Effect of copper on highly effective Fe-Mn based catalysts during production of light olefins via Fischer-Tropsch process with low CO2 emission

摘要

The effect of Cu on Fe-Mn based catalysts system in production of light olefins via Fischer-Tropsch process was investigated. Catalysts with different Cu loadings were synthesized and evaluated. The 3.0 wt% Cu promoted Fe-Mn catalyst demonstrated an activity as high as 3.58x10(-6) mol(CO) g(cat)(-1) s(-1). The corresponding conversion of CO and selectivity to light olefins are 96.9 % and 40.1 %, respectively. Characterization results indicated that the Cu promoter facilitated the reduction process and enhanced the H-assisted CO dissociative adsorption, by changing the interactions between metals and the SiO2, which lead to an improved activity. The overall weakened surface basicity caused by Cu decreased the chain growth probability and lead to a higher selectivity to light olefins by shifting the product distribution toward short-chain hydrocarbons. Furthermore, all prepared catalysts showed superior efficiency of carbon utilization with CO2 selectivity as low as 23.0 % due to the hindered water-gas shift (WGS) reaction.