Metal palladium supported on amphiphilic microporous synthetic organic supports. Part II. Catalytic investigations

Two sets of resin-supported Pd(0) catalysts were compared in the hydrogenation of cyclohexene in methanol, under ambient conditions. Two lightly crosslinked poly-{styrene/2-methacryloxyethylsulfonic acid/methylenebisacrylamide} with different degrees of crosslinking (1 and 3 mol%), have been used as catalyst supports. Two catalysts with different palladium loadings (0.22 and 2.2 wt%) have been prepared from each support. When the size of the particles was relatively small, the catalysts with 2.2% and 0.22% Pd were almost equally active with respect to the amount of palladium in the reaction mixture. In contrast, when larger catalyst particles were used, catalysts with 2.2% metal produced conversion profiles typical of diffusion-controlled regimes (productivity decreased with increasing crosslinking). These catalysts were characterised by combined ESR and static gradient spin echo NMR spectrometries, which have provided information about molecular motion inside the polymer networks. (C) 1998 Elsevier Science B.V.