratios of oxides, falling within the following ranges:
- R is an organic nitrogen-containing cation derived from a 2-(hydroxyalkyl) trialkylammonium compound and M is an alkali metal ion, and maintaining the mixture until crystals of the zeolite are formed.
- the quantity of OH- is calculated only from the inorganic sources of alkali without any organic base contribution). Thereafter, the crystals are separated from the liquid and recovered.
- Typical reaction conditions consist of heating the foregoing reaction mixture to a temperature of from about 90° to about 400° F. for a period of time of from about 6 hours to about 100 days. A more preferred temperature range is from about 150° to about 400° F. with the amount of time at a temperature in such range being from about 6 hours to about 80 days.
- the digestion of the gel particles is carried out until crystals form.
- the solid product is separated from the reaction medium, as by cooling the whole to room temperature, filtering and water washing.
- the crystalline product is thereafter dried, e.g. at 230° F. for from about 8 to 24 hours.
- the suitable zeolite catalyst is employed in combination with a support or binder material such as, for example, a porous inorganic oxide support or a clay binder.
- a support or binder material such as, for example, a porous inorganic oxide support or a clay binder.
- binder materials include alumina, zirconia, silica, magnesia, thoria, titania, boria and combinations thereof, generally in the form of dried inorganic oxide gels and gelatinous precipitates.
- Suitable clay materials include, by way of example, bentonite and kieselguhr.
- the relative proportion of suitable crystalline aluminosilicate zeolite of the total composition of catalyst and binder or support may vary widely with the zeolite content ranging from between about 30 to about 90 percent by weight and more usually in the range of about 50 to about 80 percent by weight of the composition.
- Operating conditions employed in the process of the present invention are critical. Such conditions as temperature, pressure, space velocity, molar ratio of the reactants, hydrogen to hydrocarbon mole ratio, and the presence of the diluents will have impportant affects on the process.
- the process of this invention is conducted such that isomerization of the monocyclic alkyl aromatic hydrocarbon is carried out in the vapor-phase by contact in a reaction zone, such as, for example, a fixed bed of catalyst composition, under isomerization effective conditions, said catalyst composition being characterized, as synthesized, as comprising the above-defined zeolite which has been hydrogen or hydrogen precusor and Group VIII metal exchanged.
- a reaction zone such as, for example, a fixed bed of catalyst composition
- This process may be conducted in either batch or fluid bed operation with attendent benefits of either operation readily obtainable.
- the present isomerization process may be carried out at a temperature between about 450° and 900° F. and at pressures ranging from about 50 psig up to about 500 psig.
- the weight hourly space velocities (WHSV) may be maintained at from about 0.1 to 200, and the hydrogen/hydrocarbon mole ratio should be maintained at between about 0.1 and about 100.
- WHSV weight hourly space velocities
- the conditions of temperature and pressure will vary considerably depending upon equilibrium considerations and type of feed material. Optimum conditions are those in which maximum yields of desired isomer products are obtained and hence considerations of temperature and pressure will vary within a range of conversion levels designed to provide the highest selectivity and maximum yield.
- the starting feed materials for isomerization to be employed in the process of the invention are preferably single ring aromatic hydrocarbons containing a minimum of two and a maximum of four alkyl group substituents on the ring.
- These feed materials may be illustrated by the following structural formula: ##STR1## wherein R is a lower alkyl group, straight or branch chained, having 1 to about 4 carbon atoms and n is an integer of 2 to 4.
- R is a lower alkyl group, straight or branch chained, having 1 to about 4 carbon atoms and n is an integer of 2 to 4.
- the ring may contain from 2 to 4 alkyl substituents.
- Lower alkyl groups for R include especially methyl, ethyl, n-propyl, n-butyl, isopropyl or isobutyl or any combination thereof.
- Specific compounds falling within the above structural formula include para-Xylene, meta-Xylene, ortho-Xylene, mesitylene (1, 3, 5-trimethylbenzene), durene (1, 2, 4, 5-tetramethylbenzene), hemimellitene (1, 2, 3-trimethylbenzene), pseudocumene (1, 2, 4-trimethylbenzene), prehnitene (1, 2, 3, 4-tetramethylbenzene), isodurene (1, 2, 3, 5-tetramethylbenzene), and 1, 3, 5-triethylbenzene.
- the diluent material employed in the present process is comprised of both toluene and C 9 + recycle.
- the use of such diluent reduces xylene losses.
- the C 9 + recycle material is primarily composed of trimethylbenzenes, dimethylethylbenzenes and diethylbenzenes, which tend to increase xylene yields because the trimethylbenzene shift the xylene disproportion equilibrium toward xylenes; the trimethylbenzenes compete with xylenes in the transalkylation reaction with ethylbenzene thus reducing the amount of xylenes going into C 10 product; and the dimethylethylbenzenes are deethylated over the present catalyst material producing xylenes as a product.
- the amount of diluent is not narrowly critical and will vary within the range of 3 to 30 weight percent based on the feed material undergoing isomerization. Preferably, the amount of diluent is within the range of 5 to 25 weight percent.
- a sodium silicate solution was prepared by mixing 8440 lb of sodium silicate (Q-Brand, Philadelphia Quartz Co.) and 586 gallons of water. After addition of 24 lbs Daxad 27 (W. R. Grace Chemical Division) the solution was cooled to approximately 55° F.
- An acid alum solution was prepared by dissolving 293 lb aluminum sulfate (17.2% Al 2 O 3 ), 733 lb sulfuric acid (93%) and 377 lb sodium chloride in 602 gallons of water. The solutions were passed through a mixing nozzle and into a stirred autoclave. During the mixing operation, 1200 lb of sodium chloride was added to the vessel. The resulting gel was thoroughly agitated and heated to 200° F. in the closed vessel.
