(583dq) Intrinsic Activity of Fischer-Tropsch Synthesis On Carbon Supported Cobalt Catalyst

                                                                Intrinsic Activity of Fischer-Tropsch Synthesis on Carbon Supported Cobalt Catalyst

                                                                                                                Tingjun Fu, Zhenhua Li

Key Laboratory for Green Chemical Technology of Ministry of Education

School of Chemical Engineering & Technology, Tianjin University

Tianjin, China

Abstract

Diminishing petroleum reserves, sharp fluctuations of crude oil prices and increasingly stringent environmental regulations are the main driving force for the recent renewed interest in Fischer-Tropsch (FT) synthesis both in academia and industry. FT synthesis can produce super-clean fuels or valuable chemicals at economically feasible costs from coal, natural gas or biomass.Among the reported FT synthesis catalysts, cobalt based catalyst is the preferred catalyst for the production of long-chain paraffins because of its high activity, low water-gas shift activity and comparatively low price compared to ruthenium catalyst.

Typical FT synthesis catalyst supports are Al₂O₃, SiO₂ and TiO₂. However, the use of these supports can generate a strong metal-support interaction and lead to the formation of hardly reducible compounds. As an inertia material, carbon display special properties like high purity, high mechanical strength, good electrical conductivity, high thermal stability and large surface area. In contrast to oxide supports, only weak interaction between the metal and carbon is evident on carbon supported cobalt catalysts, which can improve FT performance and allow better study of the intrinsic properties of the cobalt active sites.

In our work, several carbon materials including multiwalled carbon nanotubes, mesoporous carbon, bamboo-shaped multiwalled carbon nanotubes and actived carbon were used as support for preparing the cobalt catalyst for FT synthesis. The results indicated that the structure of the carbon support is an important factor that influences the C₅₊ selectivity and hydrocarbon distribution. Cobalt particle size had an impact on the TOF and on the C₅₊ selectivity. Both TOF and C₅₊selectivity increase with increase of cobalt particle size to 7 nm. The structure-activity relationship was proposed, which is helpful for understanding the mechanism and designing cobalt-based catalyst with good FT synthesis performance.

Keywords: Fischer-Tropsch synthesis, Cobalt catalyst, Intrinsic properties