CA1178622A - Process for the preparation of tertiary olefines - Google Patents
Process for the preparation of tertiary olefinesInfo
- Publication number
- CA1178622A CA1178622A CA000392579A CA392579A CA1178622A CA 1178622 A CA1178622 A CA 1178622A CA 000392579 A CA000392579 A CA 000392579A CA 392579 A CA392579 A CA 392579A CA 1178622 A CA1178622 A CA 1178622A
- Authority
- CA
- Canada
- Prior art keywords
- process according
- molecular sieve
- alkyl
- ether
- hydrogen
- 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
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/09—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrolysis
- C07C29/10—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrolysis of ethers, including cyclic ethers, e.g. oxiranes
-
- 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
- B01J29/18—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the mordenite type
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C1/00—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon
- C07C1/20—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon starting from organic compounds containing only oxygen atoms as heteroatoms
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2529/00—Catalysts comprising molecular sieves
- C07C2529/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites, pillared clays
- C07C2529/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
- C07C2529/18—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the mordenite type
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
Abstract
ABSTRACT OF THE DISCLOSURE
Process for the preparation of tertiary olefins by catalytic cleavage of their n-alkyl ethers at elevated temperature and with simultaneously recovery of the corresponding n-alkanols, characterized in that the cleavage is carried out in the presence of acidic molecular sieves, which have been activated, if necessary, by a treatment with hydrogen, at temperatures of from 100 to 300°C.
Process for the preparation of tertiary olefins by catalytic cleavage of their n-alkyl ethers at elevated temperature and with simultaneously recovery of the corresponding n-alkanols, characterized in that the cleavage is carried out in the presence of acidic molecular sieves, which have been activated, if necessary, by a treatment with hydrogen, at temperatures of from 100 to 300°C.
Description
The present invention relates to a process for the preparation of tertiary ole~ins by catalytic cleavage of their n-alkyl ethers.
Tertiary ol~fins are important intermediates for the preparation of polymers and higher grade chemicals. Thus, the interesting function of the dou~le ~ond at the tertiary carbon atom allows the production of numerous organic interrnediate products, such as, for example, pinacolin and neocarboxylic acids, and by dehydrogenation, conjugated diolefins, such as, ~or example, isoprene, which can be further processed in the plastics, pharmaceutical, plant protection and lubricant sectors. The prerequisite for reactions of this type is ~he avail-ability of such tertiary olefins in as high a purity as possible.
Since these tertiary olefins occur~ in the main, in mixture with other hydrocarbons in the product spectrum of thermal and catalytic crackers, an isolation process must be employed for their purification. The sulphuric acid process must be employed for their purification. The sulphuric acid process has hitherto been the primary means for the isolation of the tertiary olefins from the hydrocarbon streams mentioned, a process in which, firstly, the sulphuric acid esters of the tertiary alcohols corresponding to the tertiary olefins were formed, which were then re-formed to give the ~ertiary olefins again, by 'split-ting oEf' the sulphuric acid. The p:roblems o~ this proccss arise ~rom the unavoidaL~le corrosion and Erom the noccssity for concentr~t:ing up tlle usecl acid prior to its recycling. Cn more recont times, processes have becrl devoloped whlch, starting Erom a selective etherielcation of the tertiary oleeins with alco-hols, achieve the purification of the tertiary olefins via the decomposition of these ethers ~European Patent Application 0,003,305; United States 3,170,000 and German Offenlegungsschrift 2,924,869. In the ter~iary ethers, the formation of the dialkyl sthers from the n-alkanols split off occurs as an undesired side ~, ! J
7~
reactlon, to an increasing extent with inereasing reaction ~em-perature. A par-ticular disadvantage of this ether formation arises from the water formea thereby, which, with an alkanol cycle, must be removed again before the etherification step. Catalysts to decompose the ethers are therefore being sought, the activity of which is great enough to function at low temperatures, or the selectivity of which is high enough to produce as low a formation as possible of ethers. Such a catalyst is described in DE-OS
(German Published Specification) 2,924,~69, in the form of crystalline silicic acid. However, in order to achieve as large conversions as pos.sible, it is necessary, even with this catalyst, to work a-t the relatively high temperatures of over 190C up to the region of about 350C.
A process for the preparation of tertiary olefins by catalytic cleavage of their n-alkyl ethers at elevated temperature and with simultaneous recovery of the corresponding n-alkanols has now been found, which is characterised in that an n-alkyl ether is contacted with hydrogen in the presence o an acidic molecular sieve at a tempera-ture of erom 100 to 300QC. The acid:i.c molecular s:i.eve may have b~en activated, iE necessary, by a treatment with hydrogen.
Zeolites, acid:Lc aluminum oxides and H-mordenites may be mentioned as examples of molecular sieves which can be used in the process according to the invention. Zeolites are understood here to mean water-containing silicate frameworks of the general formula X[(M', M"o 5) A102]-y Si02 zH20 with M' = Li, Na, K etc. and M" = Mg, Ca, Sr, Ba, etc. (Fortschr.
Mineral 42, 50 (1965)). They usually have a crystalline :, ~
structure, as de-te.rmined by X-ray di~E:ract,ion analys:is, and are porous. The pores are usually uniform in size, especially diameter. Furthermore, ~-mordenites are understood to mean orthorhombic silicate frameworks of the formula Na8[(A102)8 .
