US2760994A - Process for hydrogenating aldehydes - Google Patents

Description

Aug. 28, 1956 B. H. GWYNN PRocEssFoR HYDROGENATING ALDEHYDES Filed Dec. 30, 1950 6 n n t oa I u Q o no ivm@ Mm. WH.

nited States Patent' i PROCESS FOR HYDRGENATING -ALDEHYDES Bernard H. Gwynn, Fawn Township, Alleghenyk County,

Pa., assignor to Gulf Research & Development Company, Pittsburgh, Pa., a corporation of Delaware Application December 30, 1950, Serial No. 203,588

7 claims. (Cl. 26o-638) This invention relates to a process for hydrogenating aldehydes and more particularly, to a process for preferentially hydrogenating aldehydes in a mixture containing aldehydes and olens.

Olens are hydroformylated in the iirSt, or hydroformylating, stage of the Oxo process. in this stage, which is also known as the oxonation or carbonylation stage, olens react with carbon monoxide and hydrogen to produce aldehydes. Other organic reaction products such as alcohols and acetals are also produced. The product stream from the hydroformylation stage contains aldehydes, other reaction products, and in addition unreacted oletins, carbon monoxide, and hydrogen.

ln the second, or hydrogenation stage of the Oxo process, aldehydes from a hydroformylation stage are converted to alcohols and other oxygenated products are also produced. However, in the previously proposed processes of which I am aware for hydrogenating aldehydes to alcohols in a mixture which also contains oletins, an important proportion of the olens has been hydrogenated to paraflins, thus producing a mixture of hydrocarbons or a hydrocarbon fraction of the hydrogenation products consisting of a relatively smaller 'amount of unconverted olefins and a relatively larger amount of paraiins. It is desirable to prevent this conversion of olefins to parains in the Ihydrocarbon frac- 'tion because if the oleins in this fraction are not hydrogenated the efficiency of the Oxo process can be improved by recovering the olefns from the hydrogenation stage products and using them as such or recycling them. My invention is concerned with a process for preferentially hydrogenating aldehydes in the presence of oletins while employing conventional hydrogenation pressures such as -100 to 1,000 pounds per square inch.

I have found that aldehydes mixed with olens can be hydrogenated to alcohols while a hydrocarbon fraction can be produced which consists chiefly of olens by introducing water into a -mixturevof aldehydes and olens, and then hydrogenating the resulting mixture in the presence of the added water over a catalyst efective at low temperatures, for example, temperatures below 500 F.' When operating in this manner, aldehydes are converted to alcohols and a hydrocarbon fraction consisting chiefly of olens is produced. The oletins can readily be separated from the alcohols and recycledto a lhydroformylation stage.

I have found that it is important to carry out the process at a relatively low temperature as otherwise thev olens are hydrogenated along with the aldehydes. Concomitantly, it is important to use a catalyst which is an eifective 'hydrogenationcatalyst at low temperatures because when operating at a low temperature with a catalyst which exhibits maximum activity at a high temperature of, `for example, 800 to 1,000 F.,.very little hydrogenation of either aldehydes or oletins occurs. On the other hand, when attempting tooperate at high temperatures using a high temperature catalyst, the eifect of the temperature so overbalances the effect of the added water that the hydrogenation of the olens is not substantially prevented. As stated above, the present process is carried out at temperatures below l500 F. Preferred results Yare obtained at temperatures below 450 ice F.; for example, temperatures in the range of about 300 to about 450 F. and particularly in the range of about 350 to about'400" F.

With respect tothe catalysts that can be employed, in general any catalyst eiective at low temperatures will be suitable for use. The so-called low temperature hydrogenation catalysts are well known in the art and only a few are mentioned by wayA of example. Preferred catalysts 'are nickel, cobalt, nickel tungsten sulde, cobalt molybdate, yand copper chromite catalysts. The catalyst' can be in pelleted or granulated form and can be placed in the.hydroge'nation zone as such. In general, however,` preferred results are obtained when the catalyst is deposited upon a carrier such as diatornaceous earth or kieselguhr.

