Catalytically upgraded landfill gas as a cost-effective alternative for fuel cells
"The potential use of landfill gas as feeding fuel for the so called molten carbonate fuel cells (MCFC) imposes the need for new upgrading technologies in order to meet the much tougher feed gas specifications of this type of fuel cells in comparison to gas engines. Nevertheless, MCFC has slightly lower purity demands than low temperature fuel cells. This paper outlines the idea of a new catalytic purification process for landfill gas conditioning, which may be supposed to be more competitive than state-of-the-art technologies and summarises some lab-scale results. This catalytic process transforms harmful landfill gas minor compounds into products that can be easily removed from the gas stream by a subsequent adsorption step. The optimal process temperature was found to be in the range 250-400 °C. After a catalyst screening, two materials were identified, which have the ability to remove all harmful minor compounds from landfill gas. The first material was a commercial alumina that showed a high activity towards the removal of organic silicon compounds. The alumina protects both a subsequent catalyst for the removal of other organic minor compounds and the fuel cell. Due to gradual deactivation caused by silica deposition, the activated alumina needs to be periodically replaced. The second material was a commercial V2O5/TiO2-based catalyst that exhibited a high activity for the total oxidation of a broad spectrum of other harmful organic minor compounds into a simpler compound class "acid gases (HCl, HF and SO2)", which can be easily removed by absorption with e.g. alkalised alumina. The encouraging results obtained allow the scale-up of this LFG conditioning process to test it under real LFG conditions."