Direct vapor phase oxidation of propylene by molecular oxygen over MCM-41 or MCM-22 based catalysts

Ti and Al containing MCM-41 (Al-c-MCM-41 and Al-Ti-c-MCM-41) have been synthesized and tested for direct oxidation of propylene with molecular oxygen. Al-Ti-c-MCM-41 is more effective than Al-c-MCM-41, while no product was formed for MCM-41 alone. It is also found that MCM-22 with Si/Al₂ ratio of 30 and Na/SiO₂ ratio of 0.18 is active for the reaction and a highest PO yield of 11.3% was obtained at 573 K.     

Selective solvent-free oxidation of toluene to benzaldehyde over zeolite supported iron

Iron-modified HZSM-5 materials were prepared by the impregnation techniques at ambient temperature and characterized by X-ray powder diffraction (XRD) and ICP-MS to determine the phase structure and loadings of iron dioxide. This material was tested for solvent-free catalytic oxidation of toluene under mild conditions. The result shows that Fe₂O₃/HZSM-5 is an effective catalyst, exhibiting 17.3% conversion of toluene, 51.4% selectivity to benzaldehyde at 90 °C. Furthermore, the catalyst can be easily recovered and reused for three times without a significant loss in its activity and selectivity.     

Methanol oxidation on LaCo mixed oxide supported onto MCM-41 molecular sieve

Lanthanum cobaltate LaCoO_x supported onto MCM-41 mesoporous molecular sieve was prepared by in-situ oxidative decomposition of mixed LaCo citrate complexes inside the mesopores of this support. The prepared materials were characterized by EDX, EPR and UV-Vis DRS techniques as well as by N₂-BET measurements. The nanosized LaCoO_x particles within the mesopores of MCM-41 matrix contains cobalt atoms in lower than Co(III) average oxidation state. Also, the supported cobaltate does not form short-range order species of LaCoO₃ but presents as the highly disordered, oxygen deficient Co oxide nanophase. Catalytic activity in MeOH oxidation was tested using both conventional fixed-bed flow system and “operando” mode of DRIFT technique. The very high activity of MCM-41-supported cobaltate is not only due to highly dispersed LaCoO₃ phase but also because of rather low oxidation state of Co.     

负载型磷钼钒钴杂多酸盐催化氧化乙苯合成苯乙酮

采用浸渍法制备了系列负载型杂多酸盐催化剂,并将其应用于乙苯氧化合成苯乙酮的反应中。考察了载体类型、负载量、焙烧温度、催化剂用量、反应时间等因素对催化活性的影响。结果表明,以HZSM-5为载体,杂多酸盐Co_4HP_2Mo_（15）V_3O_（62）负载量30%,固定乙苯用量25mmol,催化剂用量0.4g,m（催化剂）：m（KBr）=2：3,n（乙苯）：n（过氧化氢）=0.125：1,反应温度80℃.反应时间1h,乙苯转化率达到82.21%,苯乙酮收率为55.75%。     

An efficient oxidation of cyclohexane over Au@TiO2/MCM-41 catalyst prepared by photocatalytic reduction method using molecular oxygen as oxidant

Cyclohexane oxidation using molecular oxygen as oxidant is one of the most challenge subjects. A novel photocatalytic reduction method to prepare Gold nanoparticles Au@TiO₂/MCM-41 was proposed. The prepared samples were characterized by XRD, N₂ adsorption isotherm, FT-IR, TEM and EDS. The results showed that gold nanoparticles were well-dispersed on TiO₂/MCM-41, and TiO₂ was dispersed on the surface of the support and the gold existed as Au⁰. Newly-developed catalyst was promising for the cyclohexane oxidation, achieving a turnover frequency (TOF) as high as 29,145 h^− 1 with 9.87% conversion of cyclohexane.     

