Catalytic Oxidation Of Alcohols Research Articles

Catalytic oxidation of lignin model non-phenolic monomer Veratryl alcohol over iron containing mesoporous SBA-1

Catalytic oxidation of lignin model non-phenolic monomer Veratryl alcohol over iron containing mesoporous SBA-1

Catalytic oxidation of alcohols to aldehydes and ketones with ferric nitrate nonahydrate/trifluoroacetic acid via mechanochemical reaction

Benzylic alcohols and secondary aliphatic alcohols were readily converted into aldehydes and ketones with ferric nitrate nonahydrate/trifluoroacetic acid under ball milling. This method takes advantages of fast, effective, the use of cheap and readily available reagents and broad functional group compatibility.

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.

A new perspective for palladium(II)-catalyzed alcohol oxidation in aerobic means

The development of alternative and environmentally safe routes for the oxidation of primary and secondary alcohols has attracted the attention of several researchers due to the importance of these oxidized products in industries. Thereby, the oxidation of β-citronellol, geraniol, nerol, borneol, isoborneol, cinnamic alcohol, and benzyl alcohol is described herein. These reactions occurred in an aerobic environment, with or without system pressurization. Acetonitrile was the solvent used. The process was catalyzed by the bimetallic complex formed with palladium(II) acetate and copper(II) acetate, using p-benzoquinone as a cocatalyst in some reaction conditions. The applied system obtained 62.5 points on the eco-scale, with yields above 61%. Alcohol oxidation products are of great importance in industrial applications. Thus, this work presents a cleaner, more sustainable alternative to alcohol oxidations.

Selective direct oxidation of 1-butanol into acetal using hydrogen peroxide and Cs5 MPW11 (H2 O)O39 (M=Fe, Co, Cu) catalysts.

Direct catalytic oxidation of alcohols to acetals in one step process is very attractive, because the two steps process leads firstly to aldehydes, which are unstable species serving as reactive intermediates to generate several by-products reducing process efficiency and selectivity. In this work, a new selective catalytic acetalization of 1-butanol into 1-1-dibutoxybutane acetal using H2 O2 in one step process is investigated using Keggin-type polyoxometalates catalysts. The materials developed consisted of new lacunary phophotungstate salts Cs5 MPW11 (H2 O)O39 (M=Fe, Co and Cu) which were prepared by inorganic solution condensation method and characterized using XRD, IR, SEM and EDX analysis to verify their structure, surface morphology and chemical composition. Cs5 CuPW11 (H2 O)O39 catalyst allowed the highest performance for the oxidation of 1-butanol at 60 °C using H2 O2 excess with a yield approaching 92 % and a turnover number of 784. Such activity is related to a bifunctional behavior of the catalyst as superacid and redox operating system and the synergistic effect created between the [PW11 O39 ]7- Keggin framework, Cs+ and Cu2+ .

Operando film-electrochemical EPR spectroscopy tracks radical intermediates in surface-immobilized catalysts.

The development of surface-immobilized molecular redox catalysts is an emerging research field with promising applications in sustainable chemistry. In electrocatalysis, paramagnetic species are often key intermediates in the mechanistic cycle but are inherently difficult to detect and follow by conventional in situ techniques. We report a new method, operando film-electrochemical electron paramagnetic resonance spectroscopy (FE-EPR), which enables mechanistic studies of surface-immobilized electrocatalysts. This technique enables radicals formed during redox reactions to be followed in real time under flow conditions, at room temperature and in aqueous solution. Detailed insight into surface-immobilized catalysts, as exemplified here through alcohol oxidation catalysis by a surface-immobilized nitroxide, is possible by detecting active-site paramagnetic species sensitively and quantitatively operando, thereby enabling resolution of the reaction kinetics. Our finding that the surface electron-transfer rate, which is of the same order of magnitude as the rate of catalysis (accessible from operando FE-EPR), limits catalytic efficiency has implications for the future design of better surface-immobilized catalysts.

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.

Catalytic aerobic oxidation of lignin-based vanillyl alcohol over LaFeO3 perovskite towards vanillin production: Relationships between the activity and acid-base property as well as oxygen vacancy

Developing high-performance acid-base catalysis over perovskite for alcohol aerobic oxidation has received increasing attention, but the fundamental understanding of its surface acid-base property and performance relationship remains largely unknown. Accordingly, a series of LaFeO3 perovskites were fabricated via modified Pechini approach with the addition of different chelating agents to modulate their respective acid-base amount and oxygen vacancy concentration, which subsequently were employed in the aerobic oxidation of vanillyl alcohol (a lignin model), to generate vanillin for elucidating the relationships between the catalytic activity of LaFeO3 perovskite and its acid-base property as well as oxygen vacancy. The results demonstrated that existence of non-linear relationships between the vanillin yield and the acid-base amount as well as oxygen vacancy concentration of LaFeO3 catalyst. Moreover, neither acid-base sites nor oxygen vacancies were the solely factors affecting the activity of LaFeO3 perovskite towards vanillyl alcohol oxidation for vanillin production. Mechanism studies proclaimed that the reactive oxygen species derived from the adsorption of molecule oxygen on oxygen vacancies generated by anion defects combing with Lewis acid sites (Fe3+/Fe2+) to yield FeOx active pairs, which jointly dominated the pathway for vanillyl alcohol oxidation to produce vanillin. Overall, this work offers guidance for designing effective perovskite-based catalysts for lignin conversion to produce value-added chemicals by selectively modulating its acid-base property and oxygen vacancy.

