Thermal oxidation reaction process and oxidation kinetics of abietic acid

Abstract

The thermal oxidation reaction process and oxidation kinetics of abietic acid were investigated by using self-designed gas–solid reaction equipment. The oxidation product and intermediates of the oxidation reaction of abietic acid were tracked by LC-MS. The results revealed a two-step oxidation reaction of abietic acid: abietic acid forms a peroxide first, followed by cracking to form hydroxyl-containing oxidized abietic acid. Both of the steps followed the pseudo-first order reaction kinetics, in which the kinetic equation of the first step is r₁ = c_A × 3.51 × 10³ × exp(−58.96 × 10³/RT), with activation energy of 58.96 kJ mol⁻¹. The kinetic equation of the second step is r₂ = c_O × 6.09 × 10⁵ × exp(−48.06 × 10³/RT) with activation energy of 48.06 kJ mol⁻¹. The kinetic equation of the total reaction is r_a = c_a × 1.12 × 10⁶ × exp(49.51 × 10³/RT) with apparent activation energy of 49.51 kJ mol⁻¹.