偏三甲苯加氢转化反应的研究

发布时间：2018-04-09 02:08

本文选题：偏三甲苯　切入点：加氢脱烷基化反应　出处：《吉林大学》2017年硕士论文

【摘要】：偏三甲苯(1,2,4-TMB)是重芳烃的重要组成成份,占C9+重芳烃总质量的30.0%~40.0%。轻质芳烃是重要的化工原料,在医药中间体、染料制备、农药合成和制作表面活性剂等领域有广泛的用途。其中苯、甲苯和二甲苯(BTX)是工业生产中最常用的化工产品。由于石化资源日趋紧缺,C9+重芳烃的高效利用具有重要的现实意义。重芳烃催化加氢转化是一条环保经济的工艺路线。本文针对1,2,4-TMB加氢制备BTX进行详细的研究。分别制备了Ni/SiO_2和Co/ZSM-5催化剂,针对催化剂酸碱性质对反应性能的影响进行了详细讨论,系统考察了催化剂的制备条件和反应条件的影响。论文的主要内容如下:1.采用溶胶-凝胶法制备Ni/SiO_2催化剂,系统考察催化剂对1,2,4-TMB加氢脱烷基化反应的影响。首先,考察制备过程中无水柠檬酸(CA)的量对催化剂结构和性能的影响。结果表明,CA对催化剂孔结构和催化剂的整体结构有很大影响,CA的量影响了活性物种的分散度。其次,研究了催化剂上Ni的负载量、焙烧温度和镍源等因素对催化性能的影响。最后,通过调变反应温度和反应压力,找到适合Ni/SiO_2催化剂体系的最佳反应工艺。研究结果表明,催化剂负载量为10(wt)%左右、n(Ni)/n(CA)=1:2、镍源为Ni(NO3)2·6H2O,经过773 K空气焙烧3 h后,催化剂在723 K、3.0 MPa条件下反应,1,2,4-TMB转化率达到29.4%,BTX选择性接近100%。2.运用各种表征手段研究了催化剂酸碱性位对1,2,4-TMB加氢脱烷基化反应的影响。提高目标产物的选择性是该反应的研究重点。因此,本论文选用酸性较弱的二氧化硅为载体,制备了Ni/SiO_2催化剂,研究了其催化性能。结果表明,催化剂表面的酸性主要为Lewis酸,几乎没有B酸中心。结合其它表征结果,可知除了金属Ni外,1,2,4-TMB进行脱烷基化反应主要是与催化剂表面Lewis酸有关。3.研究了ZSM-5系列催化剂对1,2,4-TMB加氢脱烷基化反应的影响。我们制备了Co/ZSM-5负载型催化剂,并确定了催化剂合成条件。1,2,4-TMB转化率至73.2%,BTX的选择性达到87.8%。
[Abstract]:Metamethyltoluene (TMB) is an important component of heavy aromatics, which accounts for 30.010% of the total mass of C9 heavy aromatics.Light aromatics are important chemical raw materials. They are widely used in pharmaceutical intermediates, dye preparation, pesticide synthesis and surfactants.Benzene, toluene and xylene are the most commonly used chemical products in industrial production.Because of the increasing shortage of petrochemical resources, the efficient utilization of C _ 9 aromatics has important practical significance.Catalytic hydrogenation of heavy aromatics is an environmental and economic process.In this paper, the preparation of BTX by hydrogenation of 1 TMB was studied in detail.Ni/SiO_2 and Co/ZSM-5 catalysts were prepared respectively. The effects of the acid-base properties of the catalysts on the reaction performance were discussed in detail. The effects of the preparation conditions and reaction conditions of the catalysts were systematically investigated.The main contents of the thesis are as follows: 1: 1.Ni/SiO_2 catalyst was prepared by sol-gel method, and the effect of catalyst on the hydrogenation and dealkylation reaction of 1zao 2o 4-TMB was investigated systematically.Firstly, the effect of the amount of anhydrous citric acid (CA) on the structure and performance of the catalyst was investigated.The results show that the amount of CA has a great influence on the pore structure of the catalyst and the overall structure of the catalyst, which affects the dispersity of the active species.Secondly, the effects of Ni loading, calcination temperature and nickel source on the catalytic performance were studied.Finally, by adjusting the reaction temperature and reaction pressure, the optimum reaction process suitable for Ni/SiO_2 catalyst system was found.The effects of acid and basic sites on the hydrogenation of 1tmb were studied by various characterization methods.Improving the selectivity of the target product is the key point of the reaction.Therefore, in this paper, Ni/SiO_2 catalyst was prepared by using silica as the carrier, and its catalytic performance was studied.The results show that the acid on the surface of the catalyst is mainly Lewis acid, and there is almost no B acid center.Combined with other characterization results, it can be seen that the dealkylation reaction of TMB except Ni is mainly related to the Lewis acid on the catalyst surface.The effect of ZSM-5 series catalysts on the hydrogenation and dealkylation of 1H 2N 4 TMB was studied.We prepared the Co/ZSM-5 supported catalyst and determined the catalyst synthesis conditions. The conversion rate of TMB was 73.22% and the selectivity of the catalyst was 87.8%.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;O621.25

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