Selective gas-phase oxidation of ethanol by molecular oxygen over oxide and gold-containing catalysts

The rapid increase in the production rates of bioalcohols (in particular bioethanol) gives grounds for regarding them as a promising renewable chemical raw material for obtaining a number of useful organic synthesis products. In order to develop new green technologies for processing ethanol into value-added products, a systematic study of selective conversion of ethanol under conditions of oxidation by molecular oxygen in the flow gas-phase mode over such catalysts as V₂O₅-TiO₂, mixed oxides V-Mo-Te, V-Mo-Nb and V-Mo-Te-Nb, and gold supported on oxide supports is performed. The catalytic activity is determined under conditions of temperature-programmed reaction under atmospheric pressure using a gas mixture (composition, mol %: EtOH, 2; O₂, 18; He, 80) at a hourly space velocity of the mixture of 3600 h^?1 over 0.25–0.5 mm catalyst fraction. The possibility of the efficient conversion of ethanol to products of partial oxidation and accompanying conversions (acetaldehyde, 90–99% yield; acetic acid, 92-98% yield; productive capacity >3 g g-cat^?1 h^?1) and acetic acid-ethyl acetate mixtures (1: 1 ratio, total yield >90%) in a number of cases is demonstrated.     

Epoxidation of β-ionone using molecular oxygen over Pt/MCM-41 catalyst under mild conditions

The epoxidation of β-ionone over the Pt/MCM-41 catalyst using molecular oxygen in the liquid phase had been studied. The results indicated that the β-ionone was catalytically oxidized to 5,6-epoxy-β-ionone, 4-oxo-β-ionone, 4-hydroxy-β-ionone and dihydroactinidiolide using molecular oxygen as the sole oxidant. The effects of solvent, content of Pt, reaction temperature and time on the catalytic activity and product selectivity had also been investigated in detail.     

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...     

MCM-41分子筛负载甲基苯磺酸铜的合成及其催化性能

以对甲苯磺酸铜和介孔分子筛MCM-41为原料,通过浸渍法在碱性条件下将对甲基苯磺酸铜[Cu(TBS)_(2)]负载到用水热法合成的介孔分子筛MCM-41上,通过IR、TG、X射线粉末衍射技术对其进行表征,以Biginelli反应为探针研究其催化性能。结果表明,当反应原料n(苯甲醛)∶n(乙酰乙酸乙酯)∶n(N-甲基脲)=1∶1∶1.2时,催化剂Cu(TBS)_(2)/MCM-41(0.4 mmol)的催化效果较好,反应时间13 min,产率达到87.3%。     

用于氧化反应的改性介孔分子筛MCM-41研究进展

主要从金属掺杂、杂多酸负载和有机官能化等方面详细介绍了改性的MCM-41分子筛作为催化剂在氧化反应中的应用情况,分析了其优缺点。今后的研究重点将是进一步提高改性材料MCM-41分子筛的活性,解决活性组分溶脱现象以及水热稳定性等问题。     

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%。     

Selective Mono-Methylation of Phenylacetonitrile to 2-Phenyl Propionitrile over 3-Aminopropylsilyl Functionalized MCM-41

Selective mono-methylation of phenylacetonitrile to 2-phenylpropionitrile by dimethyl carbonate as an alkylating agent was studied for the first time using alkali-ion-exchanged and organic base functionalized MCM-41 as catalyst. 3-Aminopropylsilyl functionalized NH₂-Na-Al-MCM-41 is found to be the superior catalyst among a series of alkali-ion-exchanged MCM-41 and microporous basic zeolite catalysts giving 98.4 wt% conversion of phenylacetonitrile and >92 wt% selectivity to 2-phenylpropionitrile.     

New acid catalyst comprising heteropoly acid on a mesoporous molecular sieve MCM-41

New solid acid catalysts, consisting of heteropoly acid (HPA) H₃PW₁₂O₄₀ (PW) supported on a mesoporous pure-silica molecular sieve MCM-41, have been prepared and characterized by nitrogen physisorption, X-ray diffraction, FT-IR, and³¹P magic angle spinning NMR. The PW/MCM-41 compositions with PW loadings from 10 to 50 wt% have 30 Å uniformly-sized mesopores. HPA retains the Keggin structure on the MCM-41 surface and forms finely dispersed HPA species. No HPA crystal phase is developed even at HPA loadings as high as 50 wt%. PW/MCM-41 exhibits higher catalytic activity than H₂SO₄ or bulk PW in liquid-phase alkylation of 4-t-butylphenol (TBP) by isobutene and styrene. In the alkylation of TBP by styrene, PW/MCM-41 shows a size selectivity compared to bulk PW and PW/SiO₂, providing higher yields of a 2-(1-phenylethyl)-4-t-butylphenol, at the expense of the more bulky 2,6-bis-(1-phenylethyl)-4-t-butylphenol. The PW/MCM-41 compositions, having strong acid sites and a regular mesoporous system, are promising catalysts for the acid-type conversion and formation of organic compounds of large molecular size.     

