Catalytic Oxidation Of Benzyl Alcohol Research Articles

A broad-spectrum oxidation capability Ru-CeO2 catalyst for efficient synergistic selective oxidation of benzyl alcohol

Selective oxidation of alcohols to aldehydes by molecular oxygen is one of the most important transformations in multiphase catalysis. In this paper, a catalyst with selective oxidation ability was designed and synthesized for the selective catalytic oxidation of benzyl alcohol. N-doped carbon materials were prepared by high-temperature calcination using hydrothermal reaction products of citric acid and melamine as a carbon source, and a bimetallic catalyst supported by Ru-CeO2 was constructed using the mixture as the carrier for the selective oxidation of benzyl alcohol to benzaldehyde. The results showed that the introduction of CeO2 could effectively improve the oxidizing ability and catalytic activity of the catalyst. The Ru-Ce0.05/NC170–600 catalyst was able to convert 85.5 % benzyl alcohol into benzaldehyde at 140 °C, 6 h, and 2 MPa, and the selectivity for benzaldehyde was 100 %. It was demonstrated by DFT that it was theoretically feasible to generate benzaldehyde by extracting hydrogen atoms from benzyl alcohol molecules. Further, the selective oxidation experiments on other alcohols showed that the catalyst has high activity for the oxidation of various alcohols to generate the corresponding carbonyl products, and it is a catalyst with broad-spectrum selective oxidation ability. In this study, a green synthesis route of benzaldehyde was proposed to solve the problems in the traditional process. Meanwhile, it provides a new idea for the synthesis of carbonyl products by selective oxidation of alcohols.

Simultaneously catalytic oxidation of benzyl alcohol to benzaldehyde and selectively phase separation via a sandwich-like polymeric PVDF membrane

It is of significance to improve the interfacial catalytic performance of noble metal nanocatalysts in heterogeneous reactions and to achieve real-time oil-water phase separation to reduce the separation and purification process. In the current work, a sandwich-like polymeric membrane was prepared, with a core layer of poly(vinylidene fluoride) (PVDF)/poly(methacrylic acid) (PMAA) microspheres/Pd nanoparticles as the reaction center, and a hydrophilic semi-interpenetrating polymer network (semi-IPN) as well as a hydrophobic PVDF as shells for the benzaldehyde green preparation. The process proceeded by using the sandwich-like membrane to catalyze the interface reaction between the organic phase of benzyl alcohol and the aqueous phase of H2O2 and the effect factors such as reaction temperature, feed flow rate, the initial benzyl alcohol concentration and catalyst dosage were investigated to get the optimal oxidation conversion and selectivity. Results indicated that the interface reaction went well, without the aggregation and leaching of Pd nanoparticles from membrane support. Furthermore, the product benzaldehyde could be selectively transported to the organic phase. The sandwich-like catalytic composite membrane integrates the catalysis with phase separation, providing a new strategy for the preparation of the chloride-free benzaldehyde. What's more, the sandwich-like catalytic membrane acts as an ideal option for a large-scale catalysis application with integrated advantages of high activity, convenient operation and omitted separation of catalysts and products from heterogeneous catalytic interfacial reaction system.

Facile preparation and catalytic property of a sandwich composite membrane

Membrane as a support for metal nanocatalysts, can greatly enhance the catalytic activity of metal nanoparticles and promote the efficient production and separation of products. In this study, a novel sandwich-structured composite membrane was designed and facilely fabricated by using palladium nanocatalysts as the core catalytic layer and two different structured PVDF layers as the outer layers. The composite membrane was used as a reaction interface as well as a separation barrier between reactants and products, efficiently realizing the catalytic oxidation of benzyl alcohol and convenient separation of the product benzaldehyde. The membrane was characterized in detailed and the effects of the membrane structure and various reaction conditions on the catalytic oxidation were systematically investigated. The results indicated that the reaction could be conveniently carried out under very mild experimental conditions, obtaining the product benzaldehyde at as high selectivity as 93.17 %. The successful implementation of the sandwich membrane for the production of chlorine-free benzaldehyde provides a new method for the interface reaction.