(SiO2)40] . 24H20, the Na atoms of which can be _3~ t~
successively exchanged ~or ~l akoms (Am. Mineral~ 3~, 819 (195~
il-Mordenites are preferably employed. These molecuLar sieves which can be used according to the invention are available in their acidic H form.
The acidic molecular sieves described can be employed according to khe invention individually as well as in a mixture of 2 or more of the molecular sieves mentioned. In the case that the selectivity of the molecular sieve employed according to the invention as catalyst, or of the mixture of several molecular sieves, is to be increased, ~hich~ in general, is accompanied by a decrease in the activity and/or a decrease in the throughput, it can be of advan-tage to mix the molecular sieves used with, for example, 0.01 to 80% by weight, relative to the amount of the molecular sieves, of aluminum oxide and/or amor-phous alumosilicates, and to employ the mixture thereby obtained as catalyst.
For a specific task within the scope of the present inven~ion, th~ necessity and, if necessary, the extent of such an admixture can be determined by simple pre-liminary experiments.
The catalytically active acidic molecular sieves for the process according to the invention hàve an effective pore volume of, ~or example, 0.05 to 0.6, preferably 0.12 to 0.3 ml/g. Furthermore, khey have an e~fective pore diameter o, Eor example, 3 to 15, praerably 7 to l2)~particularly pr~eerabLy 8 to ll R. 'I'he specieic sur~ace arca is, for example, L00 to 700~ preforably 300 to 550 m /g. 'I'he -eoLlowi.ng moJ~cuLar sievos aro contempkltocl: X-, Y-, A-, 'I'-zeolite, fa~ site, Z.SM-5 zeolite, ~I-mordenite.
The process according to the invention is carried out, for example, at a temperature of 100 to 300C, preferably 110 to 210C, particularly preferably 120 to 180C. The raaction can be carried out in the gas phase as well as in ~he liquid phase at a pressure of, for example, 0.1 to 50 bar, preferably 1 to 20 bar.
; ,, ~1'7~
A ~IISV (weight-hourly-space-velocity) in the range ~rom 0.5 to 10 g substrate/g catalyst/hour is chosen for the catalyst load.
It has additionally been found that the catalyst for the process according to the invention undergoes an increase in activity on treatment with hydrogen before its employment as catalyst. This activity-increasing hydrogen treatment of the catalyst consisting of one or several of the molecular sieves descri'bed above and, if appropriate, o~ the components, which have been described, of the mixture can take place before its initial employment as well as be~ore a subsequent employment of an already used catalyst. This activity-increasing hydrogen treatment of an already used catalyst can be undertaken if the catalyst shows signs of exhaustion and also as a preventive measure, before signs of exhaustion in the catalyst are detectable. This hydrogen treatment can be carried out, for example, with 50 to 500 liters of hydrogen per liter of cata-lyst at 100 to 450C at 1 to 50 bar for a I to 60 hours. This hydrogen treat-ment can, of course, be carried out in a separate reactor designed for the pur-pose, but equally well also in the reactor provided for the ether cleavage according to the invention, provided this reactor is equipped for the hydrogen treatment. Thus, or example, still wnused catalyst can be poured :into the reactor provided for the ether cleavage, the catalyst can be treatetl wi-th hydro-gen under the conditlons clescril70d~ after which tlle 'hydrogell usecl for t'he treat-ment is removed, ~or examp'le by Elushillg with nitrogerl allcl, by ~eeding in t'he e~her to be cleavecl and adjus~ment oE the conditions according to the invention, the catalyst ls brought into use. Furthermore, an already used catalyst can be subjected to the hydrogen treatment without removal from the cleavage reactor by displacing the ether to be cleaved hitherto fed in, for example by means of nitrogen, and the catalyst is then activated by feeding in the desired amount of 1 ~7~
hydrogen and adjustment of the pararneters de~cribe~ ~or the hydrogen treatmerlt.
n-Alkyl ethers of tertiary olefins for ~he process according to the invention are, Eor example, those of the general formula \ /
R.fH 7 (I) HC-C-OR
CH
R~ \R6 .
which are split according to the invention to give tertiary olefins of the general formula R2/ C=C/ ( II ) ----C/ \ R 6 and n-alkanols o -the Eormula R70~ (:Cr. :t) wherein Rl denote~ hydroyen o:r strai.yht-chain or branched alkyl with 1 to 8, preferably 1 to 4, particularly preferably 1 -to 2 C a-toms, R2 to R6 denote hydrogen or alkyl with 1 to 4, preferably 1 to 2, especially preferably with 1 C atom and R7 denotes straight-chain ~,, , ~ -, '' ~' ' ' .
', . :
; -6-alkyl wit}l 1 ~o 6, preferably wlth 1 ~o ~ particularly pre~erably 1 to 2 C atoms.
The following ethers may be mentioned as examples of starting materials of the ~ormula (I) for the process accordlng to the invention: methyl~tert.-butyl ether, ethyl-tert.-butyl ether, propyl-tert.-butyl ether, n-butyl-tert.-butyl ether, n-amyl-tert.-butyl ether, methyl-tert.-amyl ether, ethyl-tert.-amyl ether, propyl-tert.-amyl ether~ n-butyl-tert.-amyl ether, n-amyl-tert.-amyl ether, n-hexyl-tert.-amyl ether, methyl-tert.-hexyl ether and ethyl-tert.-hexyl ether.
The products 0btainable according to the invention are, in addition to the particular n-alkanols, the tertiary olefinesJ such as isobutene, isoamylene, isohexene and others.
