Supercritical phase Fischer-Tropsch synthesis over cobalt catalyst

A supercritical phase Fischer-Tropsch reaction over a SiO2 supported cobalt catalyst in a fixed bed reactor was studied in this paper. Four different supercritical fluids: n-pentane, n-hexane, n-heptane and n-decane were investigated. Similar CO conversion, hydrocarbon distribution, 1-olefin content of the products, etc. were obtained in n-pentane, n-hexane and n-heptane; however, 1-olefin content of the products in n-decane was obviously lower than that in n-pentane, n-hexane and n-heptane. Under the reaction conditions used in this study, CO conversion increased with increasing temperature and decreasing W/F(CO + H2). The partial pressure of the n-hexane had little influence on the CO conversion under the conditions of that total pressure and syngas partial pressure kept constant. In general, the change of the distribution of the products was not obvious with the change of the operating conditions (time-on-stream, temperature, W/F(CO + H2). etc.). The 1-olefin content of the products, however, increased remarkably with increasing partial pressure of n-hexane and decreasing temperature and W/F(CO + H2). The reaction performances of the Fischer-Tropsch synthesis (FTS) in the supercritical phase fixed bed was also compared with those in the supercritical phase fluidized bed and the gas phase fixed bed. The results show that the 1-olefin content of the products in the supercritical phase fixed bed reactor was obviously higher than that in the gas phase fixed bed but slightly lower than that in the supercritical phase fluidized bed. (C) 2004 Elsevier B.V. All rights reserved.