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This work gives an insight into combined experimental and DFT study of water gas shift reaction on Ni catalysts at moderately elevated temperatures. The relative reactivity of surface adsorbed species O*, OH* and H* with CO* and their catalytic consequence in reaction mechanism and kinetics was studied. DFT investigation and microkinetic analysis pointed out that the favorable reaction pathway depends on the relative reactivity of O*, OH* and H* with CO* on the surface. It rationalizes the experimental observed changes in kinetics with hydrogen pressure. • Experimental and DFT study leads to WGS reaction mechanism insight on Ni catalyst. • It reveals dependency of the reaction mechanism and kinetics on hydrogen pressure. • Reaction pathway is dependent on relative reactivity of O*, OH* and H* with CO*. • DFT studies rationalize the experimental changes in kinetics with H 2 pressure. This paper presents a combined experimental and density functional theory study of the relative reactivity of surface species O*, OH*, and H* with CO* on nickel catalysts and their catalytic consequence in reaction mechanism and kinetics of water gas shift reaction. The kinetic study illustrates the hydrogen reaction order changes from 0.5 at relatively low hydrogen pressures to -1 at high hydrogen pressures. Detailed kinetic analysis indicated a hydrogen-induced change of the corresponding reaction pathway from hydrogen assisted CO activation to the redox mechanism with CO*+O* as a rate-determining step. The DFT investigation revealed that the surrounding surface H* atoms destabilize more significantly O* adsorption than H* adsorption, thus enhance more the reactivity of O* than H* towards reaction with CO* at high H* coverage. This kinetic study provides an insightful depiction for the future study of CO activation on other transition metals and the catalyst development for WGS reaction. [ABSTRACT FROM AUTHOR]

We successfully realized the directional construction of Pt-Mn 2 O 3 interfacial sites (by the combination of in-situ doping and impregnation methods) to boost selective oxidation of ethylene glycol under mild conditions. It is found that the pre-distribution of Mn 2 O 3 inside support unexpectedly induced the formation of Pt-Mn 2 O 3 interfacial active sites with strong electron coupling effect, leading to an unprecedented glycolic acid oxidation activity (turnover frequency: 3196.9 h−1) and glycolic acid yield (86.4 %). • Enhanced catalytic performance of ethylene glycol oxidation was achieved. • Strong electron coupling effect was revealed in the Pt-Mn interface. • Quantitative analysis of the intrinsic active sites was performed. • The promotion role of Pt-Mn interfacial on reaction mechanism was correlated. Rational design of desirable active sites is still a grand challenge for the efficient conversion of polyols to value-added products. Herein, we successfully constructed the Pt-Mn 2 O 3 interfacial sites rather than Pt-MnO x solid solution to boost selective oxidation of ethylene glycol to glycolic acid under mild conditions. X-ray absorption spectroscopy and high-resolution transmission electron microscope revealed that the pre-distribution of Mn 2 O 3 inside support unexpectedly induced the formation of Pt-Mn 2 O 3 interfacial active sites with strong electron coupling effect, leading to an unprecedented catalytic activity (turnover frequency: 3196.9 h−1) and glycolic acid yield (86.4 %). In addition, quantitative analysis of the intrinsic active sites was performed, and a "volcano-shape" relationship was established between initial reaction rate and Pt/Mn ratio. Moreover, the structure-dependent reaction kinetics and density functional theory calculation revealed that the synergistic effect between the Mn 2 O 3 redox cycle and Pt promotes the adsorption of ethylene glycol and the activation of C H bond, resulting in the lower activation energy of ethylene glycol oxidation. The outcome of this work offers a promising avenue for the direct construction of efficient Pt-based catalysts with desired active sites. [ABSTRACT FROM AUTHOR]