Nitrogen-Doped Porous Carbon Derived from Covalent Triazine Framework for Catalytic Oxidation of Benzyl Alcohol.

The catalytic oxidation of alcohols is an important transformation in the chemical industry. Carbon materials with a large surface area and N doping show great promise as metal-free catalysts for the reaction. In this study, a rich N-containing covalent triazine framework polymerized by cyanuric chloride and p-phenylenediamine was used to synthesize N-doped porous carbon with the assistance of a pore-forming agent-NaCl. First, the mass ratio of the polymer/NaCl was optimized to 1:9. Then, the influence of the pyrolysis temperatures (700-1000 °C) on the materials was studied in detail. It was found that the carbon materials were gradually exfoliated by molten salt at high temperatures. XRD and Raman characterizations showed them with a certain graphitization. The optimal doped carbon CNN-1-9-900 achieved the highest surface area of 199.03 m2g-1 with the largest pore volume of 0.29 cm3g-1. Furthermore, it had a high N content of 9.9 at% with the highest relative proportion of pyridinic/graphitic N. Due to the synergistic effect between the surface area and pyridinic/graphitic N, CNN-1-9-900 showed the best performance for benzyl alcohol oxidation with TBHP at moderate conditions, and the process also worked for its derivatives.

Insight into the promotional effect of Ce doped in (FeCoNiCrMn)3O4 high entropy oxides for solvent-free aerobic oxidation of benzyl alcohol

It is desired but challenging to develop a non-noble metal catalyst for the selective oxidation of benzyl alcohol with O2 under solvent-free conditions. Herein, a series of Ce-doped high entropy oxides (Ce/HEOs) were prepared via co-precipitation and subsequent thermal treatment method. It was found that, the doping of Ce could remarkably promote the catalytic activity for selective oxidation of benzyl alcohol to benzaldehyde. The improved activity was ascribed to the good distribution of active Ce species, the increased oxygen vacancies, and the synergistic effect between CeO2 and high entropy oxides (HEOs). In addition, the surface oxygen of Ce/HEOs towards Ce displayed stronger reducibility compared to that of bare CeO2, endowing it stronger deprotonation ability towards benzyl alcohol during the reaction. The prepared catalyst exhibited satisfactory reusability and stability owing to the entropy-stabilized effect of HEOs and the interaction between CeO2 and HEOs, and negligible loss in catalytic activity was observed after seven runs. Besides, DFT calculations disclosed that, with the doping of Ce, the Ce/HEOs catalyst possessed stronger adsorption ability towards benzyl alcohol, and lower free energy was required for the rate-determining step during the whole oxidative reaction. This work gave some insights into the promotional effect of Ce doped into high entropy oxides for the solvent-free catalytic oxidation of benzyl alcohol.

Mesoporous silica-supported Ni–Co composite metal oxide as a heterogeneous catalyst for air oxidation of benzyl alcohols

A mesoporous silica-supported Ni–Co composite metal oxide has been synthesized and applied as an effective heterogeneous catalyst for the selective catalytic oxidation of benzyl alcohols. Various characterization methods were employed to confirm the successful synthesis of the catalysts and their nanostructure. The catalytic performances of these catalysts in the selective oxidation of substituted benzyl alcohols to aromatic aldehydes were systematically investigated using molecular oxygen from the air as the oxidant under atmospheric pressure. The NiCo@SBA-15 catalyst exhibited remarkable performance, achieving nearly 98 % conversion and almost complete selectivity at a temperature of 120 °C for 10 h, operating at 1 atm of air pressure. This catalytic performance can be attributed to the synergistic effect between Ni and Co ions, resulting in the generation of new surface-active sites in the catalyst. The catalyst also demonstrated favorable applicability and universality. Moreover, A plausible catalytic mechanism has been proposed involving the synergistic effect between bimetal species and oxygen vacancy.

