Oxidation Of Ethylbenzene Research Articles

Synthesis and characterization of silica-supported cobalt acylpyrazolone complex and its catalytic performance in ethylbenzene oxidation

A novel β-diketone-containing acylpyrazolone (2-(3-chlorophenyl)-3‑hydroxy-5-methyl-2,3-dihydro-1H-pyrazole-4-yl) (4-nitrophenyl) methanone [HLC] ligand and its cobalt complex [Co(HLC)2(H2O)2] were synthesized and characterized. A silica-supported cobalt complex was synthesized as a heterogeneous catalyst to investigate the cobalt complex's catalytic activity. The characterization techniques used for the synthesized compounds are CHN analysis, SC-XRD, FT-IR, TGA, DRS spectra, BET and BJH measurements, ICP-MS, XPS, powder XRD and SEM. Without any solvent, the cobalt complex catalytic impact on the oxidation of ethylbenzene was investigated with tert‑butyl hydroperoxide (70 % TBHP) as an oxidant. The catalyst exhibited good conversion (88 % conversion) and selectivity (83 % acetophenone) in the oxidation of ethylbenzene. The catalyst shows no leaching occurred under the reaction conditions because it is stable and reusable for further reaction.

Hybridizing engineering strategy of decatungstate III: Transition metal modified carbon quantum dot-regulated photo-catalytic oxidation performance of decatungstate

The selective oxidation of hydrocarbons (RH) by dioxygen (O2) is a very important method for industrial production of bulk oxygen-containing compounds, However, due to the high chemical inertness of RH and O2, achieving this reaction under mild conditions still faces significant challenges. This paper discloses an efficient hybridizing engineering (HE) strategy of decatungstate (DT) with 3d transition metal ions (Mn+=Ni2+, Co2+ or Cu2+)-modified carbon quantum dots (Mn+/CQD) as the dopants. Compared to pure CQD, The Mn+/CQD can more efficiently combine with DT anion to fabricate a high-quality hybrid via electrostatic interactions, thereby bestowing the hybrid with an enhanced visible light response especially the separation efficiency of photo-generated charge pairs. Furthermore, the above hybridization effects of Mn+/CQD on DT anion can be fine-tuned and gradually improved with a change of the metal ion from Cu2+, Co2+ to Ni2+, along with a continuous enhancement of the hybrid's photo-catalytic efficiency in the visible light- triggered selective oxidation of ethylbenzene with O2 in acetonitrile. The best Ni2+/CQD-doped TBADT can achieve ca. 48% ethylbenzene conversion and 87.6% acetophenone selectivity in the presence of 2 M HCl, and it also shows a much higher photo-catalytic activity for the photo-oxidation of toluene, cyclohexane and benzyl alcohol compared to pure TBADT. The HE strategy with Mn+/CQDs as the cationized hybridizers is much superior to that with pure CQD or Ni2+ as the hybridizer in hoisting the photo-catalytic performance of DT.

Cobalt and nitrogen co-doped hollow periodic mesoporous organosilica spheres activated by potassium chloride for selective oxidation of ethylbenzene.

Enhancing the exposure of metal active sites and maximizing metal atom utilization are critical challenges in heterogeneous catalysis. To solve these issues, heterogeneous catalysts are usually activated by chemicals. Herein, potassium chloride (KCl) was used as an activator to prepare cobalt-nitrogen co-doped (Co-Nx) hollow periodic mesoporous organosilica spheres (Co-Nx/HPMOs-KCl). Co-Nx/HPMOs-KCl showed outstanding catalytic activity for the selective oxidation of ethylbenzene to acetophenone, with a conversion of up to 94.0% for ethylbenzene and a high selectivity of 98.4% towards acetophenone. Additionally, Co-Nx/HPMOs-KCl maintained excellent catalytic performance for the oxidation of ethylbenzene after six cycles. The excellent performance of Co-Nx/HPMOs-KCl was attributed to the activation of KCl, which increased the specific surface area of the catalyst and thus facilitated the exposure of more metal active sites. After the removal of unstable metal species through further acid treatment, the remaining metal active sites were thus fully exposed and stably embedded in the framework of the hollow periodic mesoporous organosilica spheres (HMPOs). This work presents an efficient catalyst and offers new insights for the improvement of heterogeneous catalysts.

