US2744939A - Production of alcohols of high purity by improved oxo process - Google Patents

Description

May 8, 1956 w. E. KENNEL PRODUCTION OF ALCOHOL-S OF HIGH PURITY BY IMPROVED oxo PROCESS Filed Nov. 26, 1954 IN VEN TOR.

William E. Kennel EBQ $58 United States PRODUCTION or ALCOHOLS OF HIGH PUiuTY BY JMPRovED oxo PROCESS William E. Kennel, Munster, Ind., assigrior to, Standard Oil Company, Chicago, 111., a corporation of Indiana Application November 26, 1954, Serial No. 471,318, 3

4 Claims. (Cl. 260638) with phthalic .acid and the like with minimumn color.

formation. I

An important use of high boiling alcohols such as octyl alcohols, nonyl alcohols and the like is in the preparation of esters such as phthalates'which are valuable for the use of plasticizers. Octyl alcohols which are substantially copolymerization ct propylene with butylenes'and from which higherand lower boiling olefins have been previtotal C7 olefin charged. The oxolation reactor is operated:

water-white when reacted with phthalic acid produce esters of objectionable color. An object of this invention is to provide a method and means for producing high boiling alcohols of improved phthalation color without appr'eci able sacrifice in alcohol yield. A further object is to obtain alcohols of improved quality and at minimum investment and operating cost. A further object is to improve the effectiveness and efficiency of an oxo process; Other objects will beapparent as the detaileddescription of the invention proceeds. H N

This invention is an improvement on'the'oxo'jpr'ocess described in U. S. 2,638,487 and 2,638,488. While the process described in these patents, and particularly in Figure 2 thereof, has been found to produce oxo alcohols of high quality, it has, been found that operationsproducing the best quality product result in.yield' losses because a substantial portion of the alcohol'product is necessarily lost in gasoline and 0x0 bottoms fractions from mediate fractionator improves the effectiveness of the latter, minimizes the amount of hydrocarbon recycle heretofore required therein and makes possible a cleaner separation between hydrocarbons and alcohol while, at the same time, enabling rehydrogenation of components in this stream which might be responsible for color degradation in the phthalation step. Finally, thefinal bottoms fraction may be recycled to the intermediate fractionator to serve an equivalent function and to prevent-alcohol losses which heretofore have occurred. As further insurance for obtaining maximum product quality, a caustic wash is preferably employed prior to the final distillation step. i v H The invention will be more clearly understood from the following detailed description of a specific example read in conjunction withthe accompanying drawing which forms a part of this specification and which is a schematic flow diagram of the improved oxo process,

ously removed by fractionation. Much of the oxo system in this invention is the same as was described in U. S. 2,638,487-8 and hence will need no further description.-

The C7 olefin stream, whichpreferablycontains less than'l per cent of C6 olefins and less than 2 per cent of Ce olefins, is introduced by lines '10 and 11 to oxolation reactor 12 at the rate of about 290 barrels per day together with about 43,000 cubic feet per day of hydrogen and carbon monoxide (in the mol ratio of 1:1 to 1.3 1) introduced by line 13 and about 3 /2 barrels per day of cobalt catalyst solution introduced through line 14, the catalyst in this case being a 6 per cent cobalt naphthenate solution in C7 olefin and being employed in such amounts as to:

provide about .1 weightper cent of cobalt basedon the.

at about 2,500 to 4,000, e. g. 3,000 p. 's.,i. g., about 250 to 400 F., e. g. 325 F., anda space velocity of about .1 to 2, e. g. .5 volumes of fresh liquid charge per hour. per Volumeof reactor space, thetemperature control being.

effected bywithdrawing reactor effluent through-line 15 to cooler 16 and thence to separator 17,1recycling about 3 to 4 volumes (per volume of olefin charged) ofcooled liquid by pump 18, line 19 and inlet .lines 20 'atspaced upper points in the reactor and'recycling coo-led gas by compressor 21 and lines 22 and 23' to the lower part of the reactor and/or through line 24 along with the entering charging stock .strea'm,v Netuncondensed gas may be vented through line 25;

Net product liquid is withdrawn from'separator 17 through line 26 "and pressure reducing valve-27' into gas separator 28 from which additional gas is vented through line '29. The pressure in separator 28 should not sub leaving theseparator to a temperature of about-150 F... or more and/or employing inert stripping .gas and/or an oxidizing agent such as hydrogen peroxide in stoichiometric amounts based on residual cobalt carbonyl'present. Due to the reaction .of about half of the-acid to form water being discardedthrough line 39. A small amount of caustic, such as sodium hydroxide, may be, introduced with the water introduced through line 33 to insure While the invention is applicable to, alcoholproduction employing Cs'to Cis-"olefins and will be described as applied to a process charging C1 olefins produced 'by removal-of acid from the washed oxolation etlluent.or a

caustic washing step may beinterposed between -.the acid wash and water wash steps.

