A multi-channel reaction model study of key primary and secondary active groups in the low-temperature oxidation process of coal.

To investigate the reaction pathways of key reactive groups in coal when coal undergoes oxidation at low temperatures, the start-up stage of the reaction pathways, and the evolution of free radicals and functional groups. Firstly, according to the similarity in the types of groups, this paper classifies many reactive groups in coal and uses GaussView 6.0 to construct molecular models of primary (-CH 3 , –OH, –CHO, –COOH) and secondary (-R∙, –C(O)∙, –COO∙, ∙OOH) groups. Then the reaction channels of primary and secondary groups were built and verified based on the similarity of the reaction forms of the groups. The results show that both primary and secondary groups have "dual channel reactions" when coal undergoes oxidation. Channel A of the primary group reacts with O 2 with a start-up stage of 70∼200 °C, and channel B reacts with ∙OH with a start-up stage of 30∼70 °C; channel C of the secondary group reacts with O 2 at about 30 °C and channel D reacts with self-decomposition with a start-up stage of 70∼200 °C. The results show that oxygen insulation and cooling can be adopted according to channels A and C. Channels B, C, and D eliminate R∙ and ∙OH to efficiently prevent and control coal spontaneous combustion(CSC). • The model of primary and secondary groups in coal was constructed. • The reaction channels of each key group were simulated and validated at the atomic and molecular levels. • A two-channel reaction model exists for both primary and secondary groups. • Delineated the initiation phase of each reaction channel. [ABSTRACT FROM AUTHOR]