Activity For Oxidation Of Alcohols Research Articles

Cu and Fe-doped monolacunary tungstosilicate catalysts with efficient catalytic activity for benzyl alcohol oxidation and simulation gasoline desulfurization

The heterogeneous catalysts of Fe and Cu-doped monolacunary tungstosilicate have been prepared and characterized by SEM, XRD, IR, XPS, ICP, TG-DSC and H2-TPR techniques. The influence factors on the structure of catalysts and catalytic properties have been investigated, such as the additive graphite, doped amount and calcination temperature. After being calcined at appropriate temperature, the graphite was totally decomposed and catalysts of irregular bulk-type structure were converted to uniform nanoplate materials. The catalytic activity of as-prepared catalysts was evaluated by the benzyl alcohol selective oxidation and the simulation gasoline desulfurization. It is proved that transition metal Cu/Fe-codoped tungstosilicates are more active than the corresponding undoped compounds under mild conditions and Cu/Fe-doped amount greatly impacted the catalytic activity, and Cu1.00Fe1.00SiW11 sample exhibited the best catalytic activity with 98.0% conversion and 98.3% selectivity in benzyl alcohol selective oxidation into benzaldehyde at 80°C only for 60min, and above 98% of the desulfurization rate at 65°C just for 80min.

Electrocatalytic Alcohol Oxidation By a Ruthenium-Modified Covalent Triazine Framework

Ruthenium (Ru) based catalysts, such as RuO2 and Ru complexes, have been widely studied for various oxidation reactions, such as oxygen evolution reaction (OER) and alcohol oxidation reactions (AOR). For example, RuO2 is an efficient anode catalyst for OER, which is a key reaction for artificial photosynthesis. However, as OER competes with AOR under the range of operating potentials, the high activity of RuO2 for OER results in the low Faradaic efficiency for AOR. In contrast, some Ru complexes are known to catalyze AOR with high efficiency [1]. However, as these Ru complexes are homogeneous catalysts, they are fragile and are difficult to separate and recycle. Recently, we have focused on covalent triazine frameworks (CTFs) as heterogeneous electrocatalysts. CTFs have 1,3,5-triazine units as linkers, and are representative microporous conjugated polymers. As CTFs possess abundant nitrogen (N) atoms with electron lone pair for metal coordination, CTFs are expected to stabilize Ru atoms through coordination with the N atoms like Ru complexes. Recently, we have indeed synthesized single-Pt atoms modified CTF hybridized with conductive carbon nanoparticles (Pt-CTF) as an electrocatalyst [2]. The Pt-CTF catalyzed the oxygen reduction with a high methanol tolerance, a unique property that was attributed to the atomic dispersion of Pt. In the present work, we successfully synthesized a Ru-modified CTF (Ru-CTF; Figure) and examined the electrochemical alcohol oxidation activity of this novel material. The Ru-CTF effectively oxidized alcohol with low OER activity. [1] TJ Meyer, M. Huynh, Inorganic chemistry, 2003, DOI 10.1021/ic020731v. [2] K. Kamiya, et al, Nat. Comm. 2014, 5, 5040. Figure 1

A Successive One-Pot Synthesis of Au@Pt - q ML/C with Enhanced Ethanol Oxidation Activity in Alkaline Media

Direct ethanol fuel cells raise the possibility for clean and high efficient energy utilization. Noble Pt-group metals are still essential for electrocatalysts related to such fuel cells. Yet, the high cost and limited reserve of Pt-group metals (especially Pt) as well as the sluggish oxidation kinetics of ethanol molecule call for facile synthesis of low-Pt-content efficient catalysts. Both experimental and simulated investigations suggested alcohol oxidation activity could be improved by coating a monolayer (ML) of Pt on Au [1]. To address the major challenge of scalable synthesis of practical carbon-supported catalysts, here we report a successive and convenient synthesis of Au@Pt-qML/C (qML: quasi-monolayer) using CO as the reducing and capping agents for Pt-qML deposition on Au/C [2]. The Au core with an average diameter of ca. 5 nm was first obtained by reducing HAuCl4 with NaBH4, and Pt-qML was later coated on Au surfaces in one pot through introducing CO and controlled amount of Pt(II). The Au core- Pt shell structure was examined through XRD, EDX, IR and electrochemical measurements. A remarkable enhancement towards ethanol oxidation reaction was obtained on the as-formed Au@Pt-ML/C as compared to that on the state-of-the art commercial Pt/C. Acknowledgements ：Financial supports from NSFC (grant No. 21273046 and 21473039）and the 973 Program (No. 2015CB932303) of MOST are highly appreciated