The purification of the tertiary olefins which can be produced accord-ing to the invention is effected in a distillation step downstream from the cleavage reactor, whereby the desired olefines are taken off as a top product in a purity of over 96~ by weight and a bottom product accumulates which, having a composition of about 90 to 99.9% by weight of alkanol, 0.1 to 10% by weight of the ether employed and small amounts o water, can be recycled to the process for etherification of the terkiary olefines.
In contrcast to the sulphuric ac:id extraction process Eor the prcpara-tion oE tertiary oleEins the process accorcling to the irlverltioll requires 1 Cat1 lyst without corros;ive propQrties" so th~t normal carbon steels CQn bc usecl Eor thc rcactor material. '~'he procuss according to thc invention is distingu:ished, in contrast with the catalytic cleavage process described above, by a higher activity of the catalyst to be used, so that the catalytic cleavage can be carried out at lower temperatures. This lower reaction temperature greatly reduces the portion of undesired di-n-alkyl ether formed of necessity, so that ,r 7~ '7~
over 90% oE the n-alkanol introduced into circulation can be reclaimed, and, as a result of the high activity oE the catalyst employed according to the inventionJ
high yields and high throughputs are simultaneously achieved in th0 cleavage process. At the same time) an energy-saving method of carrying out the reaction results from the lowering of the reaction temperature.
Examples:
A thermostat-controlled continuous reactor was employed as the alkyl ether cleavage reactor. ~or a given internal reactor radius Oe 25 mm, the height of the catalyst bed was so chosen that the catalyst charge was 100 g. To monitor the temperature, the reactor was equipped with temperature measuring devices at intervals of 100 mm. The pressure in the reactor was regulated by maintaining an overpressure. The metered addition of the substrate was effected via a diaphragm piston pump. The composition of the reaction product obtained at the exit of the reactor was examined by means of gas chromatography. The product stream was worked up in a downstream distillation column. The desired iso-olefins were obtaine~l thereby as a top product in a purity of over 95% by weight.
The following abboreviations are used: 'L'AM~ - tert.-amyl~ ethyL ether;
MB = methylbutene; ~M~ - ~limet}lyl ~Jth~r; WIISV = wciglIt-}lourLy~spaco-voLocity;
GC = gas chrorlIatograp}ly; MW ~- molecuLar weight.
~n ox.Itnples 1 - 10 tlle terlIperaturo dependence of the ether cleavage has been investigated in connection with the formation of dimethyl ether.
Catalyst: 100 g H -mordenite Starting product: 100 g TAME/h (GC 99.9% by weight) (MW 102.2) Reaction pressure 10 bar; reaction time 6 h;
WIISV -1 ( g substrate g catalyst.h .
.
~ 3~ ~ ~
Example (No.~ 1 2 ~ 4 5 Temp, (C) .120 1~0 140 160 180 TAME welgh-t % 32 . 3 24, 3 18 . 7 12 . 7 2 D 1
Tertiary ol~fins are important intermediates for the preparation of polymers and higher grade chemicals. Thus, the interesting function of the dou~le ~ond at the tertiary carbon atom allows the production of numerous organic interrnediate products, such as, for example, pinacolin and neocarboxylic acids, and by dehydrogenation, conjugated diolefins, such as, ~or example, isoprene, which can be further processed in the plastics, pharmaceutical, plant protection and lubricant sectors. The prerequisite for reactions of this type is ~he avail-ability of such tertiary olefins in as high a purity as possible.
Since these tertiary olefins occur~ in the main, in mixture with other hydrocarbons in the product spectrum of thermal and catalytic crackers, an isolation process must be employed for their purification. The sulphuric acid process must be employed for their purification. The sulphuric acid process has hitherto been the primary means for the isolation of the tertiary olefins from the hydrocarbon streams mentioned, a process in which, firstly, the sulphuric acid esters of the tertiary alcohols corresponding to the tertiary olefins were formed, which were then re-formed to give the ~ertiary olefins again, by 'split-ting oEf' the sulphuric acid. The p:roblems o~ this proccss arise ~rom the unavoidaL~le corrosion and Erom the noccssity for concentr~t:ing up tlle usecl acid prior to its recycling. Cn more recont times, processes have becrl devoloped whlch, starting Erom a selective etherielcation of the tertiary oleeins with alco-hols, achieve the purification of the tertiary olefins via the decomposition of these ethers ~European Patent Application 0,003,305; United States 3,170,000 and German Offenlegungsschrift 2,924,869. In the ter~iary ethers, the formation of the dialkyl sthers from the n-alkanols split off occurs as an undesired side ~, ! J
7~
reactlon, to an increasing extent with inereasing reaction ~em-perature. A par-ticular disadvantage of this ether formation arises from the water formea thereby, which, with an alkanol cycle, must be removed again before the etherification step. Catalysts to decompose the ethers are therefore being sought, the activity of which is great enough to function at low temperatures, or the selectivity of which is high enough to produce as low a formation as possible of ethers. Such a catalyst is described in DE-OS
(German Published Specification) 2,924,~69, in the form of crystalline silicic acid. However, in order to achieve as large conversions as pos.sible, it is necessary, even with this catalyst, to work a-t the relatively high temperatures of over 190C up to the region of about 350C.