Esterification of bioplatform molecules over 12-tungstophosphoric acid anchored to MCM-41

The catalytic conversion of bio-platform molecules into desired products can be an important unit for the future biorefinery. The present contribution consists of synthesis of solid acid catalyst comprising 20 % 12-tungstophosphoric acid (TPA) and MCM-41 and its characterization by various physico-chemical techniques such as fourier transform infrared, X-ray diffraction surface area measurement (BET method), transmission electron microscopy and total acidity. The use of synthesized catalyst was explored for esterification of bio-platform molecules such as succinic acid and malonic acid with different alcohols. The catalyst shows high activity in terms of higher yields towards all diesters. The product selectivity towards the mono and diester was found to be the same for TPA alone and supported system, TPA₂/MCM-41, that also confirms the uniform distribution of the TPA on MCM-41. The excellent catalytic performance is attributed to the large surface area and pore diameter of the mesoporous support, MCM-41 as well as the Bronsted acid strength of TPA, as active sites. The catalyst shows the potential of being used as a recyclable catalytic material after simple regeneration without significant loss in activity.     

Transesterification of diethyl malonate with n-butanol over HPWA/MCM-41 molecular sieves

Mesoporous Si-MCM-41 and Al-MCM-41 (Si/Al = 100) materials were synthesized via a hydrothermal method. Three different ratios (10, 20 and 30 wt%) of heteropoly tungstic acid (HPWA) was loaded on Si-MCM-41 by wet impregnation techniques. The characteristic structural features of the prepared materials were studied by various physico-chemical techniques such as X-ray diffraction (XRD), Nitrogen physisorption (BET), temperature programmed desorption of ammonia (TPD) and transmission electron microscopy (TEM). Transesterification of diethyl malonate (DEM) with n-butanol under autogeneous conditions in a temperature range from 50 to 125 °C was selected as the test reaction for the as synthesized materials. The reactants were fed with various mole ratios in order to determine the optimal feed composition leading to maximum yields of transesterified products. The results indicated that the conversion of diethylmalonate depends on the HPWA concentration on the support, temperature, reaction time and mole ratio of the reactants. Further, the catalytic efficiency of HPWA/MCM-41 was compared with that of Al-MCM-41. The solid acid HPWA/MCM-41 catalysts have several advantages in comparison to conventional mineral acid catalysts which are heterogeneous, eco-friendly, highly active and selective in the formation of transesters.     

Activity of Mo(II) allylic complexes supported in MCM-41 as oxidation catalysts precursors

[Mo(η³-C₃H₅)X(CO)₂(NCCH₃)₂] (X = Br, 1a; X = Cl, 1b) complexes reacted with the bidentate ligand RNC(Ph)–C(Ph)NR, R = (CH₂)₂CH₃ (DAB, 2) affording [Mo(η³-C₃H₅)X(CO)₂(DAB)] (X = Br, 4a; X = Cl, 4b), which were characterized by elemental analysis, FTIR and ¹H and ¹³C NMR spectroscopy. The modified silylated ligand RNC(Ph)C(Ph)NR, R = (CH₂)₃Si(OCH₂CH₃)₃ (DAB–Si, 3), was used to immobilize the two complexes in MCM-41 (MCM) mesoporous silica. The new materials were characterized by powder X-ray diffraction, N₂ adsorption analysis, FTIR and ²⁹Si and ¹³C CPMAS solid state NMR spectroscopy. Both the materials and the complexes were tested in the oxidation of cyclooctene and styrene and behaved as active catalyst precursors for cyclooctene and styrene epoxidation with TBHP (t-butylhydroperoxide), leading selectively to epoxides with high conversions and TOFs. Although the homogeneous systems reach 100% conversion of cyclooctene and slightly less for styrene, the loss of catalytic activity in the heterogeneous systems is small, with a 98% conversion of styrene achieved by the chloride containing material.     

