Kinetic Modelling of Co3O4- and Pd/Co3O4-Catalyzed Wet Lean Methane Combustion

Palladium dispersion effects on wet methane oxidation kinetics

“…This is in line with previous studies that report strong dependency of the reaction rate on the palladium-support interaction when impregnation methods were used. 36,43,54,[69][70][71][72][73] Further, our interpretation is supported by the fact that for prefabricated particles in the range 2 to 9 nm deposited on metal oxides, a method presumably resulting in weaker particle-support interaction, a sole effect of particle size exists but is small. 42 Upon adding water to the feed, the methane oxidation clearly becomes inhibited resulting in increased E* for all catalysts.…”

Stability of kinetic parameters of Co3O4/CeO2 catalyzed methane combustion

“…Our recent kinetic study of Co 3 O 4 catalyst in methanelean combustion in the presence of 0.05 mol/mol (5 mol%) and 0.10 mol/mol (10 mol%) of water in the feed showed zero-order to water and first order to methane at the used conditions and an activation energy of 69 kJ/mol. [5] However, we observed progressive catalyst deactivation, which manifested itself in the decrease of preexponential factor of the Arrhenius equation (ie, number of active sites) and a loss of specific surface area. Co 3 O 4 crystal size in its fresh state was in the range from 20-300 nm.…”

“…The data on the unsupported cobalt oxide catalyst are imported from our previous work. [5] The realistic cobalt loading of 0.086 g/g (8.6 mass%), which corresponds to 0.11 g/g (11 mass%) Co 3 O 4 loading, was determined by neutron active analysis at Becquerel Laboratories (Maxxam Analytics, Canada). Surface area and porosity analyses were performed using Autosorb SI, Quantachrome USA; the samples were degassed at 300 C for 3 hours prior to analysis.…”

“…[4] For CH 4lean feeds, the oxide is active at relatively low temperatures with the combustion activation energies in the range of 60-80 kJ/mol. [2,5,10] Moreover, CoO x is not poisoned by water in the wet feeds [5,11] to the same extent as the conventional PdO/Al 2 O 3 , which exhibits negative first order to water in methane combustion. [20] The thermodynamic analysis predicts only partial water coverage of cobalt oxide surface at combustion-relevant temperatures and water content.…”

“…In a search for a Pt-group-metal-free methane combustion catalyst for applications in exhaust aftertreament of natural gas vehicles, cobalt oxide-containing materials attract the most interest because of their ability to activate and oxidize methane, as well as their lower price and higher abundance as compared to the conventionally used platinum group metal (PGM) catalysts. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] For stoichiometric engines, CoO x may increase the operational window of air-to-fuel ratio (lambda) by supplying its lattice oxygen for complete combustion. [4] For CH 4lean feeds, the oxide is active at relatively low temperatures with the combustion activation energies in the range of 60-80 kJ/mol.…”