Catalytic Gasification of Coconut Shell for Producer Gas Yield Improvement: An Optimization Study with the Response Surface Methodology Approach

Catalytic biomass gasification is gaining momentum due to enhanced producer gas yield and effective tar cracking. In this study, coconut shell (feedstock) and calcium oxide (catalyst) were used in a downdraft biomass gasifier to determine optimal conditions through the Response Surface Methodology (RSM) approach, aiming for better gas generation. Waste chicken eggshells-based calcium oxide (CaO) was used as catalyst to evaluate its effectiveness in achieving improved producer gas yield and fuel quality. In optimization, the effect of two key process variables viz., equivalence ratio (0.2-0.3) and CaO loading (5-30 wt.%) were assessed on producer gas and its hydrogen content. The catalyst has more significant effect on final product yield than equivalence ratio. The maximum producer gas yield was achieved as 2.4 m³ kg^-1 during catalytic gasification process with optimized conditions of equivalence ratio of 0.25 and catalyst loading of 29.14%. The tar removal efficiency was found to be 83.7%. Additionally, it was observed that the hydrogen content was significantly enhanced (30.86%) in catalytic gasification compared to non-catalytic gasification (12.74%) under optimal process conditions.