模拟煤环境中几种无机硫的热分解行为

采用活性焦作为构造煤大分子网络的基质,将无机硫(黄铁矿、硫酸亚铁)混合于其上,形成模拟煤的环境.利用程序升温热解-火焰光度检测器或质谱联用(TPD-FPD/MS)技术和X-射线吸收精细结构(EXAFS)光谱对比研究了FeS₂、FeSO₄在活性焦上及纯态下热分解过程中硫逸出的动态特征及结构变化.结果表明:担载于活性焦上FeSO₄的分解主要发生在200℃～500℃,而纯态FeSO₄的分解温度范围为450℃～600℃,说明活性焦的存在使其分解温度显著降低,且硫的逸出情况更为复杂.黄铁矿与活性焦的物理混合并没有使FeS₂的分解温度降低,但对其分解程度有一定的影响,并与热解气氛密切相关;温度高于400℃后FeS₂分解的硫开始大量逸出,在550℃左右基本失去结构中与铁配位的第2层硫原子而形成FeS.

Investigation of Inorganic Sulfur Decomposition in a Coal-Like Environment During Pyrolysis

An activated charcoal (AC) was used to simulate coal-like environment, and the inorganic sulfur (pyrite or ferrous sulfate) was mixed with it in some ways. The dynamic characteristics and structure changes of FeS2 and FeSO4 with and without AC during pyrolysis, were investigated by temperature-programmed decomposition-flame photometric detector or mass spectrometer (TPD-FPD/ MS) and extended X-ray absorption fine Structure (EXAFS) spectroscopy. It is found that the decomposition of FeSO4 impregnated onto AC mainly happened between 200 degrees C and 500 degrees C , while the pure FeSO4 decomposed at around 450 degrees C - 600 degrees C. The comparison shows that the existence of AC lowered the decomposition temperature of FeSO4, and made the emission of sulfur more complex as well. However, the decomposition temperature of pyrite wasn't varied by the physical mixing with AC. Furthermore, the decomposition degree of pyrite depended on the existence of AC and the pyrolysis atmosphere used. Above 400 degrees C, the evolution of sulfur became remarkable. At around 550 degrees C the sulfur in the second sphere of Fe-S-S was lost, and the pyrolysis product FeS appeared simultaneously.