改性ZSM-5催化剂对神东煤热解特性影响的研究

发布时间：2018-04-13 20:49

本文选题：煤热解特性 + ZSM-5分子筛催化剂　；参考：《西北大学》2017年硕士论文

【摘要】：煤热解是煤转化的第一步,也是关键步骤,如何提高能源利用率,实现煤的清洁高效利用,是现阶段我国能源战略中的大问题,也是广大学者研究的热点。本研究通过在热重-红外联用仪和自搭建的固定床反应器上对低变质煤种-神东煤进行加氢/加氢催化热解实验,来探究催化剂和热解气氛对煤热解过程的影响。通过静态水热法合成HZSM-5型分子筛,并选取Ni、W、P等元素,采用等体积浸渍法和水热浸渍法对ZSM-5进行了多种改性,并对催化剂进行了系列表征。在5%H2+95%N2气氛下,利用TG-FTIR对不同催化剂上神东煤的热解性能进行评价。研究发现:相对于ZSM-5,单金属Ni、W改性ZSM-5能够提高煤热解转化率,降低了一次和二次热解峰温,改善了热解产物的组成和分布。两种改性方式所得的多种NiW/ZSM-5型催化剂中,Ni-W最理想的配比均为4-6%;同样Ni-W配比的NiW/ZSM-5中,水热浸渍法制备的催化剂活性更高,主要表现为煤的热解峰温提前,总转化率提高,其中4-6%NiW/ZSM-5(SR)失重最大,相对原煤热解转化率提高了 4.3%;经过P改性得到的4-6%PNiW/ZSM-5(SR)催化剂热转化率相对原煤热解提高了 7.2%,P改性有助于增强催化剂的活性,使煤热解条件更加温和。相对而言4-6%PNiW/ZSM-5(SR)对神东煤热解催化效果最佳。在固定床反应器上考察了催化剂对神东煤热解产物的催化改性,具体如下:1.H2气氛有利于提高热解转化率,增加焦油收率,对煤粉具有更好的脱硫脱氮性能,而且明显提高了焦油中BTX和萘类含量;2.相比于非催化热解,催化热解均能提高芳香烃和萘类化合物含量。在N2气氛下,ZSM-5对芳烃化合物有最大选择性,从19.07%增加到50.28%;4-6%NiW/ZSM-5(SR)能够明显促进萘类化合物的生成,从10.72%增加到39.04%;而4-6%PNiW/ZSM-5(SR)对焦油中酚类化合物的生成有明显的促进作用,从38.65%提高到50.57%。在H2气氛下,6%W/ZSM-5对芳烃化合物有最大选择性,从22.78%增加到39.34%;ZSM-5对萘类有最大选择性,从18.95%增加到53.95%;催化剂(除过ZSM-5)能够提高焦油中BTX含量,其中4-6%PNiW/ZSM-5(SR)对BTX的选择性最高。
[Abstract]:Coal pyrolysis is the first step and the key step of coal conversion. How to improve energy utilization efficiency and realize clean and efficient use of coal is a big problem in the energy strategy of our country at present, and it is also a hot topic for many scholars.In this study, the effect of catalyst and pyrolysis atmosphere on coal pyrolysis process was investigated by hydrogenation / hydrogenation catalytic pyrolysis experiment on low metamorphic coal-Shendong coal in a thermogravimetric infrared coupled instrument and a self-built fixed bed reactor.HZSM-5 molecular sieve was synthesized by static hydrothermal method. The ZSM-5 was modified by isovolumetric impregnation method and hydrothermal impregnation method, and the catalyst was characterized.The pyrolysis performance of Shendong coal on different catalysts was evaluated by TG-FTIR in 5%H2 95%N2 atmosphere.It is found that compared with ZSM-5, ZSM-5 modified by single metal NiGW can improve the conversion rate of coal pyrolysis, decrease the peak temperature of primary and secondary pyrolysis, and improve the composition and distribution of pyrolysis products.The optimum ratio of Ni-W and Ni-W was 4-6, and the catalyst prepared by hydrothermal impregnation method had higher activity in NiW/ZSM-5 with the same Ni-W ratio, which mainly showed that the peak temperature of coal pyrolysis was earlier and the total conversion rate was higher.The weight loss of 4-6NiW / ZSM-5R) is the largest, and the conversion rate of pyrolysis of raw coal is increased by 4.30.The 4-6PNiW / ZSM-5R) catalyst modified by P can improve the activity of catalyst and make the coal pyrolysis conditions more mild than that of raw coal pyrolysis.PNiW / ZSM-5R) is the best catalyst for pyrolysis of Shendong coal.The catalytic modification of the pyrolysis products of Shendong coal by the catalyst was investigated in a fixed bed reactor. The results are as follows: 1. The atmosphere of H 2 is beneficial to increase the conversion rate of pyrolysis, increase the yield of tar, and have better desulfurization and denitrification performance for pulverized coal.Moreover, the content of BTX and naphthalene in tar was increased obviously.Compared with non-catalytic pyrolysis, catalytic pyrolysis can increase the content of aromatic hydrocarbons and naphthalene compounds.ZSM-5 has the highest selectivity to aromatic compounds in N _ 2 atmosphere, from 19.07% to 50.28%. It can obviously promote the formation of naphthalene compounds from 10.72% to 39.04, while 4-6PNiW / ZSM-5SRS) can obviously promote the formation of phenolic compounds in tar from 38.65% to 50.57%.In H2 atmosphere, 6W / ZSM-5 has the highest selectivity for aromatic compounds, from 22.78% to 39.34% and ZSM-5 to naphthalene from 18.95% to 53.95.The catalyst (except ZSM-5) can increase the content of BTX in tar, of which 4-6PNiW / ZSM-5 SRs have the highest selectivity to BTX.
【学位授予单位】：西北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TQ530.2

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