Air, as an oxidant

There are two ways to produce acetaldehyde from ethanol oxidation and dehydrogenation. Oxidation of ethanol to acetaldehyde is carried out ia the vapor phase over a silver or copper catalyst (305). Conversion is slightly over 80% per pass at reaction temperatures of 450—500°C with air as an oxidant. Chloroplatinic acid selectively cataly2es the Uquid-phase oxidation of ethanol to acetaldehyde giving yields exceeding 95%. The reaction takes place ia the absence of free oxygen at 80°C and at atmospheric pressure (306). The kinetics of the vapor and Uquid-phase oxidation of ethanol have been described ia the Uterature (307,308). 

The production of synthesis gas based on heterogeneous catalytic reactions using 02 (air) as an oxidant is referred to as catalytic POx (CPO). Although the process is potentially able to process a wide range of hydrocarbon feedstocks, including heavy hydrocarbons, most of the information in the literature relates to the CPO of methane (or NG). The CPO of methane can be presented by the following equation ... 

More recently, an environmentally benign method using air as an oxidant has been developed. Following this approach, in the presence of air the... 

Six years later, we described a considerably improved total synthesis of the carbazomycins A (260) and B (261) using highly efficient synthetic routes to the arylamines 780a and 794 (610). Moreover, this methodology uses air as an oxidant for the construction of the carbazole framework by oxidative coupling of the iron-complexed cation 602 with the arylamines 780a and 794. 

Shirakawa, E. Nakao, Y. Murota, Y. Hiyama, T. Palladium-iminophosphine-catalyzed homocoupling of alkynylstannanes and other organostannanes using allyl acetate or air as an oxidant./. Organomet. Chem. 2003, 670, 132-136. 

The catalytic oxidation of alcohols to carbonyl compounds using the oxygen in air as an oxidant is an example of Green Chemistry, since no toxic by-products, such as reduced... 

Autothermal reforming is a teim adopted for the process in which a mixture of air and steam serves as the oxidant in the conversion of hydrocarbon fuels to a hydrogen-rich product. This process has also been reported to become more efficient as a result of the use of monolithic catalyst beds [11]. An example of this has been the demonstration of a modified version of the fuel-rich partial oxidation process in which noble metal catalysts were used in place of nickel on ceramic monoliths [2j. In earlier reports where packed catalyst beds were used, the concept to control carbon formation, which was predicted by thermodynamic equilibrium at low air-to-fuel ratios, was demonstrated by introducing steam, in addition to air, as an oxidant. 

This catalytic system consisted of an aqueous acidic solution of a palladium salt with a cop-per(I) salt and oxygen or air as an oxidant however, application of the Wacker process to longer chain alkenes has been a challenge due to their low solubility in aqueous media. This has led to research in biphasic systems using tetraalkylammonium salts,93 polyethylene glycols,94 as well as cyclodextrins.95,96... 

The need to operate in the presence of diluents suggests the use of air as an oxidant However, after the reaction stage, this method requires discharging all the inerts introduced in a purge, causing a significant loss of unconverted ethylene (4 to 4.5 per cent). To reduce this useless waste of raw material, Scientific Design, whose first unit went on stream in 1953, carried out the oxidation in two series of reactors, with the reactors placed in parallel in each of them. 

His establishment of fixed air as an oxide of carbon in 1783 extended in still another direction the ramifications of Black s key research for carbon dioxide, together with water, is an invariable product of the combustion of org ruc matter and Black himself had shown in 1757 that fixed air is formed in the burning of charcoal. 

The reactions are carried out at 540 C and 1 bar pressure using a silver gauze catalyst and air as an oxidant. If 50% excess air [sufficient air that 50 percent more oxygen is present than is needed for all the ethanol to react by reaction (a)] is used, calculate the equilibrium composition of the reactor effluent. 

Partial/Selective Oxidation. - While publications are numerous concerning direct, partial oxidation to methanol, high yields of commercial interest using only oxygen or air as an oxidant have not been achieved and confirmed. Economically promising conversion rates and selectivities have not yet been proven in large-scale equipment. 

Unfortunately, KOH electrol3rte does not bear traces of carbonaceous gases (CO and CO2) in the reactants even at percentages below 0.1 per cent, which rules out not only commercial-fuel-reforming-gas as a stack-fuel, but also air as an oxidant. Higher CO or CO2 percentages bring about formation of... 

I Aluminum reacts with oxygen in the air as an oxidation-reduction reaction. Which of the following best describes what happens ... 

The synthesis of 2,4,5-triarylimidazoline derivatives from aldehydes and alumina-supported ammonium acetate under solvent-free conditions using MW irradiation has been explored by Kaboudin and Saadati [184]. A similar solid-supported route from benzoin, aldehydes, and ammonium acetate, possibly involving air as an oxidant, had been reported earlier (Scheme 8.73) [185]. 

The expected substrate selectivity of FePc-NaY zeolites is demonstrated in a competing oxidation reaction of cyclohexanes and cyclododecanes in CH2CI2 solution with phenyl hypoiodide and air as an oxidizing agent at room temperature to give the corresponding alcohols [58, 59]. The oxidation rate of the sterically less bulky cyclohexane is about twice as high as that of the cyclododecane (62 ... 

Meanwhile, Lei and his colleagues discovered a novel protocol that makes use of air as an oxidant at low temperatures [111], Using a balloon pressure of CO/air mixture, arylboronates were converted into the corresponding esters in good yields (Scheme 8.29). This was the first example that could apply simply air in the oxidative carbonylation of organoboron compounds with alcohols. 

Organic wastes, an alkaline solution (used for the neutralization of the acids produced), air as an oxidant and supercritical water, are mixed and preheated, and then injected into the supercritical zone of the reactor. The wastes are oxidized and neutralized in this area. The SCF flows downwards during the reaction, and precipitates formed during the reaction fall down into the subcritical zone and are dissolved in subcritical water. The high temperature fluid turns back and upward due to convection, and then goes out from a vent. 

Dilution is another approach that can lead to attenuation (e.g., using air as an oxidant instead of using pure oxygen could avoid explosive situations). Use of 28% aqueous ammonia solution instead of anhydrous ammonia can lead to a 1 Ox decrease in the vapor cloud downwind during a reactor leak. 

LNR can be produced by thermal oxidative degradation using air as an oxidizing agent and phenylhydrazine as a reducing agent. Tillekeratne et a/. ... 

Hence with air as an oxidizer instead of oxygen, there are 2 moles of water per 10.52 moles of product, compared with 2 moles of water per 3 moles of products. 

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