A process for the preparation of tertiary olefins by catalytic cleavage of their n-alkyl ethers at elevated temperature and with simultaneous recovery of the corresponding n-alkanols has now been found, which is characterised in that an n-alkyl ether is contacted with hydrogen in the presence o an acidic molecular sieve at a tempera-ture of erom 100 to 300QC. The acid:i.c molecular s:i.eve may have b~en activated, iE necessary, by a treatment with hydrogen.
Zeolites, acid:Lc aluminum oxides and H-mordenites may be mentioned as examples of molecular sieves which can be used in the process according to the invention. Zeolites are understood here to mean water-containing silicate frameworks of the general formula X[(M', M"o 5) A102]-y Si02 zH20 with M' = Li, Na, K etc. and M" = Mg, Ca, Sr, Ba, etc. (Fortschr.
Mineral 42, 50 (1965)). They usually have a crystalline :, ~
structure, as de-te.rmined by X-ray di~E:ract,ion analys:is, and are porous. The pores are usually uniform in size, especially diameter. Furthermore, ~-mordenites are understood to mean orthorhombic silicate frameworks of the formula Na8[(A102)8 .
(SiO2)40] . 24H20, the Na atoms of which can be _3~ t~
successively exchanged ~or ~l akoms (Am. Mineral~ 3~, 819 (195~
il-Mordenites are preferably employed. These molecuLar sieves which can be used according to the invention are available in their acidic H form.
The acidic molecular sieves described can be employed according to khe invention individually as well as in a mixture of 2 or more of the molecular sieves mentioned. In the case that the selectivity of the molecular sieve employed according to the invention as catalyst, or of the mixture of several molecular sieves, is to be increased, ~hich~ in general, is accompanied by a decrease in the activity and/or a decrease in the throughput, it can be of advan-tage to mix the molecular sieves used with, for example, 0.01 to 80% by weight, relative to the amount of the molecular sieves, of aluminum oxide and/or amor-phous alumosilicates, and to employ the mixture thereby obtained as catalyst.
For a specific task within the scope of the present inven~ion, th~ necessity and, if necessary, the extent of such an admixture can be determined by simple pre-liminary experiments.
The catalytically active acidic molecular sieves for the process according to the invention hàve an effective pore volume of, ~or example, 0.05 to 0.6, preferably 0.12 to 0.3 ml/g. Furthermore, khey have an e~fective pore diameter o, Eor example, 3 to 15, praerably 7 to l2)~particularly pr~eerabLy 8 to ll R. 'I'he specieic sur~ace arca is, for example, L00 to 700~ preforably 300 to 550 m /g. 'I'he -eoLlowi.ng moJ~cuLar sievos aro contempkltocl: X-, Y-, A-, 'I'-zeolite, fa~ site, Z.SM-5 zeolite, ~I-mordenite.
The process according to the invention is carried out, for example, at a temperature of 100 to 300C, preferably 110 to 210C, particularly preferably 120 to 180C. The raaction can be carried out in the gas phase as well as in ~he liquid phase at a pressure of, for example, 0.1 to 50 bar, preferably 1 to 20 bar.
; ,, ~1'7~
A ~IISV (weight-hourly-space-velocity) in the range ~rom 0.5 to 10 g substrate/g catalyst/hour is chosen for the catalyst load.
It has additionally been found that the catalyst for the process according to the invention undergoes an increase in activity on treatment with hydrogen before its employment as catalyst. This activity-increasing hydrogen treatment of the catalyst consisting of one or several of the molecular sieves descri'bed above and, if appropriate, o~ the components, which have been described, of the mixture can take place before its initial employment as well as be~ore a subsequent employment of an already used catalyst. This activity-increasing hydrogen treatment of an already used catalyst can be undertaken if the catalyst shows signs of exhaustion and also as a preventive measure, before signs of exhaustion in the catalyst are detectable. This hydrogen treatment can be carried out, for example, with 50 to 500 liters of hydrogen per liter of cata-lyst at 100 to 450C at 1 to 50 bar for a I to 60 hours. This hydrogen treat-ment can, of course, be carried out in a separate reactor designed for the pur-pose, but equally well also in the reactor provided for the ether cleavage according to the invention, provided this reactor is equipped for the hydrogen treatment. Thus, or example, still wnused catalyst can be poured :into the reactor provided for the ether cleavage, the catalyst can be treatetl wi-th hydro-gen under the conditlons clescril70d~ after which tlle 'hydrogell usecl for t'he treat-ment is removed, ~or examp'le by Elushillg with nitrogerl allcl, by ~eeding in t'he e~her to be cleavecl and adjus~ment oE the conditions according to the invention, the catalyst ls brought into use. Furthermore, an already used catalyst can be subjected to the hydrogen treatment without removal from the cleavage reactor by displacing the ether to be cleaved hitherto fed in, for example by means of nitrogen, and the catalyst is then activated by feeding in the desired amount of 1 ~7~
hydrogen and adjustment of the pararneters de~cribe~ ~or the hydrogen treatmerlt.
n-Alkyl ethers of tertiary olefins for ~he process according to the invention are, Eor example, those of the general formula \ /
R.fH 7 (I) HC-C-OR
CH
R~ \R6 .
which are split according to the invention to give tertiary olefins of the general formula R2/ C=C/ ( II ) ----C/ \ R 6 and n-alkanols o -the Eormula R70~ (:Cr. :t) wherein Rl denote~ hydroyen o:r strai.yht-chain or branched alkyl with 1 to 8, preferably 1 to 4, particularly preferably 1 -to 2 C a-toms, R2 to R6 denote hydrogen or alkyl with 1 to 4, preferably 1 to 2, especially preferably with 1 C atom and R7 denotes straight-chain ~,, , ~ -, '' ~' ' ' .
