Sulfur dioxide oxidation space velocity

The space velocity was varied from 2539 to 9130 scf/hr ft3 catalyst. Carbon monoxide and ethane were at equilibrium conversion at all space velocities however, some carbon dioxide breakthrough was noticed at the higher space velocities. A bed of activated carbon and zinc oxide at 149 °C reduced the sulfur content of the feed gas from about 2 ppm to less than 0.1 ppm in order to avoid catalyst deactivation by sulfur poisoning. Subsequent tests have indicated that the catalyst is equally effective for feed gases containing up to 1 mole % benzene and 0.5 ppm sulfur (5). These are the maximum concentrations of impurities that can be present in methanation section feed gases. 

Figure 106. Conversion of carbon monoxide, gaseous hydrocarbons and sulfur dioxide reached over diesel oxidation catalysts as a function of the preeious metal formulation at equimolar loading (monolith catalyst with 62 cells cm - dedicated diesel washeoat formulations with platinum, palladium and rhodium at an equimolar loading of 8 mmol I, fresh model gas test at a gas temperature at catalyst inlet of 723 K a space velocity 50000Nil h model gas simulates the exhaust gas composition of an IDl passenger car diesel engine at medium load and speed and contains 100 vol. ppm SO2). Reprinted with permission from ref. [68], C 1991 Society of Automotive Engineers, Inc.

Additionally, in a microreactor the intrinsic kinetics and deactivation behavior of SCR catalysts is studied with flows up to 1.5m h . In both test facilities it is possible to vary all process parameters temperature, the ammonia to nitric oxide feed ratio, the nitric oxide and sulfur dioxide concentrations, the space velocity, and the catalyst geometry. These techniques provide information for somewhat small areas and therefore should always be performed to complement bench- or laboratory-scale activity and selectivity measurements. 

Powdered samples of the solid solution catalysts were examined after varying thermal treatment for surface area stability and stability of catalytic activity in oxidation. Selected solid solutions were supported on monolithic substrates and examined for oxidation and reduction activity as a function of space velocity, water-gas shift activity, and susceptibility to poisoning by sulfur dioxide. 

The concentration of the active metal usually ties in the range 0.35-1.76 g titerSmaller volumes of catalyst are required for diesel engines than for gasoline engines, and this results in a higher space velocity. Palladium catalysts have a lower activity for the oxidation of sulfur dioxide than platinum catalysts. Nevertheless, a lower metal content is used at the present time to avoid excessive oxidation of sulfur dioxide to the trioxide. 

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