Decomposition Of Cyclohexyl Hydroperoxide Research Articles

Atomically dispersed Co/C3N4 for boosting aerobic cyclohexane oxidation

The atomically-dispersed and high-loading Co on graphitic carbon nitrogen (Co/C3N4-w, w representing the molar ratio of Co to melamine in the synthesis recipe) was synthesized by coupling the one-pot strategy with the electrostatic adsorption method and used for the solvent-free aerobic oxidation of cyclohexane. The characterization results of Co/C3N4-w revealed that the single-atom Co with the positive charge existed in the sixfold cavities of C3N4 and was stabilized by the CoN interaction along with the electron transfer from Co atoms to C3N4. The catalytic activity of Co/C3N4-w presented the positive correlation with the loading of the single-atom Co, and the superior catalytic performance with 21 % conversion and 95 % overall selectivity was obtained over Co/C3N4-0.02, which also exhibited the excellent universality to the aerobic oxidation of other cycloalkanes and alkyl aromatics. Experiments combined with density functional theory calculations demonstrated that the favored O2 dissociation and intermediate cyclohexylhydroperoxide decomposition on the low-coordinated single-atom Co, and the promoted adsorption of cyclohexane on the electron-rich C3N4 surface, synergically boosted the cyclohexane oxidation. Distinctively, the high stability of Co/C3N4-0.02 in the cyclohexane oxidation originated from the robust single-atom Co structures and hydrophobic C3N4 surface.

Decomposition of Cyclohexyl Hydroperoxide Catalyzed by Core-shell Material Co3O4@SiO2

Decomposition of Cyclohexyl Hydroperoxide Catalyzed by Core-shell Material Co₃O₄@SiO₂

Solvent-free partial oxidation of cyclohexane to KA oil over hydrotalcite-derived Cu-MgAlO mixed metal oxides

A highly efficient and stable hydrotalcite-derived Cu-MgAlO catalyst was developed for the partial oxidation of cyclohexane with molecular oxygen. The physical–chemical properties of Cu-MgAlO catalysts were studied, and the results indicated that the copper component had been successfully introduced into the hydrotalcite unit layer structure. The catalytic reaction results showed that copper as the active species could activate CH bond and effectively promote the decomposition of cyclohexyl hydroperoxide (CHHP) to the mixture of cyclohexanol and cyclohexanone (KA oil). 8.3% of cyclohexane conversion and 82.9% of selectivity for KA oil were obtained over 9%Cu-MgAlO catalyst at 150 °C with 0.6 MPa of oxygen pressure for 2 h. Especially, its catalytic performance was still stable after five runs.

Enhanced catalytic performance of porphyrin cobalt(II) in the solvent-free oxidation of cycloalkanes (C5~C8) with molecular oxygen promoted by porphyrin zinc(II)

Dual-metalloporphyrins catalytic system based on T(p-Cl)PPCo and T(p-Cl)PPZn was presented to enhance the oxidation of cycloalkanes, especially for cyclohexane, the selectivity towards KA oil increasing from 90.7% to nearly 100.0%, meanwhile the conversion increasing from 3.42% to 4.29%. Enhancement on conversion and selectivity was realized simultaneously. In the dual-metalloporphyrins system, T(p-Cl)PPCo served the role to activate molecular oxygen and promote the decomposition of cyclohexyl hydroperoxide, and T(p-Cl)PPZn catalyzed the decomposition of cyclohexyl hydroperoxide to avoid unselective thermal decomposition. This protocol is also very applicable to other cycloalkanes and will provide a applicable strategy to enhance the oxidation of alkanes.

Organic Acid Anions Modified α-Co(OH)2 with Enhanced Activity for the Decomposition of Cyclohexyl Hydroperoxide

α-Co(OH)2 nanoplatelets with tunable wettability (hydrophilicity/hydrophobicity) and interlayer spacing were designed to catalyze cyclohexyl hydroperoxide (CHHP) decomposition in alkali-free medium...

Liquid-phase oxidation of cyclohexane. Cyclohexyl hydroperoxide, cyclohexanol, and cyclohexanone, mechanisms of formation and transformation

