Catalysts For Oxidation Of Carbon Monoxide Research Articles

ADSORPTION OF HEXACHLOROPLATINIC ACID ON γ-ALUMINA COATINGS FOR PREPARATION OF MONOLITHIC STRUCTURE CATALYSTS

The adsorption of hexachloroplatinic acid on γ-Alumina coatings is investigated in order to prepare monolithic structure catalysts for carbon monoxide oxidation. For acid concentrations in the range 0.25-1.5 mM the adsorption is examined in a batch process and a kinetic model is proposed and evaluated. The pH of the solution has a major impact on the adsorption rate and dispersion of Pt on Al2O3 and when acidity becomes lower than 1.5 pH value the deposition of Pt on the catalyst by pore volume impregnation is favourable. The catalytic properties of Pt-alumina as oxidation catalyst for CO depend strongly on the adsorption rate of H2PtCI6. A difference of 80 °C at the light off temperature is observed for catalysts prepared by adsorption from solutions with different acidity.

Calcination conditions on copper/alumina catalysts for carbon monoxide oxidation and nitric oxide reduction

A commercial copper oxide/alumina catalyst with 6.5 wt.-% copper metal was used to study the effect of calcination conditions on carbon monoxide oxidation and nitric oxide reduction with ammonia. Calcination in a reducing atmosphere, at temperatures up to 900°C, may induce a strong metal-support interaction which leads to enhanced activities not only for carbon monoxide oxidation but also for nitric oxide reduction. This strong metal-support interaction effect was stronger for higher calcination temperatures. It was found that high temperature treatment in a reducing atmosphere was beneficial to carbon monoxide oxidation while an oxidizing atmosphere was usually preferred for nitric oxide reduction. In addition, copper species at higher oxidation states may lead to a higher activity of nitric oxide reduction, but an optimum state may exist. It can be concluded that nitric oxide reduction is a structure-sensitive reaction over copper catalysts.

Effect of calcination atmosphere on CuO/γ-Al 2O 3 catalyst for carbon monoxide oxidation

The effect of the calcination atmosphere on the surface properties of CuO/γ-Al 2O 3 catalysts was studied by reactive chemisorption of nitrous oxide, temperature-programmed reduction and reactivity for carbon monoxide oxidation. High-temperature (1073 K) calcination in an oxidizing atmosphere led to a redispersed copper surface but a dramatically reduced activity. On the other hand, high-temperature calcination in a reducing atmosphere produced a sintered copper surface but induced a strong metal-support interaction which caused a large increase in activity. It is concluded that carbon monoxide oxidation is a structure-sensitive reaction over copper catalysts.

Structure and activity of chromium-promoted raney copper catalysts for carbon monoxide oxidation

Chromium promoted Raney copper catalysts of various compositions were prepared and their activity for carbon monoxide oxidation measured. The surface areas of the Raney catalysts were found to be directly related to Al content in the precursor alloy and to a lesser extent to the presence of chromium. Crystalline Al, in excess of the amount required to form Al 2Cu in the alloy, appeared to lead to the formation of a structure of channels observed by scanning electron microscopy of the Raney catalysts. Bulk CuO and Cu 2O were detected by X-ray diffraction in the Raney catalysts. The presence of chromium appeared to inhibit the formation of CuO but not of Cu 2O. The activity was found to decrease as chromium content increased. However, when catalysts were prereduced with carbon monoxide prior to reaction, an optimum was found at low values of chromium concentration. A relation between deactivation by carbon monoxide pretreatment and temperature-programmed reduction spectra was established.

Influence of nature of support on physicochemical properties of carbon monoxide oxidation catalyst

The use of an oxidation catalyst intensifies the coke burnoff from cracking catalysts, resulting in higher catalyst activity and selectivity and an increased output of motor fuels. Controlled oxidation of CO also ensures safe cat cracker operation and reduced CO discharge to the atmosphere. Toward these ends, samples of CO oxidation catalysts were synthesized using a platinized reforming catalyst as support. The platinized alumina catalysts were low in bulk density and wear resistance. A process flow plan was developed for manufacturing KO-9 oxidation catalyst for CO afterburning in the regeneration gas in cat crackers. The process includes these stages: support preparation, calcination, and impregnation with the active metal, and drying of the finished catalyst. Increased yields of gasoline and reduced energy consumption were realized from using the KO-9 catalyst.

Cyclic operation of platinum/alumina catalysts for carbon monoxide oxidation

Les meilleurs resultats sont obtenus par reaction cyclique suivie de reaction stationnaire au-dessus de 300°C

High Temperature Catalysts for Carbon Monoxide Oxidation.

High Temperature Catalysts for Carbon Monoxide Oxidation.