The role of carbon deposition on precious metal catalyst activity during dry reforming of biogas

A preliminary investigation into the dry reforming (synthesis gas production) of landfill gas (LFG) was performed using precious metal catalysts. Thermogravimetric analysis work was performed on the dry reforming reaction over 0.5% Pt/γ-Al2O3 catalysts. Variables such as reforming temperature, CO2 concentration, and the effect of pre-reduction have been studied. It was found that reforming at 900 °C with pre-reduction gave the most H2 production for reactant gas concentrations similar to LFG. However, at this high temperature there was significant weight gain measured. EDX analysis and follow up oxidation tests confirmed that it was due to carbon deposition on the catalyst surface. Yet, this weight gain, up to 24% in some cases, did not coincide with a decrease in catalyst activity as was the case for the lower temperature tests. One possible mechanism for this is the onset of the carbon gasification (Boudouard) reaction at high temperatures. For increased CO2 concentrations, the activity of the catalyst at high temperatures was maintained (high production of syngas) despite significant carbon deposition.