助剂对Co／HMS催化剂结构和F-T合成性能的影响

详细研究了钍、锆、锗及铈助剂对钴质量分数为15％的Co／HMS催化剂结构、 F-T合成CO转化率、CO2选择性及烃分布的影响，结果表明：钍能适当提高F-T合成 活性，且低温下具有较强的链增长能力；锆、锗、铈降低了催化剂CO转化率，催化 剂加氢能力变强，导致低碳烃增加较快，汽柴油馏分段减低，相应的链增长能力降 低，并以锰和铈较为明显；XRD，TPR及TG表征表明：锆和铈可提高催化剂Co还原度 ，但F-T合成反应时金属Co易披氧化，反应中金属Co量明显减少，CO转化率降低， 并以铈最为显著；Th助催化剂Co还原度稍有减低，Co分散度高于Co／HMS，且反应 中金属Co较为稳定，Co转化率得以提高；添加Mn助剂后，催化剂难以还原，反应中 活性相金属Co量较小，CO转化率较低．

Characterization and Fischer-Tropsch Synthesis of Th, Zr, Mn, Ce Promoted Co/HMS Catalysts

Characterization and Fischer-Tropsch synthesis (FTS) under classical reaction conditions for Th, Zr, Mn, Ce promoted Co/HMS catalysts were investigated. The FTS activity order was found to be: Co-1.5Th/HMS > Co/ HMS>Co-1.5Zr/HMS>Co-1.5Mn/HMS>Co-1.5Ce/HMS under the conditions of H2/CO = 2.0, T = 463 ~ 523 K, p = 2.0 MPa, GHSV = 500 h"!, which was owing to the lower cobalt reducibility for Mn promoted Co/HMS and the cobalt oxidation at the beginning of FTS for Zr and Ce promoted Co/HMS despite their higher cobalt reducibility. The highest CO2 selectivity was obtained for Mn and Ce promoted Co/HMS among all the catalysts, so the H2/CO ratio on the catalyst surface increased during FTS in contrast with Co-1.5Th/HMS, Co/HMS and Co-1. 5Zr/HMS. The increasing surface H2/CO ratio led to higher hydrogenation ability, which was further confirmed by low olefin and paraffin ratio from hydrocarbon distribution for Mn and Ce promoted Co/HMS catalysts. High hydrogenation ability for Co-1.5Mn/HMS and Co-1. 5Ce/HMS presented the high methane and low chain propagation.