不同种类木质素热解特征及热解产物分析

发布时间：2018-04-28 18:17

  本文选题：木质素 + 马尾松　； 参考：《中南林业科技大学》2017年硕士论文

【摘要】：目前,工业木质素的利用率还不到10%,其中绝大部分作为废物排放,既浪费资源又污染环境。故本课题希望能通过对属于针叶材的马尾松和属于阔叶材的杨木用不同提取方法提取出不同种类木质素(酸不溶木素、碱木素、磨木木素),然后在不同条件下对三种不同种类木质素进行热重分析以及热裂解和催化热裂解,能得到不同种类木质素的热解特性,选择出合适的条件(温度、催化剂等),在木质素热解中能提高热解产物中单一酚组分的含量,降低分离成本,同时探索木质素热解机理,为木质素资源化利用奠定基础。通过对马尾松、杨木不同种类木质素热重分析,得知木质素热解主要阶段即挥发份析出阶段,不同种类木质素热解的表观活化能主要集中在39-55KJ/mol。以马尾松酸不溶木素、碱木素、磨木木素为原料,通过Py-GC-MS联用分析技术,分析500℃条件下热裂解产物的结构和含量。磨木木素裂解产物中总酚相对含量高达62.3%,其中愈创木酚为9.75%、4-甲基-2-甲氧基苯酚为8.56%。碱木素的热裂解产物中总酚的相对含量为44.86%,其中愈创木酚为7.76%,而酸不溶木素裂解产物中总酚相对含量仅为16.25%,无一酚类组分相对含量超过5%。热裂解温度从400℃升高到700℃的过程中,马尾松磨木木素的裂解产物中,总酚的相对含量从59.78%升高到62.31%再升高到65.72%再下降到45.54%。愈创木酚等部分愈创木酚类化合物相对含量随着温度升高呈现先增后减的趋势,而4-乙烯基-2-甲氧基苯酚等的相对含量则随着温度的升高而不断下降。而邻苯二酚类化合物的相对含量则随热裂解温度的升高而增加,不含甲氧基的烷基酚类化合物的相对含量均比较低,也呈现随温度升高而略有升高的趋势。热裂解产物中还存在部分含有愈创木酚基本结构的醛酮类化合物随着温度的升高相对含量呈下降趋势。以杨木酸不溶木素、碱木素、磨木木素为原料,在500℃条件下进行裂解分析。磨木木素裂解产物中总酚相对含量达到54.28%,2-甲氧基-3-甲基苯酚(5.44%)等多种化合物的相对含量均超过5%。碱木素的热裂解产物中总酚的相对含量为48.96%,2-甲氧基苯酚(5.7%)等部分化合物的相对含量都超过5%,而酸不溶木素裂解产物中总酚相对含量仅为37.65%,只有二氧化硫(6.44%)等四种化合物的相对含量也都超过5%。以杨木磨木木素为原料,分析不同温度条件下热裂解产物的结构和含量。热裂解温度从400℃升高到700℃的过程中,总酚的相对含量从31.44%升高到54.28%再下降到42.85%再下降到25.16%。对于主要酚类组分,愈创木酚等酚类化合物相对含量随着温度升高呈现先增后减的趋势,而2-甲氧基-4-乙烯基苯酚等化合物的相对含量则随着温度的升高而不断下降。以工业碱木素为原料,分析不同温度、不同催化剂条件下裂解产物的结构和含量,热裂解温度从400℃升高到700℃的过程中,总酚相对含量从51.86%升高到54.37%再升高到55.08%再下将到40.86%。愈创木酚(2-甲氧基苯酚)的相对含量从400℃时相对含量6.69%升高到500℃时的9.78%再下降到600℃时的7.07%再到700℃时的5.40%;4-丙烯基-2-甲氧基苯酚的相对含量从400℃时相对含量8.41%下降到500℃时的5.30%再下降到600℃时的5.28%再下降到700℃时的 4.67%。以马尾松磨木木素为原料,分别加入Na型分子筛ZSM-5(硅铝比25、50)、H型分子筛HZSM-5(硅铝比25、50、130)、钛硅型分子筛Ts-1六种分子筛催化剂进行催化裂解。六种催化剂对大部分酚类化合物的生成均有抑制作用,其中H型HZSM型和Ts-1型催化剂影响最明显。但也有部分物质如3-甲基苯酚、愈创木酚、4-乙基-2-甲氧基苯酚、3,4-二甲氧基甲苯等在Na型分子筛(硅铝比25)催化作用下相对含量均出现升高,其中3,4-二甲氧基甲苯的相对含量甚至升高了40%左右。在TiO2、ZSM-5分子筛Na型-25两种催化剂作用下,工业碱木素裂解产物的总酚含量均存在一定的下降,从54.37%分别下降到50.13%和48.94%。愈创木酚在Na型-25的作用下含量有明显提高,从9.78%升高到11.28%,但在TiO2的作用下,相对含量从9.78%下降至9.15%;邻苯二酚的相对含量在两种催化剂作用下均略有下降,从12.42%分别下降至12.11%和12.19%。
[Abstract]:At present, the utilization of industrial lignin is less than 10%, most of which are used as waste, not only to waste resources but also to pollute the environment. Therefore, we hope to extract different lignin (acid insoluble lignin, alkali lignin and milkwood lignin) by different extraction methods for Pinus massoniana and broadleaf wood. Thermogravimetric analysis and pyrolysis and catalytic pyrolysis of three different kinds of lignin under different conditions can obtain the pyrolysis characteristics of different kinds of lignin. The suitable conditions (temperature, catalyst, etc.) can be selected. In lignin pyrolysis, the content of single phenolic components in the pyrolysis products can be increased, the separation cost is reduced, and wood is explored at the same time. The mechanism of lignin pyrolysis is the foundation for the utilization of lignin. Through the analysis of the thermogravimetric analysis of different lignin of Masson Pine and poplar wood, it is found that the main stage of lignin pyrolysis is volatilization phase, and the apparent activation energy of different lignin pyrolysis is mainly concentrated in 39-55KJ/mol. with Masson Pine acid insoluble lignin, alkali lignin and lignin. The structure and content of pyrolysis products at 500 C were analyzed by Py-GC-MS combined analysis technology. The relative content of total phenol in the products of lignin cracking was 62.3%, of which guaiacol was 9.75% and 4- methyl -2- methoxy phenol was 8.56%. alkali lignin, the relative content of total phenol was 44.86%, and guaiacol was 7.7. 