TG-FTIR analysis of pecan shells thermal decomposition

The thermal decomposition of pecan shells within the temperature range of 30 °C to 800 °C and at heating rates of 5 to 30 °C/min was studied by the use of TG-FTIR. Friedman's isoconversional method was used for kinetic analysis of the thermal decomposition process. Differential scanning calorimetry was also used to quantify the amount of energy required to thermally degrade pecan shells. The thermal decomposition process was found to compose of four stages—moisture evaporation, hemicelluloses decomposition, cellulose decomposition and lignin degradation. The peak temperatures for hemicelluloses (275 to 315 °C) and cellulose (348 to 385 °C) degradation increased with heating rate. The major gases given off were identified to be carbon dioxide, carbon monoxide, acetic acid and ethanol. The amount of energy required to thermally degrade pecan shells was about 30% of the energy content of the shells.

► The rate and kinetics of thermal decomposition of pecan shells was modeled.
► Thermal decomposition activation energy was estimated to be 177 to 193 kJ/mol.
► FTIR was used to quantify the amount of gases evolved during thermal decomposition.
► Energy for thermal degradation was 30% of the energy content of pecan shells.