Direct oxidation of hydrogen

In the so-called Superclaus process, the last catalytic converter of the conventional Claus process is replaced by a catalytic converter containing the Superclaus catalyst . This catalyst consists of an a-alumina support with iron and chromium oxides as catalytic material. The Superclaus catalyst is highly selective for the direct oxidation of hydrogen sulphide ... 

The direct oxidation of hydrogen by nitrogen dioxide has been studied by Ashmore and Levitt [261], and Rosser and Wise [262]. The reaction proceeds rapidly at 600—700 K without change of pressure, according to the overall stoichiometry... 

Both catalysts supported on silica produce a small amoimt of propene oxide at the highest temperatures however, the selectivities remain low, proving the necessity of titania on the support to have an effective epoxidation catalyst. Furthermore, these catalysts by far have the lowest hydrogen efficiency because of the direct oxidation of hydrogen into water, making the economics of these catalysts very unattractive. 

Still other approaches to methods for cost reduction have been patented for the formation of hydrogen peroxide by direct oxidation of hydrogen and of hydrocarbons, such as propane, n-butane, and isobutane and for its recovery from the aqueous solutions thus formed. 

The anode reaction in fuel cells is either the direct oxidation of hydrogen or the oxidation of methanol. An indirect oxidation via a reforming step can also occur. The cathode reaction in fuel cells is oxygen reduction, in most cases from air. For the case of a hydrogen/oxygen fuel cell the overall reaction according to Equation 9-29 is ... 

Direct oxidation of hydrogen to hydrogen peroxide Asymmetric ceramic support Pd, Pd-Ag dense layers hydrophobic gas permeable polymer Tubular single channel O2 saturated liquid on the hydrophobized Pd dense layer H2 gas on the support side Choudhary et al. (2001)... 

Choudhary, V.R., Gaikwad, A.G., Sansare, S.D., 2001. Nonhazardous direct oxidation of hydrogen to hydrogen peroxide using a novel membrane catalyst. Angewandte Chemie International Edition 40,1776-1779. 

This reversible work is regarded as the maximum work. For the case of direct oxidation of hydrogen, one has... 

Using Eq. (2.8), the actual or observed electrical work for direct oxidation of hydrogen, a fuel cell is given by... 

Choudhary, V., Gaikwad, A. and Sansare, S. (2001). Non-Hazardous Direct Oxidation of Hydrogen to Hydrogen Peroxide Using a Novel Membrane Catalyst, Angew. Chetn. Int. Edit., 40, pp. 1776-1779. 

Douglas, R. A., 1990B, Direct Oxidation of Hydrogen Sulfide in a Regenerable, Naphthoquinone-Based Process. paper presented at the August AIChE Summer National Meeting, San Diego, CA. 

At the University of Utrecht a new catalytic process has been developed to oxidize these low concentrations of H2S selectively to sulfur without establishing the equilibrium of reaction (2). The newly developed process involves direct oxidation of hydrogen sulfide to elemental sulfur [1] ... 

CH2 CH CH0. a colourless, volatile liquid, with characteristic odour. The vapour is poisonous, and intensely irritating to eyes and nose b.p. 53"C. It is prepared by the distillation of a mixture of glycerin, potassium sulphate and potassium hydrogen sulphate. It is manufactured by direct oxidation of propene or cross-condensation of ethanal with meth-anal. 

Direct oxidation of pyridazine and its derivatives with hydrogen peroxide (50-90%) in acetic acid gives, besides the isomeric mono 1- and 2-oxides, also the corresponding... 

Numerous examples of N—S bond formation using oxidative conditions have been described in the literature. A convenient synthesis of isothiazoles involves the direct oxidation of -y-iminothiols and numerous variations have been studied (see Chapter 4.17), The oxidation of the amidine (248) to give the 3-aminoisothiazole (249) illustrates the reaction scheme (65AHC(4)107, 72AHC(14)1), which has been extended to the synthetically useful 5-amino-4-cyano-3-methylisothiazole (251) obtained by oxidation of (250) with hydrogen peroxide (75JHC883). 

The direct oxidation of propylene with oxygen is a noncatalytic reaction occurring at approximately 90-140°C and 15-20 atmospheres. In this reaction hydrogen peroxide is coproduced with acetone. At 15% isopropanol conversion, the approximate yield of acetone is 93% and that for H2O2 is 87% ... 

Similarly, the most common method of preparing the substituted, fully unsaturated thiolane system, e.g. thiophene dioxides, is by direct oxidation of the readily available substituted thiophenes with hydrogen peroxide, perbenzoic acid and m-chloroperbenzoic acid280 283. Alternatively, thiophene dioxides are conveniently prepared via the double elimination methodology280 305 illustrated in equation 117. 

The Active Oxygen for Direct Oxidation of Methane to Methanol in the Presence of Hydrogen... 

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