MCM-22 分子筛的合成及液相烷基化合成乙苯性能研究

对各种条件下合成的MCM-22沸石进行了表征研究。研究表明晶化时间对MCM-22沸石的层间结构有着显著的影响,晶化40 h后,其结构趋向稳定。MCM-22沸石沸石具有较高的B酸含量,强酸中心主要为B酸,MCM-22晶体呈片状结构,其结构中存在丰富的大孔。以MCM-22沸石为催化剂考察了其催化乙烯和苯的液相烷基化的反应性能。结果表明,MCM-22沸石催化剂具有优良的选择性,在低苯烯比(B/E)的反应条件下,其反应稳定性优良。在乙烯质量空速达到0.7 h~(-1),苯烯摩尔比(B/E)可以降低到2.0,乙苯选择性达到84%,二甲苯含量小于50 mg/kg。     

离子液体催化苯与长链烯烃烷基化的连续反应性能

在强制混合-反应-分离-循环实验装置上考察了酸性氯铝酸盐室温离子液体[BMIM][AlCl4]催化苯与长链烯烃烷基化反应的连续操作、沿反应管侧线分布式连续进料和工业烯烃原料进料的连续反应性能。实验结果表明,即使在相对苛刻的反应条件下,纯烯烃原料1-十二烯单程转化率也能在反应器内达到100.0%,2-苯基异构体选择性高于37.7%。虽然侧线连续进料的位置不同,但在反应器出口前1-十二烯可完全转化。精制过的工业烯烃原料可以满足连续烷基化反应的要求。     

VPT法制备MCM-22分子筛催化剂颗粒及其烷基化性能

采用汽相法（VPT）制备了以成型干胶颗粒为基体的MCM-22分子筛催化剂.利用XRD、SEM和BET测试技术对所制备催化剂进行了物相表征、形貌观察和织构分析,并以苯和丙烯烷基化合成异丙苯为模型反应,在液-固固定床反应器上对所制备催化剂的性能进行了评价.结果表明：汽相法制备的MCM-22分子筛催化剂不仅具有较好的结晶度和较高的微孔表面积,而且具有更好的晶体生长取向性和更加致密的结构;在烷基化反应中也具有很好的活性、选择性和稳定性,特别是对目的产物异丙苯的选择性明显高于水热法（HTS）合成的催化剂,在异丙苯合成上具有很好的应用前景.     

不同沸石催化剂上苯与1-十二烯烷基化

利用NH3 TPD测定了 4种沸石分子筛的酸性 ,并考察了 4种分子筛在苯与 1-十二烯烷基化反应中的催化性能 ,揭示了沸石分子筛的酸性、孔结构对其催化活性和产物选择性的作用规律 ,发现沸石分子筛经水热处理和酸处理 ,调变了孔结构和酸性 ,进而提高其催化活性     

苯与长链烯烃烷基化反应的催化剂研究进展

长链烷基苯是合成洗涤剂的重要原料,是由苯与长链烯烃在酸性催化剂作用下烷基化反应生成的.目前生产工艺中大多使用HF或AlCl3为催化剂,由于它们的腐蚀性和毒性及对环境的污染,需要开发新的催化剂及生产工艺.简要对国内外合成线性长链烷基苯的各种固体酸、负载酸和酸性离子液体催化剂的研究进展进行了综述.     

苯与1-十二烯烷基化反应的研究进展

介绍了苯与1-十二烯烷基化反应制备直链烷基苯(LAB)的国内生产近况,讨论了固体酸催化剂催化苯与1-十二烯烷基化反应的研究情况,分析了离子液体催化苯与1-十二烯烷基化反应的研究进展,同时,对苯与1-十二烯烷基化反应的研发趋势提出了展望。     

苯与长链烯烃烷基化反应催化剂的研究进展

催化剂是决定烷基化反应技术水平的关键因素之一,本文从催化剂的催化活性,产品中直链烷基苯的选择性,催化剂的使用寿命等方面评价了现有的各种催化剂,并介绍了包括杂多酸、分子筛、离子溶液等各种新型改性催化剂的研制开发。提出今后应进一步深入研究包括杂多酸在内的符合环保要求和工业化需求的新型改性催化剂。     