', . :
; -6-alkyl wit}l 1 ~o 6, preferably wlth 1 ~o ~ particularly pre~erably 1 to 2 C atoms.
The following ethers may be mentioned as examples of starting materials of the ~ormula (I) for the process accordlng to the invention: methyl~tert.-butyl ether, ethyl-tert.-butyl ether, propyl-tert.-butyl ether, n-butyl-tert.-butyl ether, n-amyl-tert.-butyl ether, methyl-tert.-amyl ether, ethyl-tert.-amyl ether, propyl-tert.-amyl ether~ n-butyl-tert.-amyl ether, n-amyl-tert.-amyl ether, n-hexyl-tert.-amyl ether, methyl-tert.-hexyl ether and ethyl-tert.-hexyl ether.
The products 0btainable according to the invention are, in addition to the particular n-alkanols, the tertiary olefinesJ such as isobutene, isoamylene, isohexene and others.
The purification of the tertiary olefins which can be produced accord-ing to the invention is effected in a distillation step downstream from the cleavage reactor, whereby the desired olefines are taken off as a top product in a purity of over 96~ by weight and a bottom product accumulates which, having a composition of about 90 to 99.9% by weight of alkanol, 0.1 to 10% by weight of the ether employed and small amounts o water, can be recycled to the process for etherification of the terkiary olefines.
In contrcast to the sulphuric ac:id extraction process Eor the prcpara-tion oE tertiary oleEins the process accorcling to the irlverltioll requires 1 Cat1 lyst without corros;ive propQrties" so th~t normal carbon steels CQn bc usecl Eor thc rcactor material. '~'he procuss according to thc invention is distingu:ished, in contrast with the catalytic cleavage process described above, by a higher activity of the catalyst to be used, so that the catalytic cleavage can be carried out at lower temperatures. This lower reaction temperature greatly reduces the portion of undesired di-n-alkyl ether formed of necessity, so that ,r 7~ '7~
over 90% oE the n-alkanol introduced into circulation can be reclaimed, and, as a result of the high activity oE the catalyst employed according to the inventionJ
high yields and high throughputs are simultaneously achieved in th0 cleavage process. At the same time) an energy-saving method of carrying out the reaction results from the lowering of the reaction temperature.
Examples:
A thermostat-controlled continuous reactor was employed as the alkyl ether cleavage reactor. ~or a given internal reactor radius Oe 25 mm, the height of the catalyst bed was so chosen that the catalyst charge was 100 g. To monitor the temperature, the reactor was equipped with temperature measuring devices at intervals of 100 mm. The pressure in the reactor was regulated by maintaining an overpressure. The metered addition of the substrate was effected via a diaphragm piston pump. The composition of the reaction product obtained at the exit of the reactor was examined by means of gas chromatography. The product stream was worked up in a downstream distillation column. The desired iso-olefins were obtaine~l thereby as a top product in a purity of over 95% by weight.
The following abboreviations are used: 'L'AM~ - tert.-amyl~ ethyL ether;
MB = methylbutene; ~M~ - ~limet}lyl ~Jth~r; WIISV = wciglIt-}lourLy~spaco-voLocity;
GC = gas chrorlIatograp}ly; MW ~- molecuLar weight.
~n ox.Itnples 1 - 10 tlle terlIperaturo dependence of the ether cleavage has been investigated in connection with the formation of dimethyl ether.
Catalyst: 100 g H -mordenite Starting product: 100 g TAME/h (GC 99.9% by weight) (MW 102.2) Reaction pressure 10 bar; reaction time 6 h;
WIISV -1 ( g substrate g catalyst.h .
.
~ 3~ ~ ~
Example (No.~ 1 2 ~ 4 5 Temp, (C) .120 1~0 140 160 180 TAME welgh-t % 32 . 3 24, 3 18 . 7 12 . 7 2 D 1
2-Ms-2 ~ 34 o 3'7.2 41,0 4L~,o 53.4 2 MB-l " 12.5 14.8 14.~ 15.9 13.8
3-MB~
CH30H 11 19 . 9 22, 2 23.8 25, 4 24. 6 D~E " 0.9 1.1 1.2 1,4 4,4 H20 ~11 0.4 0,4 o.5 o.6 1.7 : 10 Conversion ~AME % 67,7 75.~7 81.3 87.3 97.9 Selectivity 93,7 93:6 93.3' 92.7 80.1 Yield % 63.5 70.8 75.9 81,0 78.4 CH ~OH
Example (No. ) 6 7 8 9 10 Temp. (C) 200 220 2~50 280 300 TA~[E weight 9b 1. 2 0 . 9 0 . 4 0 . 2 0, 2 2-MB-2 51.9 53.2 53.5 52,9 53,4 20 2-MB-1 15,9 14.8 14,8 15,4 14,8 3-MB-1 0.1 0.1 '- 0.1 0,2 0.~
3 2L~,6 2L~.0 2303 18,8 17.5 D~E L~,5 5,0 5.7 9,o 9~9 ~I2~ 1.8 2,0 2,2 3.5 3.9 25 Co~ver,sio~
TAME % 98.8 99,1 99.6 99.8 99.8 Yield % 79.6 77, 4 7LI,3 59. 9 55, 9 Selectivity 78.4 76.5 7L~,3 59.9 55~8 __ q ~ 78~
The prellm~nary treatment w~th H~ o:~ the H~-mordenite employed was investlgated ln Exa~ple~
13. Data for the preliminary treatment:
Catalyst: 100 g H~-mordeni~e T-preliminary treatment: 190C
p-preliminary treatmen~: 27 bar t~preliminary treatment: 24 h H2 40 l/h After this preliminary treatment, the H2 pres~
sure was released and the reaction pressure adjusted to ~ 10 bar with N2.
