Catalytic activity of high-silica TsVK and TsVM zeolites in hydrodesulphurization

Abstract

High-silica zeolites TsVK-TsVM of the pentasil family, recently synthesized by Soviet industry, are active catalysts for many petrochemical and petroleum processing processes such as cracking, hydrorefming of straight-run petrols, isomerization of xylenes, transformation of methanol into aromatic hydrocarbons and aromatization of lower alkanes and olefins [ 1, 2]. Publications dealing with investigation of the physicochemical properties of TsVK-TsVM zeolites, including their H forms, are widely represented in the Soviet literature [3-7]. Meanwhile there is much, mainly patent information on the use of ZSM-class high-silica zeolites in processes of hydrotreatment of petroleum products, including residual petroleum stock, and hydrodesulphurization of sulphur-containing organic compounds [8-14]. In earlier papers [15, 16] we showed that high-silica metal-containing (Me -Ni, Co, Fe and Mo) element-silicate (E = B, Fe) zeolites isomorphously substituted in the lattice induce hydrogenolysis of thiophene with 30-40% conversion, actively carrying out hydrogenation with n-Call10 formation in fractions of C a hydrocarbons. TsVK-TsVM high-silica zeolites based on aluminosilicates, taken selectively and studied in a flow-type microunit, exhibited no catalytic activity. However, no systematic investigations of metal-containing TsVK and TsVM zeolites were carried out. Thus, at present there is almost no published information concerning TsVK-TsVM pentasils in hydrodesulphurization. There is little information on the capacity for C--S bond rupture on this type of catalyst or on the possible formation of C a olefins in the reaction and their hydrogenation. There are virtually no data on the cracking activity of C--C bonds on TsVK-TsVM-type aluminosilicates, whereas it is known that in the processing of petroleum distillate feedstock by hydrotreatment such activity should be low and is undesirable. There are no quantitative data on the composition of reaction products and the way it changes during the reaction. It is unclear how high-silica TsVK and TsVM zeolites without a binder behave in the hydrogenolysis of thiophene, and what role a Al203-type matrix plays in compounds with TsVK-TsVM zeolites. The aim of the present work was to study the catalytic activity of metal-containing (Me = Ni, Co, Fe and Mo) high-silica zeolites of the TsVK and TsVM type, without a binder and in a matrix with an AI203 binder, in the hydrodesulphurization of model sulphur-containing