- an organic solution prepared by mixing 568 lb tri-n-propylamine, 488 lb n-propylbromide was reacted for 14 hours at a temperature of 200°-220° F. At the end of this period, agitation was increased and these conditions maintained until the ZSM-5 crystallinity reached at least 65%. Temperature was then increased to 320° F. until crystallization was complete. The residual organics were flashed from the autoclave and the product slurry was cooled.
- the product was washed by decantation using Rohm and Haas Permafloc C-7 flocculant.
- the washed product containing less than 1% sodium was filtered and dried.
- the weight of dried zeolite was approximately 2300 lb. It was determined to be zeolite ZSM-5 having a silica/alumina ratio of greater than 12, a constraint index of about 8.3 and a crystal framework density of about 1.79.
- the dried product was mixed with Continental Oil Catapal SB ( ⁇ alumina monohydrate) and water (65% zeolite, 35% alumina binder on ignited bases) then extruded to form of 1/16 inch pellet.
- Continental Oil Catapal SB ⁇ alumina monohydrate
- water 65% zeolite, 35% alumina binder on ignited bases
- An 1120 gram quantity of dried extrudate was calcined at 1000° F. for 3 hours in the presence of N 2 gas flow at a rate of 3 volumes of N 2 per volume of extrudate per minute. The temperature was brought up at a heating rate of about 3°-5° F. per minute.
- the precalcined extrudate was ammonium exchanged with 1N NH 4 NO 3 solution, 5 ml of solution for every gram extrudate. After two 1 hour exchanges at room temperature, the extrudate was drained, washed and dried. The final Na content of the extrudate was found to be 0.03 wt. percent.
- the ammonium exchanged product was calcined in air at 1000° F. for three hours.
- the air flow rate was 3 volumes per volume of extrudate per minute.
- the heating rate was 3°-5° F. per minute.
- a 100 gram quantity of the ammonium exchanged extrudate was then Ni exchanged with 1.0N Ni(NO 3 ) 2 solution (5 ml to every gram extrudate) at 190° F. for 4 hours. After exchange, the extrudate was drained, washed Ni free and dried. The Ni exchanged product was calcined in air at 1000° F. for three hours. The air flow rate was 3 volumes per volume of extrudate per minute. The heating rate was 3°-5° F. per minute. The final product was analyzed to have 1.0 wt. percent Ni and 0.02 wt. percent Na.
- Example 1 The catalyst material prepared in Example 1 is placed in a reactor and contacted with a mixed xylene feed (see Table 4, hereinafter presented) containing additionally 5 combined weight percent diluent composed of toluene and C 9 + recycle material (Primarily trimethylbenzenes, dimethylethylbenzenes and diethylbenzenes) under vapor-phase isomerization reaction conditions identified in Table 4.
- a mixed xylene feed see Table 4, hereinafter presented
- C 9 + recycle material Principal trimethylbenzenes, dimethylethylbenzenes and diethylbenzenes
- the liquid product analysis as well as normalized ortho-, meta-, and para-xylene content of the product are also listed in Table 4.
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Abstract
A process is provided for isomerization of monocyclic alkyl aromatic hydrocarbons in a reaction zone maintained under conditions such that said isomerization is accomplished in the vapor phase.
Description
1. Field of the Invention
The present invention relates to the use of specific diluents, i.e. toluene and C9 + recycle material, with the monocyclic alkyl aromatic hydrocarbon feed in a vapor phase isomerization process over a catalyst comprising a crystalline aluminosilicate zeolite characterized by a silica/alumina mole ratio of at least 12 and a constraint index, hereinafter defined, within the approximate range of 1 to 12.
2. Description of the Prior Art
The catalytic rearrangement of alkyl groups present in alkyl aromatic hydrocarbons to provide one or more products suitable for use in the petroleum and chemical industries has heretofore been effected by a wide variety of catalysts. Acidic halides such as aluminum chloride, aluminum bromide, boron trifluoride--hydrogen fluoride mixtures, etc. have been used in the rearrangement of alkyl benzenes to provide valuable intermediates which find utility in the synthesis of rubber, plastic, fibers and dyes. Other catalysts which have been used include solid siliceous cracking-type catalysts such as silica-alumina and clays and platinum deposited on silica-alumina. Although various catalysts possess one or more desired characteristics, a majority of catalysts heretofore employed suffer from several disadvantages. Acidic halides such as aluminum chloride, for example, are partially soluble in the feed material and are easily lost fromm the catalyst zone. Catalysts of this type are also uneconomical because of their extreme corrosiveness and requirement for recovery from the effluent products. Other catalysts of the heterogeneous type, such as silica-alumina, platinum on alumina, etc., do not possess sufficient acidity to provide effective conversion and necessitate the use of relatively high temperatures above the order of 800° to 950° F. High temperatures frequently lead to coke formation which lowers the yield of desired product and necessitates frequent regeneration of the catalyst to remove coke. This results in reducing on-stream time and leads to high catalyst consumption due to loss of catalyst activity. Heterogeneous catalyst such as the crystalline aluminosilicates, both natural and synthetic, possess sufficient acidity but suffer the disadvantage or poor selectivity and aging as evidenced by "coke" make and the excessive amounts of disproportionated product formed in isomerization reactions.
This invention relates to the use of from about 3 to about 30 combined weight percent, preferably from about 5 to about 25 combined weight percent of toluene and C9 + recycle material as diluents with the monocyclic alkyl aromatic hydrocarbon feed in vapor phase isomerization thereof. The isomerization reaction is carried out in the presence of a catalyst composition comprising a crystalline aluminosilicate zeolite characterized by a silica/alumina mole ratio of greater than 12 and a constraint index of from about 1 to about 12. The catalyst composition must contain, as replacement for at least a part of the original cations, cations of a metal of Group VIII of the Periodic Table of Elements, e.g. nickel, iron and/or cobalt. Further, it is preferred that the catalyst composition also contain, as replacement for at least a part of the original cations, hydrogen or hydrogen precursor cations.