: The following reaction conditions ~ere fixed:
p-reaction - 10 bar; T-reaction = 1~.0C, t-reaction =
24 h; WHSV:= 1 ( ~ ) starting material 100 g TAME/h (GC 99.9~0 by weight).
Example (No.S: 11 12 13 : Hz treatment (-) (+) :(+) T~'~Eweight % 18.7 3.8 4 3 4 2-MB-2 " 41.0:49.2~ 48.3 20 2-MB-1 " 14,8 16.8 17.3 3-~3-1 " _ _ _ CH30H " 23.8 28.0 27.4 DME " 1.2 1.~ 1.9 H 0 ~' 0.5 0.~ 0.7 25 Convorsion T~ % 81.3 96,2 95,6 Selectivity % 93,3 92.7 91.3 Yield % 75,9 89.3 87.1 -~
f Regeneratio~ of an already used catalyst The dependence of the ether cleavage on the-catalyst load was examined in Examples 14 - 18, .
. ~ ~
,, The H~mordenite employed wa~ subjected toan H2 pre-liminary treatment analogously to Example~ 12 and 13.
Catalyst : 100 g H~-mord0nit~ (H~ acti~ated) Star-ting ma-terial : TAME (99.9% by weight) Reaction condltions: p-reaction = 10 bar; T~reaotion 140~C; t-reaction - 6 h Catalyst load : WHSV ( ~ ) 0 5 3 0 Example No. 14 15 16 17 18 ~SV 0.5 1.0 1.5 2.0 3.0 10 TAME weight % 13.4 3.8 3.6 4,o 5.2 2-MB-2 " 44.0 49.2 51.4 52.15~.3 2-MB-1 " 15.2 16.8 1~,8 13.810.8 3-MB-l " ~
3 23.5 28.0 28.0 28.2~28.8 15 DME .~l 2.8 1.6 1.6 1.4 0.7 H20 ~ ~ 1.1 o.6 o,6 0.5 0.2 Conversion TA3JI:E % 86, 3 96 . 2 96 . 4 96, o94 0 8 Selectivity : 20 CH30H % 85,8 92.7 92.7 93.797.0 Yield 3 % 75,0 89.3 ~ 89.3 89.991.8 Various alkyl e-thers were examined with re~-pect to their cleavabili-ty ln the E~ample~ 19 to ~0~
25The reactlon conditions analogous to the TAME
cleavage e~peri.ments were assumedO
Compounds employed: MTBE (methyl-tert.-buty~ ethér), MW 88.~
TAEE Stert.-amyl-eth~l ether), 3MW 116,~ ~
In the case of ~TBE, isobuténe and methanol are obtained as the cleavage product~ -In the case o~ TAEE, iso~amylene and ethanol , ~ `:' " ~ 3~
~, ~
are obtained as the cleavage pro~uct, Example 19:
Gatalyst : 100 g H~-mordenite (H2 activated) Star-ting material : ~TBE (99.9/0 ~y weight) 5 Reaction T-reactlon = 140C
conditions p-reaction = lO bar t-reaction = 6 h Catalyst load : WHSV = 1 ~ ~ ) MTBE weight % 9.2 10 i C4 " 57.8 CH30H " 30.5 DME " 1.8 .~ : O . Z
~ .
Con~ersion 15 MTBE % 90.8 Selectivity 3 92.4 Yield % 83.9 CH3oH
20 Example 20:
Catalyst : 100 g H~mordenite : Starting material : TAEE (GC 99 9% by wei.ght) Reaction T~reactio~ ~ 140C
conditions p-reactlon = lO bar t-r~action ~ 6 h Catalyst load : WHSV = 1 ( ~ ) TAEE we.ight /0 5.1 2-MB-2 ll 42,g --2-MB-l " 14.
30 3-MB~
2 5 ~4.1 DEE " 2.9 ~2 " 0.7 __ .
Con~erslon % 9L~, 9 TAE~
S el ectivity C2H50H % 90- 5 5 Yield % 85,9 , .
....
~.......
CH30H 11 19 . 9 22, 2 23.8 25, 4 24. 6 D~E " 0.9 1.1 1.2 1,4 4,4 H20 ~11 0.4 0,4 o.5 o.6 1.7 : 10 Conversion ~AME % 67,7 75.~7 81.3 87.3 97.9 Selectivity 93,7 93:6 93.3' 92.7 80.1 Yield % 63.5 70.8 75.9 81,0 78.4 CH ~OH
Example (No. ) 6 7 8 9 10 Temp. (C) 200 220 2~50 280 300 TA~[E weight 9b 1. 2 0 . 9 0 . 4 0 . 2 0, 2 2-MB-2 51.9 53.2 53.5 52,9 53,4 20 2-MB-1 15,9 14.8 14,8 15,4 14,8 3-MB-1 0.1 0.1 '- 0.1 0,2 0.~
3 2L~,6 2L~.0 2303 18,8 17.5 D~E L~,5 5,0 5.7 9,o 9~9 ~I2~ 1.8 2,0 2,2 3.5 3.9 25 Co~ver,sio~
TAME % 98.8 99,1 99.6 99.8 99.8 Yield % 79.6 77, 4 7LI,3 59. 9 55, 9 Selectivity 78.4 76.5 7L~,3 59.9 55~8 __ q ~ 78~
The prellm~nary treatment w~th H~ o:~ the H~-mordenite employed was investlgated ln Exa~ple~
13. Data for the preliminary treatment:
Catalyst: 100 g H~-mordeni~e T-preliminary treatment: 190C
p-preliminary treatmen~: 27 bar t~preliminary treatment: 24 h H2 40 l/h After this preliminary treatment, the H2 pres~
sure was released and the reaction pressure adjusted to ~ 10 bar with N2.
