The Effect of Metallic Promoters on Supported Cobalt Catalysts

Abstract

In recent years, there has been a renewed interest in the Fischer–Tropsch (FT) synthesis as a possible means of converting natural gas to transportation fuels and chemicals. Recent developments in FT-technology are focused on the production of high molecular, straight-chain waxes that can be hydrocracked to products in the middle distillate range. With methane as the synthesis gas feedstock, Co is the preferred FT catalyst because of the low water-gas shift activity. It has been proven difficult to prepare cobalt catalysts with both high dispersion and a high degree of reduction because of the strong interaction between cobalt oxides and supports, such as alumina. This interaction depends on metal loading, preparation, and pretreatment. It has also been shown that the catalytic properties of Co/Al 2 O 3 are influenced by the same parameters. In addition to Co, many recently developed catalysts contain a noble metal promoter. However, the function of this second metal is not clear. It has been proposed that the addition of a noble metal would lower the reduction temperature and that it could act as a source of spillover hydrogen atoms at lower temperatures. This chapter explains the effect of Pt on the behavior of an alumina-supported Co catalyst.