分子筛上择形合成2,6-二烷基萘的研究进展

2,6-二烷基萘是非常有价值的有机化工原料.以萘或甲基萘为原料的择形烷基化合成2,6-二烷基萘的路线简单,被认为是最合理的技术路线.用酸性分子筛作为催化剂具有活性高、选择性好及环境友好等优点.从烷基化试剂、溶剂和分子筛催化剂的选择等方面,综述了分子筛催化下择形合成2,6-二烷基萘的研究进展.目前常用的分子筛催化剂有HY、Hβ、SAPO-5、HZSM-5和MCM-41等;所用的烷基化试剂主要是醇、烯烃、卤代烃和多烷基芳烃等;溶剂一般选用环己烷,也有少数选用四氢萘、二氧化碳和异辛烷等.     

2,6-二甲基萘的技术进展

对萘、2-甲基萘、甲苯和二甲苯等原料制备2,6-二甲基萘的各种工艺进行了综述,并对目前工业化路线的生产成本进行了比较,提出在我国实现工业化生产时应注意的问题。     

Zn2+改性β沸石催化合成2,6-二甲基萘

在Zn^2 改性邱分子筛催化剂上进行了甲基萘与甲醇的烷基化合成2,6-DMN反应。考察了Zn^2 交换容量对Hβ分子筛催化剂的比表面积、表面弱酸量和催化甲基萘与甲醇烷基化效果的影响。实验结果表明：随Zn^2 交换容量增加,催化剂的比表面积下降,催化剂表面的弱酸量有所增加。经Zn^2 改性后催化剂的反应效果均有提高,同时发现影响甲基萘甲醇烷基化反应的主要因素是催化剂的表面弱酸量。     

ZSM-12分子筛研究进展

综述了水热合成法制备ZSM-12分子筛的影响因素、改性方法及其在催化反应中的应用。众多研究表明,模板剂种类影响ZSM-12分子筛晶粒的尺寸、形状以及酸性,硅铝比和碱度是影响ZSM-12分子筛合成的主要因素,硅凝胶是合成ZSM-12的适宜硅源。Ga、Fe、B、P等适宜的杂原子对ZSM-12进行同晶置换改性可以调节其酸性,酸脱铝改性可以使其总酸量减少、Lewis酸消失。ZSM-12可作为芳烃烷基化、异构化、裂化、重整等诸多反应的催化剂,在反应中表现出良好的催化活性及对目标产物的高选择性,是目前用于择形催化一步法合成2,6-二甲基萘最适宜的分子筛催化剂。     

2,6-二甲基萘空气液相氧化制备2,6-萘二甲酸的研究

2,6-萘二甲酸（2,6-NDCA）及其衍生物是制备各种聚酯和聚氨酯材料的重要单体,在钛材间歇式搅拌釜中,以2,6-二甲基萘为原料,醋酸钴、醋酸锰、醋酸钾和溴化物等为催化剂,研究了2,6-二甲基萘空气液相氧化制备2,6-萘二甲酸的过程。确定n（Co＋Mn）/n（HAc）,n（Co）/n（Co＋Mn）,n（Br）/n（Co＋Mn）,n（Co＋Mn）/n（2,6-DMN）,n（K＋）/n（Co＋Mn）和助催化剂对收率和纯度的影响,从而得到比较适宜的催化条件。在此催化条件下,还考察了引发温度、反应压力、反应温度、溶剂比以及醋酸的浓度对收率和纯度的影响,确定了最佳合成2,6-萘二甲酸反应条件。     

铝酸型离子液体催化制备2,6-二甲基萘的研究

以β-甲基萘和萘为原料,自制铝酸型离子液体作催化剂,1,2,4,5-四甲基苯作烷基化试剂合成2,6-二甲基萘。研究了氯铝酸盐类离子液体的酸强度、反应温度、反应时间对产率和2,6-二甲基萘选择性的影响。以Et3NHCl-x Al Cl3和[C4py]Cl-x Al Cl3为催化剂时,最佳反应条件是Al Cl3摩尔分数为0.75、反应温度为20℃、反应时间为8 h,原料的转化率均能达到60%左右,而2,6-二甲基萘的选择性可以分别达到了66.9%和76.5%。     

