Effect of Acid–Base Characteristics of In2O3-Al2O3 (ZrO2) Compositions on Their Catalytic Properties in the Oxidative Dehydrogenation of Propane to Propylene with CO2

Theoretical and Experimental Chemistry - The effect of the nature of the support and the method of preparation of indium–aluminum(zirconium) oxide compositions on their acid–base...     

Influence of the composition of composites based on Y-and Sc-stabilized zirconium dioxide on catalytic properties in the oxidative conversion of methane

The effect of the composition of composites based on Y-and Sc-stabilized zirconium dioxide doped with CeO₂ and transition metal (Cu, Co, Ni) oxides on catalytic properties in the oxidative conversion of methane was studied. The activity of the composites correlated with the quantity and mobility of oxygen in them. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 3, pp. 184–188, May–June, 2006.     

Effect of size and morphology of chromium(III) oxide nanoparticles on their catalytic properties in deep oxidation of methane

We have shown that the activity of catalysts based on Cr₂O₃ in deep oxidation of methane is determined by both the sizes of the crystallites and their morphology. In the temperature range up to 450 °C, we observe the appearance of a size effect: an increase in the specific catalytic activity of the chromium oxide as its particle size decreases. Formation of chromium oxide on the surface of Al₂O₃ increases the dispersity of the active component and increases the thermal stability of the catalyst.     

Sulfur resistance and stability of yttrium-stabilized binary Co-Cu and Ni-Cu composites with zirconium dioxide in the oxidative conversion of methane

Binary Co-Cu and Ni-Cu composites with YSZ have demonstrated rather high thermal resistance (up to 1000 °C) and stability in the extensive oxidation of methane. The tendency of the nickel–copper composites to carbon deposition depends on the amount of nickel introduced. The higher stability was found for the sample with active phase containing 4% Ni, 16% Cu. The sulfur resistance of the palladium-doped Ni–Cu composite is attributed to the formation of an adsorbed [PdO·SO₂] complex. TPHR data indicated that the oxygen in this sample is less reactive in methane oxidation.     

Effect of a structure-size factor on the catalytic properties of complex oxide compositions in the reaction of deep methane oxidation

The following catalysts for deep methane oxidation were studied using X-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, temperature-programmed reduction with hydrogen, and temperature-programmed ammonia desorption: highly dispersed supported aluminum-manganese and cobalt-zirconium catalysts; bulk and supported nanosized spinel ferrites. It was found that structure-size factors in complex oxide nanocomposites are responsible for differences in the catalytic properties (activity and thermal stability). The efficiency of the supported ferrite and cobalt-zirconium catalysts depends on both the oxygen-catalyst bond strength and the acid properties of catalyst surfaces.     

Deep Oxidation of Methane over Nano-Sized Ferrites with Spinel Structures

Ferrites with spinel structures as catalysts for the deep oxidation of methane have been studied by X-ray phase analysis and temperature programmed reduction. The most active catalysts are the nano-sized ferrites of cobalt and nickel, prepared by the decomposition of polynuclear complexes, with Al₂O₃ as carrier and with addition of a surface active agent to increase the thermal stability of the catalysts. At low temperatures (up to 450 °C), the effect of the size factor appears with the increase in specific catalytic activity of cobalt and nickel ferrites with decreasing of their particles. A correlation of the catalytic activity with the quantity and mobility (reactivity) of oxygen in the ferrites has been established.     

Catalytic activity of nanosized Co-Cu oxide systems in the deep oxidation of methane

The effect of the composition of nanosized catalysts, produced by thermal decomposition of Co(II) and Cu(II) formates deposited on ZrO₂, SBA-15, and MCM-41, on their activity in the deep oxidation of methane was investigated. It was shown that the activity of the catalyst depends on the nature of the support and on the Co/Cu ratio. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 41, No. 6, pp. 331–335, November–December, 2005.