Sulfur dioxide oxidation reaction

As mentioned before, heterogeneous sulfur dioxide oxidation reactions... 

Martin, L. R., Damschen, D. E., and Judeikis, H. S. (1981) Sulfur Dioxide Oxidation Reactions in Aqueous Solution, EPA 600/7-81-085. U.S. Environmental Protection Agency, Research Triangle Park, NC. 

The sulfur dioxide of reaction 1 is cooled in a waste-heat boiler, freed from calcine, and converted to trioxide. The oxidation and conversion to sulfuric acid is conducted in a conventional acid plant (see also Sulfuric acid and sulfur trioxide). 

Reproducible measurements of absolute activity for sulfur dioxide oxidation catalysts are very difficult to obtain for a number of reasons, including the fact that the reaction is extremely fast. In addition, there are differences in techniques and reporting methods used by the various workers. Pulse microreactors have been used to study quantities of these catalysts as small as 500 mg (83). 

It is partly the fault of statistics that experimenters have misconstrued the value of the number and precision of data points relative to the value of the location of the points. The importance of the location of the data in the model specification stage can be seen from Fig. 1, which represents literature data (M3) on sulfur dioxide oxidation. The dashed and solid lines represent the predicted rates of two rival models, and the points are the results of two series of experimental runs. It can be seen that neither a greater number of experimental points nor data of greater precision will be of major assistance in discriminating between the two rival models, if data are restricted to the total pressure range from 2 to 10 atm. These data simply do not place the models in jeopardy, as would data below 2 atm and greater than 10 atm total pressure. This is presumably the problem in the water-gas shift reaction, which is classical in terms of the number of models proposed, each of which adequately represent given sets of data. 

The important commercial process of sulfur dioxide oxidation has been studied by a number of investigators. A set of steps that has been proposed for both platinum and vanadium oxide-based catalysis by Horiuti (7) for the overall reaction 2SOz + 02 2SOs is as follows ... 

Sulfides are converted to the oxide of the metal and sulfur dioxide by reaction with atmospheric oxygen ... 

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. 

Figure 9 Temperature of the reaction mixture, T, and of the coolant, Ta, in the plug flow reactor for sulfur dioxide oxidation according to Johannessen and Kjelstrup ...

The chemical reactions involved in this process were outlined in the patent, which laid the basis for this industry. However, many improvements in practice have been achieved from a more detailed knowledge of the gas phase kinetics of the sulfur dioxide oxidation step, as well as from a better understanding of the gas-liquid equilibria associated with the hydration step. 

The reverse-flow chemical reactor (RFR) has been shown to be a potentially effective technique for many industrial chemical processes, including oxidation of volatile organic compounds such as propane, propylene, and carbon monoxide removal of nitrogen oxides sulfur dioxide oxidation or reduction production of synthesis gas methanol formation and ethylbenzene dehydration into styrene. An excellent introductory article in the topic is given by Eigenberger and Nieken on the effect of the kinetic reaction parameters, reactor size, and operating parameters on RFR performance. A detailed review that summarizes the applications and theory of RFR operation is given by Matros and Bunimovich. 

Activated Carbon Sulfur removal from natural gas by adsorption at ambient temperature on carbon, activated with cupric oxide, is widely used. Carbon physically adsorbs sulfur compounds to its surface and the cupric oxide reacts with hydrogen sulfide. The activated carbon is typically regenerated every 30 days by passing steam through the bed at a temperature of 230°C (450°F) for 8—10 hr while air is injected. Oxygen in the air reacts with the metal sulfide to form the metal oxide and sulfur dioxide. These reactions are ... 

Ibusuki, T., and Takeuchi, K, Sulfur dioxide oxidation by oxygen catalyzed by mixtures of manganese(II) and iron(III) in aqueous solutions at environmental reaction conditions. Atmos. Environ. 21, 1555 (1987). 

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