Effect of Limestone Catalyst on Production of Synthesis Gas in a Downdraft Co-Gasification of Coconut Frond and Wood Chips

The global energy demand is increasing rapidly and biomass has been identifying as one of the major renewable resources for energy which meet the growing ‘green’ inspiration. Malaysia is rich in agriculture resources that are suitable to develop into sustainable biomass fuel. Studies on lignocellulosic biomass from the residues of agriculture by product have been conduction for power generation. These studies show the capability of Malaysia’s biomass in reducing environmental pollution and in providing carbon-neutral energy generation. Throughout many years, co-gasification of lignocellulosic biomass and different fuels such as coal have been conducted for reduction of greenhouse gasses emission by coal and to increase the efficiency of the gasification. Currently, there have been studies on co-gasification of two different lignocellulosic biomass however the resulting energy content is low and improvement of the gasification process is needed. In the current work, catalytic co-gasification of coconut frond and wood chips in a laboratory-scale downdraft gasifier by limestone was investigated. The experiments were performed to identify the effects of catalyst to biomass ratio (0:1, 0.3:1, 0.5:1, and 0.7:1) on product composition, gas yield, carbon conversion efficiency and heating value. The feedstock were mixed a constant weight ratio which was 70:30; 70% of wood chips and 30% of coconut frond. The main gas species generated, as identified by the gas analyser were H2, CO, CO2 and CH4. From the result, it was shown that at 50% catalyst addition ratio, maximum hydrogen content of 11.39% v/v, carbon conversion efficiency of 69.49%, gas yield of 1.677Nm3/kg and higher heating value of 5.11MJ/Nm3. The presence of limestone catalyst was found to improve the higher heating value, carbon conversion efficiency and gas yield due to the increases in H2, CO, CO2 and CH4. In conclusion, limestone catalyst can help facilitating the reaction rate of partial oxidation and water-gas shift reaction, enhancing the quality of synthesis gas.