Insight into the Role of the Amino‐Organosilane Modifier in Improving the Catalytic Activity of ZnO‐Supported Gold Species in Base‐Free Oxidation of Benzyl Alcohol

AbstractUnderstanding the factors that affect the reactivity of gold nanoparticles (Au NPs) in the catalytic oxidation of organic compounds remains an important issue. Of particular significance is tuning the effect of metal‐support interaction toward improving the catalytic performance of Au NPs. The main goal of this study is to provide new insight into the role of the amino‐organosilane (APMS) modifier, used for anchoring of gold species on ZnO support, in controlling the reactivity of Au NPs in H2O2 activation and the subsequent catalytic oxidation of benzyl alcohol. This study reveals that APMS modifier weakens the electronic interaction between ZnO and Au NPs, leading to a lower catalase‐like activity toward H2O2 in comparison to that observed for modifier‐free gold catalyst of similar size of nanoparticles. As a result, a slower rate of oxygen evolution resulted in higher activity in the oxidation of benzyl alcohol and enabled more efficient utilization of H2O2 under base‐free conditions. No radical species were formed during the oxidation reaction, and molecular oxygen formed in situ in the reaction medium was the primary oxidant responsible for the catalytic conversion of benzyl alcohol.

Co-Schiff base complexes functionalized on graphene as efficient heterogeneous nanocatalysts for alcohols oxidation

Different Schiff base complexes were prepared by immobilizing three aldehydes (4-Hydroxybenzaldehyde, 2-hydroxybenzaldehyde, and 2-Pyridinecarboxaldehyde) on graphene oxide and were fully characterized using multiple techniques such as FTIR, XRD, TGA, BET, SEM-EDS, and TEM. Then efficient heterogeneous catalysts were checked out in the selective catalytic oxidation of benzylic alcohols. The effects of different parameters, such as reaction time and temperature, were examined to obtain optimum reaction conditions. The solvent-free oxidation reaction of benzylic alcohols showed a conversion above 70% and selectivity higher than 95% in the presence of cobalt (II) Schiff base catalysts using H2O2 as an oxidant after 40 min of reaction. The reusability experiment results specified that the prepared catalysts could maintain high catalytic activity in the oxidation of benzylic alcohols (>80%) and selectivity (>96%) even after being used for three cycles.

A DFT investigation of the catalytic oxidation of benzyl alcohol using graphene oxide.

Metal-free heterogeneous materials have attracted great interest due to their potential to facilitate various organic transformations in line with circular economy and green chemistry principles. Among various 2D materials, graphene oxide (GO) is considered an attractive material for numerous applications in physics, chemistry, biology, material sciences, and catalysis. Furthermore, graphene-based catalysts exhibit good catalytic activity toward the selective oxidation of benzyl alcohol to benzaldehyde or benzoic acid under eco-friendly conditions. In this regard, a theoretical investigation was carried out to study both catalytic oxidation reaction pathways (i.e., benzyl alcohols to aldehyde and to benzoic acid) using GO as an eco-friendly and metal-free catalyst. In this study, we report a theoretical investigation at the B3LYP/6-31G level to better understand the oxidation of benzyl alcohol using GO as a metal-free catalyst. The possible bond formation was investigated using the global and local reactivity indexes derived from Fukui functions. Furthermore, we performed a non-covalent interaction (NCI) analysis to unveil the stability and the interaction nature between both reagents and GO surface. The effect of the solvent on the oxidation efficiency was also performed and the results indicate that the solvent significantly affects the decrease of reactivity by increasing the activation barriers through oxidation reactions of benzyl alcohol. Additionally, the electron localization function (ELF) analysis was performed for all intermediates showing the ionic nature of the studied epoxide structure of GO and rules out any type of covalent interaction during the oxidation reaction of benzyl alcohol. All these obtained results are in good agreement with experimental observations and reveal that the epoxide functions on the graphene surface promote an excellent catalyst turnover.