Au/graphene quantum dots/ferroferric oxide composites as catalysts for the solvent-free oxidation of alcohols

Nanocomposites of graphene quantum dots and Au nanoparticles (GQDs/Au) are immobilized on the Fe3O4 nanoparticles, forming GQDs/Au/Fe3O4 ternary composites. The as-prepared ternary composites exhibit superparamagnetic property rendering them easy to be isolated from the reaction mixture. More importantly, they show superb catalytic activity for solvent-free oxidation of VA and other alcohols that contain an aromatic benzyl group, to the corresponding aldehydes exclusively with air as oxidant. The great stability and selectivity of the GQDs/Au/Fe3O4 indicate that they might be applicable catalysts for the oxidation of aromatic alcohols.

Thin Heterojunctions and Spatially Separated Cocatalysts To Simultaneously Reduce Bulk and Surface Recombination in Photocatalysts

AbstractEfficient charge separation and light absorption are crucial for solar energy conversion over solid photocatalysts. This paper describes the construction of Pt@TiO2@In2O3@MnOx mesoporous hollow spheres (PTIM‐MSs) for highly efficient photocatalytic oxidation. TiO2–In2O3 double‐layered shells were selectively decorated with Pt nanoparticles and MnOx on the inner and outer surfaces, respectively. The spatially separated cocatalysts drive electrons and holes near the surface to flow in opposite directions, while the thin heterogeneous shell separates the charges generated in the bulk phase. The synergy between the thin heterojunctions and the spatially separated cocatalysts can simultaneously reduce bulk and surface/subsurface recombination. In2O3 also serves as a sensitizer to enhance light absorption. The PTIM‐MSs exhibit high photocatalytic activity for both water and alcohol oxidation.

Thin Heterojunctions and Spatially Separated Cocatalysts To Simultaneously Reduce Bulk and Surface Recombination in Photocatalysts.

Efficient charge separation and light absorption are crucial for solar energy conversion over solid photocatalysts. This paper describes the construction of Pt@TiO2 @In2 O3 @MnOx mesoporous hollow spheres (PTIM-MSs) for highly efficient photocatalytic oxidation. TiO2 -In2 O3 double-layered shells were selectively decorated with Pt nanoparticles and MnOx on the inner and outer surfaces, respectively. The spatially separated cocatalysts drive electrons and holes near the surface to flow in opposite directions, while the thin heterogeneous shell separates the charges generated in the bulk phase. The synergy between the thin heterojunctions and the spatially separated cocatalysts can simultaneously reduce bulk and surface/subsurface recombination. In2 O3 also serves as a sensitizer to enhance light absorption. The PTIM-MSs exhibit high photocatalytic activity for both water and alcohol oxidation.

Metal Nanoparticles Covered with a Metal-Organic Framework: From One-Pot Synthetic Methods to Synergistic Energy Storage and Conversion Functions.

Hybrid materials composed of metal nanoparticles and metal-organic frameworks (MOFs) have attracted much attention in many applications, such as enhanced gas storage and catalytic, magnetic, and optical properties, because of the synergetic effects between the metal nanoparticles and MOFs. In this Forum Article, we describe our recent progress on novel synthetic methods to produce metal nanoparticles covered with a MOF (metal@MOF). We first present Pd@copper(II) 1,3,5-benzenetricarboxylate (HKUST-1) as a novel hydrogen-storage material. The HKUST-1 coating on Pd nanocrystals results in a remarkably enhanced hydrogen-storage capacity and speed in the Pd nanocrystals, originating from charge transfer from Pd nanocrystals to HKUST-1. Another material, Pd-Au@Zn(MeIM)2 (ZIF-8, where HMeIM = 2-methylimidazole), exhibits much different catalytic activity for alcohol oxidation compared with Pd-Au nanoparticles, indicating a design guideline for the development of composite catalysts with high selectivity. A composite material composed of Cu nanoparticles and Cr3F(H2O)2O{C6H3(CO2)3}2 (MIL-100-Cr) demonstrates higher catalytic activity for CO2 reduction into methanol than Cu/γ-Al2O3. We also present novel one-pot synthetic methods to produce composite materials including Pd/ZIF-8 and Ni@Ni2(dhtp) (MOF-74, where H4dhtp = 2,5-dihydroxyterephthalic acid).

