Valorization of char from biomass gasification as catalyst support: preliminary results of Fischer-Tropsch tests

Char, a carbonaceous solid residue derived from biomass gasification, exhibits remarkable properties very similar to activated carbon (AC) and potentially it could replace it in many applications. In particular, this study investigates the feasibility of using char from commercial biomass gasifiers as catalyst support for the Fischer-Tropsch (FT) synthesis. 20% Co-based catalysts supported on char and on a commercial AC selected as reference, were prepared through incipient wetness impregnation and characterized through elemental analysis, physisorption analysis, thermogravimetric analysis, XRD and SEM techniques. Both catalysts were tested for 25 h in a fixed bed reactor operating at 240 °C, 16 bar, H2/CO = 2 and 3600 mL g-1 h-1. The AC-based catalyst proved to be more active than the char-based one. The CO conversion measured using char as support (2.6 % average value) was very low compared to the one measured using AC (27.68 % average value). Only hydrocarbons in the range of C1-C4 could be detected for the char-based catalyst, while also hydrocarbons in the range of C5-C10 could be detected for the AC-based one. The dissimilarities in the catalyst performances are mainly attributed to the intrinsic differences between the two catalysts in terms of thermal and structural stability, and porosity development.