碳酸钠催化碱木质素的热解动力学研究

Pyrolysis Kinetics of Alkali Lignin Catalyzed by Sodium Carbonate

采用热重分析法研究了碳酸钠对碱木质素的热解行为及其动力学规律的影响。结果表明:碳酸钠的存在影响到碱木质素的解聚或"玻璃化转化",使热重曲线向低温侧移动,并对焦炭的形成具有促进效果。加入碳酸钠后碱木质素热解的DTG曲线由原来单峰变为一大一小两个峰。采用Coats-Redfern法对热失重过程的数据进行了动力学模拟,结果显示碱木质素的热解为两段连续一级反应过程,碳酸钠使两段一级反应的转折点向低温区移动。碳酸钠对碱木质素热解的低温阶段有促进效果而对高温阶段有抑制作用。添加碳酸钠后碱木质素的主热解区活化能降低,有利于热解反应的进行。

Influence of sodium carbonate（Na2CO3） on pyrolysis characteristics and kinetics of alkali lignin were studied by thermo-gravimetric（TG） analysis.Result show that depolymerization or glass transformation of alkali lignin are effected by Na2CO3,moving TG curve towards lower temperature.Na2CO3 has a promoting effect on the formation of char.Derivative thermogravimetry（DTG） curves of alkali lignin change from the original single peak to double peak.Coats-Redfern method was used to analyze the pyrolysis process and dynamics simulation was carried out.The pyrolysis of alkali lignin is a two-consecutive step first-order reaction,and the turning point of which moves towards lower temperature area.At lower temperature area,Na2CO3 shows a promoting effect on pyrolysis of alkali lignin,while an inhibitory effect at higher temperature area.Activation energy of main pyrolysis area of alkali lignin decreases after adding Na2CO3,indicating Na2CO3 to be benefitial for the pyrolysis of alkali lignin.