United States Patent (19) [11] 3,862,236 Scharff et al. (45) Jan. 21, 1975 54 PRODUCTION OF PROPIONALDEHYDE OTHER PUBLICATIONS 75 Inventors: Gerhard Scharff, Leverkusen; Manfred Martin, Cologne; Okada et al., Chemical Abstracts, Volume 72, p. 277, Wolfgang Swodenk, 1970. Odenthal-Globusch; Wolfram Dewolfe et al., Chemical Reviews, Vol. 56, pp. Dornfeldt, Leichlingen; Johann 757,758,786 and 878, 1956. Okada et al., Chemical Abstracts, Volume 72, page Grolig, Leverkusen, all of Germany 277, 1970. 73) Assignee: Bayer Aktiengesellschaft, Sabatier, Catalysis in Org. Chem., 1923, p. 658. Leverkusen, Germany Dewolfe et al., Chemical Reviews, Vol. 56, pages 757, 22 Filed: Nov. 6, 1970 758, 786 and 787, 1956. (21) Appl. No. 87,394 Okada et al., Chemical Abstracts. Primary Examiner-Bernard Helfin 30 Foreign Application Priority Data Assistant Examiner-R. H. Liles Nov. 28, 1969 Germany............................ 1959776 Attorney, Agent, or Firm-Burgess, Dinklage & Nov. 28, 1969 Germany............................ 1959780 Sprung 52 U.S. Cl....... 260/603 R, 260/497 R, 260/638 R (57) ABSTRACT 51 Int. Cl............................................. C07 c 45/16 A process comprising passing allyl alcohol in the gas 58 Field of Search....... 260/603 HF, 497 A, 638 R phase over a palladium catalyst at elevated tempera ture, whereby the allyl alcohol is converted to propi 56) References Cited onaldenyde. The allyl alcohol may be produced by re UNITED STATES PATENTS acting propylene with oxygen and acetic acid to form 2011,317 8/1935 Groll............................... 260/603 R a product containing allyl acetate which is hydrolyzed 2,428,590 10/1947 Shokal et al..... ... 260/497 A to allyl alcohol and acetic acid, the acetic acid being 2,441,540 4f 1948 Ash et al............................. 260/638 recycled. 3,156,735 1 11964 Armstrong....... ... 260/603 R 3, 190,912 6/1965 Robinson........................ 2601497 A 9 Claims, 1 Drawing Figure PATENTEDJAN2 1975 3,862,236 ALLY ALCOHOL REACTOR CON DENSER 4 EraNEETHYLENE COOLER CO H2 PROPIONALDEHYDE INVENTORS: GEkitiki) 3CHARFi, i ANFREI) L.ARTIN, NOLFGANG SWODENK, WOLFRAY DORNFELDT, JOHN EUGEN Gi (). Li G. BY d Boga 4.4%. --f al 3. 3,862,236 2 PRODUCTION OF PROPIONALDEHYDE Where they are supported, the catalysts used for the reaction advantageously contain from about 0.1 to 10 This invention relates to a commercially practical g, more particularly about 0.1 to 5 g, of palladium per process for the production of propionaldehyde from liter of the catalyst. In cases where, in addition to palla ally alcohol. 5 dium, other metals or metal compounds are used, the It is known that propionaldehyde can be obtained by catalysts may advantageously contain in addition from reacting ethylene with carbon monoxide and hydrogen about 0.1 to 5g of the metal or metal compounds, for (oxosynthesis). example gold, per liter of the catalyst. It has now been found that propionaldehyde can be The gaseous reaction products can be cooled under obtained in an economically advantageous, and there the reaction pressure, usually resulting in the formation fore commercially practical, manner by passing ally of a liquid phase which contains a large proportion of alcohol in the gaseous phase at an elevated tempera the propionaldehyde formed together with the unre ture over a catalyst containing palladium. acted allyl alcohol and the condensible compounds op The reaction can be carried out at reduced pressure, tionally present in the starting material, for example ni normal pressure or at elevated pressure. The reaction 15 trogen, hydrogen, and carbon dioxide, as well as, corre temperatures are variable within wide limits. For exam sponding to the vapor pressure of the propionaldehyde, ple the reaction can be carried out at a temperature of certain quantities of propionaldehyde and optionally from about 50 to 250°C and preferably at a tempera certain quantities of allyl alcohol, water, and acetic ture of from about 100 to 200°C and at a pressure of acid, as well as the gaseous reaction products formed up to about 10 atmospheres gauge. 20 during the reaction such as carbon monoxide, hydro The reaction is advantageously carried out in the ab gen, ethylene and ethane. The propionaldehyde can sence of oxygen. The absence of oxygen favorably af then be isolated from the liquid phase by distillation. fects both the activity and the selectivity of the catalyst. The distillation residue of the higher-boiling com By operating in the absence of oxygen, it is possible to pounds such as allyl alcohol and water for example can avoid the formation of acrolein which otherwise would 25 then be recycled to the reaction through an evaporator. be extremely difficult to separate from the desired pro The propionaldehyde present in the gaseous product pionaldehyde. can be separated by Suitable physical processes such as The reaction can be carried out in the presence of or fractional condensation or