程序升温还原法研究氧化对煤中硫形态及结构的影响

The sulfur-containing gases evolved from three kinds of coal and their oxidized samples by air and HNO3 were investigated by atmospheric pressure-temperature programmed reduction (AP-TPR) with H2. The results show that although the amount of organic sulfur did not change remarkably, the H2S evolved from the oxidized sample decreased, COS and SO2 evolved increased significantly. This indicated that the aliphatic sulphides were selectively oxidized to sulphoxide and sulphone. Different with the previous study, it was found that the formation of CS2, arising from the reaction of H2S and COS, has a close relationship with FeS. The amount of CS2 in air-oxidized coal is similar with that from raw coal, but less than that from HNO3-oxidized sample. The ratio of (COS+SO2)／H2S was suggested to stand for the oxidation extent. The higher this ratio, the more severer the oxidation. The results showed that the (COS+SO2)/H2S ratio decreased with the coal rank and the amount of thiophenes. For the same coal, the oxidation by nitric acid is deeper than that by air.