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Platinum group metals (PGMs) are indispensable for the automobile, petrochemical, energy, and national defense industries. However, the mineral resources of PGMs are extremely scarce in China, and the contradiction is prominent between the supply and demand of the resources. Therefore, recycling PGMs becomes an important measure to ensure the safe supply of PGMs and support the high-quality development of related industries. This study analyzes the supply and application of PGMs, clarifies the supply and demand trend of the PGMs market, and sorts out the recycling technologies of PGMs. The hydrometallurgical process includes cyanidation as well as hydrogen chloride combined oxidant method. The pyrometallurgical process includes capture by lead,copper, matte, and iron. The research and application of the pyro-hydro-metallurgical recycling process for PGMs are elaborated from the aspects of the roasting-leaching, iron capture-acid leaching, and low-temperature iron capture-electrolysis-centrifugal extraction processes. The low-temperature iron capture-electrolysis-centrifugal extraction process follows the research idea of low-temperatureiron capture. Through the design of slags with a low melting point, the iron capture temperature is reduced from beyond 1800 ℃ to around 1400 ℃. The enriched Fe-PGM alloy is further enriched by electrolysis, and Pd, Pt, and Rh are successively obtained through centrifugal extraction and purification, realizing the short-process separation and purification of PGMs. This process has the advantages of green, high efficiency, and low cost. Focusing on the high-quality development of the PGM recycling industry, we propose the following suggestions: (1) conducting basic research and technical breakthroughs centering the entire process of PGM enrichment, separation and purification, as well as pollution prevention and control; (2) accelerating the construction of a full-chain standards system for PGM recycling and a green and low-carbon industrial ecological environment; and (3) improving the Internet Plus capabilities through the entire business links to realize the intellectualization of the whole recycling-processing-reuse process.

H2O in flue gas causes the deactivation of V2O5/TiO2 catalysts for selective catalytic reduction (SCR) of NOx with NH3 at low temperatures. Developing water resistance requires understanding the theoretical mechanism of H2O impact on the catalysts. The aim of this work was to clarify the adsorption process of H2O and the deactivation mechanism induced by H2O through density functional theory (DFT). The process of H2O adsorption was studied based on a modeled V2O5/TiO2 catalyst surface. It was found that H2O had a strong interaction with exposed titanium atoms. Water adsorption on the catalyst surface significantly alters the electronic structure of VOx sites, transforming Lewis acid sites into Brønsted acid sites. Exposed titanium sites contribute to the decrease of Lewis acidity via adsorbed water. Ab initio thermodynamic calculations show that H2O adsorption on V2O5/TiO2 is stable at low coverage but less favorable at high coverage. Adsorption of NH3 is the most critical step for the SCR of NOx, and the adsorption of H2O can hinder this process. The H2O coverage below 15% of adsorption sites could enhance the NH3 adsorption rate and have a limited effect on the acidity, while higher coverage impeded the adsorption ability of VOx sites. This work provided electron-scale insight into the adsorption impact of H2O on the surface of V2O5/TiO2 catalysts, presented thermodynamic analysis of the adsorption of H2O and NH3, paving the way for the exploration of V2O5/TiO2 catalysts with improved water resistance. [ABSTRACT FROM AUTHOR]

This study investigates the influence of super-fast heating rate and holding time on the microstructure and mechanical properties of dual-phase (DP) Fe-0.16C-1.4Mn sheet steel. Super-fast heating and cooling rates were achieved via induction heating and gas quenching. The results were also compared with those for a conventional low-speed heat treatment. The microstructures were characterized in detail using X-ray diffraction, scanning electron microscopy, electron backscatter diffraction, and electron probe microanalysis. The results showed that the layered structure of the DP Fe-0.16C-1.4Mn steel after super-fast heating was mainly composed of recrystallized ferrite, martensite clusters, and a small amount of residual austenite. Compared with the conventional method, super-fast heating significantly refined the grains and improved yield and tensile strength, but it slightly reduced the elongation. The fraction of martensite, which depends on the nucleation and growth behavior of austenite, was significantly affected by the heating rate and holding time. The DP structure of Fe-0.16C-1.4Mn steel had an atypical layered heterogeneous structure, with an uneven plastic strain between the two phases occurring during the deformation process, which is something that can improve fracture elongation.

H 2 O in flue gas causes the deactivation of V 2 O 5 /TiO 2 catalysts for selective catalytic reduction (SCR) of NO x with NH 3 at low temperatures. Developing water resistance requires understanding the theoretical mechanism of H 2 O impact on the catalysts. The aim of this work was to clarify the adsorption process of H 2 O and the deactivation mechanism induced by H 2 O through density functional theory (DFT). The process of H 2 O adsorption was studied based on a modeled V 2 O 5 /TiO 2 catalyst surface. It was found that H 2 O had a strong interaction with exposed titanium atoms. Water adsorption on the catalyst surface significantly alters the electronic structure of VO x sites, transforming Lewis acid sites into Brønsted acid sites. Exposed titanium sites contribute to the decrease of Lewis acidity via adsorbed water. Ab initio thermodynamic calculations show that H 2 O adsorption on V 2 O 5 /TiO 2 is stable at low coverage but less favorable at high coverage. Adsorption of NH 3 is the most critical step for the SCR of NO x , and the adsorption of H 2 O can hinder this process. The H 2 O coverage below 15% of adsorption sites could enhance the NH 3 adsorption rate and have a limited effect on the acidity, while higher coverage impeded the adsorption ability of VO x sites. This work provided electron-scale insight into the adsorption impact of H 2 O on the surface of V 2 O 5 /TiO 2 catalysts, presented thermodynamic analysis of the adsorption of H 2 O and NH 3 , paving the way for the exploration of V 2 O 5 /TiO 2 catalysts with improved water resistance.