Abstract

The reduction pathway of Co catalysts supported on untreated SiO₂ along with two pretreated SiO₂ support materials was investigated. In situ XRD studies clearly showed the likely reduction pathways of the cobalt oxides on the untreated SiO₂, ethylene glycol pretreated SiO₂, and annealing pretreated SiO₂ supports. Ethylene glycol pretreated SiO₂-supported Co (Co/E–SiO₂) catalyst showed smaller metal crystallites, highly dispersed Co and high Co(hcp)/Co(fcc) ratio because of the high percentage of non-H-bonded silanols; however, the high percentage of the non-H-bonded silanols created a strong Co-SiO₂ interaction which caused a low degree of reduction of CoO resulting in lower FT activity. In contrast, the annealing pretreated SiO₂-supported Co (Co/A–SiO₂) catalyst did not significantly increase the percentage of non-H-bonded silanols and Co(hcp)/Co(fcc) ratio when compared with Co/E–SiO₂, but it exhibited a better catalytic activity during FTS.

摘要

_{研究了负载在未处理的 SiO 2}以及两种预处理的 SiO ₂载体材料上的 Co 催化剂的还原途径。原位XRD 研究清楚地显示了钴氧化物在未处理的 SiO ₂、乙二醇预处理的 SiO ₂和退火预处理的 SiO ₂载体上的可能还原途径。乙二醇预处理的 SiO ₂负载的 Co (Co/E–SiO ₂ ) 催化剂显示出较小的金属微晶、高度分散的 Co 和高 Co(hcp)/Co(fcc) 比，因为非氢键硅醇的百分比很高；然而，高百分比的非氢键硅烷醇产生了强 Co-SiO ₂导致 CoO 低程度还原的相互作用导致较低的 FT 活性。相比之下，与 Co/E 相比，退火预处理的 SiO ₂负载的 Co (Co/A–SiO ₂ ) 催化剂没有显着增加非氢键合硅醇的百分比和 Co(hcp)/Co(fcc) 比–SiO ₂，​​但它在费托合成过程中表现出更好的催化活性。