A recoverable sandwich phosphorotungstate stabilized palladium (0) catalyst for aerobic oxidation of alcohols in water

The preparation, characterization and catalytic properties of tetra metal substituted sandwich phosphorotungstate [M4(H2O)2(PW9O34)2]10−(M4P2W18, M2+=Fe2+, Co2+, Mn2+, Cu2+, VO2+) stabilized Pd nanoparticles, which were in-situ encapsulated in mesoporous aluminum phosphate (mAPO) by a one-pot method, were demonstrated for aerobic oxidation of alcohol in water. The synthesized catalysts were characterized with N2 adsorption, XRD, TEM, FT-IR and UV–vis. TEM analysis revealed that Pd-M4P2W18/mAPO thus obtained has a mean palladium particle size of less than 5nm. The solid Pd-M4P2W18/mAPO catalysts exhibit excellent activity for aerobic oxidation of benzyl alcohols in water without any base additives. It was found the introduced M4P2W18 polyoxanions encapsulated palladium nanoparticles as both stabilizing agent and promoters, leading to enhanced activity and recyclability of palladium catalyst. The recycling test of representative Pd-(VO)4P2W18/mAPO for oxidation of benzyl alcohol suggested no significant decrease in activity and selectivity even after twelve times of successive reactions. This novel heterogeneous catalyst composed of polyoxometalates stabilized palladium nanocatalysts and mesoporous aluminophosphate can also be extended to the selective oxidation of various alcohols.

Yttrium Containing Dimeric and Tetrameric Keggin Type Phosphotungstates: Syntheses, Crystal Structure and Catalytic Activity for Alcohol Oxidation Using H2O2 as an Oxidant in Water

Background: The aim of this paper is to introduce about the synthetic strategy of new polyoxometalate compounds using single step reaction procedure and their oxidative catalytic activity. In this context herein, we report green oxidation process for the oxidation of alcohols to carbonyl compounds, using yttrium containing dimeric K11[Y(PW11O39)2]·35H2O (1) and tetrameric K16Na6[(PY2W10O38)4 (W3O8)(OH)4(H2O)2]·56H2O (2) phosphotungstates compounds in the presence of H2O2 oxidant and reused up to five catalytic cycles. Methods: The conventional aqueous solution method was used to synthesize a single crystalline solid material with good yields. The different parameters such as pH, temperature, time and nature of ligand were taken under consideration for the single step reaction procedure under mild conditions. The catalytic alcohol oxidation reactions were performed using very less catalyst loading and H2O2 co-oxidant in eco-friendly water as a solvent. Results: The solid state characterization of compounds 1 and 2 was performed using single crystal X-ray diffraction, FT-IR spectroscopy, thermogravimetric analysis and solution stability was also checked by 31P NMR spectroscopy. The ICP-AES analysis was performed for the chemical composition of the compounds. A variety of primary and secondary alcohols were oxidized to corresponding carbonyl compounds with excellent yields in presence of very less catalyst loading and 2:1 H2O2/substrate ratio in water. Conclusion: In conclusion, we have isolated two yttrium containing Keggin type dimeric and tetrameric phosphotungstate complexes by the single step reaction of K14[P2W19O69(H2O)]·24H2O POM ligand with Y(NO3)3·6H2O salt. The isolated compounds were further characterized with FT-IR spectroscopy, single crystal X-ray diffraction, 31P NMR, thermogravimetric and elemental analysis. The catalytic alcohol oxidation studies show good catalytic conversions, and finally FT-IR spectra of recovered catalysts after fifth cycle shows both catalysts retains their identity after fifth catalytic cycle. Keywords: Polyoxometalates, yttrium, catalysis, alcohol oxidation.

