Patent ID: 9624153
Date: 2017-04-18
CPC Classifications: B01D,B01J,C07C

Claim:
1. Process for preparing aldehydes by hydroformylation of alkenes, in which an alkene-containing feed mixture is subjected to a primary hydroformylation with synthesis gas in the presence of a homogeneous catalyst system, the primary hydroformylation being effected in a primary reaction zone from which a cycle gas containing at least some of the products and unconverted reactants of the primary hydroformylation are drawn off continuously and partly condensed, with recycling of uncondensed components of the cycle gas into the primary reaction zone, and with distillative separation of condensed components of the cycle gas in an aldehyde removal stage to give an aldehyde-rich mixture and a low-aldehyde mixture, wherein the low-aldehyde mixture is separated into a retentate and a permeate by means of a membrane separation unit in such a way that alkenes present in the low-aldehyde mixture become enriched in the permeate, while alkanes present in the low-aldehyde mixture become enriched in the retentate, and in that the permeate is transferred into a secondary reaction zone and subjected to a secondary hydroformylation therein with synthesis gas in the presence of an SILP catalyst system, with supply of the reaction product obtained from the secondary hydroformylation to the aldehyde removal stage.