MCM-41负载Lewis酸催化合成2-甲基吲哚

以苯肼和丙酮为原料,在负载有各种Lewis酸的MCM-41分子筛催化下采用Fischer吲哚合成法合成2-甲基吲哚,在比较了AlCl3/MCM-41、ZnCl2/MCM-41和FeCl3/MCM-41对反应的选择性和收率后发现,负载量为4mmol/g的ZnCl2/MCM-41具有对反应较好的选择性,目标产物收率达到了76.2%。     

MCM-41分子筛的水热合成、改性及其应用研究进展

介绍了以水热合成法为主的介孔MCM-41分子筛的合成,简述了近几年国内外介孔MCM-41材料的改性,尤其是金属掺杂改性以及杂多酸改性等方面的最新研究,详细介绍了关于功能化的MCM-41在诸多工业反应上的应用,如在烷基化催化、酯化催化、异构化催化等反应中的应用,最后对介孔MCM-41分子筛材料的发展前景以及未来亟需解决的问题进行了展望。     

Ni_2P/MCM-41催化剂的制备及其加氢脱氧反应工艺条件的优化

采用程序升温还原次磷酸盐法合成了Ni2P/MCM-41催化剂,并结合X射线衍射(XRD)、N2等温吸附手段对催化剂进行了表征。以苯并呋喃(BF)为模型化合物进行加氢脱氧(HDO)反应性能研究。考察了反应温度、反应压力、空速、氢油比对Ni2P/MCM-41 HDO反应的影响。反应温度300 oC,反应压力3 MPa,氢油比500(V/V),空速4.0 h-1时,连续反应100 h,BF HDO活性稳定在90%以上。     

分子筛MCM-48负载硅钨酸催化合成丁酮-1,2-丙二醇缩酮

报道了以分子筛MCM-48负载硅钨酸H4SiW12O40/MCM-48为催化剂,通过丁酮和1,2-丙二醇反应合成了丁酮-1,2-丙二醇缩酮。探讨了H4SiW12O40/MCM-48对缩酮反应的催化活性,较系统地研究了酮醇物质的量比、催化剂用量、反应时间诸因素对产品收率的影响。实验表明:H4SiW12O40/MCM-48是合成丁酮-1,2-丙二醇缩酮的良好催化剂,在n(丁酮)∶n(1,2-丙二醇)=1∶1.6,催化剂用量为反应物料总质量的0.6%,环己烷为带水剂,反应时间45 min的优化条件下,丁酮-1,2-丙二醇缩酮的收率可达91.9%。     

WO3/MCM-41催化合成己二酸

以MCM-41为载体,负载活性组分WO_3,自制催化剂WO_3/MCM-41,并采用XRD、SEM、EDX对催化剂进行表征,并用于催化氧化环己酮合成己二酸,考察了其性能,通过正交试验探讨30%H_2O_2用量、反应温度、反应时间及催化剂的重复使用性能。实验结果表明:自制催化剂较优负载率为40%,优化合成条件为:w(催化剂)=8.2%(基于环己酮质量)、环己酮︰30%H_2O_2=100︰500、反应时间为5 h、反应温度115℃,在此条件下,己二酸收率为62.1%。且催化剂重复使用5次后,产物收率依旧达到59.8%,表明WO_3/MCM-41具有良好的重复使用性能,是易回收、绿色环保及高效的催化剂。     

硅基介孔材料MCM-48的合成、改性及催化领域应用的研究进展

概述了硅基介孔材料MCM-48的发展、合成及应用,介绍了具有三维螺旋孔道结构的MCM-48的主要合成方法及各个方法的优缺点,分析了MCM-48合成过程中原料,反应条件对合成产物的影响.总结了金属改性MCM-48的两种方法,以及改性后在吸附和催化领域的应用,指出了未来MCM-48的研究方向.     

