Catalytic reduction of NOx over transition-metal-containing MCM-41

The catalytic properties of Pt, Rh and Co supported on mesoporous molecular sieves with MCM-41-type structure consisting of SiO₂ and Al₂O₃ were studied for the reduction of NO with propene. Pt supported on siliceous MCM-41 was the most active catalyst, however, significant quantities of undesirable N₂O were formed during the reaction. Pt supported on mesoporous Al₂O₃ and Rh supported on both mesoporous oxides showed a lower activity, but an improved selectivity towards N₂ formation. Co supported on MCM-41-type materials had only a low level of activity for the reduction of NO with propene. For Pt supported on MCM-41-type materials only a minor decrease in the activity was observed when water vapor was added into the reactant gas mixture, while on Rh- and Co-containing catalysts the activity strongly decreased. This revised version was published online in July 2006 with corrections to the Cover Date.     

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-41分子筛的制备及催化性能研究

用微波法合成MCM-41中孔分子筛.并采用液相沉积法制备了以MCM-41分子筛为载体负载TiO2/S2O82-的同体酸催化剂,以乙酸与异戊醇的酯化反应作为探针反应,考察了焙烧温度、焙烧时间、浸渍溶液的浓度、浸渍时间以及钛硅比等制备条件对催化剂催化活性的影响,得到了最佳的制备条件.最佳条件是:n(Ti)/n(Si)=2,...     

Catalytic oxidation of styrene by manganese(II) bipyridine complex cations immobilized in mesoporous Al-MCM-41

Manganese 2,2'-bipyridine (bpy) complex cations, [Mn(bpy)₂]²⁺, have been immobilized in mesoporous Al-MCM-41 (Si/Al=9) and used as a catalyst for the oxidation of styrene by iodosylbenzene, H₂O₂ and tert-butyl hydroperoxide (TBHP). The oxidation products included epoxide, diol and aldehyde. Al-MCM-41-immobilized [Mn(bpy)₂]²⁺ exhibited a higher catalytic activity for styrene oxidation than the corresponding homogeneous catalyst and showed no significant loss of catalytic activity when recycled. This revised version was published online in July 2006 with corrections to the Cover Date.     

MCM-41介孔分子筛催化剂的制备及催化性能的研究

文章采用碱性水热晶化法制备MCM-41介孔分子筛为载体,用浸渍法将非贵金属Ni和12-硅钨杂多酸(HSi W)固载于分子筛上,制备得Ni-HSi W/MCM-41金属-酸双功能催化剂作为新型的长链烷烃异构化催化剂。研究了Ni-HSi W/MCM-41双功能催化剂在常压固定床反应器上,以正庚烷异构化反应为探针反应,催化剂在不同制备条件下的催化性能。结果表明催化剂在一定还原条件和反应条件下当Ni固载量为4 wt.%、HSi W固载量为30%,催化剂的焙烧温度为400℃时是最佳制备条件。     

介孔分子筛的制备及催化合成2-三氟甲氧基-5-硝基苯胺

采用直接合成法制备出由MCM-41介孔分子筛负载SO3H的催化剂,测定了催化剂表面的酸中心组成,并考察了不同工艺条件下邻三氟甲氧基苯胺区域选择性硝化的催化性能。用硫酸钡重量法、TEM和N2吸附-脱附表征了MCM-41-SO3H的结构。结果表明,MCM-41-SO3H保持了MCM-41的介孔结构,BET表面积高达560 m2/g,表面含有质子酸中心;得到最佳的工艺条件:m(邻三氟甲氧基苯胺)/m(催化剂)=32,n(硝酸)/n(邻三氟甲氧基苯胺)=3.0,反应温度65°C,反应时间3 h,邻三氟甲氧基苯胺转化率为93.5%,2-三氟甲氧基-5-硝基苯胺含量达到84.2%。催化剂焙烧温度290°C,催化剂重复使用6次仍保持较高活性。     

