胜利褐煤焦钙催化水蒸气气化反应中活性微结构分析

针对胜利褐煤焦水蒸气气化反应过程中钙组分的催化作用,在脱除矿物质胜利褐煤煤样SL~+中添加CaO在1 100℃热解得到添钙煤焦样品Ca-J,Ca-J经盐酸处理脱除其游离钙组分,得到添钙焦酸洗煤样Ca-J~+,采用BET、SEM-EDS、XRD、FT-IR及XPS等技术对所制备煤样进行表征,并在微型固定床反应装置上进行水蒸气气化反应性测试,对煤样微结构特性进行研究,提出了钙催化水蒸气气化反应中的活性微结构模型。结果表明,水蒸气气化反应中,添钙焦样酸洗前后的Ca-J和CaJ~+碳转化率及反应活性指数基本相同,但比酸洗煤焦样SL~+-J高出许多。样品XPS的Ca2p谱图分峰说明,Ca-J~+中存在Ca(CH_3COO)_2与Ca-OOR两种化学形态的钙。化学分析及SEM-EDS表征均表明,Ca-J~+中钙含量比Ca-J减少了97%以上;XRD表明,Ca-J中游离存在的CaS、CaO经酸洗被脱除;FT-IR表明,Ca-J及Ca-J~+中含有C=O、C-O等特征吸收峰。综合上述结果,可推测"R-O-Ca-O-R'"(R及R'可为脂肪族或芳香族结构体)是钙组分催化胜利褐煤焦水蒸气气化的活性微结构。

Analysis of active microstructure during steam gasification of Shengli char catalyzed by calcium component

The catalytic effect of calcium component on steam gasification of Shengli lignite char was studied. Demineralized coal samples were loaded with calcium oxide and pyrolyzed at 1 100℃ (Ca-J). Ca-J⁺ was prepared from Ca-J treated by hydrochloric acid. The char samples were characterized by BET, SEM-EDS, XRD, FT-IR and XPS. The steam gasification of the char samples was performed in a micro fixed bed reactor. The possible catalytic active micro structure was discussed and proposed. The results show that carbon conversion and reactivity index of Ca-J and Ca-J⁺ samples during steam gasification were substantially similar, but much higher than those of demineralized char samples (SL⁺-J). Ca(CH₃COO)₂ and Ca-OOR, two calcium species are present in Ca-J⁺ sample determined by XPS. Chemical analysis and SEM-EDS prove that calcium content of Ca-J⁺ decreases by more than 97% than that of Ca-J sample. XRD analysis indicates free inorganic mineral (CaS, CaO) is removed by hydrochloric acid. FT-IR spectra show C=O, C-O peaks present in Ca-J and Ca-J⁺ samples. So it is postulated that "R-O-Ca-O-R'" (R and R' are aliphatic and aromatic structures, respectively) is the catalyst active microstructure during char steam gasification.