Nanoarchitectonics of vanadium nanoparticles decorated mesoporous carbon nitride in photocatalytic systems: A study on ethylbenzene oxidation reaction

In this work, we have described the synthesis of vanadium (V) nanoparticles (NPs) anchored on mesoporous graphitic carbon nitride (V@mpg-C3N4) and their uses in photocatalytic ethylbenzene oxidation to the respective acetophenones. The mpg-C3N4 serves as the support for the decoration of V NPs, through a simple impregnation method. Various advanced techniques, such as XRD, UV–vis spectrometry, HRTEM, HAADF-STEM, AC-STEM, elemental mapping, and BET surface area analysis, were employed for the characterization of V@mpg-C3N4. The detailed characterization studies reveal that the V@mpg-C3N4 catalyst has a medium band gap (2.78 eV), a high surface area (76.7 m2g−1), and a mesoporous nature. The V@mpg-C3N4 photocatalysts demonstrated excellent performance in the light-assisted oxidation of ethylbenzene, achieving over 99 % conversion and selectivity for acetophenone in an environmentally friendly solvent (water) using a domestic light source (50 W white light). This developed synthesis strategy will be useful for synthesizing various noble and non-noble metal-based catalysts and their applications in organic transformation and environmental remediation.

Supported copper nanoarchitecture for selective ethylbenzene oxidation (EBO) reaction

Copper-based (Cu-NP) uniformly dispersed on various inorganic supports (alumina, silica, titania, and zirconia) were prepared by the reverse microemulsion technique. These nanoparticles were used for the selective oxidation of ethylbenzene (EB) to produce acetophenone (AP) as the main product in the presence of Tert‑butyl hydroperoxide(TBHP) as an oxidant. This study focused on creating Cu-nanoparticles evenly dispersed on alumina using varying Cu-loadings (5 %, 10 %, and 15% wt.) and Brij-35 as the surfactant. The resulting catalytic material was characterized using various physicochemical techniques like XRD, FESEM, HRTEM, XPS and physisorption techniques. Various parametric studies were conducted, such as the effects of temperature, catalyst support, catalyst loading, and TBHP loading to optimize the EB conversions and AP selectivity. Among the various catalyst loadings, 15 % CuO/Al2O3 (15 % of the copper content) nanocomposites showed exceptional performance, with the highest EB conversion rate (99.7 %) and AP selectivity (98.5 %) compared to other nanocomposites. The catalyst's stability and recyclability over four cycles were attributed to the strong copper oxide-alumina interaction. These findings suggest that this nanocomposite material is a promising candidate for catalytic applications, offering high selectivity and consistent EB conversion rates.

Manipulation of Electronic Effect and Assembly Architecture to Invoke Oxidation of Ethylbenzene by Hierarchical Co3O4 Wreaths.

A high-performance transition-metal oxide catalyst can be designed by appropriately integrating the concepts of morphology regulation and electronic structure modulation. In this work, hierarchical Co3O4 wreaths (CCW) enriched with oxygen vacancies (Ov) were facilely constructed for the selective oxidation of ethylbenzene (EB) to acetophenone (AP). Under the screened optimal reaction conditions, the CCW catalyst can offer a 79.1% conversion of EB (ri = 0.244 mol gcat-1 h-1) accompanied by a selectivity of 92.3% to AP. The good reaction performance can be attributed to the cooperation of defect engineering and architecture design, which can synergistically facilitate the EB oxidation performance by augmenting the intrinsic reactivity and accessibility of active sites. This work presents a reliable route to construct a high-performance transitional metal oxide catalyst via manipulation of electronic effect and assembly architecture for the selective oxidation of EB and beyond.

