Experimental and quantum chemical study on the inhibition characteristics of triphenyl phosphite to lignite oxidation at low temperature

•The inhibiting effect of TPPI with different concentrations on COLT was studied.•The inhibiting effect of TPPI is realized by polymerizing with ROO· and RO· radicals and reducing the R· radicals.•The inhibition mechanism of TPPI was discussed by quantum chemical theory. In this study, the inhibition characteristics of triphenyl phosphite (TPPI) to the lignite oxidation at low temperature was studied. The experimental methods were applied to analyze the inhibition effect of TPPI. The results show that TPPI has a significant inhibition effect on the lignite oxidation at low temperature and the higher the concentration, the more obvious the inhibition effect. Simultaneously, the strong radical scavenging ability of TPPI leads to a significant change in raw coal. The quantum chemical calculations indicate that the inhibition mechanism of TPPI is to inert the highly reactive ROO· and RO· in the coal, while reducing the content of the oxidation precursor R·. The activation energy of each reaction is small and can occur at normal temperature and pressure. This study may provide a reference for the development and utilization of inhibitors.