Hopcalite catalysts carbon monoxide oxidation

A 10 Ndm3 min-1 feed composed of 75.0% H2, 0.7% CO and balance C02 with air for oxidation was fed into the relatively large test reactor carrying 230 cm3 catalyst microsperes of 1 mm diameter. Of the non-precious metal catalysts, that composed of hopcalite showed the highest activity, achieving almost full conversion in the temperature range 130-160 °C. The minimum CO output achieved was 40 ppm. A minimum 02/CO ratio of 2.5 was determined for this catalyst to achieve a carbon monoxide conversion exceeding 90%. The catalysts tested are summarized in Table 2.7. 

Low Temperature Oxidatix)n. The majority of heterogeneous catalysts used for oxidation are used at elevated temperatures. However, some of these metal oxide systems are capable of catalyzing specific oxidation reactions at ambient temperature. The most widely studied catalyst of this type is the mixed oxide CuMn204, which is active for the oxidation of carbon monoxide at room temperature. The same catalyst is also an active oxidation catalyst at increased temperatures, and this has been demonstrated in the previous section. The mixed copper manganese oxide is called hopcalite and was first discovered around 90 years ago (96). Early studies demonstrated that manganese oxides promoted with various transition metal oxides were active catalysts. 

A catalyst that has been used effectively for oxidizing traces of acetylene in the air feed to low temperature separation plants and for providing hydrocarbon-free air for instruments and other special applications consists of a mixture of manganese dioxide and copper oxide, called Hopcalite. This catalyst also converts traces of carbon monoxide to carbon dioxide and u-aces of ozone to oxygen. The basic composition is about 60% manganese dioxide and 40% copper oxide however, relatively small additions of silver as a promoter have been found to make the catalyst particularly effective for most air streams (Rushton, 1954). Hie degree of conversion of several hydrocarbons over a commercial Hopcalite catalyst as a function of temperature is shown in Figure 13-10. 

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