Effect of K and P On Rh Catalysts for Autothermal Reforming

K and P are alkaline and acidic inorganics found in biomass. Rh-based catalysts have been shown to autothermally reform lignocellulosic biomass containing low concentrations of inorganics to syngas with high selectivities at high temperatures (600-1000 °C). The acidity and alkalinity of K and P respectively can have an effect on biomass processing by altering catalyst activity thereby affecting the product distribution. To understand the effect on the chemistry of catalytic gasification over Rh-based catalysts, K and P were added to the catalyst at different loadings and their effect was examined over methane and ethanol. In addition, to understand their effect in presence of each other, the effect of doping the catalyst with potassium phosphate monobasic was also studied. Methane represents a fuel with negligible homogenous chemistry at the temperatures involved whereas ethanol represents a simple surrogate for biomass. For both fuels, the baseline performance was measured with an undoped catalyst and was with the performance of the catalyst after doping with inorganic precursors. Potassium doped catalysts showed volatilization of potassium with temperature whereas phosphorus doped catalyst showed influence of phosphorus chemistry even at higher temperatures. Phosphorus also strongly decreased hydrogen selectivity with both fuels. Catalysts were characterized by SEM and XRD to study changes in microstructure and crystallite formation respectively.