Fe对胜利褐煤焦结构和气化反应性能的影响

酸洗褐煤负载不同含量的Fe催化剂在固定床反应器上进行热解,然后采用FT-IR、Raman spectra、TPD和TG研究Fe催化剂对煤焦官能团、碳微晶结构、表面活性位和气化反应性的影响。FT-IR结果表明,催化热解作用下煤焦中-OH、-CH₃、-CH₂活性官能团数量增加。Raman光谱测试结果显示,随着Fe含量的增加,I_G/I_all由0.095减少到0.087,I_D3/I_all由0.090增加至0.097,表明在Fe催化作用下部分大芳香环结构转变为小芳香环结构。TPD实验结果表明,活性位数量随着煤焦中Fe含量升高而不断增加。在3%含Fe量时煤焦活性位数量随着吸附温度的升高而增加,800 ℃后煤焦表面活性位数量开始降低。750 ℃条件下CO₂吸附量随着吸附时间的延长而增加,45 min后煤焦达到饱和吸附状态。煤焦-水蒸气等温气化实验表明,煤焦气化反应性与活性位数量有密切的关系,Fe催化剂主要通过增加煤焦表面活性位数量提高煤焦气化反应性。

Effect of iron on Shengli brown coal char structure and its influence on gasification reactivity

Acid-washing brown coal samples loaded with different content of iron catalyst were pyrolyzed in a fixed bed reactor. The effect of iron on coal char functional group, carbon crystallite structure, surface active site and gasification reactivity were investigated by FT-IR, Raman spectra,TPD and TG. FT-IR results reveal that the numbers of -OH、-CH₃、-CH₂ active functional groups increase significantly during catalytic pyrolysis. Raman spectra results show that I_G/I_all reduces from 0.095 to 0.087 and I_D3/I_all increases from 0.090 to 0.097 with the increase of iron loading, respectively. It means that partial large polyaromatic ring structures transform into small polyaromatic ring structures under the catalytic action of iron. TPD experimental results indicate that the numbers of active sites increase with the increase of iron loading. With 3% Fe loading, the numbers of active sites rise with the increase of adsorption temperature until 800 ℃, and then start to decrease. The adsorption quantity of CO₂ increases with time at 750 ℃, and reaches saturated adsorption state after 45 min. Coal char-steam isothermal gasification experiment result suggests that the gasification reactivity of coal char has a close relationship with the number of active sites, and the iron catalyst can enhance the char gasification reactivity by increase the number of surface active sites.