Biomass fly ash granules as a promising catalyst to promote producer gas quality from residual forest biomass steam gasification

In the present study, industrial biomass fly ash (BFA)-based materials were successfully used as in-situ low-cost catalysts during biomass steam gasification in a bench-scale bubbling fluidised bed reactor, aiming to improve producer gas quality. BFA was used in three forms: (i) granulated (G BFA fresh ), (ii) granulated and thermally treated (G BFA treated ) and (iii) thermally treated in its original powder form (P BFA treated ). CaCO 3 and SiO 2 were the main compounds in the G BFA fresh . Thermal treatment successfully converted CaCO 3 to CaO in G BFA treated and P BFA treated samples. All BFA-based catalysts substantially increased the H 2 concentration in the producer gas from pine gasification, in the order G BFA treated > P BFA treated > G BFA fresh > reference condition (inert material – granulated alumina). H 2 concentration increased from 40.53 %vol. dry and inert (N₂, Ar) free gas in the reference condition up to 54.12 %vol. dry and inert (N₂, Ar) free gas using G BFA treated . The richness in CaO on treated samples enhanced the water gas shift reaction. All catalysts had a major effect on the H 2 :CO molar ratio (up to 140 % increase with G BFA treated ). BFA-based materials also positively impacted the performance parameters, indicating their catalytic activity towards reforming and cracking reactions. • Biomass fly ash was granulated (G BFA ) and used as in-situ catalyst in biomass gasification. • Thermal pretreatment was studied to further improve G BFA catalytic performance. • Around 50 %vol. hydrogen content was achieved using all the produced catalysts. • Pretreated G BFA catalyst increased H 2 yield in the producer gas by up to 92 %. • With pretreated G BFA catalyst, H 2 :CO molar ratio rose 140 %, reaching as high as 3.7