Prospects of the Use of Synthetic or Natural Silica Aluminas in the Composition of a Fischer–Tropsch Catalyst

Abstract Silica aluminas are advantageous as an alternative to zeolites in the composition of catalysts for one-pot Fischer–Tropsch synthesis. The aim of this work was to study the possibility of use of synthetic or natural silica aluminas in the composition of cobalt Fischer–Tropsch synthesis catalyst to increase the content of wide base oil fraction in the resulting products. The influence of the calcination temperature of silica aluminas on the characteristics of the prepared catalysts and the composition of C5+ hydrocarbons formed in their presence was investigated. Silica aluminas powders were studied by X-ray diffraction, thermogravimetric analysis, IR spectroscopy and low-temperature nitrogen sorption methods. Catalysts prepared based on silica aluminas were tested in Fischer–Tropsch synthesis. The results obtained confirm the possibility of one-pot synthesis of C5+ hydrocarbons enriched with base oil fraction. The catalyst based on amorphous synthetic silica alumina provides product containing up to 37 wt % of fraction with a boiling range of 300–490°С. The conditions for the selective production of base oil fraction in the presence of such catalysts were optimized as 2.5 MPa, 210°С, 500 h–1. It was shown that it is possible to obtain C5+ hydrocarbons containing up to 60 wt % of diesel fraction at 1.5 MPa, especially in the presence of pyrophyllite-based catalysts.