程序升温还原法研究氧化对煤中硫形态及结构的影响

用程序升温还原法研究了三种不同硫含量的煤被空气和HNO3氧化后含硫气体的逸出规律。结果表明，空气和HNO3氧化后，尽管煤中有机硫总量变化不大，但煤中H2S的释放量有所下降，而COS和SO2的生成量明显增加，这说明氧化作用使得煤中弱的有机硫变成S=O和SO2结构。与以往的研究结果不同的是，发现CS2的生成与FeS密切相关，同时对HNO3氧化后的煤来说，CS2的生成主要以气相中H2S和COS的反应为主。空气氧化后煤中CS2的生成量与原煤的差不多，但HNO3氧化后煤中释放出的CS2有所下降。提出通过（COS+SO2）/H2S的比值来研究煤及其中硫被氧化的程度，并对比了不同煤种及氧化后样品的气相含硫化合物发现：随变质程度的提高和煤中噻吩硫含量的增加，煤被氧化的程度下降。对同一煤种而言，HNO3的氧化程度要高于空气氧化的。

TPR STUDY ON THE VARIATION OF SULFUR IN COAL AFTER OXIDATION

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.