The mechanisms of formation and transformation of cyclohexyl hydroperoxide, cyclohexanol, and cyclohexanone in the liquid-phase oxidation of cyclohexane are reviewed. Cyclohexyl hydroperoxide is formed in chain propagation reactions and decomposes via the degenerate branching reactions under the action of alkoxyl, alkyl, and peroxyl radicals, as well as via nonradical channels to form alcohol and ketone. The radicals of two types, $${\rm{H}}{{\rm{O}}_2}^ \cdot $$ radical and α-hydroxycyclohexylperoxyl radical, are involved in chain propagation in the course of cyclohexanol oxidation. In the chain propagation reactions, $${\rm{H}}{{\rm{O}}_2}^ \cdot $$ radicals are more reactive than α-hydroxycyclohexylperoxyl radicals. The dynamic equilibrium was established in the dissociation of 1-hydroxycyclohexylperoxyl radical to cyclohexanone and radical $${\rm{H}}{{\rm{O}}_2}^ \cdot $$ . During oxidation of cyclohexane, cyclohexanone is formed from peroxyl radicals, as well as by the decomposition of cyclohexyl hydroperoxide and chain-radical oxidation of cyclohexanol. The oxidation of cyclohexanone in positions 2 and 6 affords 2-hydroperoxycyclohexanone, which predominantly decomposes to form 2-hydroxycyclohexanone. The oxidation of 2-hydroxy-cyclohexanone proceeds via the main channels of destruction of the carbon chain of cyclohexane leading to adipic acid and adipic anhydride. The oxidation products of C—H bonds of all types in alcohol and ketone are accumulated simultaneously with the oxidation products of C(1)—H bonds in cyclohexanol and of C(2)—H and C(6)—H bonds in cyclohexanone.

Hydrotalcite-derived Co-MgAlO mixed metal oxides as efficient and stable catalyst for the solvent-free selective oxidation of cyclohexane with molecular oxygen

Developing a highly efficient and stable catalyst for the selective aerobic oxidation of saturated hydrocarbons to functional compounds is highly desirable in chemical industry. In our present work, hydrotalcite-derived Co-MgAlO mixed metal oxides as efficient and stable heterogeneous catalyst for the selective aerobic oxidation of cyclohexane to KA-oil has been developed. The results indicate that hydrotalcite-derived Co-MgAlO mixed metal oxides catalysts are active and selective; the synergistic catalysis of Co3+ and Co2+ can effectively promote the decomposition of cyclohexyl hydroperoxide (CHHP) intermediate to KA-oil. 9.1% of cyclohexane conversion and 82.0% of KA-oil selectivity over 2%Co-MgAlO catalyst with high turnover numbers (3800) was obtained at 423 K and 0.6 MPa for 2 h in this oxidation reaction. Moreover, the hydrotalcite-derived Co-MgAlO catalyst is easy to be separated and recycled, and its catalytic performance was still stable after five runs. The schematic reaction pathway for the oxidation of cyclohexane to KA-oil over Co-MgAlO mixed metal oxides catalyst was also suggested. Maybe this work employing inexpensive hydrotalcite-derived Co-MgAlO as highly efficient and environmentally friendly catalyst for the preparation of KA-oil has potential industrial application prospects.

Tackling Challenges in Industrially Relevant Homogeneous Catalysis: The Catalysis Research Laboratory (CaRLa), an Industrial-Academic Partnership.

Industrial-academic collaborations are broadly used for the development of new industrial processes. To achieve a strong and deep collaboration in the field of homogeneous catalysis, BASF and the Heidelberg University have been running the Catalysis Research Laboratory together in Heidelberg since 2006. This Perspective highlights the concept of this laboratory and our experiences over the past few years in this joint laboratory. How this collaboration works is explained in more detail using three selected projects: sodium acrylate based on CO2, the selective decomposition of cyclohexyl hydroperoxide to cyclohexanone, and the asymmetric amination of ketones with NH3/H2.

Selective Decomposition of Cyclohexyl Hydroperoxide using Homogeneous and Heterogeneous CrVI Catalysts: Optimizing the Reaction by Evaluating the Reaction Mechanism

AbstractIn this study, known homogeneous and heterogeneous chromium(VI) catalyst systems were investigated with respect to the favored formation of cyclohexanone during the decomposition of cyclohexyl hydroperoxide (CHHP). The focus was on mechanistic studies using different spectroscopic methods as well as DFT calculations to further optimize the reaction conditions. As in previous decomposition studies, a mechanism via the formation of a metal alkylperoxido intermediate is probable. In situ spectroscopic studies revealed that in case of both the soluble and insoluble catalyst, the selective decomposition happens via a non‐radical, non‐redox mechanism at the CrVI stage through the formation of a cyclohexylperoxychromium(VI) complex. The proposed mechanism is supported by thorough DFT calculations.

Coupling reaction in catalytic decomposition of cyclohexyl hydroperoxide

Coupling reaction of cyclohexyl hydroperoxide (CHHP) decomposition and cyclohexane oxidation in the process of catalytic decomposition of CHHP was identified via cyclopentane instead of cyclohexane used as solvent. A method was established to evaluate this coupling reaction. Based on this method, it can be accurately distinguished the product of cyclohexanol and cyclohexanone (K/A oil) derived from whether decomposition of CHHP or oxidation of cyclohexane. The established method is of great significance to the further study of the coupling reaction.

