Oxidative depolymerization of Zhundong subbituminous coal in H2O2 solution

Coal oxidation by H2 O2 can serve as a method to study the coal structure,while it is also capable to convert coal to value-added chemicals,being a promising way to utilize low-rank coal resources. The Zhundong subbituminous coal is China’s current reserves of low-rank coal resources. The H2 O2 oxidation of Zhundong subbituminous coal was investigated to provide some necessary basic data for its utilization. The Zhundong subbituminous coal was oxidized with H2 O2 ,and its physicochemical properties were analyzed by N2 adsorption and FTIR. The combustion characteris- tics and the composition of the oxidation products were also analyzed by thermogravimetric analyzer ( TG) and GC /MS,respectively. Results show that as the temperature increases,the conversion rate increases,and the conversion rate reaches 45. 67% when the temperature is 80 ℃ . The pore structure in coal is destroyed,the specific surface area and total pore volume reduce that cause coal particles to shrink and make coal structure dense,the bridge bond and C—O ether bond in coal are ruptured,and the ring opening of aromatic structure is enhanced during the reaction of H2 O2 with Zhundong subbituminous coal. The ash content reduces,the N and S contents reduce,the volatile content increa- ses,and H / C and O / C atomic ratios increase in the oxidized residual coal. Compared with raw coal,the fatty side chains become longer,the fatty branch chains decrease,the content of C O increases,and the content of C—O and aliphatic hydrogen decrease in the oxidized residual coal. Meanwhile,the oxidized residual coal maintains the combus- tion characteristics of the raw coal better. 14 compounds are detected with GC / MS in the oxidation product,including 2 alkanoic acids,2 benzenecarboxylic acids,5 hydrocarbons,4 nitrogen-containing or sulfur-containing species and 1 kind of ester. Among the compounds detected,in (Z)-docosa-13-enamide,bis(6-methylheptyl) phthalate and palmitic acid are the highest. The detected nitrogen or sulfur-containing compounds reveal that the presence of organic nitrogen and organic sulfur in the Zhundong coal includes amides,sulfonic acids and sulfonyl groups.