Microwave-Assisted Synthesis of Fe/Co catalysts for the Fischer-Tropsch synthesis on biomass-derived syngas

In recent years, considerable efforts have been done to reduce worldwide fossil fuels dependence exploiting renewable feedstock for the production of biofuels and thus reducing greenhouse gas emission. In this context, there has been a revitalized interest for the Fischer-Tropsch synthesis (FTS) (1) applied in the valorisation of biomass for the biofuels production. In particular, improvements in the catalytic efficiency of classical Fe and Co based catalysts have been driven by the need to enhance the characteristic low H2/CO ratio of biomass-derived syngas. Under these conditions, Fe has a low FTS catalytic efficiency but is able to promote the water gas shift reaction (WGS) (2) with the result of increasing the H2 content of the reaction mixture. Cobalt shows a better catalytic activity toward medium and long chain hydrocarbons but can undergo partial deactivation/sintering at high temperature. FTS: CO + 2H2 ? -CH2- + H2O (1) WGS: CO + H2O ? H2 + CO2 (2) According to these premises, in the present work the catalytic efficiency of mono- and bimetallic Fe/Co catalysts on the FTS on biomass-derived syngas, was investigated keeping into account the effect of the metal loadings, the different supports (SiO2, TiO2 and Al2O3) and the different reaction conditions. The materials were synthesised by a microwave assisted co-precipitation procedure and tested at atmospheric pressure in a flow reactor using different H2/CO feed ratio, temperature and flow rate. The surface and structural properties of the catalysts were investigated by means of N2 adsorption isotherms (BET), temperature programmed reduction analysis (TPR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) performed on fresh and spent materials. Preliminary results show a direct correlation between the catalytic efficiency and the nature and surface area of the support used.