Catalytic performance of MCM-22 zeolite for alkylation of toluene with methanol

MCM-22 zeolite with mid-strong acidity and openings of 10-membered ring channels may obtain a high catalytic activity and selectivity for alkylation of toluene with methanol. The acidic sites, for catalyzing alkylation of toluene with methanol, are weaker than that for catalyzing toluene disproportionation. Compared with silicon as a modifier, modification of MCM-22 with La(NO3)(3) is a promising way to improve the catalytic selectivity of para-xylene. In addition, the experimental results also clearly indicate the characteristics of MCM-22 structure consisting of large intracrystalline cages, some of which may locate on surface of MCM-22. (C) 2004 Elsevier B.V. All rights reserved.

Enlarged area A-type zeolite membranes prepared by vacuum seeding method

High quality A-type zeolite membranes, with enlarged area over 70 cm(2), were successfully synthesized on a tubular alpha-Al2O3 support by applying the vacuum seeding method.

Synthesis of NaA zeolite membrane on a ceramic hollow fiber

NaA zeolite membrane was successfully synthesized on a ceramic hollow fiber with an outer diameter of 400 mum, a thickness of 100 mum and an average pore radius of 0.1 mum. The as-synthesized membranes were characterized by XRD, SEM as well as gas permeation. A continuous C NaA zeolite membrane formed after a three-stage synthesis. The membrane thickness was similar to5 mum. Gas permeation data indicated that a relatively high quality NaA zeolite membrane formed on the ceramic hollow fiber support. (C) 2003 Elsevier B.V. All rights reserved.