咪唑改性MCM-22分子筛的制备及甲烷无氧芳构化性能

以硅溶胶为硅源,环己亚胺为模板剂,在动态条件下利用水热合成法合成了MCM-22分子筛,并在该体系下以咪唑为添加剂合成了咪唑改性MCM-22-I分子筛,考察了咪唑对MCM-22-I分子筛合成的影响,利用FTIR、XRD、SEM、ICP、BET、NH₃-TPD、H₂-TPR和TG/DTG等手段分别对咪唑改性前后分子筛的物化性质进行了表征。结果表明,咪唑改性能够增大MCM-22的比表面积、孔容和酸性,同时可有效降低模板剂HMI的用量。采用等体积浸渍法制备了6Mo/MCM-22和6Mo/MCM-22-I双功能催化剂,在连续流动固定床反应器上,反应温度700℃、反应压力1.01×10⁵Pa（1atm）、空速1500mL/(g-cat·h)的反应条件下,考察了催化剂催化甲烷无氧芳构化合成苯的催化剂性能。结果表明,与6Mo/MCM-22催化剂相比,咪唑改性的6Mo/MCM-22-I催化剂具有更高的择形性能和催化活性,甲烷的平均转化率提高了24.1%,苯的平均生成速率和选择性分别提高了24.3%和10.0%。     

负载型功能化离子液体的催化性能

用MCM-41为载体,通过化学法合成了负载羟基功能化的咪唑类离子液体催化剂HIILsBr/MCM-41,考察了在碳酸丙烯酯（PC）合成中的催化作用。考察了负载温度、负载时间、离子液体与载体的配比、溶剂等负载反应条件对催化剂催化性能的影响。结果表明： 在115 ℃,2.0 MPa,4 h条件下,PC产率为89.9%,选择性为99.5%。     

MCM-22、MCM-49和MCM-56三种分子筛的合成

MWW结构分子筛是一类新型的催化材料，具有独特的10元环孔道和12元环孔穴结构，在多种反应中表现出良好的催化活性。以六亚甲基亚胺作为模板剂，合成了MCM-22、MCM-49和MCM-56三种分子筛，并详细考察了不同硅源、凝胶配比、晶化温度和晶化时间对合成过程的影响。结果表明，凝胶配比和晶化温度对分子筛物相的影响较大。以硅胶粉为硅源，无论在何种晶化时间下都不能得到MCM-56，只能合成出MCM-49。而以碱性硅溶胶为硅源，在较短的晶化时间内就可以得到MCM-56。     

HMCM-22/MCM-41的制备及其在甲苯碳酸二甲酯烷基化中的催化性能

以自制的HMCM-22作为原料,与中孔分子筛MCM-41的凝胶在水热条件下进行组装得到HMCM-22/MCM-41中微孔复合分子筛,采用XRD、N2吸附-脱附及NH3-TPD等方法对合成样品进行表征。结果表明,合成的样品同时具有中孔分子筛MCM-41与微孔分子筛HMCM-22的特点。采用固定床微型连续流反应器对HMCM-22/MCM-41复合分子筛催化甲苯与碳酸二甲酯(DMC)的烷基化反应性能进行了评价,考察了反应温度、甲苯与DMC摩尔配比及空速对烷基化反应的影响。实验发现,HMCM-22/MCM-41催化甲苯DMC烷基化反应的产物中,对二甲苯的选择性远高于间位和邻位异构体的选择性,表现出良好的催化活性和选择性。     

Synthesis, characterization and catalytic properties of MCM-36 pillared via the MCM-56 precursor

Pillared layered MCM-36 zeolite (MCM-36-I) was successfully synthesized from MCM-56 precursor with polymeric silica as the pillaring agent. The structure and properties of the sample was characterized by means of N₂ adsorption, XRD, TEM and IR spectroscopy of pyridine adsorption. The results showed that MCM-36-I has higher external surface area and more Brönsted acidic sites on external surface than that on the MCM-36 sample (MCM-36-II) which was synthesized from layered MCM-22 precursor. The catalytic properties of these samples were tested for alkylation of benzene with isopropanol. Compared with MCM-36-II catalyst, MCM-36-I showed higher conversion of benzene and selectivity to cumene. This should be mainly assigned to the fact that MCM-36-I possesses larger amount of accessible Brönsted acid sites which located on the external surface than that of MCM-36-II.     

