Modification Of X Zeolites And Their Catalytic Application In Toluene Side Chain Alkylation With Methanol

Nowadays, side chain alkylation of toluene with methanol is the kind ofmethod to synthesis styrene which is widely discussed in the industry. Comparedwith the traditional method of ethyl benzene dehydrogenation, side chain alkylationhas the characteristics of low energy consumption, less by-product and simpleprocess. As the new route for preparation of styrene, the reaction has gained a lot ofattention. But the design of catalyst has been faced with the problem of lowconversion rate, poor repeatability. So to explore an efficient and stable catalyst,prepare catalytic materials for side chain alkylation has become a hot issue in thefield.As a typical catalyst for side chain alkylation of toluene with methanol, Xzeolite has been widely reported in the literature and patent. Previous studies haveshown the internal structure, surface physicochemical properties, pH of X zeolitecan affect the side chain alkylation. On this basis, the modification of X zeolite canimprove the catalytic performance.In this paper, we use X zeolite as carrier, CsNO3as cesium source, synthesis aseries of CsX zeolite by ion exchange. Meanwhile, we studied the effects of thecarrier, cesium source, exchange degree, time, temperature and other condition onthe catalytic properties. We also use H3BO3as boron source,(NH4)3PO4asphosphorus source, investigated different loadings of two component, such as Zr, Bor La. P. In addition, characterization methods such as XRD, FT-IR, TG/DTA, SEM,CO2-TPD were used to study the surface structure and the physicochemicalproperties of catalyst. The result showed that the morphology of CsX did not changesignificantly. Modification methods and reaction conditions are affecting thecatalytic performance.CsX zeolite which is modified by La, P or Zr, B has different performances inside chain alkylation of toluene with methanol. When the mass loading of Zr is0.3%,the mass loading of B is0.5%or when the mass loading of Zr is0.5%, the massloading of B is1.0%, they all showed good catalytic activity. Studies have shown that the catalyst which is modified by Zr, B owns weakly basic position. It isconductive to the occurrence of side chain alkylation. Meanwhile, the catalystsurface can be observed irregular particles about100nm which come from theintroduction of additives.