: The following reaction conditions ~ere fixed:
p-reaction - 10 bar; T-reaction = 1~.0C, t-reaction =
24 h; WHSV:= 1 ( ~ ) starting material 100 g TAME/h (GC 99.9~0 by weight).
Example (No.S: 11 12 13 : Hz treatment (-) (+) :(+) T~'~Eweight % 18.7 3.8 4 3 4 2-MB-2 " 41.0:49.2~ 48.3 20 2-MB-1 " 14,8 16.8 17.3 3-~3-1 " _ _ _ CH30H " 23.8 28.0 27.4 DME " 1.2 1.~ 1.9 H 0 ~' 0.5 0.~ 0.7 25 Convorsion T~ % 81.3 96,2 95,6 Selectivity % 93,3 92.7 91.3 Yield % 75,9 89.3 87.1 -~
f Regeneratio~ of an already used catalyst The dependence of the ether cleavage on the-catalyst load was examined in Examples 14 - 18, .
. ~ ~
,, The H~mordenite employed wa~ subjected toan H2 pre-liminary treatment analogously to Example~ 12 and 13.
Catalyst : 100 g H~-mord0nit~ (H~ acti~ated) Star-ting ma-terial : TAME (99.9% by weight) Reaction condltions: p-reaction = 10 bar; T~reaotion 140~C; t-reaction - 6 h Catalyst load : WHSV ( ~ ) 0 5 3 0 Example No. 14 15 16 17 18 ~SV 0.5 1.0 1.5 2.0 3.0 10 TAME weight % 13.4 3.8 3.6 4,o 5.2 2-MB-2 " 44.0 49.2 51.4 52.15~.3 2-MB-1 " 15.2 16.8 1~,8 13.810.8 3-MB-l " ~
3 23.5 28.0 28.0 28.2~28.8 15 DME .~l 2.8 1.6 1.6 1.4 0.7 H20 ~ ~ 1.1 o.6 o,6 0.5 0.2 Conversion TA3JI:E % 86, 3 96 . 2 96 . 4 96, o94 0 8 Selectivity : 20 CH30H % 85,8 92.7 92.7 93.797.0 Yield 3 % 75,0 89.3 ~ 89.3 89.991.8 Various alkyl e-thers were examined with re~-pect to their cleavabili-ty ln the E~ample~ 19 to ~0~
25The reactlon conditions analogous to the TAME
cleavage e~peri.ments were assumedO
Compounds employed: MTBE (methyl-tert.-buty~ ethér), MW 88.~
TAEE Stert.-amyl-eth~l ether), 3MW 116,~ ~
In the case of ~TBE, isobuténe and methanol are obtained as the cleavage product~ -In the case o~ TAEE, iso~amylene and ethanol , ~ `:' " ~ 3~
~, ~
are obtained as the cleavage pro~uct, Example 19:
Gatalyst : 100 g H~-mordenite (H2 activated) Star-ting material : ~TBE (99.9/0 ~y weight) 5 Reaction T-reactlon = 140C
conditions p-reaction = lO bar t-reaction = 6 h Catalyst load : WHSV = 1 ~ ~ ) MTBE weight % 9.2 10 i C4 " 57.8 CH30H " 30.5 DME " 1.8 .~ : O . Z
~ .
Con~ersion 15 MTBE % 90.8 Selectivity 3 92.4 Yield % 83.9 CH3oH
20 Example 20:
Catalyst : 100 g H~mordenite : Starting material : TAEE (GC 99 9% by wei.ght) Reaction T~reactio~ ~ 140C
conditions p-reactlon = lO bar t-r~action ~ 6 h Catalyst load : WHSV = 1 ( ~ ) TAEE we.ight /0 5.1 2-MB-2 ll 42,g --2-MB-l " 14.
30 3-MB~
2 5 ~4.1 DEE " 2.9 ~2 " 0.7 __ .
Con~erslon % 9L~, 9 TAE~
S el ectivity C2H50H % 90- 5 5 Yield % 85,9 , .
....
~.......
Claims (15)
1. A process for preparing a tertiary olefin from the corresponding n-alkyl ether thereof which comprises contacting said n-alkyl ether with hydrogen in the pre-sence of an acidic molecular sieve at a temperature from 100 to 300°C and simultaneously removing the n-alkanol which forms.
2. A process according to claim 1, wherein said acid molecular sieve is X-, Y-, A-, T-zeolite, faujasite, ZSM-5-zeolite or H-mordenite, especially H-mordenite.
3. A process according to claim 1, wherein said molecular sieve is a molecular sieve having a pore dia-meter of 3 to 15 angstroms.