One-pot fabrication of vanadium-doped ordered mesoporous zirconium oxophosphate catalyst for the synthesis of carbonyl compounds

Carbonyl compounds serve as essential raw materials in the production of fine chemicals and pharmaceuticals. An economical and environmentally-friendly route to generating carbonyl compounds involves the catalytic oxidation of alcohols...

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.

Atomically Dispersed Co on N-Doped Porous Carbon for the Highly Efficient Catalytic Oxidation of Aromatic Alcohols to Acids and Nitriles

Atomically Dispersed Co on N-Doped Porous Carbon for the Highly Efficient Catalytic Oxidation of Aromatic Alcohols to Acids and Nitriles

Catalytic Oxidation of Aliphatic Alcohols by Graphene Oxide Supported Binuclear Dioxidovanadium (V) Complexes

Catalytic Oxidation of Aliphatic Alcohols by Graphene Oxide Supported Binuclear Dioxidovanadium (V) Complexes

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.

Well-defined ruthenium-hexamethylenetetramine complex: Synthesis, characterization, and catalytic activity towards base and acceptor free oxidation of alcohols and amines

A ruthenium hexamethylenetetramine complex [RuCl2(p-cym)HMTA] was prepared in quantitative yield at room temperature for 30 m. NMR and fluorescence spectroscopic studies revealed that the complex is unstable in solution resulting in the decomposition of HMTA unit with the elimination of p-cymene moiety. The newly synthesized complex is very efficient for the conversion of amines and alcohols into imines and ketones, respectively, in the absence of any base/additive/acceptor. The synthetic viabilty of the catalyst was successfully tested for the gram scale synthesis of industrially important product bis(4-chlorophenyl)methanone. The spectroscopic and experimental studies showed that ruthenium-hydride species was formed as active catalyst during the catalytic reactions and oxidation of alcohols and amines follows a dehydrogenative oxidation mechanism. The amount of hydrogen gas evolved during the ruthenium complex catalysed oxidation of diphenylmethanol was estimated to be 92%, implies the potential usage of catalyst in the field of liquid organic hydrogen storage.

Preparation of porous carbon supported Co element doping spinel copper ferrite for the catalytic oxidation of vanillyl alcohol

Spinel ferrite has been widely applied in the field of catalytic oxidation with its high selectivity, magnetic separation, and strong chemical stability. In this work, a series of porous carbon supported Co doping spinel copper ferrite (CuxCo1-xFe2O4@PC) were prepared via impregnation method for the catalytic oxidation of vanillyl alcohol (VAL) to vanillin (VN). The optimized Cu0.4Co0.6Fe2O4 @PC exhibited a nanoparticle morphology with mesoporous structure and BET surface area of 553.3 m2·g−1. Results showed that the conversion of VAL (CVAL) can reach to 96 % with 81 % of VN selectivity (SVN) in the presence of Cu0.4Co0.6Fe2O4 @PC at 80 °C for 40 min. Reusability experiment displayed that the CVAL (89 %) and SVN (79 %) can still achieve 92.3 % and 96.6 % of the initial ones after being used for 3 times. Furthermore, a possible pathway for the oxidation of VAL via·OH and·O2- active substances was also proposed. The work presents a supported doping spinel with enhanced VAL oxidation performance, which may be expected to apply in the field of selective catalysis.

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.

Redox properties of N-hydroxyimides in sulfuric acid-acetonitrile mixed solution as a HAT mediator for alcohol oxidation

Two hydroxyimides, N-hydroxysuccinimide and N-hydroxy-1,8-naphthalimide, showed chemically reversible redox responses in a sulfuric acid-acetonitrile mixture. In the mixed solution containing benzyl alcohol, catalytic oxidation of alcohol using N-oxyl radicals generated by the oxidation of hydroxyimide as a mediator was observed. The reaction between the mediator and alcohol was quantitatively evaluated from measurements by rotating disk electrode voltammetry.

Selective photocatalytic oxidation of aromatic alcohols using B-g-C3N4/Bi2WO6 composites

In this work, B-g-C3N4/Bi2WO6 composites were synthesized by simple hydrothermal reaction and calcination, and their morphology, composition and physicochemical properties were characterized. The results show that the composite can selectively oxidize aromatic alcohols to aromatic aldehydes under visible light. The conversion rate of benzyl alcohol can reach 98.9% and the selectivity can reach 99% in 4 h, which are 1.59 times and 5.03 times that of Bi2WO6 alone, respectively. Further photoelectric performance investigation revealed that the recombination of B-g-C3N4 with Bi2WO6 effectively enhanced the separation of photogenerated carriers of B-g-C3N4 and suppressed the generation of holes on Bi2WO6, thereby improving the photocatalytic activity and the selectivity of the catalytic reaction of p-benzyl alcohol. In addition, the electronic effect and steric hindrance effect of substituents on the benzene ring on the selective catalytic oxidation of aromatic alcohols were also explored. Our work also reveals that the bandgap structure of the composites and the efficient separation of photogenerated electron transport are key factors to improve the photocatalytic reactivity and selectivity of organic reactions.