双功能硅烷化修饰MCM-41固载Cosalen催化环己烷氧化

采用双功能硅烷化试剂γ-氨丙基甲基二乙氧基硅烷(AMS),对(MCM-41)全硅介孔分子筛一步进行氨基官能团化和甲基疏水性修饰,然后将双水杨醛缩乙二胺合钴(Cosalen)通过氨基的轴向配位固载在修饰后的载体MCM-41上。X射线衍射和N2物理吸附/脱附的结果表明:经过AMS双功能硅烷化修饰以及固载Cosalen后载体的孔道结构保持良好。考察了硅烷试剂用量对硅烷化效率的影响,结果表明:当AMS的加入量为4.00mmol/g时,甲基修饰量达到1.95mmol/g;水和环己烷的静态吸附结果表明硅烷化修饰后,催化剂载体的疏水性明显增强。制得的催化剂应用于环己烷的分子氧氧化反应,130℃反应2h,环己烷转化率达到7.2%,环己醇和环己酮总选择性达到70.5%,较未经AMS修饰的催化剂Cosalen/MCM-41获得的醇酮总选择性提高了13%。     

Catalytic Oxidation of Alkylaromatics over Mesoporous (Cr)MCM-41

Liquid-phase catalytic oxidation of certain alkylaromatics over mesoporous (Cr)MCM-41 molecular sieves in the presence of chlorobenzene and tertiary butylhydroperoxide showed high substrate conversion and excellent product selectivity. The high catalytic activity of the materials is attributed to the complete oxidation of chromium ions to hexavalent chromium and the absence of pentavalent chromium in the mesoporous matrix.     

Catalytic performance of metal ion doped MCM-41 for methanol dehydration to dimethyl ether

Metal ion doped MCM-41 mesoporous molecular sieves (M-MCM-41, M = Al, Ga, Sn, Zr and Fe) were prepared using a hydrothermal synthesis method, with metal chlorides serving as the dopant sources. The M-MCM-41 structures were characterized by Fourier transform infrared spectroscopic (FTIR) analysis, X-ray diffraction, energy dispersive spectroscopy and N₂ adsorption–desorption measurement. The surface of M-MCM-41 acidities were determined by NH₃ temperature-programmed desorption and pyridine-adsorption FTIR analysis, and their catalytic performance for methanol dehydration to dimethyl ether (DME) was evaluated. The results showed that the prepared M-MCM-41, which exhibited a structure similar to that of MCM-41 with long-range ordered mesoporous structure, contained weak acidic sites. The number of weak acid sites in Al-MCM-41 increased as the Al content increased. The Al content in Al-MCM-41 had an important effect on its catalytic performance, where the highest catalytic activity was 80 and 100 % DME selectivity was achieved at a Si/Al molar ratio of 10. For MCM-41 doped with various types of metal ions, M-MCM-41 (M = Al, Ga, Sn and Zr) also presented a similar wide distribution of acidity, and their catalytic activities were ranked in the following order: Al-MCM-41 > Ga-MCM-41 > Zr-MCM-41 > Fe-MCM-41 > Sn-MCM-41, which were related to the coordination of the metal ions.     

Catalytic Aerobic Epoxidation of Olefins by Nanostructured Amorphous CoO–MCM-41

Nanostructured amorphous cobalt oxide deposited inside the pores of MCM-41 using ultrasonic deposition--precipitation of cobalt tricarbonyl nitrosyl in decalin was found to be an efficient catalyst for the epoxidation of olefins under aerobic conditions.     

苄基磺酸官能化MCM-41介孔分子筛催化合成季戊四醇三丙烯酸酯

以苄基磺酸官能化MCM-41介孔分子筛为催化剂,丙烯酸(AA)和季戊四醇为原料,合成季戊四醇三丙烯酸酯(PETA),研究了诸多反应条件的影响,发现其催化活性高于硫酸和其他质子酸。结果表明,在酸醇摩尔比为3.3∶1,催化剂用量为AA质量的2.5%,阻聚剂4-甲氧基酚的用量为反应物总质量的1.2%,共沸剂环己烷用量为反应总质量的60%,反应温度125℃和回流时间为150 min的优化条件下,PETA的收率可达79.3%,且产品外观质量好,反应后处理方便,催化剂可循环使用多次。并用X-射线衍射、红外光谱、差示扫描量热和Hammett指示剂对催化剂的结构和酸强度进行了表征和测定。     

