Heterogeneous Catalyst For Epoxidation Research Articles

A novel heteropolyanion-based amino-containing cross-linked ionic copolymer catalyst for epoxidation of alkenes with H2O2

A heteropolyanion-based cross-linked ionic copolymer was prepared by the anion-exchange of a newly task-specific designed amino-containing ionic copolymer with a Keggin heteropolyacid, and characterized by FT-IR, SEM, TG, XRD, UV–vis, ESR, 1H NMR, and elemental analysis. Its catalytic activity was evaluated in the epoxidation of alkenes with aqueous H2O2. The resultant heteropolyanion-based ionic copolymer is revealed to be a highly efficient heterogeneous catalyst for epoxidation of alkenes with H2O2, adding the advantages of convenient recovery and steady reuse.

PZnMo2W9O39]5− immobilized on ionic liquid-modified silica as a heterogeneous catalyst for epoxidation of olefins with hydrogen peroxide

Abstract The epoxidation of alkenes with hydrogen peroxide catalyzed by [PZnMo 2 W 9 O 39 ] 5- , ZnPOM, supported on ionic liquid-modified silica, Im-SiO 2 , is reported. The immobilized catalyst, [ZnPOM@Im-SiO 2 ] was characterized by elemental analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), FT-IR and UV–Vis spectroscopic methods. This new synthesized hybrid catalyst was applied for efficient epoxidation of various olefins with aqueous H 2 O 2 in acetonitrile under reflux conditions. This solid catalyst can be easily recovered by simple filtration and reused several times without significant loss of its catalytic activity.

Synthesis, Structural Elucidation, and Application of a Pyrazolylpyridine–Molybdenum Oxide Composite as a Heterogeneous Catalyst for Olefin Epoxidation

The reaction of [MoO(2)Cl(2)(pypzEA)] (1) (pypzEA = ethyl[3-(pyridin-2-yl)-1H-pyrazol-1-yl]acetate) with water in a Teflon-lined stainless steel autoclave (100 °C) or in an open reflux system leads to the isolation of the molybdenum oxide/pyrazolylpyridine composite material [Mo(2)O(6)(HpypzA)] (2; HpypzA = [3-(pyridinium-2-yl)-1H-pyrazol-1-yl]acetate). The solid state structure of 2 was solved through single crystal and powder X-ray diffraction analyses in conjunction with information derived from FT-IR and (13)C CP MAS NMR spectroscopies and elemental analyses. In the asymmetric unit of 2, two crystallographically distinct Mo(6+) centers are bridged by a syn,syn-carboxylate group of HpypzA. The periodic repetition of these units along the a axis of the unit cell leads to the formation of a one-dimensional composite polymer, (∞)(1)[Mo(2)O(6)(HpypzA)]. The outstretched pyrazolylpyridine groups of adjacent polymers interdigitate to form a zipper-like motif, generating strong onset π-π contacts between adjacent rings of coordinated HpypzA molecules. The composite oxide 2 is a stable heterogeneous catalyst for liquid-phase olefin epoxidation.

Phosphotungstates as catalysts for monoterpenes oxidation: Homo- and heterogeneous performance

Lacunary (PW11), mono-substituted (PW11M) and sandwich type M4(PW9)2 phosphotungstates (M=CoII, FeIII) exhibits high catalytic activity for geraniol and R-(+)-limonene oxidation under mild conditions, using hydrogen peroxide as oxidant and acetonitrile as solvent. The best homogeneous performance was found for the PW11 and for the Co4(PW9)2. Complete conversion of geraniol and R-(+)-limonene was achieved after 1.5h and 3h of reaction, respectively, when catalyzed by PW11. The yield of 2,3-epoxygeraniol was 100% in the presence of lacunary PW11 and mono-substituted compounds. PW11 and Co4(PW9)2 were immobilized on an amine-functionalized SBA-15 (aptesSBA-15) and the composites materials were characterized by FT-IR, FT-Raman, UV–vis/DRS, 31P MAS NMR, elemental analysis and SEM-EDS. Their heterogeneous catalytic activity was investigated for the same substrates and compared with that in homogeneous conditions. The PW11@aptesSBA-15 and Co4(PW9)2@aptesSBA-15 showed to be active heterogeneous catalysts for geraniol epoxidation with 100% of selectivity for 2,3-epoxide. R-(+)-limonene was also oxidized by PW11@aptesSBA-15 achieving 90% of conversion after 24h of reaction. Both composites could be separated after the reaction and reused for at least three cycles without loss of activity. The stability of the heterogeneous catalysts after catalytic reactions was investigated by different techniques of characterization.

