Influence of the location of Rh(0) particles within MCM-41 materials on the selectivity of hydrogenation reactions

Rh 0 -MCM-41 solids have been prepared by the alkaline hydrolysis of silicon precursors in the presence of cetyltrimethylammonium bromide (CTABr) and Rh(III) salts or 2-3 nm Rh° colloids. All the resulting solids were used in the catalytic hydrogenation of xylenes and lead to lower selectivities in cis dimethylcyclohexanes than Rh 0 colloids tested either under biphasic conditions or deposited onto silica gel. Such variations have been attributed to the insertion of the Rh precursors into the MCM-41 synthesis gel.