1. State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China; 2. CNOOC Research Institute of Refining and Petrochemicals, Beijing 102209, China
Abstract: Taking tetrapropylammonium hydroxide as a template,tetraethyl orthosilicate as silicon source,and aluminum sulfate as aluminum source,Pt@ZSM-5 molecular sieve is directly synthesized by in-situ synthesis method.Silicaite-1 shell grows on the surface of Pt@ZSM-5 via epitaxial growth method,and a Pt molecular sieve catalyst with core-shell structure and silicon-rich surface is gained.The catalyst is characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM),transmission electron microscopy (TEM),N2 adsorption-desorption,inductively coupled plasma (ICP-AES),and thermogravimetry (TG).The catalytic performance of Pt@ZSM-5@S-1 molecular sieves with different shell layers thickness is evaluated in the alkylation of toluene and methanol.The results show that as the thickness of the shell increases,the conversion of toluene gradually decreases and the selectivity of para-xylene increases.
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