The water can beintroduced in liquid or vapor phase to the mixture 4lof aldehydes and oletins before or after the mixture is' introduced to the hydrogenation stage. Usually when hydrogenation is carried out at an elevated pressure such as at 1,000 pounds per square inch, it is more convenient to introduce water in liquid phase and to heat the mixture of ihydroformylation products and water to the desired hydrogenation temperature. Part of the watercan be introduced at room temperature in liquid phase into the hydrogenation reactor at intervals along the direction 'of flow in the reactor. ln this way the temperature in the "reactorcan be controlled because the heatv of hydrogenation is dissipated in vaporizing and heating vthe lwater to/ the hydrogenation temperature.

The mixture of 'aldehydes'and oleins which is preferentially lhydrogen'ated yin accordance with the process of-my invention can b'e'obtained in a number of ways, but usually it 1i's'cbtz'iined by lremovingcarbon monoxide 'andy hydrogen `andcaltaly'tic metals from a product stream obtained 4from a hydroformylation stage of an 'Oxo process. yThe mixture will therefore be identiied hereafter as hyd'r'oformylation products.

' The amount' of water Achargediwith the hydroformylation product's'td'th'ehydrogenation zone can be Varied. It is preferably "Lto-use as small an amount of water as 'possible `and'stil-lointain the advantages of my invention "embo'diinetfwill -nwbedescribed in connection with the accompanying drawing. The single figure shows a schematic representation 'of` asuitable plant system for carrying out the 'proeess of my 'in'veniton A 'synthesis mixture of carbon monoxide and hydrogen yis introduced by iline 23, yand a mixture of oleiins and a hydroformyla'tion catalyst, usually an iron or cobalt catalyst'by'line 4, to hydro'fo'r-rylation stage 6. The oleins and the synthesis gas-are reacted and the catalytic metal salts or carbonyls are removed. Hydroforrnylation products containing aldehydes, other reaction products, andunreactedlolelihsfat a pressure of about 500 pounds per square inch'and -a l'temperature of about 150 F. are removedfromzhydroformylation stage 6 by line 7. Water is introducedfbyline '8 to vpump 9 and is then introduced at a pressur'efoff-about '500 pounds per square inch into the hydroform'ylation''products by line 11. The resultng mixtureof rwater and hydroformylation products is passed byline 12.l through heat exchanger 13 wherein the mixture is heated t'o la temperature of about 400 F. The heated mixture is the'n passed-from heat exchanger i3 by line 14"-to hydrogenation reactor 16. The hydrogenation reactor 16 contains a number of baskets, 17a to lf, which are packed with 1r-inch nickel on kiesclguhr catalyst pellets 16. The pellets which contain about 44 per cent nickel in their original state may be used as the oxide after calcining or may be partially reduced at 900 F. by passing hydrogen over them for four hours at atmospheric pressure at the rate of about 635 volumes of hydrogen per hour per volume of catalyst.

After the catalyst is prepared, hydrogen at a pressure of about 500 pounds per square inch is passed by line 19 to heat exchanger 20 in which it is heated to a temperature of about 400 F. The heated hydrogen is introduced by line 21 to the top of hydrogenation reactor 16. The mixture of hydroformylation products, water, and hydrogen passes downwardly through the hydrogenation reactor 16. the aldehydes in the hydrogenation reactor reacting with hydrogen to produce alcohols.

Additional hydrogen at a pressure of about 500 pounds per square inch and a temperature of about 100 F. is introduced beneath the catalyst baskets in the hydrogenation reactor from the hydrogen inlet line 19 by line 22 and a parallel system of valved lines, 23a to 23e. The amount of hydrogen passed through the hydrogen heater and through the various lines is controlled. In this way the heat of reaction is dissipated in heating the hydrogen, and the temperature of the hydrogenation reactor is controlled at about 400 F. At the bottom of the hydrogenation reactor substantially all of the aldehydes have been converted to alcohols but the olens are not substantially hydrogenated.