Iron-palladium supported graphene as an efficient bimetallic catalyst for the selective oxidation of benzyl alcohol to benzaldehyde

The catalytic oxidation of benzyl alcohol (OBA) is one of the significant methods to produce benzaldehyde, an essential reagent in the chemical and pharmaceutical industries. However, developing an active and efficient catalyst for OBA is a tremendous challenge in commercialization. This research describes a simple, eco-friendly method for producing Fe, Pd, and Fe: Pd bimetallic nanoparticles fabricated by sol immobilization over graphene to conduct OBA. The resulting composite nano-alloys were then characterized using X-ray diffraction (XRD), Fourier transforms infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM). The oxidation state and elemental composition of as-fabricated nanoparticles were analyzed using XPS. The point of zero charges (pHPZC) was analyzed and the PZC value indicated that the proposed adsorbent material tends to have a positive charge. The OBA reaction efficiency (87%) of bimetallic nanocatalysts stabilized in graphene support was increased through surface modification of the ratio of both metals. The experimental error was based on three parallel tests and the carbon balance (99.6%) was analyzed during the experiments A proposed reaction mechanism of OBA validated the β-hydride step's elimination by molecular oxygen converting the metal hydride into a water molecule, forming a peroxide intermediate to form water and oxygen molecules. The Fe on the nanocatalyst’s surface is preferentially responsible for the adsorption of the substrate molecule, resulting in the formation of metal-alkoxide. Since it lacks electrons, Fe is more likely to be oxidized, allowing it to perform better than monometallic catalysts in terms of catalytic activity. The present study has great potential to be applied on an industrial scale and studied for industrialists, researchers, and academicians.

A Double Open-Shelled Au43 Nanocluster with Increased Catalytic Activity and Stability

Atomically precise metal nanoclusters (NCs) are an intriguing class of crystalline solids with unique physicochemical properties derived from tunable structures and compositions. Most atomically precise NCs require closed-shells and coordinatively saturated surface metals in order to be stable. Herein, we report Au43(C≡CtBu)20 and Au42Ag1(C≡CtBu)20, which feature open electronic and geometric shells, leading to both paramagnetism (23 valence e-) and enhanced catalytic activity from a single coordinatively unsaturated surface metal. The Au-alkynyl surface motifs of these NCs form five helical stripes around the inner Au12 kernel, imparting chirality and high thermal stability. Density functional theory (DFT) calculations suggest that there are minimal energy differences between the open-shelled NCs and hypothetical closed-shell systems and that the open-shelled electronic configuration gives rise to the largest band gap, which is known to promote cluster stability. Furthermore, we highlight how coordinatively unsaturated surface metals create active sites for the catalytic oxidation of benzyl alcohol to benzaldehyde, leading to high selectivity and increased conversion. This work represents the first example of an atomically precise Au NC with a double open-shelled structure and provides a promising platform for investigating the magnetic and catalytic properties of noble metal nanoparticles.

An efficient mixed micellar strategy for the catalytic oxidation of benzyl alcohol by diperiodatoargentate(iii) in aqueous media

A mixed micellar microenvironment appeared as an efficient catalytic nanoreactor for the oxidation of benzyl alcohol by diperiodatoargentate(iii) in aqueous media.

Gas Chromatographic Technique Employed for Catalytic Investigation of Novel Phthalocyanines

The primaquine substituted Fe(II) phthalocyanine (PQFePc) and Co(II) phthalocyanine (PQCoPc) catalysts were prepared by using amide linkage method. The physical and chemical properties have been investigated by FTIR, mass, UV-Vis, TGA, XRD and elemental analysis. The catalytic oxidation of benzyl alcohol was determined by PQFePc and PQCoPc complexes by varying parameters like temperature, oxidant/catalytic ratio and substance/catalyst ratio. The optimization of catalytic oxidation reaction has been effectively achieved for the determination of benzyl alcohol (Bzalc) to benzaldehyde (Bzald). The PQCoPc and PQFePc exhibited excellent catalytic behaviour for the oxidation of benzyl alcohol obtaining high yield and good selectivity.

