Process for producing an alcohol by hydroformylation

In a process for producing an alcohol by hydroformylation which comprises reacting straight chained, branched, or alicyclic mono-olefin having from 3 to 20 carbon atoms with carbon monoxide and hydrogen to form an alcohol having carbon atoms greater in number by one than the carbon atoms of the mono-olefin, the improvement which comprises:

• (a) a first step in which the mono-olefin is hydroformylated with use of a cobalt carbonyl catalyst selected from the group consisting of HCo(CO).sub.4 and Co.sub.2 (CO).sub.8 catalysts in the presence of a gas mixture of carbon monoxide and hydrogen in a volume ratio of the hydrogen to the carbon monoxide of from 0.8 to 2.0 at a temperature of from 80.degree. to 180.degree. C. under pressure of from 150 to 250 kg/cm.sup.2 to selectively form an aldehyde at a conversion of the mono-olefin being from 50 to 95 mol % while suppressing the formation of an alcohol, and the cobalt carbonyl catalyst is then removed from the unreacted olefin and the formed aldehyde by decomposition or extraction, and
• (b) a second step in which the mixture of the unreacted mono-olefin and the formed aldehyde freed from the cobalt carbonyl catalyst in the first step is reacted with a gas mixture of carbon monoxide and hydrogen in a volume ratio of the hydrogen to the carbon monoxide of from 1.1 to 10 with use of a cobalt trialkylphosphine complex catalyst at a temperature of from 160.degree. to 250.degree. under pressure of from 30 to 200 kg/cm.sup.2 thereby simultaneously hydroformylating the unreacted mono-olefin and hydrogenating the aldehyde to form the alcohol.