Fischer–Tropsch synthesis: EXAFS study of Ru and Pt bimetallic Co based catalysts

Co/Ru and Co/Pt bimetallic catalysts supported on silica prepared by successive impregnation were characterized, in particular with EXAFS spectroscopy, and tested in Fischer Tropsch synthesis reaction. Both the CO conversion and the total yield towards desired products were tripled thanks to the action of low amount (0.5 wt%) of noble metal. Different interactions of the two noble metals with cobalt in bimetallic catalysts (BMCs) were demonstrated by EXAFS. Ru1−yCoy solid solutions with hexagonal close packed structure form were identified with y in the 0.1–0.23 range for all the concentration of noble metal. In the Co/Pt BMCs the structure of Pt containing phase is strongly dependent on Pt amount. Co and Pt form the intermetallic compound PtCo for low Pt amount (0.1%) with a face centered tetragonal structure. Differently for the sample with higher loading of Pt (2%) the EXAFS spectrum could be fitted using the a structural model derived from the close packed cubic structure of Pt.