Catalytic membrane reactor to simultaneously concentrate and react organics

Catalytically active membranes containing palladium nanoclusters of 3-5 nm were prepared from poly(ether-b-amide) (PEBA) and the catalyst precursor palladium diacetate in a solution-casting-reduction procedure. These membranes were used to simultaneously concentrate and react organics by catalytic pervaporation. The model reaction considered is the hydrogenation of 4-chlorophenol in aqueous solution using dissolved hydrogen as reducing agent. The reaction produced phenol and, in smaller yields, cyclohexanone and cyclohexanol were detected in the permeate but also in the feed solution. Conversion of 4-chlorophenol is up to 80% after 20 It of operation. However, a considerable amount of 4-chlorophenol passed the membrane unreacted. Pervaporative enrichment of the organics was by a factor of 100. The effectivity of the process was influenced by the palladium cluster size, feed temperature and permeate pressure. A significant conversion is realized only when employing the catalytic membrane in the pervaporation mode. (C) 2002 Elsevier Science B.V. All rights reserved.