2022 Annual Meeting
Impact of Pyrolysis Temperature on Enthalpy of Reaction in the Production of Biochar
Biochar can be used as a method to remove carbon dioxide from the air, via Pyrogenic Carbon Capture and Storage (PCCS). Biochar is typically produced from organic wastes that are heated in an oxygen-deficient environment. This reaction is known as pyrolysis. In this study, we investigate the enthalpy of the pyrolysis reaction, at conditions typically used for PCCS. Time-temperature curves were used to determine the enthalpies of reaction and to approximate reaction times for walnut shell pyrolysis at different pyrolysis temperatures. Moisture was found to greatly influence the time-temperature curves, and thus samples were pre-dried by vacuum-pump desiccation. Walnut shell pyrolysis was determined to be exothermic when the reaction took place under 500 °C, and endothermic when it took place above 500 °C. Although the change in endothermicity of the walnut shell pyrolysis appears to be linear at temperatures higher than 600 °C, the reaction was also found to exhibit an unexpected jump in endothermicity between 500 °C and 600 °C. These findings hint at a change in the reactions associated with the pyrolysis of walnut shells between 500 °C and 600 °C.