Cu、K助剂对FeMn/SiO2催化费托合成的影响

研究了Cu、K助剂对共沉淀型FeMn/SiO2催化剂还原行为、吸附行为及费托(F-T)合成活性和选择性的影响. Cu助剂以与Fe、Mn、SiO2共沉淀的方式引入, 而K助剂是在喷雾干燥前均匀加入沉淀浆料引入的. 结果表明, Cu可明显提高催化剂的还原性能, K助剂能促进催化剂在CO中的还原但抑制在H2中的还原, 而同时加入Cu和K会进一步促进催化剂在H2或CO中的还原; Cu助剂能促进H2吸附而K助剂对H2吸附无明显影响; Cu在一定程度上提高了F-T合成活性, 缩短了反应诱导期, K明显促进了CO的转化而相对抑制了H2的转化, 并且延长了反应的诱导期, Cu与K协同作用不仅提高反应的转化率而且缩短了反应的诱导期; K使得烃产物平均分子量增加, Cu单独对烃产物分布影响不明显, 而与K共同作用会进一步增加烃产物的分子量.

Effects of Cu and K on Co-precipitated FeMn/SiO2 Catalysts for Fischer-Tropsch Synthesis

The effects of copper and potassium on the activity and selectivity of coprecipitated Fe-Mn/SiO2 catalysts for Fischer-Tropsch (F-T) synthesis were studied in a slurry phase continuous stirred tank reactor. The reduction and adsorption behaviors of the catalysts were investigated using temperature programmed reduction/temperature programmed desorption (TPR/TPD) methods. It was found that copper improves the reduction of the catalyst in H2 or CO. Potassium improves the reduction of the catalyst in CO, whereas it suppresses the reduction of the catalyst in H2. Copper enhances the H2 adsorption, whereas potassium has no influence on the H2 adsorption. In the F-T synthesis reaction, copper shortens the induction period required for reaching the steady state activity, whereas potassium prolongs the induction period. The potassium promoter increases the activity and decreases the selectivity of methane. The promotion effects of Cu and K on the activity and selectivity is more obvious than that of Cu, that is, the activity is higher and the methane selectivity is lower on the doubly promoted catalyst.