extraction. ganic or inorganic compounds, for example in the pres However, it is also possible to recycle the gaseous ence of one or more of water vapor, gaseous acetic 30 phase to the reaction vessel without separating the pro acid, allyl acetate, nitrogen, hydrogen, carbon monox pionaldehyde present in it. Since in cases where the re ide and carbon dioxide. action is optimally carried out there is usually formed In general, the reaction is carried out by converting a small quantity of gaseous secondary product such as a large proportion of the allyl alcohol used into propi hydrogen, carbon monoxide, ethane and ethylene, the onaldehyde in a single pass. Conversions of from 50 to 35 proportion of these compounds will rise where the gas 100%, for example, take place in a single pass. Propion is completely recycled. For this reason, it is necessary aldehyde is formed as the main product during the re to remove some of these gaseous reaction products action. In addition, secondary products such as hydro from the recycled gas. gen, ethylene, ethane and carbon monoxide can occur Pure allyl alcohol may be used as the starting mate in fluctuating quantities. The temperature, throughput 40 rial for the production of propionaldehyde, although it rate and the presence of diluents for the allyl alcohol is also possible to use mixtures containing allyl alcohol are all of significance so far as the formation of the sec such as mixtures containing water, like the azeotrope ondary products are concerned. As already mentioned, of allyl alcohol and water which contains approxi suitable diluents for the allyl alcohol to be reacted in mately 27% of water, as well as aqueous solutions of clude organic or inorganic compounds in whose pres 45 allyl alcohol, mixtures of allyl alcohol, water and acetic ence the reaction can be carried out. By virtue of the acid or mixtures of allyl alcohol, water, acetic acid and process according to the invention, it is possible to ob allyl acetate. In cases where pure allyl alcohol is not tain selectivities of at least 90% for conversions of from used as the starting material, it is undesirable in some 50 to 100% in a single pass. cases completely to recycle the liquid reaction prod The catalysts used for the reaction contain palladium 50 ucts after separation of the propionaldehyde because in the form of palladium metal or in the form of palla the proportion of these products in the starting material dium compounds. It is preferred to use a catalyst which would build up. In this case, it is best suitably to remove contains the palladium on a support. It is possible to use some of these compounds, for example water and a variety of supports, for example, silica, aluminum sili 55. acetic acid, from the circuit. cates, active carbon, aluminum oxide and aluminum The catalyst can be used for example in the form of spinel. Suitable palladium concentrations on the Sup pellets, slugs or beads, for example in the form of beads port are for example from about 0.01 to 10% by weight from 4 to 6 mm in diameter. and preferably from about 0.1 to 2% by weight, calcu The catalysts can be prepared in different ways. For lated as free metal, It is possible to use a catalyst which example, the support can be impregnated with palla contains only palladium metal on a uniform support 60 dium in the form of a soluble salt, for example in the such as SiO, for example, although it is also possible to form of an aqueous sodium palladate solution. The cat use a catalyst which in addition to the palladium or pal alyst can then be treated with an aqueous reducing ladium compound contains other metals or metal com agent, for example hydrazine, and the palladium re pounds such as platinum, ruthenium, gold, nickel, cop duced to palladium metal. It is also possible, however, per, molybdenum, vanadium, chromium, manganese, 65 to carry out reduction with a gaseous reducing agent iron and compounds of the alkali metals and alkaline such as hydrogen for example. The support may also be earth metals. impregnated with the palladium compound which is 3,862,236 3 4 then converted by treatment with an alkali metal hy This crude reaction mixture may be used as the start droxide into a water-insoluble palladium compound, ing material for the production of propionaldehyde by for example palladium hydroxide. The catalysts ob the process according to the invention. The allyl alco tained after the treatment described above can be freed hol present in the reaction mixture is converted at least from inorganic salts, for example alkali metal chlorides, in part into propionaldehyde. A liquid product com by washing and then dried. In cases where the palla prising propionaldehyde, allyl acetate, water, acetic dium salts are converted into palladium hydroxide, the acid and optionally unreacted allyl alcohol, can be ob catalyst can be reduced to the metal form either before tained from the gaseous reaction product by cooling.