Exploring the effects of active sulfur on the pyrophoricity of corrosion products in oil tanks from the perspectives of microstructure and thermodynamics

Active sulfur in crude oil may be an important factor influencing the pyrophoricity of oil tank corrosion products and triggering tank fires and explosion accidents. In this work, 1-hexanethiol, dibutyl sulfide, elemental sulfur, and model compounds of oil tank corrosion products were selected and investigated. The effect of active sulfur on the pyrophoricity of the oil tank corrosion products and its mechanism were investigated by specific surface area and pore size measurements and thermodynamic theory. The results showed that after active sulfur treatment, the intensity of the peaks in the X-ray diffraction pattern of the oil tank corrosion products changed, agglomerates appeared on the surface of the samples, the specific surface area and pore volume increased in the direction of air adsorption on the surface of the samples, and the samples became more prone to oxidation reactions. Moreover, active sulfur could also decrease the characteristic temperature of the oxidative weight loss of oil tank corrosion products and the apparent activation energy of high-temperature oxidative weight loss, leading to changes in the reaction mechanism of high-temperature oxidative weight loss. After treatment with 1-hexanethiol, dibutyl sulfide, and elemental sulfur, the apparent activation energies at high-temperature oxidative weight loss of the oil tank corrosion products decreased by 37.38, 19.98, and 48.18 kJ/mol, respectively, and the pyrophoricity was increased.