无粘结剂MCM-22分子筛催化剂制备及其催化性能

采用NaOH溶液对含粘结剂的成型工业MCM-22分子筛催化剂进行后处理以脱除粘结剂,制备无粘结剂MCM-22分子筛催化剂,并实验考察了碱浓度、处理时间对催化剂的强度、活性组分的含量、酸量及催化性能的影响。结果表明:在NaOH溶液的质量分数为0.3%、150℃的条件下对圆柱形含粘结剂MCM-22分子筛催化剂处理4h,即可制得无粘结MCM-22分子筛催化剂。在苯与乙烯液相烷基化反应中,在苯与乙烯物质的量比为3.0,乙烯质量空速为9.0h~(-1),温度200℃,压力3.5 MPa的反应条件下,无粘结剂MCM-22分子筛催化剂的乙烯转化率维持在60%以上,催化性能与分子筛原粉相当,明显优于含粘结剂的催化剂(低于40%),且其强度能够满足工业应用的要求。     

LB-16有机硅杂化分子筛催化剂的制备及其在长链烷基苯合成中的应用

长链烷基苯(LAB)是制备合成洗涤剂烷基苯磺酸钠的主要原料,传统上LAB采用无机液体酸(HF)为催化剂将苯和长链烯烃烷基化而制得。在LAB的诸多异构体中,2-LAB因其更高的溶解性和可降解性而更受欢迎。使用低温成胶的策略,以水热合成法合成LB-16有机硅杂化分子筛催化剂,并考察其在LAB合成中的催化性能。结果表明,在反应温度190℃、空速0.2 h-1、苯烯物质的量比15∶1条件下,经过1 000 h催化试验,1-十二烯转化率大于99%,2-LAB选择性51%。LB-16有机硅杂化分子筛催化剂对苯与1-十二烯合成反应具有较好的催化活性和稳定性,同时对2-LAB具有较高的选择性,具有工业化应用前景。     

纳米片状MCM-22沸石的合成及表征

采用动态水热合成的方法,以环己亚胺(HMI)为模板剂,合成了纳米片状MCM-22沸石。并考察了不同硅源、HMI用量以及碱源对沸石合成的影响规律。结果表明:以硅溶胶为硅源时,在较宽的硅铝摩尔比范围(SiO_2/Al_2O_3,30—100)内得到高结晶度的MCM-22沸石;而以气相二氧化硅为硅源时,则在较窄的硅铝比范围内(30—70)才能得到结晶度较好的沸石样品;用NaF或KF为碱源,代替传统的NaOH,同样能够合成高结晶度MCM-22沸石。上述合成的MCM-22沸石样品具有纳米片交错堆积的花状形貌,比表面积为500—600 m~2/g,总孔容为0.4—0.6 cm~3/g。此外,以MCM-22沸石为模板,通过高温分解乙烯将碳沉积到沸石片的表面,除去MCM-22沸石后,获得纳米多孔碳材料。     

Study on alkylation of benzene with propylene over MCM-22 zeolite catalyst by in situ IR

For the alkylation reaction of benzene with propylene over MCM-22 zeolite catalyst, two completely different results can be obtained for two different operating procedures. If the benzene is pumped into a reactor then followed by propylene (operation 1), the alkylation reaction proceeds normally, while the reaction can not occur if the propylene is introduced first followed by benzene (operation 2). In situ IR technology was used to investigate two modes designed to simulate the above operating processes. The mechanisms of the two operations are as follows: in operation 1, benzene molecules first fully were adsorbed on the acidic sites of MCM-22 zeolite, when propylene was introduced, propylene molecules seized the acidic sites by repelling benzene, at the same times propylene molecules were polarized and reacted with absorbed benzene molecules. This is synchronous reaction mechanism; in operation 2, propylene introduced was molecularly absorbed on acidic sites strongly resulting in producing carbonium ions of CH₃–C⁺H–CH₃, then the carbonium ions reacts with other propylene molecules further to form polymeric species. The polymers blocked the pores and covered the acidic sites so that the alkylation reaction with benzene can not take place. This process is carbonium ions reaction mechanism of propylene itself.     