Bioinspired oxidation of benzyl alcohol: The role of environment and nuclearity of the catalyst evaluated by multivariate analysis

Inspired by copper-containing enzymes such as galactose oxidase and catechol oxidase, in which distinct coordination environments and nuclearities lead to specific catalytic activities, we summarize here the catalytic properties of dinuclear and mononuclear copper species towards benzyl alcohol oxidation using a multivariate statistical approach. The new dinuclear [Cu2(μ-L1)(μ-pz)]2+ (1) is compared against the mononuclear [CuL2Cl] (2), where (L1)− and (L2)− are the respective deprotonated forms of 2,6-bis((bis(pyridin-2-ylmethyl)amino)methyl)-4-methylphenol, and 3-((bis(pyridin-2-ylmethyl)amino)methyl)-2-hydroxy-5-methylbenzaldehyde and (pz)− is a pyrazolato bridge. Copper(II) perchlorate (CP) is used as control. The catalytic oxidation of benzyl alcohol is pursued, aiming to assess the role of the ligand environment and nuclearity. The multivariate statistical approach allows for the search of optimal catalytic conditions, considering variables such as catalyst load, hydrogen peroxide load, and time. Species 1, 2 and CP promoted selective production of benzaldehyde at different yields, with only negligible amounts of benzoic acid. Under normalized conditions, 2 showed superior catalytic activity. This species is 3.5-fold more active than the monometallic control CP, and points out to the need for an efficient ligand framework. Species 2 is 6-fold more active than the dinuclear 1, and indicates the favored nuclearity for the conversion of alcohols into aldehydes.

Vanadium Supported on Titanium Pillared Montmorillonite Clay for the Selective Catalytic Oxidation of Benzyl Alcohol

Vanadium Supported on Titanium Pillared Montmorillonite Clay for the Selective Catalytic Oxidation of Benzyl Alcohol

One pot synthesis of chromium incorporated SBA-16 under acid medium-Application in the selective oxidation of benzyl alcohol derivatives

Cr-SBA-16 mesoporous silica heterogeneous catalysts (Si/Cr = 7, 14, and 28) were successfully synthesized by one-pot hydrothermal method at low acidic medium. The catalysts were characterized by means of X-ray diffraction (XRD), N 2 adsorption-desorption at 77 K, Fourier Transform Infrared (FTIR), X-ray photoelectron (XPS) and Diffuse Reflectance UV–Vis (DRS) Spectroscopies, Thermogravimetric analysis (TGA), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) techniques. Herein, Cr-SBA-16 catalysts are evaluated in the selective catalytic oxidation of benzyl alcohol derivatives using H 2 O 2 as oxidant. From XPS and UV–Vis (DRS) spectroscopies the molar ratios between Cr 6+ /Cr 3+ are found to increase versus chromium loading in the following order: Cr-SBA-16(28) < Cr-SBA-16(14) < Cr-SBA-16(7). Hence the highest Cr 6+ in tetrahedrally environment is observed for Si/Cr = 7. We demonstrated for the first time that the selective catalytic oxidation of benzyl alcohol (BzOH) using H 2 O 2 over Cr-SBA-16 occurs through noncompetitive adsorption mechanism and the reaction is pseudo-first order to BzOH. The activity of the reaction depends on the symmetry of chromium species, herein, high activity is observed for tetrahedral chromium species in Cr-SBA-16(7). The absence of any chromium ions in the filtrate shows no chromium leaching from the silica framework.

Efficient catalytic oxidation of benzyl alcohol by tetrasubstituted cobalt phthalocyanine-MWCNTs composites

In this paper, the tetra-[α-(p-formyl) phenoxy] phthalocyanine cobalt (II)/multiwalled carbon nanotubes (CoPc/MWCNTs) composites were prepared through the π-π interactions between CoPc and MWCNTs. UV–vis spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and transmission electron microscopy were employed to characterize the structures of the prepared CoPc/MWCNTs composites. Its catalyzed oxidation properties were studied by carrying out the oxidation reaction of benzyl alcohol. The catalytic efficiency of these compounds under different reaction parameters such as catalyst dosage, temperature, time and various organic solvent was investigated.