6%, the relative content of total phenol in the acid insoluble lignin cracking product is only 16.25%, and the relative content of no one phenolic component exceeds the 5%. thermal cracking temperature from 400 to 700. In Mayo Matsumakikiso's pyrolysis products, the relative content of total phenol rises from 59.78% to 62.31% and then rises to 65.72%, and then drops to 45.54%. guaiacol. The relative content of the guaiacols increased first and then decreased with the increase of temperature, while the relative content of 4- vinyl -2- methoxy phenol decreased with the increase of temperature, while the relative content of catechol compounds increased with the increase of thermal cracking temperature, and the alkyl phenolic compounds without methoxy were added. The relative content is low, and there is a tendency to increase slightly with the increase of temperature. In the pyrolysis products, some aldehydes and ketones containing the basic structure of guaiacol also decrease with the increase of the temperature. Yang Musuan insoluble lignin, alkali lignin and milkwood are used as raw materials, and the pyrolysis points are carried out at 500 degrees centigrade. The relative content of 2- methoxy -3- methyl phenol (5.44%) and so on is 54.28%, and the relative content of the total phenol in the pyrolysis products of 5%. alkali lignin is 48.96%, and the relative content of 2- methoxy phenol (5.7%) is more than 5%, and the acid insoluble lignin cracking product The relative content of total phenol is only 37.65%, and the relative content of four compounds, such as sulfur dioxide (6.44%), is also more than 5%.. The structure and content of the pyrolytic products are analyzed under different temperature conditions. The relative content of total phenol is increased from 31.44% to 54.28% in the process of thermal cracking temperature rising from 400 to 700. The relative content of the phenolic compounds, such as guaiacol and other phenolic compounds, increased first and then decreased with the increase of temperature, while the relative content of 2- methoxy -4- vinyl phenol and other compounds decreased with the increase of temperature, while the relative content of 25.16%. methoxy -4- vinyl phenol and other compounds decreased with the increase of temperature. Under the conditions of catalyst, the relative content of total phenol in the process of increasing from 400 to 700 C, the relative content of total phenol increased from 51.86% to 54.37% and then to 55.08%, and the relative content of 40.86%. guaiacol (2- methoxy phenol) decreased from 6.69% to 500 degrees C at 400 C and then 9.78% to 600 centigrade. The relative content of 4- acryl -2- methoxy phenol at the time of 7.07% to 700 C; the relative content of 4- methoxy phenol decreased from 8.41% to 500 C at 500 C and then dropped to 600 degrees C, and then dropped to 600 degrees C, and then dropped to 700 centigrade, with Masson Pine grinding lignin as raw material, adding Na molecular sieve ZSM-5 (Si / Al ratio 25,50), H type molecular sieve HZSM-5 (silicon), respectively. Six kinds of molecular sieves are catalytic cracking. Six kinds of catalysts have inhibitory effect on the formation of most phenolic compounds. The H type HZSM type and Ts-1 type catalyst are most obvious, but there are some substances such as 3- methyl phenol, healing lignan, 4- ethyl -2- methoxy phenol, 3,4- two methoxy. The relative content of toluene was increased under the catalysis of Na type molecular sieves (Si / Al 25), and the relative content of 3,4- two methoxy toluene increased by about 40%. Under the action of TiO2, ZSM-5 molecular sieve Na -25 two catalysts, the total phenolic content of industrial alkali lignin cracking products decreased from 54.37% to 50., respectively. 13% and 48.94%. guaiacol content increased significantly under the action of Na -25, rising from 9.78% to 11.28%, but the relative content of guaiacol decreased from 9.78% to 9.15% under the action of TiO2, and the relative content of catechol decreased slightly under the action of two catalysts, from 12.42% to 12.11% and 12.19%., respectively.

【学位授予单位】：中南林业科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O636.2
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本文编号：1816351