Combustion of Methane in Lean Mixtures over Bulk Transition-Metal Oxides: Evaluation of the Activity and Self-Deactivation

Abstract

Different bulk transition-metal oxides (NiO, CuO, Mn 2 O 3 , Cr 2 O 3 , and Co 3 O 4 ) were prepared, by precipitation from nitrate precursors, and tested for the combustion of methane-air lean mixtures (1000-5000 ppmv of CH 4 ). Catalyst performances were compared in terms of both intrinsic activity and resistance to self-deactivation. Methane combustion experiments were carried out at ambient pressure and a space velocity of 62 h -1 [weight hourly space velocity (WHSV)]. The activity of the studied catalysts (determined by the recording of light-off curves in the interval of 250-600 °C) decreases in the order:However, deactivation studies, carried out both at constant temperature (620 °C) and in hysteresis experiments, reveal that Mn 2 O 3 is the most stable catalyst.

Oxidation of Methane to Methanol over Single Site Palladium Oxide Species on Silica: A Mechanistic view from DFT

“…[1][2][3][4] Numerous catalysts have been used, the most popular supported noble metals such as Pd, Pt and Rh 5 , and common transition metal oxides or mixed metal oxides as bulk or supported catalysts. 6 Recently, supported palladium appeared to be a highly active catalyst for the direct oxidation of methane. [7][8][9][10][11] Several studies have shown that PdO is the active phase for the catalytic combustion of methane.…”

“…7,14 Because of this, supported palladium oxides have been widely studied. [3][4][5][6][7][8][9][10][11][12][13] The oxidation state, dispersion, oxide nature and the morphology of the particles are dependent on the preparation method and on the nature of the support, which complicates the characterization efforts to elucidate the nature of the active site for methane oxidation. Experimental studies confirmed that the cleavage of the strong C-H bond in CH 4 is the rate-determining step for the catalytic o xidation of methane.…”

Characterization of MOy–MxCe1−xO2−δ (M: Co, Ni & Cu) nano powders and anode materials for low and intermediate temperature solid oxide fuel cells

“…The ash powder color varied from dark black to dark and light brown. There has been substantial debate about the color of the ash powders synthesized by GNP [10,17,19]. The color of the synthesized powders was observed to stay stable even after changing the mentioned parameters after combustion of glycine-nitrate gel, especially after heat treatment of the powders over 300 C. The powders had crystalline structure and black color after calcinations and they remained same throughout the powder processing steps as have been described by Paredes et al [17].…”

Tuning the Synthesis of Manganese Oxides Nanoparticles for Efficient Oxidation of Benzyl Alcohol

“…Only a slightly small peak at 800 °C was observed for S3-600. Lattice oxygen O 2− , surface O − , or β-oxygen were mainly related to partial oxidation, while the active chemisorbed oxygen was very active in the deep oxidation [31]. S3-600, a Mn 3 O 4 -rich material with a small amount of Mn 2 O 3 , could generate significant amount of species on the surface during oxidation that would be responsible for the deep oxidation of alcohols.…”