Effect of certain catalytic poisons on the activity of cuprum-paladium complexes applied on carbon material in the reaction in the reaction of carbon monoxide oxidation by air oxygen

Oxide and metal complex catalysts for low temperature gas-phase oxidation of carbon monoxide by air oxygen lose their activity under the action of chemical poisons such as SO2, H2S, PH3, H2O. We have developed a highly efficient Wacker-type catalyst in which the carrier is a carbon fiber material (CFM), the precursor of which was cellulose hydrate. For such a catalyst, there are no studies on the effect of catalytic poisons, namely SO2 and H2O, on its activity in the reaction of low-temperature oxidation of CO with oxygen. The morphology, elemental composition and adsorption properties of carbon fiber material and carbon monoxide oxidation catalyst are investigated. Pd(II)-Cu(II)/CFM relative to water vapor and sulfur dioxide, as well as their effect on the protective properties of the catalyst. SEM studies (scanning electron microscope) confirmed the morphology typical of CFM and found very small agglomerates in the case of the catalyst, which are formed by paratacamite Cu2(OH)3Cl crystallites caused by oxidation of the carbon surface by palladium (II). When applying the catalyst components, the fibers do not lose their shape, but the surface of the fibers is unevenly covered with impurities. Palladium (II) is reduced by a carbon surface by about 10%, agglomerates [Pdo]n are not observed, while fiber erosion increases and very small agglomerates are formed on the surface, which are formed by Cu2(OH)3Cl phase crystallites. Carbon material is generally characterized by a high content of carbon and oxygen, but their distribution is heterogeneous. In the analysis of adsorption isotherms, which are classified as type IV, it was found that CFM and the catalyst based on it belong to the microporous samples. It is proved that only at the relative humidity of the gas-air mixture, which is equal to 30% C < MPCSO2 (20 mg/m3). Catalyst poisoning does not disrupt the catalytic process, but with increasing amount of absorbed sulfur dioxide (QSO2 ) the degree of conversion of carbon monoxide decreases and especially sharply at the absorption of 10.3⋅10–4 mol SO2. Thus, the results obtained on the effect of relative humidity and the amount of adsorbed by the catalyst SO2 on the activity of Pd(II)-Cu(II)/CFM catalyst, indicate a significant reduction in the degree of conversion of carbon monoxide. Therefore, in the case of applying of such a catalyst, for example in respiratory protection against CO, a preliminary stage of absorption of moisture and sulfur dioxide should be provided.