V. A. Sobyanin

Co-Pt bimetallic catalysts for the selective oxidation of carbon monoxide in hydrogen-containing mixtures

The performance of a Co-Pt powder and of Co-Pt catalysts supported on γ-Al2O3 and on the graphite-like carbon material Sibunit in selective CO oxidation in hydrogen-containing mixtures is considered. Fine particles of metal-metal solid solutions and intermetallides were obtained by the decomposition of a Co- and Pt-containing double complex salt in a hydrogen atmosphere at ∼400°C. As compared to their Pt and Co monometallic counterparts, the bimetallic catalysts are more active and allow the CO concentration in hydrogen-containing mixtures to be reduced from 1 to 10−3 vol %. This effect is likely due to the formation of bimetallic particles of a Co-Pt solid solution on the support surface.

Copper-cerium oxide catalysts prepared by the Pechini method for CO removal from hydrogen-containing mixtures

A series of copper-cerium oxide catalysts was prepared by the Pechini method, and their physicochemical and catalytic properties in CO oxidation in hydrogen-containing gas mixtures were studied. The method chosen for catalyst preparation yields finely dispersed copper and cerium oxides in the catalyst.

Selective methanation of CO in the presence of CO2 in hydrogen-containing mixtures on nickel catalysts

The screening of commercial nickel catalysts for methanation and a series of nickel catalysts supported on CeO2, γ-Al2O3, and ZrO2 in the reaction of selective CO methanation in the presence of CO2 in hydrogen-containing mixtures (1.5 vol % CO, 20 vol % CO2, 10 vol % H2O, and the balance H2) was performed at the flow rate WHSV = 26000 cm3 (g Cat)−1 h−1. It was found that commercial catalytic systems like NKM-2A and NKM-4A (NIAP-07-02) were insufficiently effective for the selective removal of CO to a level of <100 ppm. The most promising catalyst is 2 wt % Ni/CeO2. This catalyst decreased the concentration of CO from 1.5 vol % to 100 ppm in the presence of 20 vol % CO2 in the temperature range of 280–360°C at a selectivity of >40%, and it retained its activity even after contact with air. The minimum outlet CO concentration of 10 ppm at 80% selectivity on a 2 wt % Ni/CeO2 catalyst was reached at a temperature of 300°C.

Bimetallic Rh-Co/ZrO2 catalysts for ethanol steam reforming into hydrogen-containing gas

The properties of supported bimetallic Rh-Co/ZrO2 catalysts in ethanol steam reforming into hydrogen-containing gas were studied. The particles of Rh-Co solid solutions on the catalyst surface were prepared by the thermal decomposition of the double complex salt [Co(NH3)6][Rh(NO2)6] and the solid solution Na3[RhCo(NO2)6]. It was found that the bimetallic Rh-Co/ZrO2 catalysts exhibited high activity in the reaction of ethanol steam reforming. The equilibrium composition of reaction products was attained at 500–700°C and a reaction mixture space velocity of 10000 h−1.

Copper-cerium oxide catalysts for the selective oxidation of carbon monoxide in hydrogen-containing mixtures: I. Catalytic activity

A series of copper-cerium oxide catalysts were prepared, and their properties toward the reaction of CO oxidation in hydrogen-containing gas mixtures were studied. It was found that the copper-cerium oxide catalysts are stable, active, and selective in this reaction. The conditions under which these catalysts decreased the concentration of CO from 1 to <10−3 vol % in hydrogen containing water vapor and carbon dioxide were determined.

Reduction of nitrogen oxides in diesel exhaust: Prospects for use of synthesis gas

Already commercialized and some of the most promising technologies of nitrogen oxide reduction in automotive diesel exhaust are compared. The Boreskov Institute of Catalysis (Siberian Branch, Russian Academy of Sciences) is developing an advanced method for the selective catalytic reduction of NOx with synthesis gas produced on board by the catalytic conversion of diesel fuel. The activity of the Ag/Al2O3 catalytic system in NOx reduction by H2 + CO admixtures is studied for both a model composition of the exhaust gas and under real diesel operation conditions.

Copper-cerium oxide catalysts for the selective oxidation of carbon monoxide in hydrogen-containing mixtures: II. Physicochemical characterization of the catalysts

The copper-cerium oxide catalysts were characterized using a set of physicochemical techniques including in situ FTIR spectroscopy, XPS, and XRD. It was found that copper segregated on the surface of cerium oxide and its states were labile and dependent on catalyst pretreatment conditions. Copper in a dispersed state was responsible for the reaction of CO oxidation in the presence of H2 on the copper-cerium oxide catalysts. It is likely that this state of copper was composed of two-dimensional or three-dimensional surface clusters containing Cu+ ions.

Kinetic model and mechanism of the selective oxidation of CO in the presence of hydrogen on platinum catalysts

The reaction kinetics of the selective oxidation of carbon monoxide in the presence of hydrogen on a Pt/carbon support catalyst was studied. It was found that this catalyst exhibited high activity and decreased the concentration of CO in a hydrogen-containing gas from 0.6–1.0 vol % to less than 10 ppm at the inlet concentration ratio O2/CO = 1.0–1.5. A kinetic model of the reaction was proposed to describe quantitatively the experimental results.

Synergetic effect in PdAu/CeO2 catalysts for the low-temperature oxidation of CO

Gold-palladium catalysts supported on cerium oxide were synthesized with the double complex salts. X-ray photoelectron spectroscopy (XPS) and other physicochemical methods (TEM, TPR) were used to demonstrate that synthesis of highly active palladium catalysts requires the oxidative treatment stimulating the formation of a catalytically active surface solid solution PdxCe1−xO2, which is responsible for the lowtemperature activity (LTA) in the reaction CO + O2. In the case of gold catalysts, active sites for the lowtemperature oxidation of CO are represented by gold nanoparticles and its cationic interface species. Simultaneous deposition of two metals increases the catalyst LTA due to interaction of both gold and palladium with the support surface to form a Pd1−xCexO2 solid solution and cationic interface species of palladium and gold on the boundary of Pd-Au alloy particles anchored on the solid solution surface.

Effect of internal diffusion on preferential CO oxidation in a hydrogen-rich mixture on a copper-cerium oxide catalyst in a microchannel reactor

The effect of internal diffusion on preferential CO oxidation in a hydrogen-rich mixture on a copper-cerium catalyst in a microchannel reactor was estimated. It was found that the internal effectiveness factor ηCO > 0.8 was reached at a catalytic coating thickness of ∼30 μm.