The crystalline aluminosilicate zeolites used in the catalyst composition of the process of this invention are referred to generally as ZSM-5 type or as behaving like ZSM-5 and are represented by the general formulas, expressed in terms of mole ratios of oxides in the anhydrous state, as follows: ##EQU1## wherein M is a cation, predominately non-noble metal of Group VIII of the Periodic Table and/or hydrogen, n is the valence of M and X is at least 5, ##EQU2## wherein M is a cation, predominately non-noble metal of Group VIII of the Periodic Table and/or hydrogen, n is the valence of M and y is from 20 to 90, ##EQU3## wherein M is a cation, predominately non-noble metal of Group VIII of the Periodic Table and/or hydrogen and n is the valence of M,
(0.3-2.5)R.sub.2 O:(0-0.8)M.sub.2 O:Al.sub.2 O.sub.3 :>8 SiO.sub.2
wherein R is an organic nitrogen-containing cation derived from ethylenediamine or pyrrolidine for ZSM-35 and from a 2-(hydroxyalkyl)trialkylammonium compound, wherein alkyl is methyl, ethyl or a combination thereof, for ZSM-38, and M is a cation, predominately non-noble metal of Group VIII of the Periodic Table and/or hydrogen.
The catalyst composition useful in this invention comprises a crystalline aluminosilicate zeolite characterized by a silica/alumina mole ratio of at least 12 and a constraint index of from about 1 to about 12, non-limiting examples of which include ZSM-5, ZSM-11, ZSM-12, ZSM-35 and ZSM-38.
Zeolite ZSM-5 is taught by U.S. Pat. No. 3,702,886, issued November 14, 1972, the disclosure of which is incorporated herein by reference. In a preferred synthesized form, the zeolite ZSM-5 for use in the catalyst composition useful in this invention has a formula, in terms of mole ratios of oxides in anhydrous state, as follows: ##EQU4## wherein M is selected from the group consisting of a mixture of alkali metal cations, especially sodium, and tetraalkylammonium cations, the alkyl groups of which preferably contain 2 to 5 carbon atoms, and x is at least 5. Particularly preferred is a zeolite having the formula in the anhydrous state as follows: ##EQU5## wherein Z is from greater than 30 to about 350 or higher.
Zeolite ZSM-11 is taught by U.S. Pat. No. 3,709,979, issued January 9, 1973, the disclosure of which is incorporated herein by reference. In the as synthesized form, the zeolite ZSM-11 for use in the catalyst composition useful in this invention has a formula, in terms of mole ratios of oxides in the anhydrous state, as follows: ##EQU6## wherein M is a mixture of at least one of the quaternary cations of a Group V-A element of the Periodic Table and alkali metal cations, especially sodium. The original cations can be present so that the amount of quaternary metal cations is between 10 and 90 percent of the total amount of the original cations. Thus, the zeolite can be expressed by the following formula in terms of mole ratios of oxides: ##EQU7## wherein R is an alkyl or aryl group having between 1 and 7 carbon atoms, M is an alkali metal cation, X is a group V-A element, especially a metal, and x is between 0.1 and 0.9.
Zeolite ZSM-12 is taught by U.S. Pat. No. 3,832,449, issued Aug. 27, 1974, the disclosure of which is incorporated herein by reference.
ZSM-35 is described in U.S. application Ser. No. 582,061, filed Nov. 29, 1974. This zeolite can be identified, in terms of mole ratios of oxides and in the anhydrous state, as follows:
(0.3-2.5)R.sub.2 O:(0-0.8)M.sub.2 O:Al.sub.2 O.sub.3 :xSiO.sub.2
wherein R is an organic nitrogen-containing cation derived from ethylenediamine or pyrrolidine, M is an alkali metal cation and x is greater than 8, and is characterized by a specified X-ray powder diffraction pattern.
In a preferred synthesized form, zeolite ZSM-35 has a formula in terms of mole ratios of oxides and in the anhydrous state, as follows:
(0.4-2.5)R.sub.2 O:(0-0.6)M.sub.2 O:Al.sub.2 O.sub.3 :ySiO.sub.2
wherein R is an organic nitrogen-containing cation derived from ethylenediamine or pyrrolidine, M is an alkali metal, especially sodium, and y is from greater than 8 to about 50.
ZSM-38 is described in U.S. application Ser. No. 560,412, filed Mar. 20, 1975. This zeolite can be identified, in terms of mole ratios of oxides and in the anhydrous state, as follows:
(0.3-2.5)R.sub.2 O:(0-0.8)M.sub.2 O:Al.sub.2 O.sub.3 :xSiO.sub.2
wherein R is an organic nitrogen-containing cation derived from a 2-(hydroxyalkyl) trialkylammonium compound, x is greater than 8 and M is an alkali metal cation, and is characterized by a specified X-ray powder diffraction pattern.
In a preferred synthesized form, the zeolite has a formula, in terms of mole ratios of oxides and in the anhydrous state, as follows:
(0.4-2.5)R.sub.2 O:(0-0.6)M.sub.2 O:Al.sub.2 O.sub.3 :ySiO.sub.2
wherein R is an organic nitrogen-containing carbon derived from a 2-(hydroxyalkyl) trialkylammonium compound, wherein alkyl is methyl, ethyl or a combination thereof, M is an alkali metal, especially sodium, and y is from greater than 8 to about 50.