Characterization and catalytic properties of MCM-56 and MCM-22 zeolites

We present an investigation of the structure and properties of MCM-56 and MCM-22. These materials have been characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and N₂ adsorption isotherms. DIFFaX was used to simulate pronounced peak broadening in the X-ray diffraction patterns of MCM-56. Toluene disproportionation is used as a test reaction to compare the catalytic activity of MCM-22 and MCM-56. We have found that MCM-56 is made of very thin MWW-type layers. The layers are typically one unit cell along the c direction (with a few of them having two or three unit cells). These very thin layers of MCM-56 become tightly curled upon calcination. The structures thus formed pack very efficiently, and this phenomenon prevents access of organic molecules like toluene to most of the 12 MR cups on the crystal exterior. Although MCM-56 is active for the disproportionation of toluene, its activity is lower than that of MCM-22. A calcination procedure that prevents the curling up of the MCM-56 layers is needed to make MCM-56 a useful catalyst for large organic molecules.     

Multinuclear MAS NMR studies of zeolites MCM-22 and MCM-49

MCM-22 and MCM-49 comprise a new class of molecular sieves that crystallizes as thin sheets or platelets and has many unusual structural features. MCM-22 is first synthesized hydrothermally as a precursor, MCM-22(P), that condenses upon calcination to a three-dimensional framework (MCM-22). Its framework topology is comprised of two independent pore systems, both accessible through 10-membered rings. One of these pore systems is defined by two-dimensional sinusoidal channels, which maintain an effective 10-ring diameter throughout the structure. The other consists of large supercages whose inner free diameter, 7.1 Å, is defined by 12 rings with inner height of 18.2 Å. MCM-49 has the same framework topology as MCM-22, but is synthesized directly in the reaction gel and therefore still contains the organic template. Multinuclear MAS NMR studies of MCM-22 (P), MCM-22, and MCM-49 are presented and discussed in light of the proposed structure and provide new insights into this novel class of materials. The structural information obtained from this NMR investigation is complementary to and consistent with the structure proposed from X-ray diffraction measurements. ¹³C NMR data support the existence of different dual pore systems within both MCM-22(P) and MCM-49. ²⁷Al MAS NMR spectra exhibit three distinct T_d resonances that can be interpreted in terms of the proposed framework topology. ²⁹Si MAS studies of a highly siliceous MCM-22 prepared by hydrothermal dealumination confirm the presence of at least one buried T-site in its framework structure that is not accessible to a channel wall, favor the orthorhombic form of the proposed structure, and support the presence of the modified dodecasil-1H cage.     

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。     

Chemical Stability of Ti-Modified MCM-41 Catalysts in the Hydroxylation of Benzene in the Liquid Phase

Ti-substituted MCM-41 and Ti-grafted MCM-41 materials possessing both well-ordered long-range and pore structures have been used as catalysts for the hydroxylation of benzene in the liquid phase. The stability of the catalytic performance and the changes in the structural characteristics of Ti-modified MCM-41 resulting from the hydroxylation reaction have been investigated. It has been found that Ti-grafted MCM-41 exhibits better stability of catalytic performance than Ti-substituted MCM-41. For the Ti-substituted MCM-41, the migration of framework Ti into non-framework sites results in a decrease in the catalytic performance and the partial collapse of the pore structure. For the Ti-grafted MCM-41, the hydroxylation of benzene induces a smaller decrease in the pore volume and specific surface area than that observed for Ti-substituted MCM-41.     

MCM-22、MCM-49和MCM-56分子筛的表征

MWW结构分子筛是一类新型的催化材料，具有独特的10元环孔道和12元环孔穴结构、优良的水热稳定性和特殊的酸中心分布，在多种反应中表现出良好的催化活性。以六亚甲基亚胺为模板剂，合成了具有MWW结构的MCM-22、MCM-49和MCM-56三种分子筛，并采用XRD、BET、TG/DTG和SEM手段对合成分子筛进行了表征，表明它们具有相同的单层结构，彼此之间的区别只有层间排列的结合层度和结合方式不同。MCM-56是薄层结构，晶体的层数少，MCM-22和MCM-49是多层结构，层数多。MCM-22的层间结合比较疏松，MCM-49的层间结合比较紧密。     