Basic ionic liquid supported on mesoporous SBA-15: An efficient heterogeneous catalyst for epoxidation of olefins with H2O2 as oxidant

Basic ionic liquid functionalized mesoporous silica SBA-15 was prepared and characterized by XRD, N2 adsorption–desorption, FT-IR and TEM. The catalyst demonstrated to be an efficient heterogeneous catalyst for olefin epoxidation using H2O2 as oxidant. The catalyst could be recycled at least five times without appreciable loss of catalytic activity.

Structural and dynamical aspects of alkylammonium salts of a silicodecatungstate as heterogeneous epoxidation catalysts

The structural and dynamical aspects of alkylammonium salts of a silicodecatungstate [(CH(3))(4)N](4)[γ-SiW(10)O(34)(H(2)O)(2)] [C1], [(n-C(3)H(7))(4)N](4)[γ-SiW(10)O(34)(H(2)O)(2)] [C3], [(n-C(4)H(9))(4)N](4)[γ-SiW(10)O(34)(H(2)O)(2)] [C4], and [(n-C(5)H(11))(4)N](4)[γ-SiW(10)O(34)(H(2)O)(2)] [C5] were investigated. The results of sorption isotherms, XRD analyses, and solid-state NMR spectroscopy show that facile sorption of solvent molecules, flexibility of structures, and high mobility of alkylammonium cations are crucial to the uniform distribution of reactant and oxidant molecules throughout the bulk solid, which are related to the high catalytic activities for epoxidation of alkenes.

A surface-confined OMnV(salen) oxene catalyst and high turnover values in asymmetric epoxidation of unfunctionalized olefins

Given the widespread importance of chiral epoxides in chemical, biochemical and agricultural fields, an efficient synthesis that avoids wasteful use of the catalyst and assures its total recovery and reuse and high turnover values is highly desirable. We report on a thermally and temporally robust covalent monolayer of (salen)Mn(III) molecules on silica functionalized substrates that resulted in an active heterogeneous catalyst for enantioselective epoxidation of 6-ciano-2,2-dimethyl-chromene, chosen as a model alkene, in high yields and high turnover numbers. No catalyst leaching was observed thus allowing continuous recycling. Experimental XPS evidence for the formation of the surface confined OMnV(salen) oxene species has been obtained.

Highly efficient epoxidation of alkenes with hydrogen peroxide catalyzed by tungsten hexacarbonyl supported on multi-wall carbon nanotubes

The preparation, characterization, and catalytic activity of W(CO)6 supported on multi-wall carbon nanotubes modified with 4-aminopyridine is reported. The catalyst, [W(CO)5@Apy-MWCNT], was characterized by physico-chemical and spectroscopic methods and found to be an efficient heterogeneous catalyst for green epoxidation of alkenes with hydrogen peroxide in MeCN solvent. The catalyst showed good stability and reusability properties in the epoxidation reactions.

Mesoporous Titanium–Silica Composite Encapsulated γ-Fe2O3: Novel Magnetically Recyclable Heterogeneous Catalysts for Olefin Epoxidation Reactions

γ-Fe2O3 microparticles encapsulated with silica and an outer layer of ordered mesoporous titanium–silica (γ-Fe2O3@nSiO2@mTi–Si) were synthesized and used for the epoxidation of olefins. Characterization results showed that this material exhibits a typical core–shell structure with high surface area, narrow pore size distribution and high magnetization. Catalytic activity tests showed that this material presents high activity for the epoxidation of olefins, and the catalyst could be easily recycled and reused for several times. Silica-coated magnetic hematite (γ-Fe2O3) core has been coated with mesoporous titanium–silica shell and used as a magnetically separable heterogeneous catalyst for epoxidation of olefin. This catalyst can be recycled and reused at least five times in the epoxidation of cyclohexene with no major loss of activity.

Selective epoxidation of alkenes with hydrogen peroxide over efficient and recyclable manganese oxides

Abstract A series of manganese oxides (MnO, Mn3O4, Mn2O3 and MnO2) were prepared and firstly applied as heterogeneous catalysts for the liquid phase epoxidation of alkenes with 30% H2O2 in bicarbonate solution. Under our experimental conditions, MnO exhibited superior activity for the conversion of styrene to achieve ca. 100% with 92.4% selectivity of epoxide, compared to the other three manganese oxides as well as other metal oxides. Furthermore, recycling studies showed the good recyclability of MnO as a heterogeneous catalyst, which did not lose the catalytic activity after four reuses appreciably.

