The catalytic oxidation of cyclohexanone to caprolactone using hexagonal mesoporous silica supported SbF3

In this work, crumb rubber was chemically modified to sulfonic acid-containing rubber via a controlled oxidation with hydrogen peroxide or nitric acid at ambient pressure. The influences of oxidation conditions, including type and concentration of oxidizing of oxidizing agent were studied. The original and oxidized crumb rubbers were measured for the sulfur content by bomb calorimetry, the swelling degree according to ASTM D47 1 and the sol/gel ratio according to ASTM D47 1. Moreover, the physicochemical properties of rubber were characterized by Fourier-transform infrared spectroscopy (FTIR), thermogravimetric/differential thermal analysis (TG/DTA) and acid-base titration. The results showed that the properties of the crumb rubber oxidized with only hydrogen peroxide were not significantly changed. Nitric acid and hydrogen peroxide with formic acid oxidized the crumb rubber, giving short-chain polymer with the polar acid functions. especially sulfonic acid and carboxylic acid groups. As the nitric acid had higher oxidizing power than the hydrogen peroxide, the product generated from the oxidation with nitric acid exhibited high acidity and high stability in polar /non-polar solvents. The suitable conditions for the modification of crumb rubber to sulfonic acid-containing rubber were the nitric acid concentration of 6 M at 80 ℃ for 3 h. Then the oxidized crumb rubbers were applied as the heterogeneous acid catalysts in the esterification of octanoic acid with long chain alcohols, i.e. octanol and 2 - ethyl - 1- hexanol, 120 ℃ for 8 h. The octanoic acid conversion and catalyst recovery were analyzed by the gas chromatography and the filtration, respectively. The crumb rubber oxidized by using nitric acid was successfully applied as the catalyst in the esterification in which the octanoic acid conversion was 50.4% and 75.3% for the esterification with octanol and 2 – ethyl – 1 hexanol, respectively. However, the catalyst recovery was lower than 50% due to the dissolution of catalyst in the reaction mixture.

Catalytic oxidations with hydrogen peroxide: new and selective catalysts

A new strategy was developed to produce cellulose nanofibrils (CNFs) and films from raw elephant grass using deep eutectic solvents and a recyclable spent coffee-derived solid acid (SC-SO3H) catalyst with assistance of ultrasonic disintegration and a suction filtration film forming method. The effects of a solid acid and reused solid acid were comprehensively studied by comparing with catalyst-free conditions and using sulfuric acid as the catalyst. The CNF fibers obtained from this novel SC-SO3H catalyst method showed the longest fiber length. The corresponding films achieved the strongest tensile strength of 79.8 MPa and the elongation at break of 13.6%, and best thermostability. In addition, the performance of CNFs and films prepared by the fourth recovered SC-SO3H-4 catalyst was close to that obtained with the first use. The SC-SO3H could be reused by a simple decantation method, meaning this novel method has the potential for green and sustainable preparation of CNFs and films.

Selenium substituted MCM-41(SeMCM-41) samples have been synthesized by using hydrothermal method and characterized by spectroscopic techniques. The oxidation of 2-methylnaphthalene to 2-methyl-1,4-naphthoquinone with hydrogen peroxide in the presence of SeMCM-41 as catalyst in acetic acid is described. The catalyst exhibits excellent substrate conversion and product selectivity. It was found to be a true heterogeneous catalyst as the activity was practically unaffected upon recycling. The highest conversion at highest selectivity has been obtained at 100 °C. Different parameters effecting the oxidation of 2-methylnaphthalene with hydrogen peroxide on SeMCM-41 are described.

The oxygen reduction reaction on palladium with low metal loadings: The effects of chlorides on the stability and activity towards hydrogen peroxide

The epoxidation of olefins catalyzed by a new heterogeneous polyoxometalate-based catalyst with hydrogen peroxide

Development of new and effective solid catalysts (solid acid base to immobilized enzyme) is necessary for renewable and green energy production. The various choices of heterogeneous solid catalysis were reported recently, and the specific research outcomes of trans-esterification on heterogeneous catalysis are discussed in the present article. The studies on biodiesel production are mainly focused on the following aspects: (i) examining the appropriate oil source, (ii) establishing the adequate alcohol to oil molar ratio, and (iii) evaluating the available solid acid catalysts, solid base catalysts, and lipase immobilized enzyme catalysts. Although homogeneous catalysis are superior in terms of reaction rate compared to heterogeneous catalysis, the focus of research on development of solid catalysts for heterogeneous catalytic transesterification is directed from the point of easy process and possible adoption for large scale production. The scope of this presentation is to examine these aspects in detail and to provide a comprehensive outlook on the aspects mentioned.