Iron/ABNO-Catalyzed Aerobic Oxidation of Alcohols to Aldehydes and Ketones under Ambient Atmosphere.

We report a new Fe(NO3)3·9H2O/9-azabicyclo[3.3.1]nonan-N-oxyl catalyst system that enables efficient aerobic oxidation of a broad range of primary and secondary alcohols to the corresponding aldehydes and ketones at room temperature with ambient air as the oxidant. The catalyst system exhibits excellent activity and selectivity for primary aliphatic alcohol oxidation. This procedure can also be scaled up. Kinetic analysis demonstrates that C-H bond cleavage is the rate-determining step and that cationic species are involved in the reaction.

Ultrasmall Platinum Nanoparticles Supported Inside the Nanospaces of Periodic Mesoporous Organosilica with an Imidazolium Network: An Efficient Catalyst for the Aerobic Oxidation of Unactivated Alcohols in Water

AbstractThe imidazolium group inside the wall of a periodic mesoporous organosilica provides an excellent environment for the stabilization of ultrasmall Pt nanoparticles (<1.5 nm), and this allowed the formation of a catalyst system (i.e., Pt(NP)@PMO‐IL) with significant activity and recyclability in the selective aerobic oxidation of various alcohols in water at ambient pressure of oxygen. In particular, the catalyst exhibited high activity in the oxidation of unactivated primary alcohols and sterically encumbered secondary aliphatic alcohols, which remain challenging substrates for many catalytic aerobic protocols.

Immobilization of palladium (II) complexes on ethylenediamine functionalized core–shell magnetic nanoparticles: An efficient and recyclable catalyst for aerobic oxidation of alcohols and carbonylative Suzuki coupling reaction

A novel Pd(II) complex immobilized on ethylenediamine-functionalized core–shell magnetic nanoparticles [Fe3O4@SiO2–2N–Pd(II)] was successfully synthesized by a facile procedure, and various characterizations (TEM, XRD, FT-IR, TGA, XPS and VSM) were performed to identify its intrinsic features. The amino groups in two kinds from ethylenediamine-functionalized magnetic nanoparticles (Fe3O4@SiO2–2N) performed as robust anchors and efficient stabilizers during the fabrication of Fe3O4@SiO2–2N–Pd(II). As a heterogeneous phosphine-free Pd(II) complex catalyst, it showed excellent catalytic activity for aerobic oxidation of alcohols, and up to >99% yield of unsymmetrical biaryl ketone was obtained in the carbonylative Suzuki coupling reaction of carbon monoxide, 4-methylbenzeneboronic acid and the 4-iodonitrobenzene. Moreover, the catalyst could be completely recovered by magnetic separation from the reaction mixture and remained unaltered activity even after six repeated cycles.

Nanostructured Mn-doped ceria solid solutions for efficient oxidation of vanillyl alcohol

Ceria is the hub of constant and diverse research interest due to its wide industrial applications. In the present work, we have developed Mn-doped CeO2 catalysts for vanillyl alcohol oxidation. Accordingly, we synthesized nanostructured Mn-doped CeO2 catalysts with various concentration of MnOx by an economical coprecipitation method and characterized using XRD, ICP-OES, BET surface area, Raman spectroscopy, TEM, XPS, and H2-TPR techniques. XRD and TEM results confirmed formation of nanocrystalline solid solutions with the incorporation of Mn into ceria lattice. ICP-OES analysis confirmed actual amount of MnOx loadings in the respective catalysts. The BET surface area of CeO2 significantly enhanced after the incorporation of MnOx dopant. Raman results disclosed that the incorporation of MnOx into ceria lattice greatly enhances the oxygen vacancies, which are responsible for the improved catalytic activity. XPS analysis revealed that Ce and Mn exist in +3, +4 and +2, +3, +4 oxidation states, respectively, on the surface of the samples. H2-TPR results showed pronounced enhancement in the reduction of CeO2 by MnOx doping. Catalytic activity studies confirmed that among all the catalysts, the Ce0.7Mn0.3O2−δ showed superior activity for vanillyl alcohol oxidation with 89% conversion and 95% selectivity, which could be attributed to higher concentration of oxygen vacancies, a high BET surface area, low temperature reducibility, and facile synergetic interaction between CeO2 and MnOx.

