Carbon dioxide, from catalytic oxidation metal catalysts

In a separate investigation MargeHs and Roginekii1107 carried nut catalytic oxidation of ethylene at 350° over vanadium pentoxidc. reportedly similar to metallic silver in catalytic properties. TVv asoertainod that carbon dioxide was formed faster from, ethylene oxide, or from acetaldehyde under comparable conditions, than from ethylene itself. Further, they noted the formation of carbon monoxide, and determined that its rate of formation was considerably greater than that of carbon dioxide, increasing still more in the presence of adtk-d ethylene oxide. The addition of ethylene oxide also appeared to depro both ethylene oxide and acetaldehyde formation. They concluded that reactions leading to carbon dioxide and water did not proceed by wav of ethylene oxide, but by way of some other intermediates, and tlmt-this process could occur either on the catalyst surface or in the gas phase. 

The reviews by Spivey [3] and by Jennings et al. [156] are excellent sources for further details on catalytic incineration of volatile organics emissions. Spivey [3] describes two types of techniques for removal of VOC from off-gases, namely one without preheater and one with a direct flame preheater. From an economically point of view it is more beneficial to carry out the catalytic oxidation at lower temperatures. In a catalytic incinerator, sometimes called an afterburner, VOCs are oxidized into carbon dioxide and water. The efficiency is about 70-90%. The incinerator has a preheat burner, a mixing chamber, a catalyst bed, and a heat recovery equipment. Temperatures of about 590 K are sirfficient for the destruction of VOCs. Various catalyst geometries have been used metal ribbons, spherical pellets, ceramic rods, ceramic honeycombs, and metal honeycombs. Precious metals such as platinum and palladium are often used in catalytic incinerators. 

A mixture of formalin and ethanol was passed at 240—320 C over various metal oxides supported on silica gel and metal phosphates. The main products were acrolein, acetaldehyde, methanol, and carbon dioxide. Acidic catalysts such as V-P oxides promoted the dehydration of ethanol to ethene. The best catalytic performances for acrolein formation are obtained with nickel phosphate and silica-supported tungsten, zinc, nickel, and magnesium oxides. With a catalyst with a P/Ni atomic ratio of 2/3, the yields of acrolein reach 52 and 65 mol% on ethanol basis with HCHO/ethanol molar ratios of 2 and 3, respectively. Acetaldehyde and methanol are formed by a hydrogen transfer reaction from ethanol to formaldehyde. Then acrolein is formed by an aldol condensation of formaldehyde with the produced acetaldehyde [40],... 

The use of lead oxide (PbO) for the conversion of ethyl carbamate (EC) to form diethyl carbonate (DEC) using ethanol has been reported this reaction is the second step in the conversion of urea to DEC by alcoholysis (Scheme 22.15). Of interest is that the catalytic species appears to be a mixture of metallic Pb and PbOj, generated under the reactions conditions from the initially added PbO by reaction with ethanol to generate ethane, acetaldehyde, carbon dioxide and water. This lead oxide catalyst exhibited excellent activity in comparison other metals and high conversion yield (16%), and could be reused up to five times without significant loss in activity. ... 

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