Characteristics of pore structure of rice husk char during high-temperature steam gasification

The characteristics of the pore structure of rice husk char during high-temperature steam gasification was investigated in a fixed bed gasifier. The raw rice husk was heated to various temperatures (600-1400 °C) to generate rice husk char. The yield of rice husk char decreases with char generation temperature. Carbon conversion rate of rice husk char after steam gasification decreases significantly with char generation temperature, which is 91.95% at 600 °C, and 52.51% at 1400 °C. The surface of the rice husk char generated at higher temperatures is rougher with more thermal etching marks. The adsorption and desorption isotherms of char and ash indicate the distribution of the pore size is relatively continuous. The desorption isotherm is greater than the adsorption isotherm at high relative pressure. The amount of adsorption and specific surface area of the rice husk char increase first and then decrease with the rise of char generation temperature. The pore structure of rice husk char is the most abundant at 1000 °C, and the specific surface area is 316 m2/g. After high-temperature (1000-1200 °C) gasification, the pore size increases, and the surface area of the rice husk ash is significantly reduced to 1-4 m2/g.