Fischer–Tropsch synthesis on CaO-promoted Co/Al2O3 catalysts

A series of calcium oxide promoted cobalt catalysts were prepared by incipient wetness impregnation. The influence of the calcium oxide on the dispersion, reducibility and cobalt particle size of the catalysts was studied by different techniques, including N2 adsorption, X-ray diffraction, temperature-programmed reduction, temperature-programmed desorption and oxygen titration. It was found that calcium oxide improved the cobalt oxide reducibility, especially for the reduction of CoO to Co0. Since the interaction between cobalt oxide and the calcium oxide promoted support was suppressed, larger Co3O4 particles were formed on the surface. The catalytic activity for Fischer–Tropsch synthesis was evaluated in a continuous stirred tank reactor (CSTR). A positive correlation was observed between CO conversion, C5+ selectivity and calcium oxide content. Furthermore, methane selectivity decreased with increasing calcium oxide content. These could be attributed to the enhanced reducibility that provides abundant active sites.

Graphical abstractAddition of small amount of calcium oxide promotes cobalt reducibility on alumina supported Fischer–Tropsch synthesis catalyst resulting in increased CO conversion and C5+ selectivity while methane selectivity decreased slightly.Figure optionsDownload full-size imageDownload as PowerPoint slide