Temperature-programmed reduction oxygen adsorption

The pros and cons of oxidative dehydrogenation for alkene synthesis using doped cerianites as solid oxygen carriers are studied. The hydrogen oxidation properties of a set of ten doped cerianite catalysts (Ce0.9X0.1Oy, where X = Bi, In, La, Mo, Pb, Sn, V, W, Y, and Zr) are examined under cyclic redox conditions. X-ray diffraction, X-ray photoelectron spectroscopy, adsorption measurements, and temperature programmed reduction are used to try and clarify structure-activity relationships and the different dopant effects. 

Lieske, H., Lietz, G., Spindler, H. Volter, J. Reactions of platinum in oxygen- and hydrogen-treated Pt/lgammal-AljOj catalysts I. Temperature-programmed reduction, adsorption, and redispersion of platinum. Journal of Catalysis 81, 8-16 (1983). 

The primaiy emphasis in this review article is to showcase the use of LEISS to examine the outermost layers of Pt-Co alloys in order to correlate interfacial composition with electrocatalytic reactivity towards oxygen reduction. In some instances, it is desirable to compare the properties of the outermost layer with those of the (near-surface) bulk an example is when it becomes imperative to explain the unique stability the alloyed Co under anodic-oxidation potentials. In such cases. X-ray photoelectron spectroscopy and temperature-programmed desorption may be employed since both methods are also able to generate information on the electronic (binding-energy shift measurements by XPS) and thermochemical (adsorption enthalpy determinations by TPD) properties at the sub-surface. However, an in-depth discourse on these and related aspects was not intended to be part of this review article. 

AgNaZSM-5 catalysts were investigated for the selectively catalytic reduction of NO by methane in the excess of oxygen. It was clearly depicted that the conversion rate of NO to N2 had a linear dependence on the silver loading (4.32 13.64%), which indicated that all silver species in the zeolite were active for the CH4-SCR reaction. The presence of excessive oxygen in the feed gas favored the CH4-SCR reaction. The temperature programmed desorption profiles in He and 2%CH4/He after the co-adsorption of NO and O2 revealed that surface nitrates were formed on silver catalyst, and could be effectively reduced by methane... 

Moreover, the application of oxygen chemisorption techniques assumes that reduced surface transition metal species are responsible for the catalytic activity [4], However, detailed investigation through successive cycles of reactant adsorption and temperature programmed surface reaction (TPSR) without reoxidation of the surface showed the deactivation of molybdenum and vanadium oxide-based catalysts upon reduction [9]. These results clearly indicate that oxidized surface metal oxide species are the active surface sites to be investigated. 

---