AAEM赋存形态对生物质半焦反应活性的影响

Effect of speciation of AAEM species on reactivity of biochar

为深入研究碱金属碱土金属元素(AAEM)赋存形态对生物质热解半焦反应活性的影响,采用化学分析分馏法与ICP-AES测定半焦内AAEM元素赋存形态的分布情况,用热重分析法分析AAEM元素赋存形态对半焦反应活性的影响.结果表明:半焦中Na、K元素以水溶态为主,Mg、Ca元素则以不溶态为主;370℃下,NH4Ac溶态AAEM元素主要在反应中后期起作用;经H2O、NH4Ac、HCl洗后半焦比反应速率依次降低;在碳转化率较小时,AAEM对焦炭反应活性起促进作用,碳转化率大于一定值时,原始半焦活性低于H2O洗半焦活性;NH4AC溶态AAEM对半焦反应活性的催化作用相对稳定,HCl态AAEM对生物质快速热解半焦反应活性的影响最大.

AAEM species, such as inorganic and organic states, are distributed in the pyrolysis biochar, which affect the reactivity of biochar. The speciation of AAEM species in biochar was determined by chemical analysis fractionation and ICP-AES. The effect of AAEM species on the reactivity of biochar was analyzed by the thermal gravimetric analysis. The results show that the Na and K elements are mainly water-soluble, while the Ca and Mg elements are mainly in the insoluble state. At 370℃, NH4 Ac-soluble AAEM species are responsible for the middle and late stage in the reaction. Washed by H2O, NH4 Ac and HCl successively, the reactivity of biochar decreases. When the carbon conversion rate is relatively small, the water-soluble AAEM species play an important role in promoting the reactivity of biochar. When the carbon conversion rate is higher than a certain value, the reactivity of original biochar is lower than that of the H2 O-washed biochar. The catalytic effect of NH4 Ac-soluble AAEM species on the reactivity of biochar is relatively stable, and the effect of HCl-soluble AAEM species is the most.