Temperature-controlled phase-transfer hydrothermal synthesis of MWW zeolites and their alkylation performances

Abstract

MWW zeolites have been synthesized with hexamethyleneimine/aniline as the structure-directing/promoting agent. As structure-promoting agent, aniline contributes to the crystallization of MWW zeolites without being trapped within zeolites. Meanwhile the temperature-controlled phase-transfer hydrothermal synthesis of MWW zeolites could be achieved because the solubility of aniline increases with a rise of temperature. For delaminated MCM-56 with intermediate nature, the conversion to MCM-49 could be avoided even when subjected to a much longer crystallization time. Partially delaminated MWW monolayers of MCM-56 possesses larger external surface area, pore volumes, better accessibility of active centers, which resulted in higher ethylene conversion than MCM-22 and MCM-49 in the liquid-phase alkylation of benzene with ethylene above 210 °C.