Supercritical-phase process for selective synthesis of wax from syngas: Catalyst and process development

Abstract

Cobalt-based catalysts which showed high activity and wax selectivity even at a relatively low-reaction temperature such as 210°C were studied. Lanthanum and nickel additions to the catalysts were investigated. Both these additions could promote Co-based catalyst activities. Structure factors concerning these additions were discussed. Calcination temperature effect as well as loading amount influence were also investigated for these catalysts. Addition of a small amount of middle olefins into a supercritical-phase or liquid-phase Fischer-Tropsch (FT) reaction medium could significantly promote the carbon-chain growth and greatly enhance the selectivity of waxy products, with increased CO conversion while suppressing methane and CO 2 selectivity. Hydrocarbon products exhibited anti-Anderson-Schultz-Flory (anti-ASF) distribution. The influences of reaction conditions, catalyst pore size, and catalyst calcination temperature, were studied for the supercritical-phase FT reaction where middle olefin was co-fed. This phenomenon was not observed in the gas-phase reaction and liquid-phase reaction conducted in the trickle bed. But the liquid-phase reaction conducted in the batch-type reactor exhibited the same olefin addition effect.