2797. ---------------. [REICHL, E. H.] Synthesis of Hydrocarbons and Chemicals From Carbon Monoxide and Hydrogen. The Oxo Synthesis. U. S. Naval Tech. Mission in Europe Rept. 248-45, 1945, pp. 114-128; PB 22,841; TOM Reel 200.
Oxo synthesis is a process for the production of alcohols by the action of olefins with 1 mol. each of CO and H2 and subsequent hydrogenation of the resulting aldehyde. The process was developed by Ruhrchemie and I. G. Farbenindustrie and a plant was built at Holten but never operated. The information in this report is based on large-scale pilot-plant operation and laboratory work. The chemistry of the process was studied, and pure olefins of different types were subjected to the Oxo reaction and the products separated and analyzed. The compounds charged to the Oxo synthesis are known to be substantially terminal olefins, yet it was found that some of the products could have been formed only if a double bond shift had preceded the formation of the aldehyde. Tests with n-dodecylene-1 proved that from terminal normal olefins the Oxo synthesis yields branched alcohols, particularly 2-alkyl alcohols, whereby the yield decreases with increasing length of the sidechain. It was finally possible to prove that Co carbonyl was the catalyst responsible for the double bond shift. Fe carbonyl showed a similar effect but not the same activity, and Ni had no effect at all. Many materials were tested as feed for the synthesis; it appears that the reaction is applicable in principle to all monoolefins independent of origin, although synthetic olefins are preferred because of their higher purity. Compounds containing double bonds give unsatisfactory results. The customary catalyst is the CO-ThO2-kieselguhr (100:1.5:200) applied as a slurry in the liquid feed in concentration of 3% by weight of the olefins. It does not contain MgO, because this encourages condensation of the aldehydes. One of the main problems in the process, as noted above, is the formation of Co carbonyl. The I. G. Farbenindustrie developed a Co-Cu catalyst that gave only a fraction of the carbonyl and was satisfactory for the first stage (aldehyde formation) but did not hydrogenate well. The catalyst is recovered from the reactants at the end of the operation by filtration and returned for further use. In a modification of the process, Co acetate is contacted with fatty acids in an autoclave to yield the Co salt, and this is introduced in solution into the feed to give a concentration of 0.02-0.05% of Co. This mixture is charged to the reactor where it passes over a solid Co catalyst bed (Co on pumice) and is finally freed from the Co in a special smaller reactor filled with plain pumice by being reduced with H2 and deposited on the pumice. This reactor is purged of Co after several months by forming the carbonyl, which is again dissolved in oil and returned to the feed. The operating conditions for both the batch and the continuous processes and the fractionation of the products are described. The over-all cost of the final product is given as 0.60-0.65 RM per kg. of alcohol. Further development of the process probably will be toward continuous operation and better control of the synthesis, particularly the suppression or close control of the double bond shift to give clearly defined a-substituted alcohols of predetermined branching.