The water-washed oxolationjeifluent is introduced by lines: 40 and 41 throu'gh heater 42 wherein it isheated millimeters of mercury.- 'Thatportion of the fractionator which is abovethe feed inlet is preferably of larger diameter than the portion below'the feed inlet sinceit'jis' desirable to elfectas much fla'sh distillation as possible. *Thus thefractionator portion of the tower may be about 6 feet in diameter by 31 feet"tall"while the stripping section is 1 about 3'i'feet 6'incheshby--l'l feet'. Stripping steam is I. I htented May 8, 1956 introduced at the base of the narrowed section of the tower through line 44. The tower should be operated with as low a temperature and pressure and with as short a contact time as is economically feasible and the tower bottom temperature should not substantially exceed about 250 F.' Even when making higher boiling aldehydes and alcohols the temperature 'shouldbe kept below'about 350 F. and. higher vacuums employed-to. obtain the desired fractionation. v

Components lower boiling than C8 aldehydes (chiefly unconverted C'T olefins and C7 olefins which have been saturated) are withdrawn from the top of tower 43 through line 45 to condenser 46 and receiver 47 from which any gases may be ventedby line 48.' Liquid is withdrawn from the receiver by pump 49 to maintain a substantially constant liquid level therein and the amount of liquid not required for recycle through line 50 is withdrawn for gasoline blending through line 51.

Heretofore about 1,350 barrels per day of liquid had to be withdrawn through line 50 for admixture with oxolation effluent introduced to fr'actionator 43 in order to decrease the partial pressure of the steam to prevent steam condensation above the feed tray. The inlet temperature is about 200 F. and the tower bottom temperature is about 25 0" F. Effective flash vaporization of C8 aldehydealcohol components is thus obtained with minimum loss of aldehyde byaldol condensation. 7

line 50' is decreased by about 40 barrels per day and the heat input requirements of exchanger 42 are likewise decreased 70,000 B. t. u. per hour by the direct addition to the inlet stream introduced through line 41 of the total overhead vapors from the final distillation tower "as will,

catalyst such as cob'alt-on-pu'rnice under a pressure of about 500 to 4,000 p. s. i. g. at a temperature in the range of 350 to 600 F. with a fresh feed liquid space velocity of about .1 to Le. .g. about .25 volume per h our per volume of reactor space, fresh hydrogen being introduced by lines 56 and 57 to line 52 at the rate of aboutlfi mols per hour. The efiiuent from the hydrogenation reactor is introduced by line 58 to cooler '59 and thence to separator 60 from which hydrogen is withdrawn by line 61 and a portion of the hydrogen stream is recycled by com pressor 62 for introduction at space points 63 in reactor 55. Gas may be discharged through line 64 if inerts build up in the system. i

Of the hydrogenated product withdrawn from the base of receiver 60 through'line 65, about 1 to 3 volumes are recycled by pump 66 and line 67 for each volume of fresh feed coming from line 52. The rest of the liquid passes through pressure release valve 68 into separator 69 from which separated gases are vented through line 70; The liquid from receiver 69 may be introduced by line '71 directly into fractionator 72 but it is preferably introduced by line 73 together with caustic from-line74 int-o caustic scrubber 75 from which a part of the spent caustic is' discharged through line 76 and'the remainder recycled by pump 77. The caustic-washed stream then passes by line 78 to water scrubber '79 into which water is introduced through line 80 and withdrawn through line 81, the waterwashed stream then being introduced by line 82 to fractionator'72. The caustic scrubbing is preferably effected with aqueous sodium hydroxide having a concentration in the range of about 2 to 20 per cent, e. g. about 10 per cent.

