On the development of active and stable Pd–Co/γ-Al2O3 catalyst for complete oxidation of methane

The study is focused on the development of highly active and stable catalyst for combustion of methane by varying the Co loading and sequence of Pd–Co deposition onto γ-Al2O3. The catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), transmission electron microscopy (TEM) and reaction kinetics measurements. The role of the cobalt oxide phase is revealed to stabilize the palladium in oxidized state and to serve as reservoir of oxygen species. The reaction pathway over Pd–Co catalysts proceeds most probably through Mars–van Krevelen mechanism, the water molecules being in competition with the methane molecules for the PdO adsorption sites. Further experiments were carried out to prepare and test samples in the form of structured (monolithic) catalysts, based on anodic alumina and Fe–Cr–Al-alloy carriers, whereupon the composition of the active phase is the same as that of the most promising one, supported on crushed alumina particles.