Synthesis and characterization of supported heteropolymolybdate nanoparticles between silicate layers of Bentonite with enhanced catalytic activity for epoxidation of alkenes

A new heterogeneous catalyst (PVMo/Bentonite) consisting of vanadium substituted heteropolymolybdate with Keggin-type structure Na 5[PV 2Mo 10O 40]·14H 2O (PVMo) supported between silicate layers of bentonite has been synthesized by impregnation method and characterized using X-ray diffraction, Fourier-transformed infrared spectroscopy, scanning electron microscopy, UV–vis diffuse reflectance spectroscopy, transmission electron microscopy and elemental analysis. X-ray diffraction and scanning electron microscopy analysis indicated that PVMo was finely dispersed into layers of bentonite as support. The PVMo/Bentonite used as an efficient heterogeneous catalyst for epoxidation of alkenes. Various cyclic and linear alkenes were oxidized into the corresponding epoxides in high yields and selectivity with 30% aqueous H 2O 2. The catalyst was reused several times, without observable loss of activity and selectivity. The obtained results showed that the catalytic activity of the PVMo/Bentonite was higher than that of pure heteropolyanion (PVMo).

Tethering of Cu(II), Co(II) and Fe(III) tetrahydro-salen and salen complexes onto amino-functionalized SBA-15: Effects of salen ligand hydrogenation on catalytic performances for aerobic epoxidation of styrene

A variety of transition metal tetrahydro-salen complexes M-[H 4]Salen (M = Cu, Co and Fe) and the corresponding metal salen complexes M-Salen were firstly tethered onto amino-functionalized mesoporous SBA-15 and screened as heterogeneous catalysts for aerobic epoxidation of styrene. The mesoporous structural integrity throughout the tethering procedure, the successful tethering of the organometallic complexes, the loadings of metal ions and organic ligands as well as the catalyst surface constitution and location of active organometallic species on the SBA-15 support were determined by comprehensive characterization techniques such as XRD, N 2 adsorption/desorption, TEM, FT-IR, UV–vis spectroscopy, ICP-AES, XPS and TG/DSC. The tethered catalyst M-[H 4]Salen-SBA (M = Cu or Co) exhibits improved reactivity than the corresponding M-Salen-SBA catalyst due to the incorporation of a modified coordination environment of the central metal cations by C N bond hydrogenation. However, Fe-[H 4]Salen-SBA shows lower reactivity as compared to Fe-Salen-SBA possibly due to the easy formation of relatively inactive dinuclear iron(III) tetrahydro-salen complexes, verified by XPS and ESR. The recycling results of these heterogeneous catalysts exemplified by Co-Salen-SBA, Co-[H 4]Salen-SBA and Fe-Salen-SBA, show good recoverability without significant loss of activity and selectivity within successive runs. Heterogeneity tests of three sample catalysts confirm the high stability of cobalt catalysts against leaching of active species into solution.

Zirconia-supported Keggin phosphomolybdovanadate nanocomposite: A heterogeneous and reusable catalyst for alkene epoxidation under thermal and ultrasonic irradiation conditions

Abstract Keggin phosphomolybdovanadate, PVMo, was supported on a zirconia matrix by the wet impregnation method. The phase and chemical structure, optical absorption, surface physicochemical properties and morphology of PVMo–ZrO 2 composite were studied by X-ray diffraction (XRD) technique, FT-IR and diffuse reflectance UV–vis spectroscopic (DR UV–vis) methods, and scanning electron microscopy (SEM), which indicated that the primary Keggin structure has remained intact after formation of the composite. Moreover, the obtained nanocomposite was used as an efficient catalyst of olefins under reflux and ultrasonic irradiation conditions. The catalyst was reused several times, without observable loss of activity and selectivity. Indeed, the catalytic activity of the PVMo–ZrO 2 was compared with pure Keggin phosphomolybdovanadate.

ChemInform Abstract: Reactivity and Selectivity of Heterogenized Homogeneous Catalysts: Insights from Molecular Simulations

AbstractReview: 84 refs.

