Influence of Pyrolysis Parameters and CaCl2 Catalyzer on Pyrolysis of Elephant Grass (Pennisetum purpureum Schum.)

Elephant grass is a fast growing and low nutrient demand plant with significant potential as a renewable energy source. In this work, the influence of heating temperatures, N₂ sweeping gas flow rates and CaCl₂ catalyzer weights on the yields of products and chemical composition of bio-gas was investigated by pyrolysis and catalytic pyrolysis of elephant grass in a fixed bed reactor. The results showed that as the heating temperature increased, the yield of charcoal decreased, while bio-gas and bio-oil increased. The concentration of CO₂ decreased 20 vol.% at the heating temperature of 600°C than that at 350°C and the concentration of CO reached 25 vol.% in 600°C. With the flow rate of N₂ sweeping gas risen, high yield of bio-oil, low yield of bio-gas and high concentration of CO₂ were gained. CaCl₂ had an obvious catalytic effect on elephant grass pyrolysis, and the low level of CaCl₂ (less than 15.4 wt.%of grass weight) evolved high yield of charcoal. The high level of CaCl₂ doping was helpful to evolve the degree of decomposition and improve the yield of bio-oil, but had a slight effect on the chemical composition of bio-gas.