Insights into co-pyrolytic behavior, emission, kinetics, synergy of bio-oil distillation residue and waxy product via TG-FTIR-MS

Abstract

The technology pathways are maturing in the treatment of carbonaceous solid waste, however, there will inevitably be low value by-products downstream, which requires fine management. Herein, bio-oil distillation residue (DR) and waxy product (WP) as by-products contained considerable energy and chemical composition, and their similar thermogravimetric properties enable efficient synergy during co-pyrolysis. The emission decomposition kinetics, thermodynamics and synergy of DR co-pyrolysis with WP were investigated by TG-FTIR-MS. Thermal process of DR and WP occurred at 175.7–539.1 ℃ and 108.9–427.3 ℃. As the DR content increased, the absorption peak intensity of hydrocarbons was decreasing, but oxygenates changed little when the pyrolysis temperature exceeds 242 °C, the blend containing 50% DR presented the strongest synergy at the absorption peaks assigned to hydrocarbons at each blend. Evolved gas-phase species include mainly hydrocarbons, aromatics and small amount of oxygenated fractions, and higher DR share could obtain greater synergistic gain to CH4, benzene, phenol and naphthalene. Eα and ΔH decreased and then increased with increasing DR content. Average activation energy and enthalpy change of blends containing 25%, 50% and 75% DR were 88.9, 64.4 and 99.6 kJ/mol and 84.1, 59.6, 94.7 kJ/mol calculated through FR method, respectively. Order of reaction mechanism, diffusion mechanism nucleation mechanism affected the pyrolysis process of mixtures together, and the order of reaction model that better described the thermal decomposition of each pseudo-component.