Highly selective synthesis of styrene oxide over phosphotungstic acid supported on mesoporous Mn-MCM-41 molecular sieves

Tungstophosphoric acid (H₃PW₁₂O₄₀) (PW) catalysts supported on mesoporous Mn-MCM-41(n _Si/n _Mn = 25) with various (10, 20 and 30 wt%) acid loadings were prepared by impregnation, and their physical chemical properties were characterized by powder X-ray diffraction (XRD), N₂ adsorption–desorption, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), high resolution transmission electron microscopy (HRTEM), and X-Ray Photoelectron Spectroscopy (XPS). The host material suffers severe structural distortions at higher loading, which lead to a considerable loss of long-range orders. Their catalytic performances were evaluated in the epoxidation of styrene with dilute H₂O₂ (30%) as an oxidizing agent under liquid phase reaction conditions over PW/Mn-MCM-41 catalysts for selective synthesis of styrene oxide. The influences of various reaction parameters such as temperature, time, solvents, PW loading and catalyst amount, styrene to H₂O₂ mmol ratios and acetonitrile (MeCN) to N,N-dimethylformamide (DMF) volume ratios on the conversion of styrene and yield as well as selectivity of styrene oxide have also been studied in details. The results revealed that 20% PW/Mn-MCM-41 (n _Si/n _Mn = 25) was more active than other catalysts. The PW/Mn-MCM-41, moreover, was found to be reusable and environmentally benign for the epoxidation of styrene.     

MCM-41负载Pt-Al催化剂的制备及其表征

以介孔硅MCM-41为载体、无水乙醇为溶剂、氯化铝为促进剂,采用浸渍法制备了Pt-Al/MCM-41催化剂。利用XRD、XPS、TEM、FTIR、N₂吸附-脱附、NH₃-TPD对催化剂进行了表征,重点讨论了不同Pt-Al负载顺序对催化剂结构和性能的影响,并将其应用于硅氢加成反应。结果表明,Pt和Al的负载顺序不同会影响催化剂的有序度、Pt颗粒的分散程度和酸性,其中,Pt-Al/MCM-41催化剂的有序度和Pt颗粒的分散程度相对最好,酸性相对较强。在七甲基三硅氧烷与烯丙醇聚氧乙烯醚的硅氢加成反应中,不同催化剂对七甲基三硅氧烷的转化率影响顺序为Pt-Al/MCM-41 > Pt+Al/MCM-41 > Al-Pt/MCM-41 > Pt/MCM-41。     

Iron, cobalt or nickel substituted MCM-41 molecular sieves for oxidation of hydrocarbons

A series of mesoporous Fe-MCM-41, Co-MCM-41 and Ni-MCM-41 catalysts with different quantity of the metal incorporated in the framework were synthesized and characterized (as-synthesized samples and those after reaction) by X-ray diffraction pattern (XRD), N₂ adsorption–desorption, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) techniques. The effect of the incorporated metal on the MCM-41 surface hydroxyl groups has been evidenced. The catalytic activity and selectivity of these catalysts in liquid phase oxidation of 1-hexene, styrene and benzene with hydrogen peroxide were studied. The structure and morphology of the catalysts before and after reaction were also compared. The results show a high activity and selectivity of catalysts having higher Co content to benzaldehyde from styrene or phenol from benzene, and a low activity of all prepared catalysts in the oxidation of the 1-hexene. The activity and efficiency of H₂O₂ increases with the metal content and depend on the reaction parameters such as temperature, molar ratio of the reactants and the solvent, and the nature of the reactor.     

MCM-41分子筛负载金属酞菁在氧化脱硫反应中的催化性能

采用浸渍法将8种金属酞菁分别负载到MCM-41分子筛上制得负载型金属酞菁,通过红外光谱进行表征。以二苯并噻吩（DBT）为反应底物,空气为氧化剂,己内酰胺四丁基溴化铵离子液体为溶剂考察了这8种催化剂在氧化脱硫反应中的催化活性,筛选出较优催化剂,并对工艺条件进行优化。结果表明,合成的8种负载型金属酞菁催化剂中,MCM-41分子筛负载钴酞菁具有较好的催化性能,最优工艺条件为：剂油比1：1,催化剂用量0.004 g·（10 ml模型油）^-1,空气流速50 ml·min^-1,反应时间1 h,室温,DBT脱硫率最高可达97.56%。DBT的氧化产物为DBT砜。又考察了此催化氧化系统对不同硫化物的催化氧化效果,发现不同硫化物的脱硫率均在90%以上。该催化剂在重复利用4次后脱硫率无明显的降低。