The hydrogenation reaction products are removed from the bottom of the tower byline 26 and are passed through the heat exchanger 27 in which they are cooled to a temperature of `about 120 F. The cooled hydrogenation products are passed by line 28 to pressure-reducing valve 29 where they are reduced from a pressure of about 500 pounds per square inch to substantially atmospheric pressure. The cooled depressured hydrogenation products are then passed by line 31 to hydrogen flash tower 32. Hydrogen is removed overhead in this tower by line 33. The hydrogen which is removed by line 33 is passed out of the system by line 34 and may be employed as fuel, or, if desired, the hydrogen can be recycled by line 36, pump 37, and valved line 38 to hydrogen inlet line 19.

The hydrogen-free mixture is then removed from the hydrogen flash tower by line 41 and is introduced to water separator 42. A Water fraction is removed downwardly by line 43. The water fraction is recycled to water inlet line 8 by means of line 44 which contains circulatory pump 46 and valve 47. In the event a concentration of impurities such as iron oxide builds up in line 44, all or part of the water fraction can be discharged by valved line 48. When build-up of impurities is a problem, a part of the water is preferably continuously removed from the system.

A fraction containing hydrogenation products is rel moved overhead from Water separator 42 by line 51 and is passed to separation unit 52. A fraction containing hydrocarbons consisting chiefly of olens is removed in the separation unit by line 53. The hydrocarbon fraction can be recycled to olefin inlet line 4 by means of line than the hydrocarbons are passed by lines 61 and 62 to additional separating units which are not shown.

In order to compare results obtained when operating in accordance with the invention and when operating outside the invention, results obtained during two runs in each of a number of periods of hydrogenation are presented in Table 1 which follows. In these periods hydrogenation was carried out in a hydrogenation reactor formed by a steel pipe 0.824 inch in inside diameter surrounded by `a jacket containing boiling water which was maintained at 400 F.

The hydrogenation reactor was charged with about 585 milliliters of 1/8 inch nickel on kieselguhr catalyst pellets to form a bed about 6 feet long. The catalyst contained about 44 per cent nickel in its original s-tate or 70 per cent nickel when it was calcined at 1000 F. and reduced at The pressure was maintained at 500 pounds per square inch during these periods. The charge to each period Was hydroformylation reaction products from the same hydroformylation run to which heptenes had been charged.- The hydroformylation reaction products contained 43.0 per cent oxygenated materials which were chiey aldehydes and 57 per cent hydrocarbons which consisted of about per cent oletins. 'Ihe olens in the charge were thus about 55.2 weight per cent of the charge.

Hydroformylation products were charged to the top of `the hydrogenation reactor. Water, when it was added, was also charged at the top of the reactor. rI`he hydrogenation products were removed from the bottom of the hydrogenation unit, depressured, and cooled. A portion of hydrogenation products from each run was analyzed to determine the amount of unconverted aldehydes in the hydrogenation products. Another portion of hydrogenation products from each run was distilled in-to a fraction containing all of the oxygenated materials and a hydrocarbon fraction containing unconverted oleins and paraftlns produced by the hydrogenation of the olens. Each oxygenation material fraction was then distilled into a subfraction containing alcohols and aldehydes and a residue subtraction. The percent alcohol was then determined by subtracting the previously determined per cent aldehydes from the total per cent alcohols and aldehydes in that subtraction. The hydrocarbon fractions were analyzed for olens by determining bromine numbers. In the table the oxygenated materials, aldehydes, alcohols, residue, hydrocarbons, and olens are all presented as weight per cent of the total hydrogenation products.

The eiciency of the retention of oletns in the product stream Was determined by dividing the per cent olen in the charge by lthe per cent `oleiin in the products and multiplying by a hundred. This does not take into account the slight change in weight of the hydrogenation products caused by the addition of hydrogen.

The results of the periods are given in the table which follows. The weight per cent of olens in the hydrocarbon fraction is given at the bottom of Table 1 to show the extent to which hydrogenation of the hydrocarbon fraction is reduced by operating in accordance with my invention.

