Catalytic effects on the nonisothermal oxidation of solid fuels by oxygen: an experimental study

The role played by catalysts in solid fuel reactivity toward oxygen as a viable method for reducing toxic combustion emissions was studied. Catalyst (1 wt % Pd–Sn/alumina) treated and untreated solid fuels were analyzed using thermogravimetric analysis/differential scanning calorimetry (TGA/DSC) coupled with a gas detection system at heating rates of 20–40 °C/min and airflow rates of 30–100 mL/min. The relative CO emission factors, NOx, CH4, energy output, and combustion efficiency were determined as well as values of the activation energy (Ea) and pre-exponential factor (A) for the oxidation of the solid fuels. Results showed that the catalyst treatment enhanced the energy output by more than 22% and reduced CO emission factors by up to 87%. The temperature for release of nitrogen compounds was considerably reduced; however, the amounts produced were not impacted. The combustion efficiency was also improved by up to 60%. In terms of reactivity, catalyst treatment lowered the Ea for oxidation especially at 0.2 ≤ α ≤ 0.8. Catalyst treated samples had more free active sites on their surfaces, which decreased at temperatures of >500 °C possibly due to thermal deactivation of the catalyst. This is a viable method for minimizing toxic emissions from solid fuel combustion and enhancing energy output for domestic and industrial applications.