THE DEACTIVATION AND LOSS OF COBALT IN Co-ZrO_2 CATALYSTS FOR FT SYNTHESIS IN SLURRY REACTOR

摘要

The Fischer-Tropsch (FT) synthesis is a process to convert energy reserves, such as coal or natural gas, into liquid transportation fuels. As an alternative to iron catalysts for FTS, cobalt catalysts have attracted much attention due to the advantages over the former such as higher activity, longer lifetime and selectivity toward higher hydrocarbons [1] The development of a stable cobalt catalyst requires an improved fundamental understanding and quantification of the various deactivation mechanisms. Many potential causes have been widely investigated such as carbonaceous deposition [2], oxidation of the cobalt surface and /or small cobalt clusters [3] etc. It was known that the carbonaceous species was hard to be identified in FT synthesis duo to the presence of heavy hydrocarbon and/or wax products. However, the surface oxidation of highly dispersed cobalt particles was clearly observed by the XPS, MES, XANES, EXAFS, XRD, and TEM.