微波固相法制备MCM-41固定 氯化铝催化剂及其催化性能

采用微波固相法制备了MCM-41固定氯化铝固体酸催化剂。以合成乙酸正戊酯为探针反应,考察了氯化铝不同负载量、反应时间、微波功率对其催化性能的影响。结果表明,氯化铝负载量为6 mmol/g、反应时间为 15 min、微波功率为750 W时,所制得的催化剂活性最好,其酯化率可达92.7%。     

Effect of MCM-41 nanoparticles on the kinetics of free radical and RAFT polymerization of styrene

To examine the effect of mobil composition of matter 41 (MCM-41) nanoparticles on the kinetics of free radical and 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid (DDMAT)-mediated reversible addition fragmentation chain transfer (RAFT) polymerization, the polymerization reaction using various amounts of as-synthesized MCM-41 were performed. To study the reaction kinetics, conversion, molecular weight and polydispersity index (PDI) were obtained during the polymerization. Also, differential scanning calorimetry (DSC) was used to determine the glass transition temperature (T _g) values of samples. According to the results, in free radical polymerization, conversion was increased by adding nanoparticles but the reverse trend was observed in RAFT polymerization. The same results were obtained for molecular weight values. In free radical polymerization, increasing the MCM-41 content led to higher PDI value, while in RAFT polymerization it did not appreciably affect the PDI value. In RAFT polymerization, no induction time was observed which indicates that DDMAT is an appropriate RAFT agent for styrene polymerization. Also in free radical polymerization, the addition of MCM-41 particles reduced T _g values in comparison to neat PS. On the other hand, there was an increase in T _g value up to 5 wt% of MCM-41 loading and a drastic reduction was observed in 7 wt% MCM-41 loading in the RAFT polymerization. Finally, the T _g values of nanocomposites produced by RAFT method were higher than those in the nanocomposites synthesized using the free radical method.     

负载型烯烃氢甲酰化反应催化剂研究进展

因催化剂与产物不易分离的问题,氢甲酰化反应催化剂固载化研究受到广泛关注。本文从分子筛、二氧化硅、碳材料、金属氧化物、磁性纳米粒子、有机聚合物和离子液体这些不同负载材料的角度综述了过去十年来的相关研究结果,并对不同载体的优缺点和发展前景进行了简要分析。固载型催化剂分为3种不同的构建方式：载体与配体连接、载体与金属连接以及载体同时与配体和金属连接。第3种构建方式制备的催化剂更稳定,常在二氧化硅作为载体中使用。第一种构建方式为催化剂制备提供了多样性,在无机物和有机物作为载体中都有广泛使用,其中,含磷的有机聚合物在提供良好催化剂效果的同时,也提高了催化剂的稳定性,对未来的研究方向有一定的指导意义。     

Synthesis, Characterization of Ag/MCM-41 and the Catalytic Performance for Liquid-phase Oxidation of Cyclohexane

Nano-scale silver supported mesoporous molecular sieve Ag/MCM-41 was directly prepared by one-pot synthesis method. The prepared sample was characterized by XRD, TEM, and N₂ sorption. The results showed that the sample of Ag/MCM-41 had no appreciable incorporation of silver into the mesoporous matrix of MCM-41 with good crystallinity, and silver nanoparticles were dispersed inside or outside of the channels in the mesoporous host. The catalytic performance of the sample for the cyclohexane liquid-phase oxidation into cyclohexanone and cyclohexanol by oxygen in the absence of solvents without inducing agents was investigated. The 83.4% selectivity to cyclohexanol and cyclohexanone at 10.7% conversion of cyclohexane was obtained over Ag/MCM-41 catalyst at 428 K for 3 h. The turn over numbers (TONs) of Ag/MCM-41 was up to 2946. The catalytic activity of Ag/MCM-41 was also compared with Ag/TS-1 as well as Ag/Al₂O₃. The results indicated that Ag/MCM-41 showed superior activity to both Ag/TS-1 and Ag/Al₂O₃. A calcined Ag/MCM-41 was found to be an efficient catalyst for the cyclohexane oxidation into cyclohexanol and cyclohexanone using oxygen as oxidant.     

