Development of hierarchical MCM-49 zeolite with intracrystalline mesopores and improved catalytic performance in liquid alkylation of benzene with ethylene

• Uniform intracrystalline mesopores were introduced in MCM-49 zeolite.
• A CTAB micelle directed desilication mechanism was proposed.
• The extra-framework aluminum of MCM-49 could be selectively removed.
• The prepared hierarchical MCM-49 zeolite showed improved alkylation stability.

Hierarchical MCM-49 zeolite with intracrystalline mesopores was prepared through post-treating the conventional MCM-49 zeolite in hexadecyltrimethylammonium bromide (CTAB) and NaOH mixed solution. N2 adsorption and desorption, XRD, TEM, XRF, ICP and Py-IR techniques were applied to characterize the obtained samples. It was found that uniform intracrystalline mesopores were distributed in the MCM-49 crystals, and the intracrystalline meso-porosity could be modified by changing the post-treatment conditions such as CTAB concentration, NaOH concentration, temperature and time. Based on the characterization results upon the hierarchical MCM-49 zeolite samples obtained by post-treating different time, the formation of intracrystalline mesopores in MCM-49 zeolite was proposed, which followed a CTAB micelle directed desilication mechanism. By virtue of the intracrystalline mesopores, the hierarchical MCM-49 zeolite prepared under proper post-treatment condition exhibited superior stability than the conventional MCM-49 zeolite in liquid alkylation of benzene with ethylene.

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