The original cations of the above zeolites ZSM-5, ZSM-11, ZSM-12, ZSM-35 and ZSM-38 are replaced, in accordance with techniques well known in the art, at least in part, by ion exchange with hydrogen or hydrogen precursor cations and metal ions of Group VIII of the Periodic Table, e.g. nickel, iron and/or cobalt.
Although the zeolites herein described have unusually low alumina contents, i.e. high silica to alumina ratios, they are very active even when the silica to alumina ratio exceeds 30. The activity is surprising since catalytic activity is generally attributed to framework aluminum atoms and cations associated with these aluminum atoms. These catalysts retain their crystallinity for long periods in spite of the presence of steam at high temperature which induces irreversible collapse of the framework of other zeolites, e.g. of the X and A type. Furthermore, carbonaceous deposits, when formed, may be removed by burning at higher than usual temperatures to restore activity. In many environments the zeolites of this class exhibit very low coke forming capability, conducive to very long times on stream between burning regenerations.
An important characteristic of the crystal structure of the zeolites for use herein is that they provide constrained access to, and egress from, the intracrystalline free space by virtue of having a pore dimension greater than about 5 Angstroms and pore windows of about a size such as would be provided by 10-membered rings of oxygen atoms. It is to be understood, of course, that these rings are those formed by the regular disposition of the tetrahedra making up the anionic framework of the crystalline aluminosilicate, the oxygen atoms themselves being bonded to the silicon or aluminum atoms at the centers of the tetrahedra. Briefly, the preferred type catalysts useful in this invention possess, in combination: a silica to alumina ratio of at least about 12; and a structure providing constrained access to the crystalline free space.
The silica to alumina ratio referred to may be determined by conventional analysis. This ratio is meant to represent, as closely as possible, the ratio in the rigid anionic framework of the zeolite crystal and to exclude aluminum in the binder or in cationic or other form within the channels. Although catalysts with a silica to alumina ratio of at least 12 are useful, it is preferred to use catalysts having higher ratios of at least about 30. Such catalysts, after activation, acquire an intracrystalline sorption capacity for normal hexane which is greater than that for water, i.e. they exhibit "hydrophobic" properties. It is believed that this hydrophobic character is advantageous in the present invention.
The present invention provides a highly effective vapor phase isomerization process with a catalyst, the crystalline aluminosilicate zeolite portion of which, as suggested above, has a smaller pore size than those crystalline aluminosilicates previously used for such purpose. An example of this is zeolite ZSM-5 which has elliptical pores of approximately 4.8×7.1 Angstrom units.
The type zeolites useful in this invention freely sorb normal hexane and have a pore dimension greater than about 5 Angstroms, or, if elliptical in pore shape, at least the size of the pores in ZSM-5. In addition, the structure must provide constrained access to larger molecules. It is sometimes possible to judge from a known crystal structure whether such constrained access exists. For example, if the only pore windows in a crystal are formed by 8-membered rings of oxygen atoms, then access to molecules of larger cross-section than normal hexane is excluded and the zeolite is not of the desired type. Windows of 10-membered rings are preferred, although, in some instances, excessive puckering or pore blockage may render these catalysts ineffective. Twelve-membered rings do not generally appear to offer sufficient constraint to produce the advantageous conversions. Also, structures can be conceived due to pore blockage or other cause, that may be operative.
Rather than attempt to judge from crystal structure whether or not a catalyst possesses the necessary constrained access, a simple determination of the "constraint index" may be made by passing continuously a mixture of an equal weight of normal hexane and 3-methylpentane over a small sample, approximately 1 gram or less, of catalyst at atmospheric pressure according to the following procedure. A sample of the catalyst, in the form of pellets or extrudate, is crushed to a particle size about that of coarse sand and mounted in a glass tube. Prior to testing, the catalyst is treated with a stream of air at 1000° F. for at least 15 minutes. The catalyst is then flushed with helium and the temperature adjusted between 550° and 950° F. to give an overall conversion between 10% and 60%. The mixture of hydrocarbons is passed at 1 liquid hourly space velocity (i.e. 1 volume of liquid hydrocarbon per volume of catalyst per hour) over the catalyst with a helium dilution to give a helium to total hydrocarbon mole ratio of 4:1. After 20 minutes on stream, a sample of the effluent is taken and analyzed, most conveniently by gas chromatography, to determine the fraction remaining unchanged for each of the two hydrocarbons.
The "constraint index" is calculated as follows: ##EQU8##
The constraint index approximates the ratio of the cracking rate constants for the two hydrocarbons. Catalysts suitable for the present invention are those having a constraint index in the approximate range of 1 to 12. Constraint Index (CI) values for some typical catalysts, including those useful herein, are:
______________________________________ Crystalline Aluminosilicate CI ______________________________________ ZSM-5 8.3 ZSM-11 8.7 ZSM-12 2 ZSM-35 2 ZSM-38 2 Beta 0.6 ZSM-4 0.5 H--Zeolon 0.5 REY 0.4 Erionite 38 ______________________________________
It is to be realized that the above constraint index values typically characterize the specified zeolites but that such are the cumulative result of several variables used in determination and calculation thereof. Thus, for a given zeolite depending on the temperature employed within the aforenoted range of 550° F. to 950° F., with accompanying conversion between 10% and 60%, the constraint index may vary within the indicated approximate range of 1 to 12. Likewise, other variables such as the crystal size of the zeolite, the presence of possibly occluded contaminants and binders intimately combined with the zeolite may affect the constraint index. It will accordingly be understood by those skilled in the art that the constraint index, as utilized herein, while affording a highly useful means for characterizing the zeolites of interest is approximate, taking into consideration the manner of its determination, with the probability, in some instances, of compounding variable extremes. However, in all instances, at a temperature within the above-specified range of 550° to 950° F., the constraint index will have a value for any given zeolite of interest herein within the approximate range of 1 to 12.
