Hydroformylation process

In an improved liquid recycle rhodium-catalyzed hydroformylation process for producing C.sub.3 to C.sub.5 aldehydes, wherein an olefin containing from 2 to 4 carbon atoms, carbon monoxide and hydrogen are reacted in the presence of a solubilized rhodium-phosphorus complex catalyst, free phosphorus ligand and higher boiling aldehyde condensation by-products, to produce an aldehyde product selected from the class consisting of propanal, a mixture of n-butanal and iso-butanal, and a mixture of n-pentanal and branched-chain pentanals, and wherein a gaseous effluent comprising unreacted olefin, carbon monoxide and hydrogen gases is vented from the process, the improvement which comprises recovering said unreacted olefin from said vent gas by (1) absorbing the unreacted olefin in an absorbent comprising the liquid aldehyde product produced by said hydroformylation process and wherein the absorption treatment is carried out at a pressure of from 3.5 bar to about 9.5 bar and at a temperature of from about 0.degree. C. to about 60.degree. C.;

• (2) stripping the absorbed unreacted olefin from said absorbent by passing synthesis gas through the resultant absorbent containing said unreacted olefin to obtain a gaseous mixture of synthesis gas and the stripped unreacted olefin and wherein the stripping treatment is carried out at a pressure of from about 100 psia to about500 psia and at a temperature of from about 0.degree. C. to about 130.degree. C.;
• and (3) recycling said gaseous mixture to the hydroformylation reactor of said hydroformylation process.