Supported Iron-Based Catalysts For The Efficient Synthesis Of Lower Olefins From The Hydrogenation Of Carbon Monoxide

As the key chemical building blocks, lower olefins are extensively applied in industry and its demand increases year by year at present. Accordingly, it becomes increasely significant to develop alternative routes to produce lower olefins. Currently, the Fischer-Tropsch synthesis of lower olefins (FTO) is a promising route to produce the C2 to C4 olefins from the hydrogenation of carbon monoxide. Iron-based catalysts are widely used due to its strong dissociated capability of carbon monoxide and hydrogen. However, the still low selectivity to desired lower olefins is the most challenging problem, which is always limited by the strong capability of carbon chain growth and hydrogenation of the active sites at the surface.In connection with the challenge of low selectivity to desired lower olefins, the adsorption properties of carbon monoxide and the capability of carbon chain growth and hydrogenation was changed by means of controlling the microscopic structures of active center with different design ideas. As a result, the catalytic properties of the supported iron-based catalysts would be improved. The design ideas and achievements of this paper are as follows:1. Improved the dispersion of the active center. When aluminum was introduced into the Fe-MgO catalyst, the interaction between active metal and carriers would be increased. Simultaneously, the dispersion of the active center will be improved, which resulted in a higher conversion of carbon monoxide.2. The Fe-MgAl-LDO catalysts with different particle sizes was synthesized by changing the reduction temperature of the catalyst precursors. The adsorption properties and dissociated capability of carbon monoxide would be strengthened with the increase of particle sizes, which could improve the reaction activity and conversion of carbon monoxide.3. When another metal (such as Cu, Ce, Pt, Mo) was introduced, the geometry or electronic structure could be changed, which inhibited the capability of carbon chain growth and hydrogenation. Consequently, the selectivity to light olefins would be improved.