钾元素对生物质主要组分热解特性的影响

摘要

The pyrolysis of K2CO3-impregnated hemicelluloses,cellulose,lignin and pine was investigated by TG-FTIR to assess the influence of potassium on the pyrolysis mechanisms of the main components of biomass.The results show that the pyrolysis temperature range of hemicelluloses,cellulose and lignin is 200 ～ 350 ℃,300～365 ℃,200 ～600 ℃,respectively.CO and CO2 are mainly produced during hemicellulose pyrolysis,and levoglucosan and carbonyl group are mainly produced during cellulose pyrolysis,while solid product is the main product for lignin pyrolysis.The pyrolysis of the mixture of three components reveals that there are interactions among biomass components.Potassium could catalyze the pyrolysis process of hemicelluloses and cellulose,lower the pyrolysis temperature,and increase the char yields.Potassium influences the pyrolysis of cellulose most obviously,leading to a marked increase in the yields of CO,CO2 and solid product,and a decrease in carbonyl compound yield.However,potassium has little effect on the char yield of lignin,and the catalysis of potassium for the pyrolysis of mixture weakens.%采用热重-红外联用仪对松木及生物质主要化学组分半纤维素、纤维素、木质素的热解特性及钾元素对其热解特性的影响进行了研究.结果表明,半纤维素、纤维素、木质素发生热解的主要温度分别为200 ～ 350℃、300 ～ 365℃和200～600℃;半纤维热解产物中CO、CO2较多;纤维素热解产物中LG和醛酮类化合物最多;木质素热解主要形成固体产物,气体中CH4相对含量较高.三种组分共热解过程中发生相互作用使热解温度提高、固体产物增加,气体中CO增加而CH4减少.添加K2CO3后半纤维素和纤维素热解温度区间向低温方向移动,固体产率提高.K对纤维素作用最明显,CO、CO2气体与固体产物产率明显增加,醛酮类和酸类物质的产率降低;木质素受K影响相对较小,热解固体产物略有增加,挥发分中H2O和羰基物质增加;三组分共热解减弱了钾元素的催化作用.