【作者】 赵亮；

【导师】 宋春山； 郭新闻；

【作者基本信息】 大连理工大学 ， 工业催化， 2010， 博士

【摘要】 线性多环芳烃(如2,6-二烷基萘)是重要的化工原料,其氧化后生成相应的羧酸是热致性液晶、耐热材料、人造纤维以及高性能工程塑料等聚合物的重要单体。在β,β’-位取代的2-甲基萘中,甲基取代的2-甲基萘由于在进一步氧化时条件温和,且没有碳损失,受到了越来越多的关注。而异丙基取代的2-甲基萘由于异丙基基团的空间位阻效应,可以获得较高的选择性。本论文对沸石分子筛催化2-甲基萘甲基化合成2,6-二甲基萘(2,6-DMN)进行了系统研究。发现ZSM-5分子筛是较为理想的催化剂,最佳反应条件为反应温度360℃、质量空速2 h-1、常压。提高反应压力降低了2,6-DMN选择性及2,6-／2,7-DMN比值。论文还对沸石分子筛催化2-甲基萘异丙基化合成2-甲基-6-异丙基萘(2,6-MIPN)进行了研究。发现HM分子筛是较为理想的催化剂,合适的反应条件为反应温度200℃、反应压力2.0MPa、物料配比2-甲基萘：异丙醇：环己烷=1：3：70。为了提高HZSM-5分子筛催化剂的稳定性,采用水热处理结合酸洗的方法对母体催化剂进行脱铝处理,发现550℃水热处理的催化剂,其稳定性显著提高。水热处理后的催化剂生成了较多的介孔,原料及产物分子在孔道内的扩散速率加快,导致2,6-DMN的产率增加；同时,催化剂酸强度有所降低、强酸中心数目有所减少,即减少了非择形催化反应的发生,提高了2,6-DMN的选择性；另外,强酸中心数目的减少也减少了积炭的生成,减少了原料异构化及产物间异构化反应,提高了2,6-／2,7-DMN比值。反应8 h后,2-甲基萘的转化率仍保持在13.4%,2,6-DMN选择性可达59.1%,在8 h的反应期内,2,6-DMN最高产率达到7.1%。采用NH4F和Pt复合改性的修饰方法对母体催化剂进行处理,一方面Pt的氢溢流效应可以减缓积炭生成,另一方面NH4F的脱铝作用可以降低催化剂酸强度和酸量,催化剂的稳定性和活性也得到改善。之后考察了HM催化剂上2-甲基萘甲基化的反应性能,发现提高反应压力、使用氢气做载气可以延缓催化剂积炭失活速率,MgO和CeO2复合改性可以提高催化剂选择性。在HM催化剂上考察了2-甲基萘异丙基化反应,由于异丙基基团的空间位阻效应,在母体催化剂上即获得了较高的2,6-MIPN选择性。对催化剂进行复合改性,发现CeO2主要覆盖催化剂外表面酸中心,抑制副反应发生,提高催化剂的择形性；MgO可以进入沸石孔道,降低催化剂内表面的酸强度,同时窄化了孔口,进一步提高催化剂的选择性,反应8 h后,3%MgO／20%CeO2／HM催化剂上,2,6-MIPN选择性高达89.5%。更多还原

【Abstract】 Linear polynuclear aromatic hydrocarbons, such as 2,6-dialkylnaphthalene(2,6-DAN) are raw materials of advanced polymer materials. The corresponding acid produced by their oxidation is an important precursor used for thermotropic liquid crystal polymers, heat-resistant polymers, synthetic fibers and engineering plastics with superior properties. Amongβ,β’-alkylated isomers, the methylated 2-methylnaphthalene(2-MN) has attracted more and more attention because its oxidation to the corresponding carboxylic acid proceeds under mild conditions and without carbon loss. Because of the steric hindrance, the isopropylated 2-MN can gain higher 2,6-selectivity than the methylated one.In this paper, the methylation of 2-MN to 2,6-dimethylnaphthalene(2,6-DMN) over zeolite catalysts was studied. It was found that HZSM-5 was the appropriate catalyst for this reaction. Reaction temperature of 360℃, WHSV 2 h-1, atmospheric pressure were the optimal reaction conditions. With increasing reaction pressure, the selectivity of 2,6-DMN and 2,6-/2, 7-DMN ratio reduced. Here, the isopropylation of 2-MN to 2-methyl-6-isopropylnaphthalene (2,6-MIPN) over zeolite catalysts was also studied. It was found that HM was the appropriate catalyst for this reaction. The optimal reaction conditions were reaction temperature 200℃, reaction pressure 2.0MPa,2-methylnaphthalene:isopropanol:cyclohexane= 1:3:70.In order to improve the catalytic stability of HZSM-5 catalyst, the parent catalyst was firstly modified by hydrothermal treatment with acid leaching, it was found that the catalytic stability was improved with 550℃hydrothermal treated catalyst. It can be concluded that pore structure of HZSM-5 catalyst was modified by hydrothermal treatment, the increased mesopore volume enhanced diffusion of molecules, so that more 2,6-DMN emerged; at the same time, the acid strength and the number of strong acid sites of HZSM-5 catalyst were both reduced by hydrothermal treatment, especially for the reduction of non-shape-selective, the selectivity to 2,6-DMN increased; furthermore, as the reduction of the number of strong acid sites, the coke formation and the isomerization of 2-MN and DMNs were both decreased. After 8 h, the conversion of 2-MN was still 13.4%,2,6-DMN can reach 59.1%, among the 8 h, the maximum of 2,6-DMN was 7.1%. Secondly, the parent catalyst was modified by NH4F and Pt. On one hand, the coke formation was restrained through hydrogen overfall of Pt, On the other hand, the acid strength and the number of strong acid sites of HZSM-5 catalyst were reduced by NH4F, so that the catalytic activity and stability were improved. Thirdly, It can be seen that coke formation was restrained by enhancing reaction pressure and using H2 as carrier gas, MgO and CeO2 modified HM catalyst can improve the selectivity of 2,6-DMN.The isopropylation of 2-MN was studied on the HM catalyst, due to the steric hindrance, the selectivity of 2,6-MIPN was better over the parent catalyst. The external acid sites of HM catalyst was mainly deactivated by CeO2, MgO can enter into the inside of catalyst, modify the internal acid sites, and narrow the pore dimension, enhance the selectivity of 2,6-MIPN. After 8 h, the 2,6-MIPN selectivity can reach 89.5% over 3%MgO/20%CeO2/HM catalyst.更多还原