Table 1 FEED RATE AND REACTION CONDITIONS Period 1 Period 2 Period 3 Run Run Run Run Run Run 1 2 1 2 1 2 Water, mls/hr 0 0 100 100 250 250 Hydroformylation Products,

mls. r 500 500 500 500 500 500 Hydrogen, Std. Cu. Ft./hr 35 35 35 35 i 35 35 Total Pressure, lbs/sq. in 500 500 500 500 500 500 Temperature, Reactor Jacket,

F 400 400 400 400 400 400 Temperature, Hot Zone, F- 405 406 403 404 404 404 COMPOSITION OF HYDROGENATION PRODUCTS Oxygenated Materials, Wt. Percent Hydrogenation Productsw 40.0 41.0 43. 0 42.5 42. 5 44.0

Aldehydes, Wt. Percent Hydrogenation Products.. 3.9 3.3 1.6 2.3 3.4 3. 5 Alcoholsy Wt. Percent Hydrogcnation Products. 22.1 24.2 33.9 34.2 31.6 33.5 Residue, Wt. Percent Hydrogenation Pr0ducts- 14.0 13.5 7.5 6.0 7.5 7.0 Hydrocarbons, Wt. Percent Hydrogenation Products 60.0 59.0 57.0 57.5 57.5 56.0

Olens, Wt. Percent Hydrogenation Products 31.9 36.9 36.2 39.7 48.8 49.0

sacca-994 A study of the data for the runs in Table l, in which a hydroformylation reaction product charge space velocity of 1.17 was employed in each run, shows that the addi- I5 tion of 0.2 liter of water per liter of hydroformylation products caused an increase in the average per cent olefins in the hydrocarbon fraction of from 57.7 per cent to 66.2 per cent. The addition of 0.5 liter of water per liter of hydroformylation products further increased the average per cent olens to 86.3 per cent.

The advantages of my invention of preferentially hydrogenating aldehydes in a mixture of aldehydes and olens and producing a hydrocarbon fraction consisting chiey of olens can be obtained while changing the conditions of operation described in Table 1. Data from a series of such periods are given in Table 2 in which hydroformylation products were passed over 200 cubic milliliters of a catalyst similar to that used for the runs of Table 1, but which was somewhat more eiicient for the conversion of alcohols. In these periods a hydroformylation products charge space velocity of 0.5 and a liquid volume ratio of water to hydroformylation products charged of0.5 :l were used. The charge and the products were analyzed in the same manner used for determining them in the periods reported in Table l. Table 2 is as follows:

Table 2 COMPOSITION OF HYDROFORMYLATION PRODUCTS CHARGED TO THE HYDROGENATION STAGE FEED RATE AND REACTION CONDITIONS Water, mls/hr 50 50 Hydroformylation Products, mls/hr. 100 100 Hydrogen, Std. Cu. Ft./hr 3.2 3. 2 Total Pressure, lbs/sq. in 500 500 Temperature, Reactor Jacket, F 365 385 Temperature, Hot Zone, F 375 395-405 COMPOSITION OF HYDROGENATION PRODUCTS Oxygenated Materials Wt. Percent Hydrogenation Products 54. 52. 5

Aldehydes, 'W Percent Hydrogenatlon Products 3. 4 1. 2 Alcohols, Wt. Percent Hydrogenatlon Products 39. 1 44. 8 Residue, Wt. Percent Hydrogenation Produ s 11.5 6. 5 Hydrocarbons, W t. Percent Hydrogenation Products 46. 0 47. 5 Olens, Wt. Percent Hydrogenation Products. 37. 4 41. 5

OLEFIN RETENTION EFFICIENCY Olelns Not Converted to Paratlns, Percent 87. 7 97. l

OLEFIN DISTRIBUTION IN HYDROCARB ON FRACTION Olens in Hydrocarbon Fraction, Wt. Percent. 81. 2 87. 2

The advantages of my invention of preferentially hydrogenating aldehydes in a mixture of aldehydes and olens .sultsfare obtained with hydrogenation temperatures below :4509.11., such as 300 to 450 F., or particularly 350 to f400 \F.,'and'with nckel, cobalt, nickel tungsten sulde, co-

balt molybdate, and copper chromite catalysts. The liquid volume ratios .of Waterto hydroformylation products in the range of'OLlSzl to 2:1 give good results; preferred results being obtainediwithratios in the range of 0.20:1 to