Engineering plastics such as polyoxymethylene (POM) are highly resistant to depolymerization due to their robust C─O backbones, posing a major challenge for sustainable recycling. Herein, we report a solid acid catalyst based on proton-exchanged montmorillonite (H-Mont) that efficiently upcycles POM into cyclic acetals under mild conditions. H-Mont exhibits high catalytic performance, converting both pristine and post-consumer POM, outperforming conventional solid and liquid acid catalysts in both catalytic efficiency and reusability. Mechanistic studies reveal that interlayer accessibility generated by solvent-induced swelling, together with strong Brønsted acidity of H-Mont, synergistically overcomes interfacial limitations between the catalyst and semi-crystalline POM, enabling efficient depolymerization. This represents the first demonstration of a streamlined, reusable heterogeneous catalysis for POM upcycling toward cyclic acetals and establishes a strategy for transforming chemically resilient engineering plastics into valuable chemicals.

Electrochemical oxygen reduction has garnered attention as an emerging alternative to the traditional anthraquinone oxidation process to enable the distributed production of hydrogen peroxide. Here, we demonstrate a selective and efficient non-precious electrocatalyst, prepared through an easily scalable mild thermal reduction of graphene oxide, to form hydrogen peroxide from oxygen. During oxygen reduction, certain variants of the mildly reduced graphene oxide electrocatalyst exhibit highly selective and stable peroxide formation activity at low overpotentials (<10 mV) under basic conditions, exceeding the performance of current state-of-the-art alkaline catalysts. Spectroscopic structural characterization and in situ Raman spectroelectrochemistry provide strong evidence that sp2-hybridized carbon near-ring ether defects along sheet edges are the most active sites for peroxide production, providing new insight into the electrocatalytic design of carbon-based materials for effective peroxide production. Electrochemical routes for the production of hydrogen peroxide would reduce the waste inherent in the current anthraquinone process, and also make distributed and on-site production more feasible. Here, inexpensive reduced graphene oxide is proven to be a stable and selective catalyst for oxygen reduction at remarkably low overpotentials.

The kinetic mechanisms of petroleum sulfoxide oxidation by hydrogen peroxide in the presence of molybdic and tungstic acid catalysts are studied. The reaction orders with respect to the reagents in the kinetic equation are determined. A scheme of catalytic peroxide oxidation of petroleum sulfoxides that explains the obtained experimental results is presented in a generalized form. Based on the kinetic data, it is shown that peroxy acids act as sulfoxide oxidants and the intermediate reaction products are most probably complexes of sulfoxide with peroxy acids present in the reverse emulsion shell.

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The electrosynthesis of hydrogen peroxide (H2O2) via two‐electron (2e−) oxygen (O2) reduction reaction (ORR) has great potential to replace the traditional energy‐intensive anthraquinone process, but the design of low‐cost and highly active and selective catalysts is greatly challenging for the long‐term H2O2 production under industrial relevant current density, especially under neutral electrolytes. To address this issue, this work constructed a carboxylated hexagonal boron nitride/graphene (h‐BN/G) heterojunction on the commercial activated carbon through the coupling of B, N co‐doping with surface oxygen groups functionalization. The champion catalyst exhibited a high 2e− ORR selectivity (&gt;95 %), production rate (up to 13.4 mol g−1 h−1), and Faradaic efficiency (FE, &gt;95 %). The long‐term H2O2 production under the high current density of 100 mA cm−2 caused the cumulative concentration as high as 2.1 wt %. The combination of in situ Raman spectra and theoretical calculation indicated that the carboxylated h‐BN/G configuration promotes the adsorption of O2 and the stabilization of the key intermediates, allowing a low energy barrier for the rate‐determining step of HOOH* release from the active site and thus improving the 2e− ORR performance. The fast dye degradation by using this electrochemical synthesized H2O2 further illustrated the promising practical application.

Commercially available carbodiimides in hydroxylic solvents containing hydrogen peroxide with mildly basic or acidic catalysts have been found to promote the epoxidation of olefins. A commercially available 30% aqueous solution of hydrogen peroxide serves as the oxidant for this process. The presumed reactive species is a peroxyisourea generated in situ by the addition of hydrogen peroxide to the carbodiimide.

Reaction of Ketones with Hydrogen Peroxide with Acid Catalysts

Epoxy is produced from an epoxidation reaction of vegetable oils such as linseed oil, corn oil, palm oil or natural oils that have unsaturated bonds. The aim of this research is to produce epoxy compound based on Crystallized Palm Fatty Acid Distillate. First, the gas chromatography analysis was done to the palm fatty acid distillate. Then, before the epoxidation reaction began, crystallization process was done based on solubility of saturated and unsaturated fatty acid in organic solvent (methanol). In this research, the Crystallized Palm Fatty Acid Distillate that has reacted with acetic acid glacial and hydrogen peroxide, toluene as solvent, sulfuric acid as a catalyst in a three-neck flask fitted with condenser reflux at 700C and stirred at 500 rpm. The catalyst concentration varied from 1.5%, 2.0%, 2.5%, 3.0% and 3.5% and epoxidation reaction time varied from 60 minutes, 120 minutes, 180 minutes, 240 minutes and 300 minutes. The results showed that the highest epoxy conversion was achieved at reaction time of 120 minutes with 2.5% sulfuric acid catalyst concentration against the amount of hydrogen peroxide and acetic acid used. The result of this analysis shows that oxirane oxygen content is 0.96%, iodine number is 17,16g iod / 100 g oil and conversion equal to 81,61%.