Abstract
Zeolites beta, Y and mordenite are modified with organic and inorganic cupric salts using a liquid phase deposit method, and their catalytic performance and the dispersion states of copper on the zeolites are characterized by using naphthalene isopropylation reaction and Xe-129 NMR, respectively. The experimental results indicate that naphthalene conversion on the catalysts decreases in the order of HY>Hbeta>HMCM-22>HM. The performance of the zeolites has been largely improved after the modification. Naphthalene conversion rate reaches 97% and 60%, and beta, beta'-selectivity 66% and 70% for CuHY and CuHbeta, respectively. Metal surfactants, such as hexanoic and octanoic copper, play a positive role in modifying the external surface and pore structure of zeolites beta and Y. Xe-129 NMR results demonstrate that the two types of the pore channels in Cu-Hbeta are unimpeded for xenon atoms, and there is a fast chemical. exchange between two xenon atoms located in different adsorption sites; Cu2+, ion is a strong adsorption site for xenon atoms and it is a strong active center as well; Cu2+ and Cu+ ions coexist in channels of zeolites, which are in agreement with the conclusions from ab initio quantum chemical calculations.
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