The specific zeolites described, when prepared in the presence of organic cations, are catalytically inactive, possibly because the intracrystalline free space is occupied by organic cations from the forming solution. They may be activated by heating, for example, in an inert atmosphere at 1000° F. for one hour, followed by base exchange with ammonium salts and by calcination at 1000° F. in air. The presence of organic cations in the forming solution may not be absolutely essential to the formation of this type zeolite; however, the presence of these cations does appear to favor the formation of this special type of zeolite. More generally, it is desirable to activate this type catalyst by base exchange with ammonium salts followed by calcination in air at about 1000° F. for from about 15 minutes to about 24 hours.
Natural zeolites may sometimes be converted to this type zeolite catalyst by various activation procedures and other treatments such as base exchange, steaming, alumina extraction and calcination, in combinations. Natural minerals which may be so treated include ferrierite, brewsterite, stilbite, dachiardite, epistilbite, heulandite and clinoptilolite. The preferred crystalline aluminosilicates are ZSM-5, ZSM-11, ZSM-12, ZSM-35 and ZSM-38, with ZSM-5 particularly preferred.
In a preferred aspect of this invention, the catalysts hereof are selected as those having a crystal framework density, in the dry hydrogen form, of not substantially below about 1.6 grams per cubic centimeter. It has been found that zeolites which satisfy all three of these criteria are most desired for the present process. Therefore, the preferred catalysts of this invention are those having a constraint index as defined above of about 1 to about 12, a silica to alumina ratio of at least about 12 and a dried crystal density of not less than about 1.6 grams per cubic centimeter. The dry density for known structures may be calculated from the number of silicon plus aluminum atoms per 1000 cubic Angstroms, as given, e.g., on page 19 of the article on Zeolite Structure by W. M. Meir. This paper, the entire contents of which are incorporated herein by reference, is included in "Proceedings of the Conference on Molecular Sieves, London, April 1967", published by the Society of Chemical Industry, London, 1968. When the crystal structure is unknown, the crystal framework density may be determined by classical pyknometer techniques. For example, it may be determined by immersing the dry hydrogen form of the zeolite in an organic solvent which is not sorbed by the crystal. It is possible that the unusual sustained activity and stability of this class of zeolite is associated with its high crystal anionic framework density of not less than about 16 grams per cubic centimeter. This high density of course must be associated with a relatively small amount of free space within the crystal, which might be expected to result in more stable structures. This free space, however, is important as the locus of catalytic activity.
Crystal framework densities of some typical zeolites are:
______________________________________ Void Framework Zeolite Volume Density ______________________________________ Ferrierite 0.28 cc/cc 1.76 g/cc Mordenite .28 1.7 ZSM-5,-11 .29 1.79 Dachiardite .32 1.72 L .32 1.61 Clinoptilolite .34 1.71 Laumontite .34 1.77 ZSM-4 .38 1.65 Heulandite .39 1.69 P .41 1.57 Offrenite .40 1.55 Levynite .40 1.54 Erionite .35 1.51 Gmelinite .44 1.46 Chabazite .47 1.45 A .5 1.3 Y .48 1.27 ______________________________________
Members of the above zeolites useful herein have an exceptionally high degree of thermal stability thereby rendering them particularly effective for use in processes involving elevated temperatures. In this connection, this group of zeolites appear to be some of the most stable zeolites known to date. However, it has been found that the process of this invention may be carried out at reactor bed temperatures not in excess of about 1100° F., which eliminates many undesirable reactions that may occur if carried out at higher temperatures. The deleterious effects of these reactions cause several basic problems for isomerization processes. At reactor bed temperatures substantially above 1100° F., the reactants and the products undergo degradation resulting in the loss of desired products and reactants. Undesirable residues are formed from the degradation reactions. These degradation products may lead to the formation of coke-like deposits on the active surfaces of the catalyst. As a result, these deposits rapidly destroy the high activity of the catalyst and greatly shorten its effective life. Such undesirable effects are obviated under the conditions and with the catalyst employed in the present process.
Members of the above group of zeolites for use in the catalyst composition of the present invention possess definite distinguishing crystalline structures as evidenced by the above U.S. Patents incorporated herein by reference.
The synthetic ZSM-35 zeolite possesses a definite distinguishing crystalline structure whose X-ray diffraction pattern shows substantially the significant lines set forth in Table 1.
TABLE 1 ______________________________________ Interplanar Spacing Relative Intensity ______________________________________ 9.6 ± 0.20 Very Strong-Very, Very Strong 7.10 ± 0.15 Medium 6.98 ± 0.14 Medium 6.64 ± 0.14 Medium 5.78 ± 0.12 Weak 5.68 ± 0.12 Weak 4.97 ± 0.10 Weak 4.58 ± 0.09 Weak 3.99 ± 0.08 Strong 3.94 ± 0.08 Medium-Strong 3.85 ± 0.08 Medium 3.78 ± 0.08 Strong 3.74 ± 0.08 Weak 3.66 ± 0.07 Medium 3.54 ± 0.07 Very Strong 3.48 ± 0.07 Very Strong 3.39 ± 0.07 Weak 3.32 ± 0.07 Weak-Medium 3.14 ± 0.06 Weak-Medium 2.90 ± 0.06 Weak 2.85 ± 0.06 Weak 2.71 ± 0.05 Weak 2.65 ± 0.05 Weak 2.62 ± 0.05 Weak 2.58 ± 0.05 Weak 2.54 ± 0.05 Weak 2.48 ± 0.05 Weak ______________________________________
The synthetic ZSM-38 zeolite possesses a definite distinguishing crystalline structure whose X-ray diffraction patterns shows substantially the significant lines set forth in Table 1A.
