Study of iron-based nanocatalysts for high-temperature fischer-tropsch synthesis

Abstract

The development of alternative energy has received renewed interests in recent years because of the global demand for a decreased dependence on petroleum for production of fuels and chemicals. Fischer-Tropsch synthesis (FTS) is a heterogeneous catalytic process for the production of clean hydrocarbon fuels or chemicals from syngas (CO + $H_2$), which can be derived from nonpetroleum feedstocks such as coal, natural gas, and biomass. Among the various metal catalysts for the FTS, Iron has many advantages for the FTS study with very cheap prices. Iron-based catalysts are used for high temperature Fischer-Tropsch (HTFT) process, and can not only used for the production of paraffin products but also suitable for the production of olefin products, which are important chemical feedstocks. The aim of study was to study of high temperature Fischer-Tropsch synthesis and to develop the efficient iron-based catalysts to afford good activities and selectivities. In the present work, two kinds of iron-based nanocatalysts were successfully synthesized (iron carbide/silica sphere assemblies and iron carbide/carbon sphere assemblies). For the silica sphere supported nanocatalyst, catalytic activity was not observed. For the carbon sphere supported nanocatalyst, the catalyst showed the much higher FTY value $(7.78 × 10^{-4} mol_{CO}/g_{Fe}·s)$ than those of the previously reported highest value. Such a high FTY can be attributed to the smaller size iron particles and low metal-support interaction observed with carbon leads to good iron oxide reduction behavior. Although this catalyst has a high FTY value, however, the total CO conversion was quite low (~19%) and the selectivity was not good enough as compared with recent researches. Further research based on the iron carbide/carbon sphere nanocatalyst could be new possibilities for tuning the catalytic properties for the high temperature Fischer-Tropsch synthesis.