Catalyzed pyrolysis of SRC poplar biomass. Alkaline carbonates and zeolites catalysts

Abstract

Poplar biomass of nine different genotypes, from short rotation coppice, was pyrolyzed in a fixed bed reactor using several solid catalysts. Pine bark was used as reference for uncatalyzed pyrolysis. Pyrolysis tests were performed for temperatures in the range 425–500 °C, selected from the thermal degradation profiles obtained by thermogravimetry under N2 flow. All the analyzed poplar genotypes showed similar pyrolysis behavior, with the highest bio-oil yield (53% average value) being obtained for the highest tested temperature (500 °C). In analogous conditions, the pine bark resulted in higher bio-char yields than poplar biomass, due to its larger lignin content.Catalyzed pyrolysis carried out at 500 °C using 10% of catalyst (Wcat/Wbiomass) for H-ZSM5 and FCC (spent catalyst from Fluid Catalytic Cracking unit) zeolites, and Mg and Na carbonates, showed improved gasification with slightly lower liquid production. The FCC catalyst promoted the lowest depreciation of bio-oil yield with the highest decrease of acid functional groups. All the used catalysts were effective to lessen the acidic components of the produced bio-oils thus having a beneficial effect on the pyrolysis liquid products.