Continuous reaction performances of benzene alkylation with long chain olefins catalyzed by ionic liquid

Based on a compulsive mixing-reacting-separating-recycling small experimental setup,the continuous reaction performances of benzene alkylation with long chain olefins catalyzed by [BMIM]Cl-AlCl₃ ionic liquid were investigated. Three different situations including normal continuous operation mode (reagent materials), sidetrack feeding from different axial positions along the static mixing reactor (reagent materials) and normal continuous alkylation using industrial paraffin and olefins materials were examined. Even under the relatively hypecritical reaction conditions, the single pass conversion of pure 1-dodecene could reach to nearly 100.0%, and the selectivity of 2-phenyl isomer was higher than 37.7%. Although the positions along the reactor for sidetrack feeding were different, the 100.0% single pass conversion of 1-dodecene was also attained before the outlet of the reactor. The refined industrial olefins as raw material could meet with the requirements of continuous alkylation. The influences of impurities such as di-olefins and non-benzene aromatics on the catalytic activity and stability should be studied further. __________ Translated from Chemical Reaction Engineering and Technology, 2006, 22(4): 289–293 [译自: 化学反应工程与工艺]     

Synthesis of dodecylbenzene via the alkylation of benzene and 1-dodecene over mesopore Beta zeolites

The alkylation of benzene with long chain α-olefins is a crucial process in the production of fine chemicals, which requires the upgrading from traditional homogeneous catalysis to heterogeneous catalysis involving zeolites. However, the application of zeolite catalysts has been limited by their fast deactivation due to constrained diffusion resulting from the sole micropores. To address this challenge, a desilication and secondary-crystallization strategy has been employed to fabricate hierarchically structured mesoporous Beta zeolites. The resultant mesoporous Beta zeolites demonstrate excellent catalytic activity and stability in the alkylation of benzene with 1-dodecene, arising from the exposed acid sites and enhanced internal diffusion. Importantly, the internal diffusion limitations for these mesopore Beta zeolites are negligible, which significantly extends their lifetime and improves their regeneration performance. To achieve these benefits, the degree of mesopores must be deliberately controlled. Overall, this approach provides a promising solution for achieving efficient and environmentally friendly alkylation processes.     

新型MCM-22/MCM-41复合分子筛上FCC汽油降烯烃芳构化反应

采用纳米组装法合成MCM-22/MCM-41微孔/介孔复合分子筛,分别以H-MCM-22和H-MCM-22/MCM-41为催化剂,在固定床微反装置上对FCC汽油进行降烯烃芳构化的对比考察。结果表明,在反应时间2 h内,与MCM-22相比, MCM-22/MCM-41具有高的芳构化性能和持久的初始活性,复合分子筛汽油改质的产物中,芳烃体积分数由28.58%上升至51.1%,烯烃体积分数由34.04％降至5.8％。探讨了新型H-MCM-22/MCM-41复合分子筛用于FCC汽油改质的操作条件以及催化剂失活再生性能。结果表明,最佳反应条件为：反应温度400 ℃,压力2 MPa,空速3 h^-1。失活催化剂经过两次再生,降烯烃芳构化性能基本不变。     

用于芳烃中微量烯烃脱除的MCM-22催化剂的研究

考察了用氯化铵离子交换处理的MCM-22分子筛催化剂在脱除芳烃中微量烯烃的催化活性,对分子筛催化剂进行了表征.结果表明离子交换增加了催化剂固体酸中心的量,而第2次离子交换的MCM-22分子筛催化剂脱烯烃效果最佳,其固体酸中心的量为最大.失活的分子筛催化剂通过焙烧再生处理,可恢复其活性.     

动态法合成MCM-22分子筛及其表征

以六亚甲基亚胺(HMI)为模板剂,采用动态水热晶化法合成出MCM—22沸石分子筛。采用XRD表征对其进行物相分析;采用氨脱附—程序升温脱附(NH3—TPD)法表征其酸性质。结果表明:合成过程中易生成混晶,而适宜的SiO2/Al203比和碱度可以合成出比较纯的MCM—22分子筛。采用常规的离子交换方法可以将其转变为氢型样品。     

苯与合成气烷基化催化剂的研究进展

对二甲苯（PX）是制备聚酯材料的重要原料,随着我国经济快速发展,对二甲苯的需求日益增长。目前PX主要通过石化路线生产,由于我国石油资源短缺,迫切需要开发基于煤化工路线的PX生产技术。通过苯与合成气烷基化制备PX是一条新的煤化工路线,近年来受到关注。本文综述了苯与合成气烷基化的最新进展,讨论了贵金属（Pt）、铜基氧化物、锌基氧化物（ZnZr、ZnCr）与沸石的复合以及负载和机械混合两类复合方式对催化效果的影响,分析了甲醇合成与烷基化反应的耦合机制以及反应条件的匹配关系;并与其他三种煤制芳烃技术,即合成气制芳烃、甲醇制芳烃以及苯与甲醇烷基化制烷基苯做了对比分析,表明该技术路线具有成本较低和工艺路线短的优势。