40.5:1 liquid lvolume ratio My invention has the additional advantage that by employing it in connection with a hydroformylation stage a stream of olens can be recovered from the hydrogenation stage which is richer in non-terminal bond oleiins than the stream originally introduced to the hydroformylation stage. This occurs because the stream of oleiins recovered from the hydroformylatiou stage is richer in non-terminal bond olens than the stream introduced to it and because when the hydroformylation stage products are hydrogenated in accordance with the process of my invention, aldehydes are preferentially hydrogenated and the hydrocarbons in the hydrogenation stage products are chiefly olefins.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

l. A process for preferentially hydrogenating aldehydes in a mixture of aldehydes and oleiins which comprises 'hydrogenating said mixture in the presence of added water in a liquid volume ratio of water to the mixture of aldehydes and oleins of from about 0.15 :1 to about 2:1, over a low temperature hydrogenation catalyst at a temperature of about 300 to 500 F.

2. A process for preferentially hydrogenating aldehydes in a mixture of aldehydes and oleiins which comprises hydrogenating said mixture in the presence of added water in a liquid volume ratio of water to the mixture of aldehydes and olefins of from about 0.1511 to about 2:1 over a nickel catalyst at a temperature of about 300 to about 500 F.

3. A process for preferentially hydrogenating aldehydes in a mixture of aldehydes and olens which comprises hydrogenating said mixture in the presence of added water in a liquid volume ratio of water to the mixture of aldehydes and olens of from about 0.15 :l to about 2:1 over a cobalt catalyst at a temperature of about 300 to about 500 F.

4. A process for preferentially hydrogenating aldehydes in a mixture of aldehydes and oleiins which comprises hydrogenating said mixture in the presence of added water in a liquid volume ratio of water to the mixture of aldehydes and olefins of from about 0.15:1 to about 2:1 over a nickel tungsten sulde catalyst at a temperature of about 300 to about 500 F.

5. A process for preferentially hydrogenating aldehydes in a mixture of aldehydes and oleiins which comprises hydrogenating said mixture in the presence of added water in a liquid volume ratio of Water to the mixture of aldehydes and oleiins of from about 0.15:1 to about 2:1 over a cobalt molybdate catalyst at a temperature of about 300 to about 500 F.

6. A process for preferentially hydrogenating aldehydes in a mixture of aldehydes and oleiins which comprises hydrogenating said mixture in the presence of added Water in a liquid volume ratio of water to the mixture of aldehydes and olens of from about 0.15 :1 to about 2:1 over a copper chromite catalyst at a temperature of about 300 to about 500 F.

7. A process for preferentially hydrogenating aldehydes 2,205,184 Woodhouse June 18, 1940 in hydroformylation products from a hydroformylation 2,359,759 Hebbard et a1. Oct. 10, 1944 stage which comprises introducing water into said'mixture 2,379,670 'Welling et a1 July 3, 1945 in a liquid volume ratio of water to hydroformylation "2,511,453 Barry June 13, 1950 products of about 0.2: 1 to 0.5: 1, flowing hydrogen and the 5 2,543,038 v McGrath Feb. 27, 1951 resulting mixture of Water and hydroformylation products 2,636,903 Mertzweiller Apr. 28, 1953 at a temperature of about 350 to about 400 F, through 2,647,149 Condit et al. July 28, 1953 a hydrogenaton zone containing nickel catalyst, removing the resulting hydrogenation products, separating olens FOREIGN PATENTS from said resulting hydrogenation products, and recycling 10 493,380 Belgium Oct- 14, 1950 said olens to said hydroformylation stage.

References Cited in the le of this patent UNITED STATES PATENTS p 1,724,761 Holden Aug. 13, 1929 A11'5-

Claims (1)

1. A PROCESS FOR PREFERENTIALLY HYDEOGENATING ALDEHYDES IN A MIXTURE OF ALDEHYDES AND OLEFINS WHICH COMPRISES HYDEOGENATING SAID MIXTURE IN THE PRESENCE OF ADDED WATER IN A LIQUID VOLUME RATIO OF WATER TO THE MIXTURE OF ALDEHYDES AND LEFINS OF FROM ABOUT 0.15:1 TO ABOUR 2:1, OVER

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