Carbon dioxide, from catalytic oxidation

WSA [Wet gas sulphuric acid] A process for recovering sulfur from flue-gases and other gaseous effluents in the form of concentrated sulfuric acid. It can be used in conjunction with the SCR process if oxides of nitrogen are present too. The sulfur dioxide is catalytically oxidized to sulfur trioxide, and any ammonia, carbon monoxide, and carbonaceous combustibles are also oxidized. The sulfur trioxide is then hydrolyzed to sulfuric acid under conditions which produce commercial quality 95 percent acid. Developed by Haldor Topsoe 15 units were commissioned between 1980 and 1995. See also SNOX. 

GREENOX A process for purifying carbon dioxide from combustion gases, so that it may be used in greenhouses for enhancing plant growth. Nitric oxide is removed by the SCR process, using urea as the reductant. Carbon monoxide and ethylene are catalytically oxidized to carbon dioxide. Developed by Haldor Topsoe in 1997. 

Westvaco (1) A variation of the Claus process for removing hydrogen sulfide from gas streams, in which the sulfur dioxide is catalytically oxidized to sulfur trioxide over activated carbon at 75 to 150°C. The adsorbed sulfur trioxide is hydrated to sulfuric acid and then converted back to sulfur dioxide by reaction with the hydrogen sulfide at a higher temperature. 

A related procedure is used in the Westvaco process, except that sulfur dioxide is catalytically oxidized to sulfur trioxide using activated carbon at 75-150°C. The sulfur trioxide is then hydrated to sulfuric acid which is absorbed onto the active carbon [36]. Sulfur recovery from the sulfuric acid is as sulfur dioxide, which is formed in a regenerator by raising the temperature of the carbon and adding hydrogen sulfide. 

Application of LDHs is mostly based on their use after thermal treatment and mixed oxide formation. If the calcination is performed at temperatures below 550 °C, mixed oxides also have, besides the aforementioned properties, the memory effect. This very specific property of mixed oxides derived from thermal degradation of LDHs allows the reconstruction of the layered structure in mild conditions when mixed oxides are in contact with aqueous solution or air. If calcination is carried out at temperatures above 827 °C, irreversible mixed spinels are formed and the memory effect is disabled [48]. The main application of the memory effect is for the synthesis of LDHs with different interlayer anions than CO ". Taking to consideration that carbonate anions have the highest affinity toward the incorporation in the LDH interlayer, during the classical synthesis methods the contamination with carbon dioxide from the air always occurs. If, for example, the synthesis LDH with OH" ions in the interlayer is required, the reconstruction of mixed oxides can be performed by steam or contact with decarbonized water. Similarly, if synthesis of LDHs with other anions in the interlayer is anticipated, reconstruction is carried out in an aqueous solution containing the desired anions. Catalytic properties of mixed oxides obtained by reconstruc-tion/recrystallization procedure depend mainly on the conditions of each activation step. 

The complete assembly for carrying out the catalytic decomposition of acids into ketones is shown in Fig. Ill, 72, 1. The main part of the apparatus consists of a device for dropping the acid at constant rate into a combustion tube containing the catalyst (manganous oxide deposited upon pumice) and heated electrically to about 350° the reaction products are condensed by a double surface condenser and coUected in a flask (which may be cooled in ice, if necessary) a glass bubbler at the end of the apparatus indicates the rate of decomposition (evolution of carbon dioxide). The furnace may be a commercial cylindrical furnace, about 70 cm. in length, but it is excellent practice, and certainly very much cheaper, to construct it from simple materials. 

Catalytic Converter an air pollution abatement device that removes pollutants from motor vehicle exhaust either by oxidizing them into carbon dioxide and water or reducing them to nitrogen. A typical catalytic oxidizer for auto emission control is illustrated in the sidebar figure. 

For many years the catalytic air oxidation of benzene was the main source of maleic anhydride. Obviously, two carbons from each ring are wasted as carbon dioxide in this process. Although some is still made that way, most modem maleic anhydride plants are based on butane oxidation. Because butane is forecast to be plentiful and low-cost, new routes to four-carbon chemicals from maleic anhydride are under active development. 

Ethylene is to be converted by catalytic air oxidation to ethylene oxide. The air and ethylene are mixed in the ratio 10 1 by volume. This mixture is combined with a recycle stream and the two streams are fed to the reactor. Of the ethylene entering the reactor, 40% is converted to ethylene oxide, 20% is converted to carbon dioxide and water, and the rest does not react. The exit gases from the reactor are treated to remove substantially all of the ethylene oxide and water, and the residue recycled. Purging of the recycle is required to avoid accumulation of carbon dioxide and hence maintain a constant feed to the reactor. Calculate the ratio of purge to recycle if not more than 8% of the ethylene fed is lost in the purge. What will be the composition of the corresponding reactor feed gas ... 

One of the conclusions deduced from the thermochemical cycle 2 in Table V, for instance, is that in the course of the catalytic combustion of carbon monoxide at 30°C, the most reactive surface sites of gallium-doped nickel oxide are inhibited by the reaction product, carbon dioxide. This conclusion ought to be verified directly by the calorimetric study of the reaction. Small doses of the stoichiometric reaction mixture (CO + IO2) were therefore introduced successively in the calorimetric cell of a Calvet microcalorimeter containing a freshly prepared sample of gallium-doped... 

Silica gel-based catalytic systems have been described as efficient promoters for a number of organic reactions.28 Illustrative examples include the oxidative cleavage of double bonds catalyzed by silica-supported KM11O4,29 reaction of epoxides with lithium halides to give /i-halohydrins performed on silica gel,30 selective deprotection of terf-butyldimethylsilyl ethers catalyzed by silica gel-supported phosphomolybdic acid (PMA),31 and synthesis of cyclic carbonates from epoxides and carbon dioxide over silica-supported quaternary ammonium salts.32... 

CSA [Catalytic solvent abatement] A process for removing chlorinated solvents from waste gases by catalytic oxidation. Two catalysts are used in series and the products are carbon dioxide, water, and hydrogen chloride. Developed in Germany by Hoechst and Degussa and licensed by Tebodin in The Netherlands. 

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