TABLE 1A ______________________________________ Interplanar Spacing Relative Intensity ______________________________________ 9.8 ± 0.20 Strong 9.1 ± 0.19 Medium 8.0 ± 0.16 Weak 7.1 ± 0.14 Medium 6.7 ± 0.14 Medium 6.0 ± 0.12 Weak 4.37 ± 0.09 Weak 4.23 ± 0.09 Weak 4.01 ± 0.08 Very Strong 3.81 ± 0.08 Very Strong 3.69 ± 0.07 Medium 3.57 ± 0.07 Very Strong 3.51 ± 0.07 Very Strong 3.34 ± 0.07 Medium 3.17 ± 0.06 Strong 3.08 ± 0.06 Medium 3.00 ± 0.06 Weak 2.92 ± 0.06 Medium 2.73 ± 0.06 Weak 2.66 ± 0.05 Weak 2.60 ± 0.05 Weak 2.49 ± 0.05 Weak ______________________________________
These values were determined by standard technique. The radiation was the K-alpha doublet of copper, and a scintillation counter spectrometer with a strip chart pen recorder was used. The peak heights, I, and the positions as a function of 2 times theta, where theta is the Bragg angle, were read from the spectrometer chart. From these, the relative intensities, 100 I/Io, where Io is the intensity of the strongest line or peak, and k (obs.), the interplanar spacing in Angstrom units, corresponding to the recorded lines, were calculated. It should be understood that these X-ray diffraction patterns are characteristic of all the species of the above respectively identified zeolites. Ion exchange of the sodium ion with cations reveals substantially the same pattern with some minor shifts in interplanar spacing and variation in relative intensity. Other minor variations can occur depending on the silicon to aluminum ratio of the particular sample, as well as if it has been subjected to thermal treatment.
Zeolites ZSM-5, ZSM-11 and ZSM-12 for use in the process of this invention are prepared as indicated in their respective patents, incorporated herein by reference above.
Zeolite ZSM-35 can be suitably prepared by preparing a solution containing sources of an alkali metal oxide, preferably sodium oxide, an organic nitrogen-containing oxide, an oxide of aluminum, an oxide of silicon and water and having a composition, in terms of mole ratios of oxides, falling within the following ranges:
TABLE 2 ______________________________________ R.sup.+ Broad Preferred ______________________________________ R.sup.+ + M.sup.+ 0.02-1.0 0.3-0.9 OH.sup.- /SiO.sub.2 0.05-0.5 0.07-0.49 H.sub.2 O/OH.sup.31 41-500 100-250 SiO.sub.2 /Al.sub.2 O.sub.3 8.8-200 12-60 ______________________________________
wherein R is an organic nitrogen-containing cation derived from pyrrolidine or ethylenediamine and M is an alkali metal ion, and maintaining the mixture until crystals of the zeolite are formed. (The quantity of OH- is calculated only from the inorganic sources of alkali without any organic base contribution). Thereafter, the crystals are separated from the liquid and recovered. Typical reaction conditions consist of heating the foregoing reaction mixture to a temperature of from about 90° to about 400° F. for a period of time of from about 6 hours to about 100 days. A more preferred temperature range is from about 150° to about 400° F. with the amount of time at a temperature in such range being from about 6 hours to about 80 days.
The digestion of the gel particles is carried out until crystals form. The solid product is separated from the reaction medium, as by cooling the whole to room temperature, filtering and water washing. The crystalline product is dried, e.g. at 230° F., for from about 8 to 24 hours.
Zeolite ZSM-38 can be suitably prepared by preparing a solution containing sources of an alkali metal oxide, preferably sodium oxide, an organic nitrogen-containing oxide, an oxide of aluminum, an oxide of silicon and water and having a composition, in terms of mole ratios of oxides, falling within the following ranges:
TABLE 3 ______________________________________ R.sup.+ Broad Preferred ______________________________________ R.sup.+ + M.sup.+ 0.2-1.0 0.3-0.9 OH.sup.- /SiO.sub.2 0.05-0.5 0.07-0.49 H.sub.2 O/OH.sup.- 41-500 100-250 SiO.sub.2 /Al.sub.2 O.sub.3 8.8-200 12-60 ______________________________________
wherein R is an organic nitrogen-containing cation derived from a 2-(hydroxyalkyl) trialkylammonium compound and M is an alkali metal ion, and maintaining the mixture until crystals of the zeolite are formed. (The quantity of OH- is calculated only from the inorganic sources of alkali without any organic base contribution). Thereafter, the crystals are separated from the liquid and recovered. Typical reaction conditions consist of heating the foregoing reaction mixture to a temperature of from about 90° to about 400° F. for a period of time of from about 6 hours to about 100 days. A more preferred temperature range is from about 150° to about 400° F. with the amount of time at a temperature in such range being from about 6 hours to about 80 days.
The digestion of the gel particles is carried out until crystals form. The solid product is separated from the reaction medium, as by cooling the whole to room temperature, filtering and water washing. The crystalline product is thereafter dried, e.g. at 230° F. for from about 8 to 24 hours.
For the isomerization process of this invention the suitable zeolite catalyst is employed in combination with a support or binder material such as, for example, a porous inorganic oxide support or a clay binder. Non-limiting examples of such binder materials include alumina, zirconia, silica, magnesia, thoria, titania, boria and combinations thereof, generally in the form of dried inorganic oxide gels and gelatinous precipitates. Suitable clay materials include, by way of example, bentonite and kieselguhr. The relative proportion of suitable crystalline aluminosilicate zeolite of the total composition of catalyst and binder or support may vary widely with the zeolite content ranging from between about 30 to about 90 percent by weight and more usually in the range of about 50 to about 80 percent by weight of the composition.
