Characterization and Reactivity Study of Coal Bottom Ash for Utilization in Biomass Gasification as an Adsorbent/Catalyst for Cleaner Fuel Production

The objective of this study is to determine the catalytic potential and adsorption characteristics of coal bottom ash (CBA) for utilization in biomass gasification for cleaner fuel production. The analysis shows the presence of metals such as Fe, Al, Ca, and Mg in CBA that have been used as common elements of catalysts in gasification. The surface of CBA is porous and consists of irregular shape particles and crystalline structure determined using characterization techniques. The surface area (51.02 m²/g), pore volume (0.1 cm³/g), and pore width (3.03 nm) of CBA were determined using Brunauer-Emmett-Teller analysis. The reactivity of CBA in a CO₂ environment at 500, 600, 700, and 800 °C is measured through thermogravimetric analysis, and variation in chemical composition of all metal oxides and CaO is measured after CO₂ treatment. The CBA adsorbs about 1.15 and 1.51 wt % of CO₂ at 25 and 60 °C in high-pressure volume adsorption tests. The highest weight loss of about 14% occurs at a heating rate of 10 °C/min in a N₂ atmosphere. Thermal analysis confirms its stability at a high temperature above 600 °C, which is a good sign for its utilization as a catalyst as gasification mostly takes place between 600 and 1100 °C. In biomass steam gasification, the H₂ production is increased from 29.29 to 36.24 vol % with the use of CBA at a temperature of 700 °C and steam/biomass ratio of 0.5. It shows the potential of the cleaner and sustainable utilization of CBA.