Geopolymer composites for the catalytic tar reforming of biomass-derived gas

Biomass gasification is a proven and effective technology for the production of syngas from renewable sources, due to its fast conversion rate and large feedstock flexibility. However, its main drawback is the formation of tar, which consists of a complex mixture of condensable hydrocarbons. Tar issues are related to its carcinogenic nature and to its condensation at temperature below 350°C, which causes critical problems in the equipment downstream the gasifiers, as fouling and plugging, and a general efficiency loss. Traditional tar cleaning procedures represent an intolerable cost for the process, since they require an additional waste disposal or an excessive amount of energy. Differently, catalytic conversion allows upgrading of tar into useful gases rather than only separating it into waste products [1]. In this work a new class of catalysts for tar reforming is presented, which consists of an active metal oxide embedded into a geopolymer (GP) matrix. Fe2O3 and Mn2O3 were considered as active phases, due to their low cost, large availability and environmental friendliness. The geopolymer matrix allows a low temperature, easy and green synthesis by alkaline activation of alumino-silicate precursors. Moreover it combines a diffused meso-porosity and a high surface area to substantially high mechanical strength, abrasion resistance and stability to temperature up to 1000°C [2]. The combination of these properties makes the produced composites optimal candidates for the catalytic application