Operating conditions employed in the process of the present invention are critical. Such conditions as temperature, pressure, space velocity, molar ratio of the reactants, hydrogen to hydrocarbon mole ratio, and the presence of the diluents will have impportant affects on the process.
The process of this invention is conducted such that isomerization of the monocyclic alkyl aromatic hydrocarbon is carried out in the vapor-phase by contact in a reaction zone, such as, for example, a fixed bed of catalyst composition, under isomerization effective conditions, said catalyst composition being characterized, as synthesized, as comprising the above-defined zeolite which has been hydrogen or hydrogen precusor and Group VIII metal exchanged. This process may be conducted in either batch or fluid bed operation with attendent benefits of either operation readily obtainable.
The present isomerization process may be carried out at a temperature between about 450° and 900° F. and at pressures ranging from about 50 psig up to about 500 psig. The weight hourly space velocities (WHSV) may be maintained at from about 0.1 to 200, and the hydrogen/hydrocarbon mole ratio should be maintained at between about 0.1 and about 100. Within these limits the conditions of temperature and pressure will vary considerably depending upon equilibrium considerations and type of feed material. Optimum conditions are those in which maximum yields of desired isomer products are obtained and hence considerations of temperature and pressure will vary within a range of conversion levels designed to provide the highest selectivity and maximum yield.
The starting feed materials for isomerization to be employed in the process of the invention are preferably single ring aromatic hydrocarbons containing a minimum of two and a maximum of four alkyl group substituents on the ring. These feed materials may be illustrated by the following structural formula: ##STR1## wherein R is a lower alkyl group, straight or branch chained, having 1 to about 4 carbon atoms and n is an integer of 2 to 4. Thus, it is to be understood that the ring may contain from 2 to 4 alkyl substituents. Lower alkyl groups for R include especially methyl, ethyl, n-propyl, n-butyl, isopropyl or isobutyl or any combination thereof.
Specific compounds falling within the above structural formula include para-Xylene, meta-Xylene, ortho-Xylene, mesitylene (1, 3, 5-trimethylbenzene), durene (1, 2, 4, 5-tetramethylbenzene), hemimellitene (1, 2, 3-trimethylbenzene), pseudocumene (1, 2, 4-trimethylbenzene), prehnitene (1, 2, 3, 4-tetramethylbenzene), isodurene (1, 2, 3, 5-tetramethylbenzene), and 1, 3, 5-triethylbenzene.
Of the above listing of specific feed materials which may be used, the xylene isomers and pseudocumene are especially preferred.
The diluent material employed in the present process is comprised of both toluene and C9 + recycle. The use of such diluent reduces xylene losses. The C9 + recycle material is primarily composed of trimethylbenzenes, dimethylethylbenzenes and diethylbenzenes, which tend to increase xylene yields because the trimethylbenzene shift the xylene disproportion equilibrium toward xylenes; the trimethylbenzenes compete with xylenes in the transalkylation reaction with ethylbenzene thus reducing the amount of xylenes going into C10 product; and the dimethylethylbenzenes are deethylated over the present catalyst material producing xylenes as a product.
The amount of diluent is not narrowly critical and will vary within the range of 3 to 30 weight percent based on the feed material undergoing isomerization. Preferably, the amount of diluent is within the range of 5 to 25 weight percent.
The following specific examples will serve to illustrate the process of the present invention, without unduly limiting same.
A sodium silicate solution was prepared by mixing 8440 lb of sodium silicate (Q-Brand, Philadelphia Quartz Co.) and 586 gallons of water. After addition of 24 lbs Daxad 27 (W. R. Grace Chemical Division) the solution was cooled to approximately 55° F. An acid alum solution was prepared by dissolving 293 lb aluminum sulfate (17.2% Al2 O3), 733 lb sulfuric acid (93%) and 377 lb sodium chloride in 602 gallons of water. The solutions were passed through a mixing nozzle and into a stirred autoclave. During the mixing operation, 1200 lb of sodium chloride was added to the vessel. The resulting gel was thoroughly agitated and heated to 200° F. in the closed vessel. After reducing agitation, an organic solution prepared by mixing 568 lb tri-n-propylamine, 488 lb n-propylbromide was reacted for 14 hours at a temperature of 200°-220° F. At the end of this period, agitation was increased and these conditions maintained until the ZSM-5 crystallinity reached at least 65%. Temperature was then increased to 320° F. until crystallization was complete. The residual organics were flashed from the autoclave and the product slurry was cooled.
The product was washed by decantation using Rohm and Haas Permafloc C-7 flocculant. The washed product containing less than 1% sodium was filtered and dried. The weight of dried zeolite was approximately 2300 lb. It was determined to be zeolite ZSM-5 having a silica/alumina ratio of greater than 12, a constraint index of about 8.3 and a crystal framework density of about 1.79.
The dried product was mixed with Continental Oil Catapal SB (α alumina monohydrate) and water (65% zeolite, 35% alumina binder on ignited bases) then extruded to form of 1/16 inch pellet.
An 1120 gram quantity of dried extrudate was calcined at 1000° F. for 3 hours in the presence of N2 gas flow at a rate of 3 volumes of N2 per volume of extrudate per minute. The temperature was brought up at a heating rate of about 3°-5° F. per minute. The precalcined extrudate was ammonium exchanged with 1N NH4 NO3 solution, 5 ml of solution for every gram extrudate. After two 1 hour exchanges at room temperature, the extrudate was drained, washed and dried. The final Na content of the extrudate was found to be 0.03 wt. percent.
