A process for producing a silver-based epoxidation catalyst, comprising i) impregnating a particulate porous refractory support with a first aqueous silver impregnation solution comprising silver ions and an aminic complexing agent selected from amines, alkanolamines and amino acids; ii) converting at least part of the silver ions impregnated on the refractory support to metallic silver by heating while directing a stream of a first gas over the impregnated refractory support to obtain an intermediate catalyst, wherein the first gas comprises at least 5 vol.-% oxygen; iii) impregnating the intermediate catalyst with a second aqueous silver impregnation solution comprising silver ions, an aminic complexing agent selected from amines, alkanolamines and amino acids, and one or more transition metal promoters, in particular rhenium; and iv) converting at least part of the silver ions impregnated on the intermediate catalyst to metallic silver by heating while directing a stream of a second gas over the impregnated intermediate catalyst to obtain the epoxidation catalyst, wherein the second gas comprises at most 2.0 vol.-% oxygen, wherein the impregnated refractory support and the impregnated intermediate catalyst are each heated to a temperature of 200 to 800° C. The process of the invention surprisingly allows for obtaining a catalyst with high selectivity in a cost-efficient manner. The invention also relates to a silver-based epoxidation catalyst obtainable by such a process, and to a process for producing an alkylene oxide by gas-phase oxidation of an alkylene, comprising reacting an alkylene and oxygen in the presence of a silver-based epoxidation catalyst obtainable by the above process.

A process for producing a silver-based epoxidation catalyst, comprising i) impregnating a particulate porous refractory support with a first aqueous silver impregnation solution comprising silver ions and an aminic complexing agent selected from amines, alkanolamines and amino acids; ii) converting at least part of the silver ions impregnated on the refractory support to metallic silver by heating while directing a stream of a first gas over the impregnated refractory support to obtain an intermediate catalyst, wherein the first gas comprises at least 5 vol.-% oxygen; iii) impregnating the intermediate catalyst with a second aqueous silver impregnation solution comprising silver ions, an aminic complexing agent selected from amines, alkanolamines and amino acids, and one or more transition metal promoters, in particular rhenium; and iv) converting at least part of the silver ions impregnated on the intermediate catalyst to metallic silver by heating while directing a stream of a second gas over the impregnated intermediate catalyst to obtain the epoxidation catalyst, wherein the second gas comprises at most 2.0 vol.-% oxygen, wherein the impregnated refractory support and the impregnated intermediate catalyst are each heated to a temperature of 200 to 800° C. The process of the invention surprisingly allows for obtaining a catalyst with high selectivity in a cost-efficient manner. The invention also relates to a silver-based epoxidation catalyst obtainable by such a process, and to a process for producing an alkylene oxide by gas-phase oxidation of an alkylene, comprising reacting an alkylene and oxygen in the presence of a silver-based epoxidation catalyst obtainable by the above process.

Provided is a post-treatment method and system for a core-shell catalyst, which relate to the field of fuel cell materials. The post-treatment method of the present disclosure includes the following steps: a core-shell catalyst is added into an electrolyte solution containing citric acid or ethylenediamine tetraacetic acid, a gas containing oxygen is introduced into the electrolyte solution followed by stirring for a predetermined reaction time, the open circuit potential of the reactor base is recorded during the reaction time, and the open circuit potential should stabilize at 0.90˜1.0 V vs. RHE when the reaction is completed. The molar ratio of citric acid or ethylenediamine tetraacetic acid to platinum of the core-shell catalyst is 10 to 1000:1. A percentage of oxygen in the gas is 10 to 100% by volume. The post-treatment method of the present disclosure can significantly improve the platinum mass activity and PGM mass activity and durability of core-shell catalyst.

Disclosed are a photocatalyst and application thereof in environmentally friendly photocatalytic treatment of a power battery. The photocatalyst is obtained by loading Ag-TaON on a hollow glass microsphere, wherein a mass ratio of the Ag-TaON to the hollow glass microsphere is 1: 5 to 10. According to the invention, the Ag-TaON and the hollow glass microsphere are compounded, the hollow glass microsphere has better light permeability, which avoids mutual shielding between catalysts, such that the photocatalyst filled in a reactor is fully excited, which is capable of effectively improving a light utilization rate, thus improving the catalytic conversion efficiency of the photocatalyst.

Disclosed are a photocatalyst and application thereof in environmentally friendly photocatalytic treatment of a power battery. The photocatalyst is obtained by loading Ag-TaON on a hollow glass microsphere, wherein a mass ratio of the Ag-TaON to the hollow glass microsphere is 1: 5 to 10. According to the invention, the Ag-TaON and the hollow glass microsphere are compounded, the hollow glass microsphere has better light permeability, which avoids mutual shielding between catalysts, such that the photocatalyst filled in a reactor is fully excited, which is capable of effectively improving a light utilization rate, thus improving the catalytic conversion efficiency of the photocatalyst.

Fluidizable catalysts for the gas phase oxygen-free oxidative dehydrogenation of alkanes, such as propane, to corresponding olefins, such as propylene. The catalysts comprise 5-20% by weight per total catalyst weight of one or more vanadium oxides (VO.sub.x), such as V.sub.2O.sub.5. The dehydrogenation catalysts are disposed on an alumina support that is modified with calcium oxide to influence characteristics of lattice oxygen at the catalyst surface. Various methods of preparing and characterizing the catalyst as well as methods for the gas phase oxygen free oxidative dehydrogenation of alkanes, such as propane, to corresponding olefins, such as propylene, with improved alkane conversion and olefin product selectivity are also disclosed.

A method for synthesis of PtNi smooth surface core/shell particles or Nano cages and porous nanocages from segregated nanoparticles.

A method for synthesis of PtNi smooth surface core/shell particles or Nano cages and porous nanocages from segregated nanoparticles.

Zeolites having highly dispersed bimetallic clusters, uniformly distributed in size and composition, encapsulated therein are disclosed. Metal encapsulation and alloying is conferred by introducing ligated metal cation precursors into zeolite synthesis gels, which are subsequently crystallized hydrothermally to form zeolites with metal cations occluded in the pores. The ligated cations are anchored to the zeolite framework via siloxane bridges which enforces their uniform dispersion throughout the zeolite crystals. Treatment of the crystallized zeolites in O.sub.2 and then H.sub.2 forms bimetallic clusters, which remain narrowly distributed in size and composition.

Zeolites having highly dispersed bimetallic clusters, uniformly distributed in size and composition, encapsulated therein are disclosed. Metal encapsulation and alloying is conferred by introducing ligated metal cation precursors into zeolite synthesis gels, which are subsequently crystallized hydrothermally to form zeolites with metal cations occluded in the pores. The ligated cations are anchored to the zeolite framework via siloxane bridges which enforces their uniform dispersion throughout the zeolite crystals. Treatment of the crystallized zeolites in O.sub.2 and then H.sub.2 forms bimetallic clusters, which remain narrowly distributed in size and composition.