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Methanol dehydrogenation (MD) is highly valuable in hydrogen energy production, and the introduction of nonmetals has received much attention to improve the activity and stability of the MD catalysts, but the understanding of the role of non-metallic elements in catalyzing the MD reaction is rather limited. Density functional theory (DFT) is employed to investigate the mechanism of methanol dehydrogenation on RuxPy surfaces. In this work, the P element is introduced into the Ru-based catalyst to obtain dispersed Ru sites and RuxPy (x/y = 2 : 1, 1 : 1, and 1 : 2) catalysts are designed. CH3OH adsorption, electronic structure of the catalyst, energy barriers for carbon accumulation reactions, and the mechanism of methanol decomposition are systematically calculated. The results of the effective reaction barrier (E effa) reveal that the order of the activity of the MD reaction is RuP(112) > Ru(0001) > Ru2P(210) > RuP2(110). The most preferable pathway on RuP(112) is pathway 1 (CH3OH* → CH3O* → CH2O* → CHO* → CO*). After the introduction of P, the weakened CO adsorption enhanced the resistance of catalysts to CO poisoning, and the activation energy of the carbon accumulation reaction increased, indicating that the anti-coking ability of the catalysts is improved. This theoretical study contributes to the design and modulation of highly active and stable metal catalysts for MD reactions. [ABSTRACT FROM AUTHOR]

The complex interaction between shock waves and two-phase interfaces can generate cavitation. In this study, the cavitation induced by the high-speed jet impact on the water surface was investigated. The mixture fluid is modeled using the barotropic equation of state under the framework of the two-phase flow model, which can describe the mixture of air, water, and vapor with any proportion. Through constructing a 1D Riemann problem for the impact-induced cavitation phase transition, it indicates that the coupling effect of multiple rarefaction waves emitted from the two-phase interface is responsible for the cavitation phase transition inside the liquid. Then, a 3D (three-dimensional) simulation regarding the impact of a high-speed jet on the water surface was conducted and validated against previous experiments that captured the cavitation phase transition phenomenon in the central region after the jet impact. The 3D simulation results revealed the spatial structure and development process of shock waves in detail. The coupling effects of shock waves and two-phase interfaces generate a ring-shaped rarefaction wave, which develops radially inward and superimposes, resulting in the formation of acorn-shaped cavitation bubble nuclei inside the water. The 3D simulation can provide spatial shock/rarefaction wave structures and internal flow details that have never been obtained in experiments, such as shock generation and propagation, rarefaction wave generation and center convergence, and the internal structure of acorn-shaped cavitation nucleation. Furthermore, the influence of the jet velocity on the cavitation intensity was analyzed, and a quantitative relationship was provided. [ABSTRACT FROM AUTHOR]