Ultrastable MSU-G molecular sieve catalysts with a lamellar framework structure and a vesicle-like particle texture

A mesoporous MSU-G molecular sieve silica, prepared through a H bonding assembly mechanism in the presence of a C12H25NH(CH2)(2)NH2 gemini surfactant as the structure director, is shown on the basis of N-2 and XRD measurements to be substantially more stable to calcination at 1000 degreesC and to hydrothermal treatment at 100 degreesC than electrostatically assembled MCM-41, KIT-1 and SBA-3 silicas. Also, 2%Al-MSU-G derivatives as prepared through grafting reactions with aluminum nitrate, aluminum iso-butoxide or sodium aluminate. are far more efficient acid catalysts than 2%Al-MCM-41 for the conversion of 2,4-di-tert-butylphenol and cinnamyl alcohol to a bulky flavan as the primary alkylation product. The exceptional stability of MSU-G mesostructures is consistent with the very high degree of framework cross-linking (Q(4)/Q(3) = 6.2) and thick framework walls (similar to 25 Angstrom). The improved catalytic activity of MSU-G mesostructures is attributable to the vesicular particle morphology, which facilitates reagent access to catalytic centers in the lamellar framework. (C) 2001 Elsevier Science B.V. All rights reserved.