Novel Cobalt(II)-Decorated 1D Covalent Organic Framework for Selective Oxidation of Ethylbenzene

Novel Cobalt(II)-Decorated 1D Covalent Organic Framework for Selective Oxidation of Ethylbenzene

Effects of Relative Humidity and Photoaging on the Formation, Composition, and Aging of Ethylbenzene SOA: Insights from Chamber Experiments on Chlorine Radical-Initiated Oxidation of Ethylbenzene

Effects of Relative Humidity and Photoaging on the Formation, Composition, and Aging of Ethylbenzene SOA: Insights from Chamber Experiments on Chlorine Radical-Initiated Oxidation of Ethylbenzene

Constructing Cu+ and Lewis acid sites enabling the generation of highly reactive N‑oxyl radical for the efficient aerobic oxidation of alkylarenes

Developing heterogeneous catalytic systems with high performance for the oxygenation of C(sp3)–H bonds to carbonyls using molecular oxygen as the oxidant is highly desirable. In the present research, active Cu+ sites have been efficiently constructed based on layered double hydroxides (LDHs) through in-situ reduction during the coprecipitation. Simultaneously, the formed CuZn(Mg)Al-LDH(R) catalysts demonstrated the characters of increased amount of oxygen vacancy and surface Lewis acid site. The newly synthesized catalysts exhibited higher catalytic performance than the samples prepared via conventional method, and up to 49.4% improvement in specific activity was observed in the aerobic oxidation of ethylbenzene. The mechanism study including a series of control experiments, semi-in-situ FT-IR analysis, and EPR analysis, demonstrated that reactive •O2– species generated via the acceleration of Cu+ species, and activated the NHPI (N-hydroxyphthalimide) molecule to form active PINO (phthalimide N-oxyl) species. The oxygen vacancy was verified to be able to activate O2 molecule and promote the formation of active 1O2 species. The surface Lewis acid site was proposed to interact with NHPI molecule, enabling the generation of highly active PINO species. The catalytic system also has the advantages of catalytical and structural stability, recyclability, and tolerance of wide substrate scope. We believe that the synergistic effect between the highly active sites and Lewis acid sites in catalyst can open up new opportunities for the activation of inert C–H bonds via O2/NHPI system.

Redox oxidative dehydrogenation of ethylbenzene over Mn–Al–O composites using active lattice oxygen at moderate temperatures

Oxidative dehydrogenation (ODH) of ethylbenzene is a promising process for styrene production. However, its application is limited by product overoxidation and purification requirements due to the co-feeding of mild oxidants. Herein, we report a facile manganese-based catalyst (K/Mn3O4-Al2O3) and achieve competitive styrene selectivity of 88 % and ethylbenzene conversion of 95 % at 450 ℃ (84 % yield vs. ∼ 60 % yield in commercial dehydrogenation process at 600 ℃) under a cyclic redox ODH scheme. The introduction of Al2O3 into MnOx restructures composite oxides and depresses bulk lattice-oxygen migration for the partial oxidation of ethylbenzene. The surface modification using potassium creates reactive sites and regulates surface properties, achieving ethylbenzene activation and high conversions. Highly active lattice oxygen in catalysts after bulk and surface modifications selectively converts ethylbenzene to styrene and water. This study provides an understanding of roles of manganese-based catalysts in styrene generation and offers a strategy to modulate lattice oxygen on catalysts.

Coupled Interface and Oxygen-Defect Engineering in Co3O4/CoMoO4 Heterostructures toward Active Oxidation of Ethylbenzene.

