Highly effective cobalt catalyst for wax production in Fischer-Tropsch synthesis

Fischer-Tropsch synthesis (FTS) was carried out in a fixed bed reactor with a highly effective cobalt catalyst for wax production. The procedure for reducing the inactive cobalt oxide to the active cobalt catalyst was examined by X-ray diffraction (XRD) and temperature-programmed reduction (TPR). The results showed that 300 ml/min H(2) at 350 degrees C for 16 h was suitable for reducing the inactive Co oxides to active metallic Co sites. In the case of the powder and pellet type cobalt catalysts with a reactant (H(2)/CO = 2:1) flow rate of 15 g(cat) min L(-1), catalyst deactivation occurred as a result of mass transfer limitations of the hydrocarbon and water produced on the catalyst. On the other hand, the pellet type cobalt catalyst with a reactant flow rate of 45 g(cat) min L(-1) showed activity not only for liquid hydrocarbon (C(5+)) formation but also for gas product (CH(4) and CO(2)) formation. In particular, the methane yield reached almost 20% due to heat transfer limitation in the catalyst. Considering the heat and mass transfer limitations in the cobalt catalyst, a Co-foam catalyst with an inner metallic foam frame and an outer cobalt catalyst was developed. SEM-EDS Co-mapping revealed the cobalt atoms to be distributed equally over the surface of the Co-foam catalyst. The Co-foam catalyst was highly selective toward liquid hydrocarbon production and the liquid hydrocarbon productivity at 203 degrees C was 52.5 ml kg(cat)(-1) cat h(-1), which was higher than that by the Co-pellet. In addition, the chain length probability, alpha, by the Co-foam catalyst was 0.923 and wax formation was especially favored. (c) 2009 Elsevier Ltd. All rights reserved.