Studies in Surface Science and Catalysis vol:117 pages:183-190
We have designed new acid catalysts by incorporation of propylsulfonic acid groups into MCM and HMS type structures, with HS-(CH2)(3)-Si(OR')(3) as the building block. Material synthesis was either primary, via sol-gel processing of TEOS and HS-(CH2)(3)-Si(OMe)(3) in the presence of an ionic or neutral template, or secondary, via silylation of a pre-synthesized MCM support. The eventual surface modification towards -(CH2)(3)-SO3H was assessed with C-13-NMR, IR, sorption measurements and TGA. In the catalytic work, two reaction types, which are inherently difficult even with optimal acid zeolites are discussed. First, 2,2-[bis-(5-methylfuryl)propane is formed by condensation of two methylfurans (MF) and acetone. With propylsulfonic acid MCMs, the furan oligomerization is largely circumvented and furan-based yields are increased from 40% (for H-P) to over 80%. In the esterification of sorbitol with long fatty acids, zeolites are hardly active; however, at the hydrophobic surface of the propylsulfonic acid MCMs, both reactant phases are brought into intimate contact and this results in considerable catalytic activity.