Alkali-Feldspar as a Catalyst for Biomass Gasification in a 2-MW Indirect Gasifier

The aim of this work was to investigate the potential of alkali-feldspar ore [(K, Na)AlSi3O8] as an alternative bed material for indirect gasification of biomass. Experiments conducted in the Chalmers 2-MW gasifier confirmed that alkali-feldspar could withstand stringent fluidizing conditions. Moreover, this material showed strong promise for promoting the water gas shift reaction and reforming higher hydrocarbons, in particular tars. This activity was enhanced by time-on-stream in the indirect gasifier, and the gas and tar yields were higher than for activated olivine or bauxite used in the same unit. SEM-EDX analysis revealed that the Observed activity of alkali-feldspar was due to the formation of active ash layers on the feldspar particles (consisting principally of Ca, Mg, K, and Na) that originated from the woody fuel. At some point, the feldspar showed capacity to transport oxygen from the boiler to the gasifier. Thus, an optimal level of bed regeneration would benefit the reforming reactions in the gasifier, while creating the possibility to improve fuel conversion in the boiler through increased access and distribution of oxygen, which is transported by the bed material throughout the boiler