ZSM-5/MCM-41复合分子筛的微波合成及催化性能

用微孔沸石硅源法微波合成ZSM-5/MCM-41复合分子筛,采用XRD、BET和NH₃-TPD技术对合成分子筛进行表征。结果表明,复合分子筛具有类MCM-41 的典型六方介孔结构,同时具有中孔和微孔结构,复合分子筛的总酸量介于HMCM-41酸量与HZSM-5酸量之间。利用脉冲微反装置考察合成分子筛的邻二甲苯异构化催化性能。结果表明,ZSM-5/MCM-41复合分子筛具有高于同硅铝比的MCM-41、ZSM-5和ZSM-5/MCM-41的机械混合物的催化活性。     

Atomistic simulations for adsorption and separation of flue gas in MFI zeolite and MFI/MCM-41 micro/mesoporous composite

Adsorption of pure CO₂ and N₂ and separation of CO₂/N₂ mixture in MFI zeolite and MFI/MCM-41 micro/mesoporous composite have been studied by using atomistic simulations. Fully atomistic models of MFI and MFI/MCM-41 are constructed and characterized. A bimodal pore size distribution is observed in MFI/MCM-41 from simulated small- and broad-angle X-ray diffraction patterns. The density of MFI/MCM-41 is lower than MFI, while its free volume and specific surface area are greater than MFI due to the presence of mesopores. CO₂ is preferentially adsorbed than N₂, and thus, the loading and isosteric heat of CO₂ are greater than N₂ in both MFI and MFI/MCM-41. CO₂ isotherm in MFI/MCM-41 is similar to that in MFI at low pressures, but resembles that in MCM-41 at high pressures. N₂ shows similar amount of loading in MFI, MCM-41 and MFI/MCM-41. The selectivity of CO₂ over N₂ in the three adsorbents decreases in the order of MFI>MFI/MCM-41>MCM-41. With increasing pressure, the selectivity increases in MFI and MFI/MCM-41, but decreases in MCM-41. The self-diffusivity of CO₂ and N₂ in MFI decreases as loading increases, while in MFI/MCM-41, it first increases and then drops.     

Cerium-containing MCM-41 materials as selective acylation and alkylation catalysts

The synthesis of Ce–MCM-41, Al–MCM-41 and Ce–Al–MCM-41-type mesoporous materials was carried out hydrothermally by refluxing the gel with magnetic stirring under atmospheric pressure for 24–36 h. The samples were characterized thoroughly in order to obtain the structural and textural properties, which reveal the presence of well-ordered M41S-type materials. The Ce–MCM-41 samples were used for catalytic acylation of alcohols, thiols, phenols and amines show good activity and selectivity including high chemoselectivity towards selective monofunctional acylation of bifunctional compounds. Quite importantly the acylation of bulky molecules such as cholesterol, ergesterol and β-sitosterol could be achieved using Ce–MCM-41 as solid catalyst. The presence of Ce along with Al in Ce–Al–MCM-41 was found to have synergistic effect as Ce–Al–MCM-41samples were more active catalysts for alkylation of naphthalene compared to either Ce–MCM-41 or Al–MCM-41 with comparable Si/Al or Si/Ce molar ratio.     

Separation and Recovery of Tetramethyl Ammonium Hydroxide with Mesoporous Silica Having a Hexagonal Structure (MCM-41)

Separation and recovery of tetramethyl ammonium hydroxide (TMAH) was investigated using several types of MCM-41 (mesoporous silica having hexagonal structure) adsorbents. The MCM-41s were prepared by hydrothermal synthesis with structure-directing agents with different alkyl chains. The prepared MCM-41s were characterized with X-ray diffraction, transmission electron microscope, nitrogen gas adsorption, and zeta potential, and then used for adsorption of TMAH. The adsorption of TMAH with MCM-41s increased with pH up to pH ≈ 10 and then decreased as the MCM-41 dissolved. The adsorption of TMAH progressed via the Langmuir mechanism. The maximum adsorption corresponded to the pore diameter and the pore volume of the MCM-41s. MCM-41 also possesses selectivity for TMAH against phenol. The chromatographic operation was conducted using granulated MCM-41 to avoid excessive pressure-drop through the packed column and quantitative adsorption-elution processing of TMAH could be achieved.