Comparative analysis of desulphurization methods of tyre pyrolysis oil (TPO)

Tyre pyrolysis oil (TPO) has a potential to be used as furnace oil. It is more economical option than diesel or other commercial fuel but its high level of impurities and resultant air pollution hinders its application. Present study focuses on the oxidative desulphurization of TPO with three different treatments, i.e. formic acid/H₂O₂, acetic acid H₂O₂ and nitric acid having different concentrations (10, 20 and 30%) at different temperature (40, 50, and 60 °C). Crude and desulphurized TPO were burned in a closed container and the variation in their gaseous emissions (O₂, CO, SO_x, NO_x and CO₂) was observed using flue gas analyser. All treatments were found effective for reduction of gaseous emissions, but 20% acetic acid at 50 °C was found as the best treatment along with 10% formic acid at 40 °C and 30% nitric acid treatment. Overall, 97.29% of SO_x, 99.6% of NO_x and 99.9% of CO₂ removal was observed from the crude TPO after its oxidative desulphurization. Desulphurization also affected the viscosity and calorific value of TPO. Viscosity of oil decreased from 0.83 to 0.202 cST at 20% formic acid 40 °C treatment, and the calorific value varied from 43.98 to 43.6 M/kg 10% nitric acid. Reduction in sulphur dioxide in exhaust of treated samples as compared to crude indicates high removal of sulphur from crude oil after treatments. Overall, acidic oxidative desulphurization proved to be effective for purification of oil by reduction in gaseous emissions and viscosity.