2,6-二甲基萘的合成

研究了以甲基萘为原料采用转移甲基化法合成2,6-二甲基萘(2,6-DMN)的工艺条件。通过考察温度、反应时间、催化剂的种类及用量、转移甲基化试剂的用量、溶剂用量等因素对2,6-DMN收率的影响,探讨了转移甲基化法合成2,6-DMN的工艺条件。结果表明,2-甲基萘(2-MN)使用量为2 g 时,反应温度为18℃、时间为2．5 h、n(无水三溴化铝)∶n(2-甲基萘)=0．8、n(转移甲基化剂四甲苯)∶n (2-甲基萘)=1．0、二氯甲烷用量为15 mL时,2,6-DMN的收率可达38％。另外,采用GCMS对产物进行了表征。     

2,6-二甲基萘生产技术进展

介绍了目前世界上4种生产2,6-二甲基萘的工艺技术,对其经济性进行了对比,概述了国内2,6-二甲基萘的研究现状,指出了我国2,6-二甲基萘的研发工作中存在的问题,并给出了进一步发展的建议。     

转移甲基化合成2,6-二甲基萘研究

以β-甲基萘为原料,均四甲基苯为烷基化剂,在催化剂作用下,进行转移甲基化反应合成2,6-二甲基萘,考察了反应的温度,催化剂和烷基化剂的加入量对反应结果的影响。     

2,6-二甲基萘技术的研究进展

2 ,6 -二甲基萘是一种重要的有机化工原料 ,是制备高性能聚酯材料聚萘二甲酸乙二醇酯的前体。本文全面的介绍了以萘、甲基萘、甲苯及二甲苯为原料合成二甲基萘的工艺。     

Hexane activation over vanadium modified zeolite ZSM-5

The influence on the form of ZSM-5, vanadium content and the elimination of the exterior surface, on the activity and selectivity of n-hexane oxidation was studied using a fixed bed reactor. Blank reactor studies (carborundum packed reactor) showed no conversion below 450 °C with the highest conversion (8 %) at 500 °C. The dominant products were found to be carbon oxides (Sel./% = 90) with minor selectivities to the hexene isomers (7 %) with the remainder being cracked products, THF and benzene. H-ZSM-5 with different SiO₂/Al₂O₃ ratios (100 and 320) and Na-ZSM-5 (SiO₂/Al₂O₃ ratio of 100) were tested under non-oxidative conditions. As the ratio of the SiO₂/Al₂O₃ increased the aluminium content decreases and so too does the cracking ability of the zeolite (i.e. yield of cracked products dropped from 36 to 8 %). However, the use of the Na- form of the ZSM-5 zeolite completely eliminated acid cracking and therefore this system was further investigated. Na-V-ZSM-5 (~1 % loading) was synthesized using the solid state ion-exchange method. Time on stream experiments (fresh batch of catalyst for each experiment with sampling at the same time for a period of 24 h) were conducted and temperature (350, 400 and 450 °C), contact time (0.5, 0.8, 1.1 and 1.5 s) and fuel/air ratios (0.7, 1.3 and 2) were varied. The optimum conditions (Conv./% = 39) for terminal functionalised products were found to be at 400 °C at a contact time of 1.1 s and a fuel air ratio of 1.3. With the lower fuel air ratio of 0.7 (oxygen rich conditions), hexanal formation was favoured.     

磷镁改性的ZSM-5分子筛催化性能研究

研究了磷、镁改性对ZSM-5分子筛的孔结构和酸性的影响。采用甲苯的歧化反应为探针反应,考察了改性后分子筛催化甲苯选择歧化反应的活性和选择性。结果表明,磷、镁单独改性时,随着负载质量分数的增加,转化率逐渐增加,且大于相同工艺条件下HZSM-5的转化率。当磷质量分数达到3％～5％ 或镁质量分数达到1％时,转化率达到最大值,这时对二甲苯为平衡组成,基本没有选择性。磷镁复合改性时,既可以提高催化剂的选择性,又可以使催化剂的活性不至于降得很低。在磷质量分数为9％、镁质量分数为1％时,改性效果最好。     

Effects of steam and TEOS modification on HZSM-5 zeolite for 2,6-dimethylnaphthalene synthesis by methylation of 2-methylnaphthalene with methanol

Shape-selective methylation of 2-methylnaphthalene (2-MN) over HZSM-5 catalysts modified by steam and tetraethoxysilane (TEOS) treatments was carried out in a fixed-bed reactor. Catalysts were characterized by XRD, NH₃-TPD, BET, FT-IR spectra of pyridine adsorbed, and by adsorption of hexane and cyclohexane. The results show that the TEOS treatment can effectively passivate external active site and narrow pore mouth of catalyst, but it has less effect on the internal surface than steam modification. Hydrothermal treatment can effectively reduce both external and internal acid sites, and adjust channel of catalyst. Steam treatment can effectively increase the ratio of 2,6/2,7-DMN, but the ratio has no increasing trend on TEOS modified catalyst. So adjusting acidity property is more useful to increase the selectivity to 2,6-DMN and the ratio of 2,6/2,7-DMN than narrowing catalyst pore mouth. Tailoring acidic characteristics is more important than spatial control for distinguishing between 2,6-DMN and 2,7-DMN.     

