A series of Co/SiO2 catalysts with different sodium （Na）loadings （0, 0.1, 0.2, 0.5 and I wt%） were prepared and evaluated for Fischer-Tropsch reaction to study the effect of Na on the catalyst structure and cataly...A series of Co/SiO2 catalysts with different sodium （Na）loadings （0, 0.1, 0.2, 0.5 and I wt%） were prepared and evaluated for Fischer-Tropsch reaction to study the effect of Na on the catalyst structure and catalytic performance. The addition of Na was found to decrease the catalytic activity and hydrocarbon selectivity, but increase CO2 selec- tivity due to the enhanced WGS activity. The addition of Na also resulted in higher selectivity to oxygenates （alco- hols and aldehydes） and O/P ratio as well as the shift of hydrocarbons to lower carbon numbers. Structure charac- terization revealed a decrease in the surface area and particles size for the calcined samples with the addition of Na. CozC was formed during the reaction process for the Na-promoted catalysts. As a result, a new Co/Co2C bifunc- tional active sites were generated for oxygenates formation leading to increasing oxygenates selectivity. In addition, the Co2C nanoparticles alone may also act as dual active sites for oxygenate formation at high reaction pressure over the promoted catalysts with high Na loading.展开更多
基金This work has been supported by the National Natu- ral Science Foundation of China （Nos. 91545112, 21573271, 21403278）, Shanghai Municipal Science and Technology Commission, China （No. 15DZ1170500）and the Chinese Academy of Sciences （No. QYZDB- SSW-SLH035, Youth Innovation Promotion Association）.
文摘A series of Co/SiO2 catalysts with different sodium （Na）loadings （0, 0.1, 0.2, 0.5 and I wt%） were prepared and evaluated for Fischer-Tropsch reaction to study the effect of Na on the catalyst structure and catalytic performance. The addition of Na was found to decrease the catalytic activity and hydrocarbon selectivity, but increase CO2 selec- tivity due to the enhanced WGS activity. The addition of Na also resulted in higher selectivity to oxygenates （alco- hols and aldehydes） and O/P ratio as well as the shift of hydrocarbons to lower carbon numbers. Structure charac- terization revealed a decrease in the surface area and particles size for the calcined samples with the addition of Na. CozC was formed during the reaction process for the Na-promoted catalysts. As a result, a new Co/Co2C bifunc- tional active sites were generated for oxygenates formation leading to increasing oxygenates selectivity. In addition, the Co2C nanoparticles alone may also act as dual active sites for oxygenate formation at high reaction pressure over the promoted catalysts with high Na loading.