Catalytic oxidation of benzyl alcohol over MnO2: Structure-activity description and reaction mechanism

Activity evaluation of metal oxide catalysts with different crystal structures has been an important prerequisite for industrial applications. This work systematically elucidates the structure-activity relationship of α-, β-, γ- and δ-MnO2 catalysts toward the selective oxidation of benzyl alcohol (BA) to benzaldehyde (BAD). Exposed surfaces of MnO2 are evaluated by a combined theoretical and experimental investigation. On this basis, a catalytic activity descriptor is established considering the surface energies, formation energies of oxygen vacancies (OVs), O2 adsorption energies, and areal densities of OVs and unsaturated Mn. Inspired by this, we fabricate β-MnO2 with a high surface area and it delivers the highest BA conversion among all MnO2. Furthermore, a developed Mars-van Krevelen (MvK) mechanism is proposed to describe the BA oxidation process on the β-MnO2 (110) surface. The research paradigm opens a door to the rational design of metal oxide catalysts.

Phyto-Assisted Assembly of Metal Nanoparticles in Chitosan Matrix Using S. argel Leaf Extract and Its Application for Catalytic Oxidation of Benzyl Alcohol.

The design and synthesis of eco-friendly solid-supported metal nanoparticles with remarkable stability and catalytic performance have gained much attention for both industrial and environmental applications. This study provides a novel, low-cost, simple, and eco-friendly approach for decorating cross-linked chitosan with gold nanoparticles (AuNPs), greenly prepared with Solenostemma argel (S. argel) leaf extract under mild conditions. Glutaraldehyde-modified chitosan beads were used to coordinate with Au(III) ions and act as stabilizing agents, and S. argel leaf extract was used as a cost-effective phyto-reducing agent to reduce gold ions to elemental Au nanoparticles. The successful cross-linking of chitosan with glutaraldehyde, the coordination of Au(III) ions into the chitosan matrix, and the phytochemical reduction of Au(III) to Au nanoparticles were investigated via FT-IR spectroscopy. The obtained Au nanoparticles have a uniform spherical shape and size <10 nm, as confirmed by both X-ray diffraction (XRD) (~8.8 nm) and TEM (6.0 ± 3 nm). The uniformity of the AuNPs’ size was confirmed by Scanning Electron Microscopy (SEM) and Transition Electron Microscopy (TEM). The powder X-ray diffraction technique showed crystalline AuNPs with a face-centered cubic structure. The elemental analysis and the Energy Dispersive Spectroscopy (EDS) analysis both confirmed the successful integration of Au nanoparticles with the chitosan network. The catalytic activity of this highly stable nanocomposite was systematically investigated via the selective oxidation of benzyl alcohol to benzaldehyde. Results showed a remarkable conversion (97%) and excellent selectivity (99%) in the formation of benzaldehyde over other side products.

Transforming Waste Clamshell into Highly Selective Nanostructured Catalysts for Solvent Free Liquid Phase Oxidation of Benzyl Alcohol

High yield production of benzaldehyde in the solvent-free oxidation of benzyl alcohol by using green catalysts is highly desirable. In this work, calcium hydroxide derived from waste clamshell was used as low-cost and environmentally friendly catalyst support (CaSUP) for Pd and V nanoparticles. The physicochemical properties of the catalysts were analyzed using X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) technique, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The catalytic oxidation of benzyl alcohol to benzaldehyde was studied in a liquid phase reaction by using H2O2 as an oxidizing agent. The effects of catalyst loading, the molar ratio of hydrogen peroxide to benzyl alcohol, temperature and reaction duration were investigated. In the optimized conditions, Pd nanoparticles supported on clamshell-derived supports displayed excellent catalytic conversion (88%) and selectivity to benzaldehyde (89%). Furthermore, the catalyst can be effectively reused without a significant loss in its activity and selectivity. The high yield and stability can be related to the structural and basic properties of the catalyst. These results provide important insights into the benzyl alcohol oxidation process for industrial applications.