Effects of NaOH solution treatment on the catalytic performances of MCM-49 in liquid alkylation of benzene with ethylene

摘要

MCM-49 zeolite was alkali-treated with NaOH solutions under mild and severe conditions. The samples before and after alkali-treatment were both used as catalysts in liquid alkylation reaction of benzene with ethylene. XRD, XRF.TPD, TPO, IR, SEM, ~(29)Si NMR, N2 adsorption and desorption techniques were employed to characterize the samples. The mildly alkali-treated samples exhibited higher catalytic stability than the parent HMCM-49, as the amorphous particles on the MCM-49 crystal surface were cleaned and the diffusion of the reactant and product was enhanced. The severe alkali-treatment condition resulted in the selective extraction of silicon atoms and the introduction of extra mesopores. The catalytic stability of the catalysts that had been severely alkali-treated was not as good as that of mildly treated ones, but was still better than that of the parent HMCM-49 catalyst if the alkali-treatment conditions were not too severe.