| In order to solve the problems of large particle size,agglomeration and low dispersion in the preparation of high loading cobalt based Fischer Tropsch catalyst,this paper aims to develop a preparation method of high loading cobalt based Fischer Tropsch synthesis catalyst Sol-gel carbonization oxidation method,which can obtain small size,high dispersion and high reduction degree nano cobalt particles at the same time of increasing metal loading.The main conclusions are as follows(1)Using cobalt nitrate as cobalt source,tetraethyl orthosilicate as silicon source,glycine as crosslinking agent,combustion supporting agent and C,N precursor,a series of Co/SiO2-SCM catalysts were prepared by Sol-gel carbonization oxidation method(SCM)by changing the carbonization temperature and heating rate.The effects of carbonization heating rate and pyrolysis temperature on catalyst structure,particle size,dispersion and reduction degree of cobalt species,catalytic activity and product distribution of Fischer-Tropsch synthesis were systematically studied.The results showed that when the carbonization temperature was 400? and the heating rate was 5?/min,the dispersion of the catalyst was 10.7%,and the particle size was controlled at 5.6 ± 1.4 nm.Under the optimal conditions of P=1.0 MPa,T=210?,GHSV=14.4 L·g-1cat·h-1 and CO/H2=1/2,the CO conversion rate is 63.56%and the CTY is 8.96×10-5molco·g-1Co·s-1.In addition,the catalyst has excellent stability,and there is no obvious deactivation phenomenon after continuous reaction for 100 h.(2)On the basis of the above optimized catalysts,MnOxpromoter was introduced to prepare Co-Mn/SiO2-SCM catalysts with different Mn/Co molar ratios.The effects of MnOxpromoter on the catalyst structure,catalytic activity and product distribution of Fischer-Tropsch synthesis were studied.The results show that the addition of a small amount of MnOxcan further improve the catalytic activity,inhibit the selectivity of methane and improve the selectivity of C5+. |
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