The ammonium exchanged product was calcined in air at 1000° F. for three hours. The air flow rate was 3 volumes per volume of extrudate per minute. The heating rate was 3°-5° F. per minute.
A 100 gram quantity of the ammonium exchanged extrudate was then Ni exchanged with 1.0N Ni(NO3)2 solution (5 ml to every gram extrudate) at 190° F. for 4 hours. After exchange, the extrudate was drained, washed Ni free and dried. The Ni exchanged product was calcined in air at 1000° F. for three hours. The air flow rate was 3 volumes per volume of extrudate per minute. The heating rate was 3°-5° F. per minute. The final product was analyzed to have 1.0 wt. percent Ni and 0.02 wt. percent Na.
The catalyst material prepared in Example 1 is placed in a reactor and contacted with a mixed xylene feed (see Table 4, hereinafter presented) containing additionally 5 combined weight percent diluent composed of toluene and C9 + recycle material (Primarily trimethylbenzenes, dimethylethylbenzenes and diethylbenzenes) under vapor-phase isomerization reaction conditions identified in Table 4. The liquid product analysis as well as normalized ortho-, meta-, and para-xylene content of the product are also listed in Table 4.
TABLE 4 ______________________________________ Example No. 2 3 4 5 ______________________________________ Operating Conditions Temperature, °F. 602 601 601 596 Pressure, psig 203 206 206 205 H.sub.2 /HC, mole ratio 1 1 1 1 WHSV 10 20.1 39.6 80.7 Time on stream, hr. 2 3 3.5 4 Liquid Product Analysis, wt. % Feed Benzene 0.06 2.3 1.3 0.8 0.4 Ethylbenzene 19.8 14.9 16.9 18.1 19.1 p-Xylene 2.7 18.1 18.2 17.7 15.6 m-Xylene 49.4 39.7 39.9 40.1 41.0 o-Xylene 23.1 16.2 16.6 17.4 19.1 Diluent 5.0 ˜5.0 ˜5.0 ˜5.0 ˜5.0 (Toluene + C.sub.9.sup.- Recycle) Xylene Loss, wt. % 1.3 0.5 0.1 (0.5) Ethylbenzene Conversion, wt. % 24.9 15.1 8.8 3.9 Normalized p-Xylene 24.4 24.3 23.6 20.6 m-Xylene 53.7 53.5 53.3 54.2 o-Xylene 21.9 22.2 23.1 25.2 ______________________________________
Claims (11)
1. A process for effecting catalytic isomerization of xylenes which comprises contacting said xylenes in the vapor phase with hydrogen at a temperature of from about 450° to about 900° F., a pressure of from about 50 psig to about 500 psig, a hydrogen/hydrocarbon mole ratio of from about 0.1 to about 100 and a weight hourly space velocity of from about 0.1 to about 200 in the presence of from about 3 to about 30 combined weight percent, based upon weight of the xylene feed, of diluent of toluene and C9 + recycle material and a crystalline aluminosilicate zeolite characterized by a silica/alumina mole ratio of greater than 12 and a constraint index within the approximate range of 1 to 12 and containing cations which are selected from the group consisting of iron, nickel and cobalt.
2. The process of claim 1 wherein said zeolite is ZSM-5, ZSM-11, ZSM-12, ZSM-35 or ZSM-38.
3. The process of claim 2 wherein said zeolite is ZSM-5.
4. The process of claim 1 wherein said zeolite is combined in an amount of from about 30 to about 90 weight percent in a binder therefor.
5. The process of claim 4 wherein said binder is alumina.
6. The process of claim 2 wherein said zeolite is combined in an amount of from about 30 to about 90 weight percent in a binder therefor.
7. The process of claim 6 wherein said binder is alumina.
8. The process of claim 1 wherein said cations are nickel.
9. The process of claim 1 wherein said diluent is present at from about 5 to about 25 weight percent of the xylene mixture feed.
10. The process of claim 2 wherein said diluent is present at from about 5 to about 25 weight percent of the xylene mixture feed. .Iadd.
11. The process of claim 1 wherein said zeolite is combined in an amount from about 30 to about 90 weight percent with a calcined α-alumina monohydrate binder. .Iaddend. .Iadd.12. The process of claim 11 wherein said zeolite has a silica to alumina ratio of at least 30..Iaddend. .Iadd.13. The process of claim 12 wherein said zeolite has a silica to alumina ratio from at least about 30 to at least about 350..Iaddend. .Iadd.14. The process of claim 13 where said zeolite consists essentially of ZSM-5..Iaddend. .Iadd.15. The process of claim 14 wherein said zeolite is extruded with the alumina monohydrate and calcined to form a catalyst having about 65 weight percent zeolite and about 35 weight percent alumina binder..Iaddend.
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US5030787A (en) * | 1990-01-24 | 1991-07-09 | Mobil Oil Corp. | Catalytic disproportionation/transalkylation utilizing a C9+ aromatics feed |
US5177656A (en) * | 1991-02-05 | 1993-01-05 | Hoechst Celanese Corporation | Flexible magnetic disc cassettes with integrally molded wear button |
US5952536A (en) | 1998-04-02 | 1999-09-14 | Chevron Chemical Co. Llc | Aromatics and toluene/trimethylbenzene gas phase transalkylation processes |
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Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5030787A (en) * | 1990-01-24 | 1991-07-09 | Mobil Oil Corp. | Catalytic disproportionation/transalkylation utilizing a C9+ aromatics feed |
US5177656A (en) * | 1991-02-05 | 1993-01-05 | Hoechst Celanese Corporation | Flexible magnetic disc cassettes with integrally molded wear button |
US5952536A (en) | 1998-04-02 | 1999-09-14 | Chevron Chemical Co. Llc | Aromatics and toluene/trimethylbenzene gas phase transalkylation processes |
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