The catalytic oxidation of ethylbenzene (EB) is a promising route to produce acetophenone (AcPO). Unfortunately, it remains a great challenge to achieve the highly efficient oxidation of EB under solvent-free conditions using molecular oxygen as the sole oxidant. In this contribution, we present a facile strategy to construct hierarchical oxygen vacancy-rich Co3O4/CoMoO4 heterostructures (Vö-CCMO), which delivers a high yield value of 74.5% at 83.2% conversion of EB and selectivity of 89.6% to AcPO. Both experimental studies and theoretical calculations substantiate the important role of oxygen-defect engineering triggered by the modified chemistry environment at the interfaces between the biphasic phases, which contributes to the good catalytic performance. This work illustrates a promising paradigm for the exploit of advanced catalysts toward boosting EB oxidation reaction in a more practical way.

Photocatalytic aerobic oxidation of C(sp3)-H bonds

In modern industries, the aerobic oxidation of C(sp3)-H bonds to achieve the value-added conversion of hydrocarbons requires high temperatures and pressures, which significantly increases energy consumption and capital investment. The development of a light-driven strategy, even under natural sunlight and ambient air, is therefore of great significance. Here we develop a series of hetero-motif molecular junction photocatalysts containing two bifunctional motifs. With these materials, the reduction of O2 and oxidation of C(sp3)-H bonds can be effectively accomplished, thus realizing efficient aerobic oxidation of C(sp3)-H bonds in e.g., toluene and ethylbenzene. Especially for ethylbenzene oxidation reactions, excellent catalytic capacity (861 mmol g cat−1) is observed. In addition to the direct oxidation of C(sp3)-H bonds, CeBTTD-A can also be applied to other types of aerobic oxidation reactions highlighting their potential for industrial applications.

Green and efficient catalytic oxidation of ethylbenzene to acetophenone over cobalt oxide supported on a carbon material derived from sugar.

The use of biomass as a carbon source to support metal oxides has significant advantages in environmental protection and reducing the cost of the catalyst. The critical point lies on the development of highly active and recyclable catalysts. In this study, sugar was used as a carbon source, and cobalt oxide was loaded via an in situ method and an impregnation method to prepare the catalyst, respectively. The catalysts were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) spectroscopy, Raman, in situ electron paramagnetic resonance (in situ EPR) and N2 adsorption-desorption. The characterization results show that the macroporous carbon-supported cobalt oxide catalyst prepared by the in situ method contains CoOx nanoparticles on the support, but the dispersion of cobalt oxide on the support is more uniform compared with the catalyst prepared by the impregnation method. The catalytic performance of the prepared catalyst was evaluated through the oxidation of ethylbenzene (EB) to acetophenone (AP) as a probe reaction. Under the optimized reaction conditions, temperature (T) = 80 °C, m(catalyst) : m(EB) = 0.15, n(H2O2) : n(EB) : n(KBr) = 14.4 : 1 : 0.1, t = 8 h, and V(EB) : V(CH3COOH) = 1 : 10, the conversion of EB and the selectivity of AP were 84.1% and 81.3%, respectively. CoOx/SC-10-in situ exhibits improved reactivity of EB oxidation owing to cobalt ions on the carbon support that promote the free radical and acid catalytic reaction pathway. The cobalt oxide catalyst supported by biomass carbon has decent recycling and regeneration ability, which provides a new idea for the application of biomass.

КИНЕТИЧЕСКИЙ АНАЛИЗ ТЕХНОЛОГИЧЕСКИХ КРИТЕРИЕВ ЭФФЕКТИВНОСТИ ПРОЦЕССА ОКИСЛЕНИЯ ЭТИЛБЕНЗОЛА В ПРИСУТСТВИИ КОМПЛЕКСОВ ДИБЕНЗО-18-КРАУН-6 ЭФИРА С ХЛОРИДАМИ CA, SR, BA

