SELECTIVE HYDROGENATION REACTIONS WITH A MICROPOROUS MEMBRANE CATALYST, PREPARED BY SOL-GEL DIP COATING

Catalytically active microporous thin film membranes were prepared by dip coating of an asymmetric ceramic support membrane in a Na2PtCl6 co ntaining sol based on Ti(OiPr)(4). After drying and calcination, the m embrane (thickness of the top layer, 0.2-0.4 mu m) shows separation pr operties typical for microporous membranes with low defect concentrati on (nanofiltration). After activation with hydrogen at 250 degrees C t he membranes exhibit a hydrogenation activity significantly higher tha n those of comparable batch catalysts. At conditions of reaction contr ol and limitation of hydrogen availability, 2-hexyne is semihydrogenat ed with such a membrane with 100% selectivity to cis-2-hexene. 1,3-Hex adiene is semihydrogenated selectively to l-hexene. The unusual select ivity observed is attributed to the prevention of back-mixing through the use of the membrane contactor. (C) 1998 Academic Press.