Preparation of a biochar with a high calorific value from chestnut shells

The recovery of biomass provides a solution for solving the energy shortage problem. Chestnut shells consist of cellulose, hemicellulose and lignin, and have a low calorific value. We propose a method to produce a biochar with a high calorific value from chestnut shells by catalytic pre-oxidation and pyrolysis with sulfuric acid and urea. The pyrolysis behavior and the changes in structure and properties were investigated. Results indicate that the catalysts slow the pyrolysis reaction, leading to a high-quality char. The carbon content and calorific value are related to the pyrolysis temperature. When the chestnut shells are pyrolyzed at 750 °C, the yield and calorific value of the char are 44.31 wt% and 35.48 MJ/Kg, respectively. The calorific value of the char is higher than that of first-level cleaned coal (30.00 MJ/Kg).