A kinetic scheme is proposed that is common to the processes of ethylbenzene oxidation and ethylbenzene hydroperoxide decomposition in the presence of dibenzo-18-crown-6 ether complexes with Ca, Sr, and Ba chlorides. The scheme includes reactions of the formation of intermediate adducts from components of the reaction mixture and catalyst molecules, classical reactions of initiation, propagation and termination of the chain, reactions of initiation and propagation of the chain with the participation of intermediate adducts, and molecular reactions (includingthose with the participation of intermediate adducts).Basedonexperimentaldataandtheproposedscheme, akineticmodelwasmade.The kinetic model, written in the form of nonlinear differential equations according to the mass action law describes in time the rate of change of the concentrations of all components of reaction mixtures for ethylbenzene oxidation and ethylbenzene hydroperoxide decomposition in the presence of dibenzo-18-crown-6 ether complexes with Ca, Sr, Ba chlorides. As a result of solving the inverse kinetic problem using the zero-order direct search method, the values of reaction rate coefficients were found where the kinetic model reproduces the experimental values of the concentrations of all components of the reaction mixtures of the processes under consideration within the average relative error of 25%.As a result of the analysis based on the kinetic model, it was established that the conversion of ethylbenzene in the process of its oxidation is most affected by the reaction of ethylbenzene with the ethylbenzene peroxyl radical (target reaction).Using the kinetic model, the following was shown: 1) the values of the conversion of ethylbenzene, depending on the nature of the catalyst, line up in a row that corresponds to a number of values of the reaction rates of ethylbenzene with ethylbenzene peroxyl radical; 2) the model qualitatively reproduces the trend of selectivity changes when changing the catalyst.

Mesoporous ceria-supported vanadia catalysts for selective aerobic oxidation of ethylbenzene

A series of mesoporous ceria-supported vanadium oxide catalysts were prepared and explored for aerobic oxidation of ethylbenzene to acetophenone without the involvement of any solvent or additive.

Cobalt Encapsulated in Nitrogen-Doped Graphite-like Shells as Efficient Catalyst for Selective Oxidation of Arylalkanes.

Selective oxidation of ethylbenzene to acetophenne is an important process in both organic synthesis and fine chemicals diligence. The cobalt-based catalysts combined with nitrogen-doped carbon have received great attention in ethylbenzene (EB) oxidation. Here, a series of cobalt catalysts with metallic cobalt nanoparticles (NPs) encapsulated in nitrogen-doped graphite-like carbon shells (Co@NC) have been constructed through the one-pot pyrolysis method in the presence of different nitrogen-containing compounds (urea, dicyandiamide and melamine), and their catalytic performance in solvent-free oxidation of EB with tert-butyl hydrogen peroxide (TBHP) as an oxidant was investigated. Under optimized conditions, the UCo@NC (urea as nitrogen source) could afford 95.2% conversion of EB and 96.0% selectivity to acetophenone, and the substrate scalability was remarkable. Kinetics show that UCo@NC contributes to EB oxidation with an apparent activation energy of 32.3 kJ/mol. The synergistic effect between metallic cobalt NPs and nitrogen-doped graphite-like carbon layers was obviously observed and, especially, the graphitic N species plays a key role during the oxidation reaction. The structure-performance relationship illustrated that EB oxidation was a free radical reaction through 1-phenylethanol as an intermediate, and the possible reaction mechanistic has been proposed.

Expediting Ethylbenzene Oxidation via a Bimetallic Cobalt-Manganese Spinel Structure with a Modulated Electronic Environment.

The catalytic oxidation of ethylbenzene (EB) into acetophenone (AP) is a vibrant area, with a growing number of researchers paying attention to this thematic investigation. Herein, we demonstrate that spinel-type (Co,Mn)(Co,Mn)2O4 can function as an efficient catalyst for the solvent-free oxidation of EB with molecular oxygen. The incorporation of Mn into the Co3O4 network can break the local structural symmetry of Co-O-Co linkages due to the bond competition, inducing the formation of an asymmetrical Co-O-Mn configuration with an electron local exchange interaction. The Co-O-Mn sites can facilitate the perturbation of nonpolar O2 and thus contribute to the generation of abundant •O2- species for initiating the oxidation of EB. We envision that this study not only provides a promising catalyst for EB oxidation but also affords a new insight into the design of advanced spinel oxides for selective oxidation reactions.