7 Fractionator 72 is provided with conventional reboiling means 83 which supplies sufficient heat to distil' overhead In accordance with this invention the amount of hydrocarbons returned by,

not only the hydrocarbons which are present in the stream and any unconverted aldehydes but also sufficient to carry overhead about 10 to 20 per cent of the octyl alcohols themselves. It has been found that by distilling overhead this relatively large quantity of the produced alcohols, the phthalation color of the remaining alcohols is markedly improved. Instead of discharging the overhead from fractionator 72 to the gasoline blending stock line, however, a total overhead vapor stream from fractionator 72 is passed by line 84 to line 41 wherein it is commingled with the acid-washed oxolation stream entering fiash distillation column 43. The heat contained in this overhead stream supplies part of the heat required for the fiash distillation of aldehydes and alcohols in the intermediate fractionator and thereby reduces the required heat input through exchanger 42. At the same time the return of the hydrocarbon-alcohol stream from fractionator 72 decreases the amount of hydrocarbons which must be returned through line 50. Finally, the overhead from fractionator 72 is more effectively separated in the efiicient flash distillation fractionator so that there is a minimum loss of alcohols to the hydrocarbon fraction withdrawn through line 51, any remaining aldehydes are returned for rehydrogenation and the low boiling alcohols are likewise retreated in the hydrogenation step for improving the ultimate yield of high quality octyl alcohols of improved phthalation color.

The topped alcohols are withdrawn from fractionator 72 through line 85 and introduced into fractionator 36 which is provided with a conventional reboiler 87 and from which substantially pure octyl alcohols are withdrawn through line 88. Heretofore the amount of bottoms withdrawn from fractionator 86 have been very small but in order to insure the highest quality alcohol, it is preferred to remove about 2 to 5 per cent of the alcohol stream, about 10 barrels per day, through line 89. This stream may be recycled by pump 90 through lines 91 and 40 to line 41 to further improve the efidciencyof the system. Thus instead of removing bottoms from line 92 and thereby losing a small amount of the alcohol product, the bottom stream from fractionator 36 may be returned to the more efiicient flash vaporization fractionator 43 so that the alcohol content of the stream is recovered and the bottoms are commingled with those removed from flash distillation column 43 by the line leading from the bottom thereof.

From theiforegoing description it will be seen that the objects of the invention have been attained, and that iso octyl alcohols of remarkably good phthalation color can be produced in yields about 10 per cent higher than was heretofore possible. The alcohols introduced to gasoline blending have been correspondingly eliminated and over all operating costs are reduced.

I claim:

1. In an 0x0 process wherein an olefin having in the range of 3 to 15 carbon atoms per molecule is reacted with carbon monoxide and hydrogen in the presence of an oil soluble cobalt catalyst under a pressure of about 2,500 to 4,000 p. s. i. at a temperature in the range of 250 to 400 F. to produce an oxclation product stream, the oxolation product stream is treated under conditions to separate cobalt therefrom, the treated stream is subjected to a flash distillation step to separate lower boiling materials a-nd bottoms from an alcohol-aldehyde fraction, the alcohol-aldehyde fraction is hydrogenated and the hydrogenated product is finally fractionated to remove components lower boiling than the alcohol product, the itnproved method of operation which comprises distilling not only products lower boiling than alcohol in the final fractionation step but also at least about 10 per cent of the produced alcohols and returning the overhead from the final fractionation'step to the stream entering the flash distillation step so that products lower boiling than produced alcohols are discharged solely from the flash distillation step.

2 The method of claim 1 which includes the further step of separating about 1 to 5 per cent of the alcohol product with higher boiling materials from the final fractionation step and returning said higher boiling materials together with 1 to 5 per cent of alcohols to the stream entering the flash distillation step.

3. The method of claim 2 which includes the further step of caustic Washing the product stream prior to the final fractionation step.

4. The method of claim 1 which includes the step of caustic Washing the product stream prior to the final 5 fractionation step.

No references cited.

Claims (1)

1. IN AN OXO PROCESS WHEREIN AN OLEFIN HAVING IN THE RANGE OF 3 TO 15 CARBON ATOMS PER MOLECULE IS REACTED WITH CARBON MONOXIDE AND HYDROGEN IN THE PRESENCE OF AN OIL SOLUBLE COBALT CATALYST UNDER A PRESSURE OF ABOUT 2,500 TO 4,000 P.S.I. AT A TEMPERATURE IN THE RANGE OF 250 TO 400* F. TO PRODUCE AN OXOLATION PRODUCT STREAM, THE OXOLATION PRODUCT STREAM IS TREATED UNDER CONDITIONS TO SEPARATE COBALT THEREFROM, THE TREATED STREAM IS SUBJECTED TO A FLASH DISTILLATION STEP TO SEPARATE LOVER BOILING MATRIALS AND BOTTOMS FROM A ALCHOL-ALDEHYDE FRACTION THE ALCOHOL-ALDEHYDYDE FRACTION IS HYDROGENATED AND THE HYDROGENATED PRODUCT IS FINALLY FRACTIONATED TO REMOVE COM-

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