钨硅酸改性ZSM-22分子筛对苯酚与异丙醇烷基化的影响

本文采用X射线衍射、BET、NH3-TPD几种表征方法,研究了ZSM-22的表面酸性和结构,以及在ZSM-22分子筛催化剂上苯酚异丙醇的烷基化反应。实验结果表明:在T=260℃、WHSV=1.8h-1、CatalystLoading=0.3g、n异丙醇/n苯酸=0.8条件下,苯酚的转化率可达6.04%,邻异丙基苯酚和对异丙基苯酚的总选择性为86.14%。浸渍钨硅酸后的ZSM-22,钨硅酸含量为10%苯酚转化率可达到68.29%。     

改性ZSM-5分子筛催化合成哌嗪

研究了不同金属离子改性得到的M-ZSM-5分子筛在以乙二胺(EDA)为原料合成哌嗪反应中的催化性能。通过NH3-TPD和BET法对催化剂进行表征,结果表明,经过离子交换后HZSM-5的骨架结构没有发生变化,仅仅是表面酸性发生了变化。重点考察了催化剂酸性对反应的影响,实验表明,提高弱酸和中强酸中心所占比例有利于哌嗪(PA)和三乙烯二胺(TEDA)生成。以Zn-ZSM-5和Zn/K-ZSM-5为催化剂,在常压,t=360℃,空速为0.25 g/(min.h),m(EDA)∶m(H2O)=4∶6的反应条件下,原料EDA的转化率分别为94.1%和82.6%;产物PA和TEDA的选择性分别为45.5%,42.1%和29.4%,50.1%。     

负载金属离子ZSM-5分子筛膜脱除苯并噻吩-二苯并噻吩的性能

采用水热合成法制备ZSM-5分子筛膜,并通过负载金属离子对其进行改性。通过X线衍射仪(XRD)、扫描电子显微镜(SEM)对所制备的膜进行表征。将所制得的ZSM-5分子筛膜经过负载金属离子改性后用于模拟汽油中苯并噻吩、二苯并噻吩二元硫化物的分离,考察负载离子种类、负载离子浓度和操作温度对二元硫化物竞争吸附和渗透通量的影响,并应用软硬酸碱理论(HSAB)分析吸附能力的强弱。结果表明:当Ag+浓度为0.2 mol/L时硫化物的分离因子最高可达1.31;随着操作温度的升高,ZSM-5分子筛膜渗透通量逐渐增大而分离因子逐渐减小。     

Hierarchical ZSM-5 zeolite designed by combining desilication and dealumination with related study of n-heptane cracking performance

The effect of the basic (NaOH) and/or acid (citric acid and EDTA-2Na) treatment of ZSM-5 zeolite has been studied comparing the structural and acidic features and their catalytic performance in n-heptane cracking. The properties of the catalysts have been elucidated using XRD, N₂ low-temperature sorption, ²⁷Al and ²⁹Si NMR, pyridine adsorbed FTIR, NH₃–TPD, SEM and TEM analysis. The results showed that the degree of desilication and dealumination of ZSM-5 zeolites was greatly dependent on the agents. NaOH obviously created new mesopores on parent ZSM-5 zeolites by desilication. Citric acid contributed to the removal of nonframework Al species, causing the increase of micropore surface area. EDTA-2Na promoted desilication and simultaneously converted part of removed framework Al species into nonframework Al species. The treatment of ZSM-5 combined with those three agents was very effective to obtain a hierarchical structure with partial breakdown of the crystallites and high acid amounts of both Brönsted and Lewis acid sites. Catalytic tests showed that the post-treated ZSM-5 catalysts had higher activity and stability than parent ZSM-5 catalyst at the same reaction temperature. The synergetic effect of Brönsted acid and Lewis acid of ZSM-5 catalyst (Z5-ACE) probably facilitated n-heptane conversion, while more clean micropore and newly created mesopores facilitated the slight increase of olefin selectivity and suppressing the formation of coke deposition in its inherent micropores to some extent.