Alkali-treatment of template-containing MCM-22 zeolite and its application in alkylation and transalkylation reactions

• Published in: Applied catalysis. A, General Vol. 468; pp. 288 - 295
• Main Authors: Liu, Kefeng, Xie, Sujuan, Wei, Huijuan, Li, Xiujie, Liu, Shenglin, Xu, Longya
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 05-11-2013; Elsevier
• Subjects: Alkali-treatment; Alkylation; Aluminum; Benzene; Catalysis; Chemistry; Crystal structure; Exact sciences and technology; General and physical chemistry; Ion-exchange; MCM-22 zeolite; Surface layer; Surface physical chemistry; Texture; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Transalkylation; Zeolites; Zeolites: preparations and properties; Alkali-treatment; MCM-22 zeolite; Benzene; Alkylation; Transalkylation; Heterogeneous catalysis; Zeolite; Molecular sieve; Template
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/j.apcata.2013.09.009

Be different from the alkali-treated template-free (MCM-22-C) MCM-22, the framework of the template-containing (MCM-22-P) MCM-22 zeolites will experience a different evolution in NaOH solutions.
•Alkali-treated template-containing MCM-22 zeolites are studied.•Alkali-treated template-containing MCM-22 has smaller crystal size.•Diffusion conditions are improved in the smaller crystals.•Ratio between different acid sites is changed.•The alkali-treated samples show higher catalytic activity.
The effects of alkali-treatment on the compositions, acidities, texture properties and pore structures of template-containing MCM-22 zeolite were studied by Py-IR, N2 adsorption–desorption, o-xylene adsorption, XRD and 29Si NMR. When template-containing MCM-22 zeolite was alkali-treated, desilication mainly occurred in the Al-poor regions, which broke the crystal sheets into smaller ones. The alkali-treatment process under the moderate conditions had little influence on the microporous properties and crystal structures of MCM-22 zeolite, but improved the diffusion conditions for aromatics mainly by reducing the crystal size. With the preserved framework Al species, the alkali-treated template-containing MCM-22 samples had higher ratio of Brönsted to Lewis acid sites, and exhibited improved catalytic performances in alkylation and transalkylation processes.