Catalytic performance of Iron-based catalyst in Fischer-Tropsch synthesis using CO2 containing syngas

摘要

This paper focuses on the catalytic performance of iron-based catalyst in Fischer-Tropsch Synthesis (FTS) using CO2 containing syngas. The catalysts were prepared by incipient wetness impregnation method of silica with solution of iron nitrate followed by calcination in air. Physical and chemical properties of iron-based catalyst were carried out using N2 adsorption-desorption, H2-TPR, CO-TPR and TPH. The catalysts were tested in Fischer-Tropsch conditions (T = 220°C, P = 1 bar, GHSV = 300 h~(-1), H2/CO_x = 0.5). The results show that iron-based catalyst activated by CO is more active for hydrogenation than the catalyst activated by H2. The activation of iron-based catalyst by CO provides iron carbide combining with iron oxide which was reduced partially. Fe3O4 (partial reduced iron oxide) is expected to be exist in the iron-based catalyst pretreated by CO. This oxide phase allows the conversion of CO2 to CO through the reverse water-gas-shift (RWGS) reaction. Thus, iron-based catalyst activated by CO is a candidate catalyst for FTS using CO2 containing syngas. Fe3O4 enhances RWGS activity while iron carbide is effective for the hydrogenation. The different product distributions of H2-CO, H2-CO2 and H2-CO-CO2 mixtures are due to the different reaction pathway of CO and CO2. The key of reaction pathway is the active site generated from pretreatment method.