Cobalt supported on Graphene – A promising novel Fischer–Tropsch synthesis catalyst
•Functionalized CNTs and graphene were used as Cobalt Fisher–Tropsch synthesis catalyst support.•Graphene increased the reduction degree, and dispersion of cobalt particles.•Graphene increased the FTS rate and %CO conversion significantly.•Catalysts supported on graphene showed better stability.
Graphene and CNTs-supported cobalt catalyst, is introduced for Fischer–Tropsch synthesis (FTS). The catalysts were prepared using wet impregnation method with cobalt loading of 15.0 wt%. The catalysts were characterized by TGA, BET, XRD, XPS, H2 chemisorption, TPR, and TEM techniques. The activity, selectivity and stability of the catalysts in FTS were assessed in a fixed-bed micro-reactor, and the results were compared with each other. Comparing TEM images showed dispersion of cobalt clusters in graphene-supported catalyst is higher and the average clusters size decreased from 7.5 to about 6.0 nm. Graphene as the support shifted the reduction temperature of cobalt oxide species to lower temperatures. Degree of CO conversion increased from 61 to 74%, FT synthesis rate increased by about 22%; the product distribution shifted to the higher molecular weight hydrocarbons, compared to CNTs-supported catalyst. On the graphene-supported cobalt catalyst, 480 h continuous FT synthesis decreased 22% of the initial CO conversion. However, at the same time for CNTs-supported catalyst the CO conversion decreased 34%.
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Journal: Applied Catalysis A: General - Volume 499, 25 June 2015, Pages 188–196