Synthesis and characteristics of MCM-41 supported CoRu catalysts

Supported CoRu catalysts have been prepared with ordered mesoporous silica (MCM-41) as the support using the incipient wetness impregnation method in order to study the effect of ordered mesoporous silica and pore size on cobalt dispersion, reduction behavior, and catalytic properties for the Fischer–Tropsch synthesis (FTS). Metal loadings of 2, 5, 8, and 14 wt.% Co with 0.5 wt.% Ru were investigated, as well as two different mesoporous silicas having average pore diameters of 3 and 7 nm. For comparison purposes, conventional amorphous silica (SiO2) supported CoRu catalysts were also prepared using the same procedure. Due probably to higher concentration of water vapor in the small pores of MCM-41 during metal reduction, CoRu/MCM-41 catalysts showed stronger interaction of Co with the support than CoRu/SiO2 as manifested by lower reducibilities of the catalysts during standard reduction. The Co dispersions were similar on MCM-41 to that on amorphous silica for a given Co loading. MCM-41 supported catalysts exhibited similar selectivities for FTS as to the SiO2-supported ones; however, they had in general greater activities. There was an absence of any obvious pore size effect on product selectivity, probably due to the pores being sufficiently large for the reaction to easily proceed at 1 atm and 220 °C, the reaction conditions used. Thus, MCM-41 supported CoRu catalysts appear to be suitable for application to FTS. Their unique and tailored properties offer interesting possibilities for catalyst design and application in particular cases.