Visible-light-induced aerobic photocatalytic oxidation of aromatic alcohols to aldehydes over Ni-doped NH2-MIL-125(Ti)

The Ni-doped NH2-MIL-125(Ti) catalyst was developed for the photocatalytic aerobic oxidation of aromatic alcohols upon visible light irradiation. The results show that different aromatic alcohols can be effectively transformed to their corresponding aldehydes with almost absolute selectivity using O2 as the oxidant over Ni-doped NH2-MIL-125(Ti) upon visible light irradiation. Compared with the parent catalyst NH2-MIL-125(Ti), Ni-doped NH2-MIL-125(Ti) exhibits a significantly enhanced photocatalytic activity for the selective oxidation of aromatic alcohols. Preliminary studies indicate that the doping of Ni nanoparticles into NH2-MIL-125(Ti) could improve the visible-light harvesting, charge-separation, and electron-transport of the resultant catalyst, leading to the enhanced photocatalytic activity. The current work provides some guidance in the development of MOF-based photocatalysts for organic syntheses.

Synergistic catalysis within TEMPO-functionalized periodic mesoporous organosilica with bridge imidazolium groups in the aerobic oxidation of alcohols

Anchoring TEMPO within the nanospaces of a PMO with bridged imidazolium groups led to an powerful bifunctional catalyst (TEMPO@PMO-IL-Br), which showed enhanced activity in the metal-free aerobic oxidation of alcohols.

Surface-oxidized carbon black as a catalyst for the water oxidation and alcohol oxidation reactions.

Carbon black (CB) is popularly used as a catalyst support for metal/metal oxide nanoparticles due to its large surface area, excellent conductivity and stability. Herein, we show that surface oxidized CB itself, after acidic treatment and electrochemical oxidation, exhibits significant catalytic activity for the electrochemical oxidation of water and alcohols.

Highly selective aerobic oxidation of alkyl arenes and alcohols: cobalt supported on natural hydroxyapatite nanocrystals

Cobalt was successfully immobilized on natural hydroxyapatite nanocrystals which was obtained from cow bones (Co–NHAp). NHAp as the support enhanced both catalytic activity and selectivity in aerobic oxidation of alkyl arenes and alcohols.

Macroporous TiO2encapsulated Au@Pd bimetal nanoparticles for the photocatalytic oxidation of alcohols in water under visible-light

A novel macroporous photocatalyst Au@Pd@TiO2has been reported and showed excellent catalytic activity and stability in the aerobic oxidation of alcohols in water at ambient temperature when using air as the oxidizing agent under visible light irradiation.

Radical pathways and O2 participation in benzyl alcohol oxidation, and catechol and o-aminophenol oxidase activity studies with novel zinc complexes: an experimental and theoretical investigation

Diphenoxo bridged dinuclear zinc complexes were found to be capable of oxidation of benzyl alcohol, catechol and o-aminophenol.

Porous chitosan–MnO2 nanohybrid: a green and biodegradable heterogeneous catalyst for aerobic oxidation of alkylarenes and alcohols

A porous chitosan–manganese dioxide (PC–MnO2) nanohybrid was synthesized using an in situ reduction method, in which potassium permanganate solution and nanoporous chitosan acted as precursor and reducing agent. The chemical and structural properties of PC–MnO2 were characterized using scanning and transmission electron microscopies, X‐ray diffraction, thermogravimetric analysis and Fourier transform infrared spectroscopy. Highly dispersed MnO2 nanoparticles in a matrix of porous chitosan showed high catalytic activity for selective aerobic oxidation of alkylarenes and alcohols without using any bases or expensive oxidants. Short reaction time, ease of product separation by filtration and recyclability of the catalyst make it environmentally and economically favoured for the synthesis of versatile aldehydes and ketones. Copyright © 2015 John Wiley & Sons, Ltd.