Elucidating the Role of Bifunctional Cobalt-Manganese Catalyst Interactions for Higher Alcohol Synthesis

Catalyst promoters are often used to tune or improve performance with little understanding as to how they work. Here we present a fundamental evaluation of cobalt-manganese interactions in Fischer-Tropsch (FT) catalysis and evaluate a new bifunctional catalyst for CO dissociation and CO insertion mechanisms. FT has gained considerable attention recently due to the potential to convert bio or municipal waste feeds into commercial fuels and chemicals. Products are commonly highly linear paraffins, but here we show how the role of manganese can tune selectivity for linear olefins and alcohols in a copper, iron and alkali metal free cobalt bifunctional catalyst. These products also have significant commercial value for lubricants, plasticizers, detergents and base chemicals. Advanced catalyst characterization is shown with in situ techniques (XRD, EXAFS, PDF & TEM), while the FT products are fully analysed by NMR, GC and GCxGC. The role of manganese during catalyst synthesis is reviewed while fundamental understanding of the formation of a mixed metal oxide spinel is presented. The Co-Mn interactions change during catalyst reduction, with EXAFS showing cobalt metal and MnO as the main species present.