Catalytic torrefaction effect on waste wood boards for sustainable biochar production and environmental remediation

Wood boards used in construction are generally treated with toxic chemicals, making them unsuitable for further use and causing environmental pollution. This study evaluates the possibility of using catalytic torrefaction as a pretreatment to improve wood pyrolysis and combustion for greener biochar production. Waste beech boards were impregnated with different K₂CO₃ solutions (0-0.012 M), then torrefied between 5 and 60 min at 275 °C. The ICP-AES showed that the board's surface held more potassium than the core. Torrefaction coupled with potassium decreased the C-O and -OH stretches. Thermogravimetric analysis of torrefied wood showed that the board's internal heating degraded the core more than the surface. The exothermic reactions made potassium's catalytic action more efficient in the core. Interactions between the potassium content and torrefaction duration decreased the pyrolysis' maximum devolatilization temperature. During combustion, potassium decreased the ignition temperature by up to 9% and 3% at the surface and core, respectively, while the torrefaction increased it. The catalytic torrefaction significantly decreased the devolatilization peak during combustion, thus making the wood's combustion similar to that of coal, having only the char oxidation step. These findings highlight the advantages and challenges of waste wood's catalytic-torrefaction for biochar production to reduce environmental pollution.