CoPc/MCM-41催化氧化环己烯合成环己烯酮

以MCM-41型介孔分子筛为载体,酞菁类金属大环配合物为活性组分合成出了CoPc/MCM-41型催化剂,并对其结构进行了表征。红外、XRD和热重分析证实,催化剂活性组分负载后其热稳定性明显增加。进而以自制的CoPc/MCM-41为催化剂,对分子氧氧化环己烯制备环己烯酮的工艺条件进行了探索,结果表明,在催化剂用量120 mg(5 mL环己烯),反应温度55℃,反应时间8 h,二氯乙烷为溶剂的条件下,环己烯酮的单程产率可达24.2%,催化剂可分离回收,回收催化剂重复使用5次后,活性下降约3%。     

MCM-41 for furosemide dissolution improvement

The ordered mesoporous silica material MCM-41 was used to prepare a novel drug delivery system (DDS) for oral administration of the diuretic furosemide (FURO), labeled in class IV of the Biopharmaceutics Classification System (BCS). This drug is characterized by both low solubility and permeability and its absorption window is the stomach and the proximal small intestine. Thus, the aim of this work was the development of an immediate formulation that could improve the drug release in its preferential absorptive regions.Three inclusion products MCM-41-FURO-E/D, MCM-41-FURO-S and MCM-41-FURO-E have been prepared in three different ways in order to find the best preparation conditions. They were characterized by XRPD, DSC, FT-IR, TGA and B.E.T. and then the inclusion products displaying the best characteristics were submitted to in vitro studies. They evidenced that the examined inclusion products displayed FURO dissolution enhancement, followed by a complete release within 90 min. Moreover, physical stability studies revealed that MCM-41 is able to stabilize the drug preventing it from re-crystallization. At last, as FURO is light sensitive, the effect of MCM-41 on drug photochemical stability was also investigated and the results indicated the protective action exerted by the matrix.     

Catalytic dehydration of glycerol to acrolein over mesoporous MCM-41 supported heteropolyacid catalysts

Journal of Porous Materials - A series of vanadium substituted phosphomolybdic acid (VPMA) supported on mesoporous MCM-41 catalysts with varying VPMA content ranging from 10 to 50 wt% were...     

超微粒介孔分子筛Ti-MCM-41的制备及苯乙烯催化氧化的研究

在强酸性条件下，在60℃水浴中，以无水乙醇和异丙醇为混合溶剂，合成了nSi)：n(Ti)分子比为30的超微粒介孔分子筛蜀-MCM-41。在超微粒介孔分子筛Ti-MCM-41和H2O2作用下，对苯乙烯进行催化氧化的反应，其产物是苯乙酮和苯甲醛，并且考察了分子筛Ti-MCM-41不同用量、H2O2和苯乙烯不同分子比、反应时间及反应温度对苯乙烯转化率的影响。实验结果表明，在苯乙烯催化氧化反应中，反应的最佳温度为60℃，最佳时间是10h，最佳分子筛用量是0．6g，n(H2O2)：n(苯乙烯)分子最佳比是4：1。由于H2O2氧化后的产物是H2O2，因此，这种清洁的方法是今后有机合成发展的趋势。     

Anchoring manganese acetylacetonate complex on MCM-41: Catalytic testing on limonene oxidation

This work reports the results of limonene oxidation in the liquid phase, over manganese acetylacetonate anchored onto MCM-41. Diluted t-butyl hydroperoxide is used as oxidant. Limonene oxide, carveol and carvone are formed, but the main product obtained is a polymer. The preservation of the MCM-41 channel system upon anchoring was checked by transmission electron microscopy (TEM), X-ray diffraction and nitrogen adsorption analysis. The complex anchoring was succeeded, since the catalyst could be used in four consecutive experiments. The maximum TOF values obtained for each run are similar and no significant metal complex leaching was observed (3% after the 4th run).