Reactivity of Amorphous Silica-Alumina Prepared by the Sol-Gel Method as a Matrix in Catalytic Cracking

摘要

In this study an amorphous silica-alumina could be prepared by the sol-gel method using carboxylic acids, malic acid (MA), succinic acid or citric acid, and its reactivity for the catalytic cracking was investigated. When the ratio of MA/TEOS (tetraethoxysilane) increased, surface area, pore volume and pore diameter increased and the mesopore was formed. The maximum total conversions of n-dodecane were around 30% with the single use of amorphous silica-alumina. In contrast, the total conversion reached 91% with the single use of beta-zeolite. In order to investigate the reactivity of amorphous silica-alumina as a matrix, the mixed catalysts which consist of zeolite, amorphous silica-alumina and binder (alumina sol) were prepared. The product distribution changed compared with the single use of zeolite or silica-alumina and the comparable activity to that of zeolite was obtained although the mixed catalysts included only 1/4 of zeolite. Further, the mixed catalysts using amorphous silica-alumina with mesopore (MA122-5) exhibited the higher ratio of multi-branched to single-branched products in the gasoline franction (C5-C11) than single zeolite. The effects of the aluminum precursor and the addition of 1-dodecene and 1-methylnaphthalene were also investigated.