Mesoporous Material Co/SBA-15 as Catalyst for the Decomposition of Cyclohexyl Hydroperoxide

以介孔分子筛SBA-15为载体, 乙酸钴为钴源, 采用浸渍法制备了2wt%、4wt%、8wt%、10wt%和20wt% Co负载量的Co/SBA-15介孔材料。采用FT-IR、XRD、N 2 物理吸附、UV-Vis、SEM、TEM、H 2 -TPR等技术对催化材料的结构进行表征, 并将其应用于环己基过氧化氢分解反应。结果表明: 负载金属钴后, 载体的介孔结构保持完好, 随着负载量的增加, Co/SBA-15的比表面积、总孔体积和平均孔径不断减小, Co由骨架内均匀分散状态向氧化物Co 3 O 4 的形式转变。不同负载量的 Co/SBA-15在环己基过氧化氢分解反应中均表现出较好的催化性能, 其中8wt%Co/SBA-15催化环己基过氧化氢的转化率达到98.1%, 环己醇和环己酮的选择性分别为70.9%和27.9%。当负载量相对较低时, 钴的流失使催化性能下降明显, 只有当钴负载量增加到20wt%, 主要以Co 3 O 4 形式存在时, 钴的流失速率得到抑制, 连续使用五次后仍能保持较高的活性和选择性。

Decomposition of cyclohexyl hydroperoxide over bimetallic mesoporous materials containing cobalt and chromium

AbstractBimetallic mesoporous Co‐Cr‐TUD‐1 and its counterparts Co‐TUD‐1 and Cr‐TUD‐1 were synthesized by a direct hydrothermal treatment (DHT) method with triethanolamine as a template. The products were characterized by many techniques. Results show that Co and Cr are incorporated into the framework of TUD‐1. The catalytic behaviours of the samples were tested in decomposition of cyclohexyl hydroperoxide (CHHP). Co‐Cr‐TUD‐1 (Si/(Co + Cr) = 25) shows the highest catalytic efficiency with a CHHP conversion of 96.9 % and total selectivity of cyclohexanone and cyclohexanol of 95.9 %, which outperforms Co‐TUD‐1 and Cr‐TUD‐1 and indicates a synergistic effect between Co and Cr in Co‐Cr‐TUD‐1. The catalysts are mainly heterogeneous as shown in various experiments, while the catalytic performances of recovered catalysts declined modestly, indicating non‐negligible amounts of Co and Cr are leached after some cycles.

Insights into the Reaction Mechanism of Cyclohexane Oxidation Catalysed by Molybdenum Blue Nanorings

Molybdenum blue (MB), is a polyoxometalate with a nanoring structure comprising Mo5+–O–Mo6+ bridges, which is active for the catalytic oxidation of cyclohexane to cyclohexanol and cyclohexanone. However, little is known about the mechanistic features responsible of this catalytic activity. In the present work, the Mo5+–O–Mo6+ moieties embedded in the MB nanoring structure were characterized using diffuse reflectance-UV–Visible spectroscopy and solid state EPR spectroscopy. The amount of Mo5+ centres was then varied by thermal treatment of the polyoxometalate in the absence of oxygen, and the resultant effect on the catalytic activity was investigated. It was observed that, an increased amount of Mo5+ centres preserved the conversion of cyclohexane (ca. 6 %) but led to a loss of selectivity to cyclohexanol giving cyclohexanone as the major product, and the simultaneous formation of adipic acid. To rationalise these results the catalysts were studied using EPR spin trapping to investigate the decomposition of cyclohexyl hydroperoxide (CHHP), a key intermediate in the oxidation process of cyclohexane. This analysis showed that CHHP has to be bound to the MB surface in order to explain its catalytic activity and product distribution.

Propene carbonate intensified cyclohexane oxidation over Au/SiO2 catalyst

Intensification of solvent for cyclohexane oxidation was performed over Au/SiO2 catalyst in different solvents. Propylene carbonate (PC) was found to significantly enhance the reaction of cyclohexane oxidation with 21.9% cyclohexane conversion while remain a high selectivity of 83.2% towards cyclohexanone and cyclohexanol. The intensified effect of PC can be attributed to its high polarity resulting from its high dipole moment that is induced by its cyclic carbonate structure, which is analyzed by quantum calculation based on Gaussian and COSMO-RS. Moreover, PC can facilitate the reaction by promoting the decomposition of cyclohexyl hydroperoxide.

