木质素加氢液化工艺研究

【作者】 张中良；

【导师】 李广学；

【作者基本信息】 安徽理工大学 ， 应用化学， 2005， 硕士

【摘要】 本文针对我国造纸行业的副产物木质素进行了加氢液化研究。首先对该物质进行了原料分析,利用元素分析仪分析了该物质的元素组成,用傅立叶变换红外光谱仪分析该物质的结构和官能团,同时利用热重—傅立叶变换红外光谱仪分析了木质素的热解性质,利用非等温热重法进行了热解、催化热解及动力学研究。然后在高压反应釜中对木质素进行了加氢液化的研究,考察了反应温度,反应时间,初始氢压,碱浓度,木质素与溶剂的配比,不同的溶剂,以及两种催化剂对木质素液化的影响。最后用GC—MS定性的分析不同反应温度下轻馏分的组成。 （1） 由元素分析可知,该木质素主要由碳、氢、氧、硫组成,分子式可表示为:C₉H_10.4O_3.6S_0.4。 （2） 由红光谱分析可知此木质素含有大量的甲氧基,羟基,愈疮木基和紫丁香基结构。 （3） 木质素的热重—红外光谱分析说明木质素的热解有三个区间分别是,25～220℃时失重为16%,这个区间主要是脱水反应;从220～487℃时失重为36%,是木质素的主要热解区间。而从487～1000℃失重只有14%,这个区间主要是发生的深度裂解。红外吸收光谱说明木质素热解产物主要有CO、CO₂、H₂O、SO₂、CH₄等。 （4） 利用非等温热重法,在N₂气氛下系统地研究了木质素在不同的升温速率下的热解特性。同时利用不同的动力学方法:Coats-redfern法、Kissinger法、Doyle法及分布活化能模型（DAEM）法求取了热解动力学参数。 （5） 通过液化条件的研究表明木质素加氢液化最佳工艺条件为反应温度为300℃,反应时间60min,氢氧化钠的浓度8%,初始氢压3MPa,最佳工艺条件下,木质素液化的总转化率为70%,轻馏分的产率为56%。转化率和轻油产率均随着温度的升高在300℃有一个极大值。催化剂的加入可以降低木质素液化的反应温度,明显提高轻油的产率。更多还原

【Abstract】 Lignin that came from black liquor of papermaking Industry was used to prepare aromatics and fatty hydrocarbon compounds through hydrogenation liquefaction process. The experiments were carried out in a 100ml micro-autoclave to investigate the effects of reaction temperature, reaction time, the pressure of H₂, the contents of NaOH, the proportion of ethanol and lignin, some solvents, catalysts on the conversion, liquid yield, light oil yield and gas yield of liquefaction. Meanwhile, the element composition、 structure、 functional group of lignin were analyzed by element analysis, FT-IR. The pyrolysis characteristics of lignin were investigated by TG, TG-FTIR.（1）The element analysis show that lignin is composed of C、 H、 O、 S and the formula can express as C₉H_10.4O_3.5S_0.4. The FTIR spectrum show there were a lots of groups such as methoxy、 hydroxy、 guaiacyl、 syringyl.（2） The pyrolysis of lignin undergoes three stages: the first stage is from 25 220℃ that mainly occurs dehydration and the weight loss is 16%. The second stage is from 220⁴87℃ that is the main area of pyrolysis of lignin and the weight loss is 36%. At 287℃ produce the most weight loss. The third stage is from 487¹000℃ that is the deep pyrolysis. The FT-IR spectrums of the pyrolysis gas show that the pyrolysis of lignin produces some gas such as H₂O, CO, CO₂, CH₄, SO₂ and so on.（3） In the stream of N₂, TGA was used to study the pyrolysis characteristics of lignin. Four kinds of methods, Coats-redfern, Doyle, Kissinger and Distributed Activation Energy Model（DAEM）, were used to determine the kinetics parameters of pyrolysis of lignin. The results indicated the kinetics parameters were different with different methods. DAEM is an efficient method to provide the good results.（5） In different conditions, the most conversion and light oil yield of hydrogenation liquefaction of lignin are about 69.8%, 56%. In the present of catalyst, the effect of liquefaction was enhanced. The catalyst can remarkably increase the yield of light oil.更多还原