4. A process according to claim 3, wherein said molecular sieve has a pore diameter of 7 to 12 angstroms.
5. A process according to claim 4, wherein said molecular sieve has pore diameters of 8 to 11 anstroms.
6. A process according to claim !, wherein said molecular sieve has A BET surface area of 100 to 700 square meters per gram.
7. A process according to claim 1, wherein said acidic molecular sieve is disposed in an aluminum oxide or alumina silica composition in an amount of 0.01 to 80 % by weight.
8. A process according to claim 1, wherein said molecular sieve has an effective pore volume of 0.05 to 0.6 ml/g.
9. A process according to claim 1, wherein the process is carried out at a temperature of 110 to 210°C.
10. A process according to claim 1, wherein the process is carried out at a temperature of 120 to 180°C.
11. A process according to claim 1, wherein the process is carried out while maintaining a catalyst load of from 0.5 to 10 grams substrate per gram catalyst per hour.
12. A process according to claim 1, wherein said acid molecular sieve is one which has been treated with 50 to 500 liters of hydrogen per liter of molecular sieve at 100 to 450°C
at 1 to 50 bars for 1 to 60 hours before empolyment in the preparation of a tertiary olefin by contacting an n-alkyl ether thereof with said acidic molecular sieve.
at 1 to 50 bars for 1 to 60 hours before empolyment in the preparation of a tertiary olefin by contacting an n-alkyl ether thereof with said acidic molecular sieve.
13. A process according to claim 1, 2 or 3 wherein the n-alkyl ether is an ether of the general formula (I) wherein R1 is hydrogen or alkyl with from 1 to 8 carbon atoms, R2 to R6 are hydrogen or alkyl with from 1 to 4 carbon atoms, and R7 is straight chain alkyl with from 1 to 6 carbon atoms.
14. A process according to claim 4, 6 or 7 wherein the n-alkyl ether is an ether of the general formula (I) wherein R1 to R6 is hydrogen or alkyl with 1 or 2 carbon atoms, and R7 is alkyl with 1 or 2 carbon atoms.
15. A process according to claim 5, 8 or 10 wherein the n-alkyl ether is tert.-amyl-methyl ether.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3048084.3 | 1980-12-19 | ||
| DE19803048084 DE3048084A1 (en) | 1980-12-19 | 1980-12-19 | METHOD FOR PRODUCING TERTIAL OLEFINS |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1178622A true CA1178622A (en) | 1984-11-27 |
Family
ID=6119719
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000392579A Expired CA1178622A (en) | 1980-12-19 | 1981-12-17 | Process for the preparation of tertiary olefines |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4371725A (en) |
| EP (1) | EP0054805B1 (en) |
| JP (1) | JPS57123124A (en) |
| CA (1) | CA1178622A (en) |
| DE (2) | DE3048084A1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4570026A (en) * | 1983-08-12 | 1986-02-11 | Petro-Tex Chemical Corporation | Production of isobutene from methyl tertiary butyl ether |
| FR2577549B1 (en) * | 1985-02-15 | 1987-03-20 | Inst Francais Du Petrole | PROCESS FOR THE CONVERSION OF METHANOL OR DIMETHYLETHER TO OLEFINS |
| US5227564A (en) * | 1991-12-09 | 1993-07-13 | Dairen Chemical Corporation | Process for the preparation of tertiary olefins |
| CA2110904A1 (en) * | 1992-04-22 | 1993-10-28 | Martin P. Atkins | Process for the production of olefins |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3170000A (en) * | 1962-10-24 | 1965-02-16 | Sinclair Research Inc | Tertiary olefin separation via etherification with small surface area catalysts |
| IT1017873B (en) * | 1974-08-02 | 1977-08-10 | Snam Progetti | PROCESS FOR THE PREPARATION OF TERTIARY OLEFINS |
| US4025575A (en) * | 1975-04-08 | 1977-05-24 | Mobil Oil Corporation | Process for manufacturing olefins |
| DE2802199B2 (en) * | 1978-01-19 | 1980-05-08 | Basf Ag, 6700 Ludwigshafen | Process for the production of isobutene from isobutene-containing C4 hydrocarbon mixtures |
| US4306106A (en) * | 1978-06-05 | 1981-12-15 | Mobil Oil Corporation | Conversion of polar compounds using a ZSM-5 zeolite catalyst |
| US4238631A (en) * | 1979-10-30 | 1980-12-09 | Mobil Oil Corporation | Fluid zeolite catalyzed conversion of alcohols and oxygenated derivatives to hydrocarbons by controlling exothermic reaction heat |
-
1980
- 1980-12-19 DE DE19803048084 patent/DE3048084A1/en not_active Withdrawn
-
1981
- 1981-12-02 US US06/326,646 patent/US4371725A/en not_active Expired - Fee Related
- 1981-12-05 DE DE8181110176T patent/DE3171268D1/en not_active Expired
- 1981-12-05 EP EP81110176A patent/EP0054805B1/en not_active Expired
- 1981-12-15 JP JP56201020A patent/JPS57123124A/en active Pending
- 1981-12-17 CA CA000392579A patent/CA1178622A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| EP0054805A1 (en) | 1982-06-30 |
| DE3048084A1 (en) | 1982-07-15 |
| US4371725A (en) | 1983-02-01 |
| DE3171268D1 (en) | 1985-08-08 |
| JPS57123124A (en) | 1982-07-31 |
| EP0054805B1 (en) | 1985-07-03 |
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