Synthesis, Structure of an Iron(Ⅲ) Complex Containing N-Donor Ligand and Its Catalytic Activity for Cyclohexane Oxidation

One novel iron complex,[Fe( H2L)2]·( CH3COO)2·(OH)·H2O( H2L = 2,6-di-( 5-methyl-1Hpyrazol-3-yl) pyridine) with N-donor ligand 2,6-di-( 5-methyl-1H-pyrazol-3-yl) pyridine,was synthesized and characterized by elemental analysis,powder X-ray diffraction( PXRD) and single-crystal X-ray diffraction. In addition,the catalytic activity of the complex to cyclohexane oxidation was examined. The effects of various reaction factors such as the amount of H2O2,HNO3and water,reaction time,as well as the temperature on the formation and decomposition of cyclohexylhydroperoxide,and the yield of C6H10O and C6H11OH were evaluated. The mechanism of oxidation reaction was also discussed. It shows that H2O2is the main oxidant for the oxidation of cyclohexane to C6H11OOH catalyzed by the titled Fe complex; HNO3has no oxidizing effect on this process,but can accelerate the formation and decomposition rates of C6H11OOH. Water has an inhibition effect on the catalytic activity,thereby lowering the formation and decomposition rates of C6H11OOH. The formation rates of C6H11OOH and C6H10O( C6H11OH) are different at different reaction stages. Higher temperature can promote the decomposition of C6H11OOH,which benefits the formation of C6H10O and C6H11OH.

Selective decomposition of cyclohexyl hydroperoxide by copper ion-containing quaternary ammonium salts in alkali-free medium

Abstract A novel catalytic system composed of quaternary ammonium salts and copper (II) chloride was prepared. The catalyst showed high conversion and selectivity in the decomposition of cyclohexyl hydroperoxide to cyclohexanol and cyclohexanone (K/A oil) at room temperature in alkali-free medium. 93% conversion with 96% selectivity for cyclohexanone and cyclohexanol could be obtained.

Preparation of copper (II) ion-containing bisimidazolium ionic liquid bridged periodic mesoporous organosilica and the catalytic decomposition of cyclohexyl hydroperoxide

A novel bisimidazolium ionic liquid bridged periodic mesoporous organosilica was prepared. Bisimidazolium ionic liquid was incorporated into the framework of mesoporous materials and copper (II) chloride can be easily introduced to the framework via the formation of CuCl 4 2 − complex. This copper (II) ion-containing bisimidazolium ionic liquid bridged material showed high activity and stability in the decomposition of cyclohexyl hydroperoxide. Ninety-nine percent conversion and 84% selectivity for cyclohexanone and cyclohexanol (K/A oil) could be obtained. ► Cu 2 + -containing bisimidazolium ionic liquid bridged PMO was prepared. ► The catalyst showed high activity in the decomposition of cyclohexyl hydroperoxide. ► The catalyst showed prominent stability.

Cyclohexane oxidation using Au/MgO: an investigation of the reaction mechanism

The liquid phase oxidation of cyclohexane was undertaken using Au/MgO and the reaction mechanism was investigated by means of continuous wave (CW) EPR spectroscopy employing the spin trapping technique. Activity tests aimed to determine the conversion and selectivity of Au/MgO catalyst showed that Au was capable of selectivity control to cyclohexanol formation up to 70%, but this was accompanied by a limited enhancement in conversion when compared with the reaction in the absence of catalyst. In contrast, when radical initiators were used, in combination with Au/MgO, an activity comparable to that observed in industrial processes at ca. 5% conversion was found, with retained high selectivity. By studying the free radical autoxidation of cyclohexane and the cyclohexyl hydroperoxide decomposition in the presence of spin traps, we show that Au nanoparticles are capable of an enhanced generation of cyclohexyl alkoxy radicals, and the role of Au is identified as a promoter of the catalytic autoxidation processes, therefore demonstrating that the reaction proceeds via a radical chain mechanism.

Cobalt ammonia complex mediated preparation of hollow silica nanospheres with multi-nanochambers

Cobalt-containing SiO2-based nanosphere with multi-nanochambers was prepared via a microemulsion method. Addition of cobalt ammonia complex to microemulsion is a necessary step to obtain this specific structure. This novel material was found to be an efficient catalyst for the decomposition of cyclohexyl hydroperoxide, and high activity of 94% conversion with 93% selectivity for K–A oil could be obtained.

Preparation of self-assembled cobalt hydroxide nanoflowers and the catalytic decomposition of cyclohexyl hydroperoxide

α-Co(OH)2 hierarchical nanoflowers were synthesized using a microemulsion as a nanoreactor. These structures were self-assembled from cobalt hydroxide nanoflakes and possessed flowerlike morphology with a diameter of 200–500 nm. These α-Co(OH)2 nanoflowers exhibited high specific area and porosity and show high activity in the decomposition of cyclohexyl hydroperoxide. 99% conversion and 94% selectivity for K–A oil could be obtained.