Insights into ethylbenzene oxidation catalyzed by transition-metal oxides: Crucial role of hydroperoxide transformation

Selective oxidation of aromatics via a free-radical process is a crucial ingredient in the chemical industry, in which the transformation of hydroperoxide was considered the key step to facilitate the reaction. In this study, the aerobic oxidation of ethylbenzene (EB) to acetophenone (AcPO) catalyzed by carbon nitrides (CNx) supported the transition-metal oxides was performed. Among these catalysts, Co3O4/CNx displayed the highest activity with 48.09 % EB conversion and 77.8 % AcPO selectivity, due to the efficient decomposition of 1-phenylethyl hydroperoxide (PEHP). Notably, in the case of CuO/CNx, the relatively low EB conversion (19.8 %) and high selectivity of AcPO (70.2 %) were observed, while almost no PEHP was detected. Further mechanism investigations revealed that the decomposition of hydroperoxide over CuO/CNx was too fast to generate the reactive free-radicals, which could not efficiently facilitate the propagation steps. Moreover, the addition of tert-butyl hydroperoxide (TBHP) participated in the α-H abstraction of EB and facilitated of radical propagation, showing the distinguished activities over Co3O4/CNx and CuO/CNx.

Bridging Effect of Carbon Nitride with More Negative Conduction Potential and Halogens Promotes the Liquid-Phase Oxidation of Aromatic C-H Bonds.

The selective oxidation of benzyl C-H bonds of alkyl aromatic hydrocarbons under solvent-free conditions by using heterogeneous catalysis is a challenging task. In this work, we designed a carbon nitride photocatalyst with a high charge separation efficiency and a directed charge transfer path, which was doped with Ni and Br in the carbon nitride skeleton. Br was deposited directionally onto the electron-rich Ni surface traps to form a bond with Ni, which acted as a charge transfer bridge connecting CN and Br, resulting in a bridging effect. Photogenerated electrons were transferred from Ni target to Br, and electrons were aggregated to form a directional charge transfer path, thereby enhancing the photocatalytic performance of CN. The photocatalyst was utilized for the selective oxidation of ethylbenzene at room temperature, atmospheric pressure, and solvent-free conditions. Under batch conditions simulating solar irradiation, the conversion of ethylbenzene was 43.3% and the selectivity of the product acetophenone was up to 92.0%. With the continuous flow strategy, the conversion of ethylbenzene was increased to 52.4 and 48.1%, respectively, while the selectivity reached 92.7 and 91.0%, and the reaction time was reduced from 24 to 2.1 h. The catalyst was also found to be broadly applicable for the selective oxidation of C-H bonds in the benzyl position of alkyl aromatic hydrocarbons.

Acetophenone preparation via continuous bubbling of ozone for catalyst-free ethylbenzene oxidation

Acetophenone is essential to chemical synthesis. Hence, completely using coal tar resources via liquid-phase oxidization to obtain acetophenone is crucial. This study demonstrates a novel, efficient, and environment-friendly technique for converting ethylbenzene to acetophenone based on ozone oxidation and continuous bubbling. Analysis of the mass transfer characteristics of the continuously bubbling ozone in various polar organic solvents showed that alcohol solvents had a higher equilibrium concentration than ethyl acetate and acetone. Equilibrium ozone concentrations were identical in solvents such as chlorinated methane. The solubility of ozone in different solvents may be affected by hydrogen bonding or dipole–dipole interactions between ozone and the solvent molecules. Ethyl acetate was found to be the best solvent after the ozone oxidation conditions of ethylbenzene were refined. The highest amount of acetophenone produced was 74%, and the reaction duration was 120 min; and the corresponding molar ratio of ozone to ethylbenzene was 1.6. Finally, the oxidation of ethylbenzene using ozone was proposed. Hydrogen peroxide accelerated this process, while ethanol slowed it down. The hydroxyl, alkyl, and superoxide free radicals in the reaction system were confirmed via electron paramagnetic resonance studies. Results showed that the key chemical process is indirect ozone oxidation.