Supramolecular Assemblies Directed by Hydrogen Bonds and π–π Interactions and Based on N‐Heterocyclic‐Ligand‐Modified β‐Octamolybdate – Structure and Catalytic Application in Olefin Epoxidation

AbstractA series of supramolecular assemblies based on POMs modified by organic ligands, including (Himi)4[(imi)2(Mo8O26)]·H2O (1), (H2bbi)2[Mo8O26] (2), and (H2bbi)[(Hbbi)2 (Mo8O26)]·H2O (3), were synthesized by a one‐step hydrothermal method. All of them are active catalysts for the epoxidation of olefins with tert‐butyl hydroperoxide as the oxidant. Most interestingly, (Himi)4[(imi)2(Mo8O26)]·H2O (1) exhibits very high catalytic activity and stability, which makes it a truly efficient heterogeneous catalyst for olefin epoxidation.

A Ti-substituted polyoxometalate as a heterogeneous catalyst for olefin epoxidation with aqueous hydrogen peroxide

The Ti-substituted polyoxometalates ([C12mim]5PTiW11O40, [CTA]5PTiW11O40 and [TBA]5PTiW11O40) were prepared and characterized by FT-IR, NMR, UV-vis and ICP-AES. Then the polyoxometalates (POM) were used as catalysts for the epoxidation of various olefins. It was found that the organic countercations had a considerable effect on the catalytic performance. In addition, UV-vis and the FT-IR spectroscopy indicated that the peroxo structure regarded as the active site for oxygen transfer was present even after the reaction, which led to the increasing reaction rate in the second run due to the disappearance of the induction period, as compared with that in the first run. A heterogeneous reaction mechanism has been suggested in olefin epoxidation catalyzed by a Ti-substituted polyoxometalate ([C12mim]5PTiW11O40) with aqueous hydrogen peroxide in ethyl acetate. The heterogeneous POM catalyst can be easily separated and recycled eight times without decreasing the catalytic activities.

A new heterogeneous catalyst for epoxidation of alkenes via one-step post-functionalization of IRMOF-3 with a manganese(ii) acetylacetonate complex

A manganese(II) acetylacetonate complex has been immobilized to the metal-organic framework IRMOF-3 through a one-step post-synthetic route for the first time, providing an effective and recyclable heterogeneous catalyst for epoxidation of alkenes.

Highly efficient and excellent reusable catalysts of molybdenum(VI) complexes grafted on ZPS‐PVPA for epoxidation of olefins with tert‐BuOOH

AbstractFour new kinds of heterogeneous catalysts for olefins epoxidation were obtained by grafting diamines on organic polymer–inorganic hybrid material, zirconium poly (styrene‐phenylvinylphosphonate)‐phosphate (ZPS‐PVPA), and subsequently coordinating with Schiff base Mo(VI) complexes. The catalysts were characterized by IR, XPS, SEM and TEM. All catalysts were evaluated through the epoxidation of olefins using tert‐BuOOH as oxidant. The heterogeneous catalysts possess the advantages of high conversion, selectivity and excellent reusability. The catalysts were easily separated from the reaction systems and could be reused 13 times without significant loss of catalytic activity. Copyright © 2010 John Wiley & Sons, Ltd.

Preparation, characterization and heterogeneous catalytic activity of heteropolyanion/polyaniline nanocomposite

A heteropolyanion–polyaniline (Na5[PV2Mo10O40] PVMo/PANI) nanocomposite was prepared through two different method. In the one-step method, aniline was polymerized in the presence of PVMo, and PVMo was incorporated into the polymer matrix during the polymerization process. While, in the two-step method, PVMo was immobilized only on the surface of the ready-made PANI support. The nanocomposite was characterized by FT-IR, XRD, UV–vis, SEM and elemental analysis and used as an efficient heterogeneous catalyst for epoxidation of alkenes.Various linear and cyclic alkenes were oxidized into the corresponding epoxides in high yield in the presence of PVMo/PANI nanocomposite under reflux and ultrasonic irradiation conditions.

ChemInform Abstract: Mild and Efficient Alkene Epoxidation and Alkane Hydroxylation by Manganese(III) Porphyrin Supported on IRA-400 Ion-Exchange Resin.

Sulfonated manganese(III) tetraphenylporphyrin supported on Amberlite IRA-400 ion-exchange resin (MnTPPS-Ad), can act as an efficient heterogeneous catalyst for alkene epoxidation and alkane hydroxylation by sodium periodate in the presence of imadazole.