Fe/Mn oxide-based foams via geopolymerization process as novel catalysts for tar removal in biomass gasification

Novel ceramic foams loaded with Fe and Fe/Mn oxides were developed via geopolymerization process as catalysts for tar removal in syngas cleaning operations. The foams were realized through polymer scaffold template replica, by impregnating polyurethane or cellulose foams with a metakaolin based geopolymer slurry loaded with 19 wt.% powdered Fe2O3 and Mn2O3 metal oxides. A thermal treatment up to 900° C was applied to vitrify and partially crystallize into leucite the geopolymer binder. Foams from cellulose showed better structural properties compared to those from polyurethane. Preliminary test in real gasification conditions were carried out on a lab scale double fixed bed reactor. In working conditions, vitrified phases derived from geopolymer binder promoted the formation of mixed phases of (Fe, Mn) oxides and silicates, beneficial for improving the catalytic activity. Furthermore, foams loaded with mixed Fe-Mn oxides were more effective than granules in reducing the produced tar.