Calcium loading during the dewatering of wet biomass in kerosene and catalytic activity for subsequent char gasification

This paper describes a novel approach for upgrading biomass fuels with high water content for gasification, using an oil-slurry dewatering (OSD) process and wet coffee grounds (CG) as a feedstock. The point of novelty is that calcium loading is carried out during the dewatering of wet CG in kerosene. The present work is focused on characterizing the dispersion state of calcium and its catalytic activity for subsequent char gasification. XRD and CO2 chemisorption techniques have been applied to access the crystallite characteristics of calcium species in OSD-upgraded CG samples and their derived chars. The results obtained show that, for calcium loadings lower than 3 wt%, calcium highly disperses into the CG matrix under dewatering condition, and its catalytic activity for char gasification is comparable to that obtained by impregnation with an aqueous solution of calcium acetate. The results conclude that the dewatering process can provide an effective and practical catalyst loading procedure for biomass fuels with high water content. On the other hand, calcium loadings higher than 3 wt% give raise to poor dispersion in terms of significant decrease in the external surface area of the catalyst, being no longer proportional to the catalytic activity for char gasification.