CATALYTIC PERFORMANCE OF Ni/ZSM-5 CATALYSTS FOR C9 ALKYL-AROMATICS HYDRODEALKYLATION

摘要

Aromatics are an important raw material for the production of monomer for polyesters and engineering plastics, detergents, pharmaceuticals, etc. Benzene, toluene, and xylenes (BTX) is produced by naphtha reforming and pyrolysis, in which the proportion of each aromatic is controlled thermodynamically. BTX are the three basic aromatic starting reactants (1). Hydrodealkylation is a common route in the petrochemical industry. Benzene for example is produced from either pyrolysis gasoline or pure alkylaromatic hydrocarbons, mostly toluene, thermally or catalytically reaction (2). As is known, thermal processes require relatively high temperatures (973–998 K) compared to catalytic ones which usually take place at 873–898 K and high temperatures increase the heavy aromatic hydrocarbon content such as naphthalene and decrease the benzene selectivity. Moreover, catalytic processes are of course more economic provided a highly selective catalyst can be found (3). A series of H/ZSM-5 and Ni/ZSM-5 catalysts were chosen to improve catalytic activity, permitting an increase in C9 alkyl-aromatics conversion, increase the selectivity of the process by reducing the final concentration of by-products, increase catalyst life, thus prolonging regeneration cycles. In the work, they were studied to evaluate the role of metallic function and catalyst activity in the process of BTX.