Abstract: A positive active material comprising active material bulk particles and a coating layer of an oxide containing N element is disclosed, wherein the surface of the active material bulk particle is doped with M element to form a doped layer, and the content of the M element is 400 ppm to 3000 ppm, and the content of the M element gradually decreases from the outer surface of active material bulk particles towards the core direction; wherein the content of the N element in the coating layer is 100 ppm to 2000 ppm; wherein the average content of the N element per unit volume of the coating layer is greater than the average content of the M element per unit volume of the doped layer; wherein the M element and the N element are each independently selected from one or more of Mg, Ca, Ce, Ti, Zr, Al, Zn, and B.

Abstract: Disclosed is a method for preparing a heteropolyacid salt catalyst, comprising dissolving the lead compounds for each element to prepare a suspension and dispersion slurry of catalyst precursor, which comprises all of the catalyst components; drying the catalyst precursor, mixing them with an organic compound, molding, and calcining to produce the catalyst.

Abstract: Disclosed are a molybdenum based composite oxide catalyst, its preparation method and use. The catalyst has the following general formula: BiMoxMyNzOa; wherein M is one of V, Cr, Mn, Fe, Co, Ni and Cu, or a mixture of two or more of V, Cr, Mn, Fe, Co, Ni and Cu in any ratio; N is one of Na, K, Cs, Ca and Ba, or a mixture of two or more of Na, K, Cs, Ca and Ba in any ratio; x=0.5˜20; y=0.05˜20; z=0.01˜5; a is a number satisfying the valance of each atom. The catalyst is prepared by the following method: firstly mixing a certain amount of the lead metal oxides according to the chemical proportion and then grinding the mixture with high-energy ball milling for a period of time to obtain the molybdenum based composite oxide catalyst. The catalyst exhibits excellent performance when using for preparation of butadiene by oxidative dehydrogenation of butene, and the preparation process is simple, controllable, and repeatable.

Abstract: A method for preparing methacrolein from t-butanol, specifically a method for preparing methacrolein by using t-butanol as a starting material, is disclosed, comprising passing the starting material through a fixed bed reactor filled with catalyst, wherein the fixed bed reactor is divided to n reaction zones from the inlet of the starting material to the outlet of the starting material and each zone is filled with catalysts of different catalytic activities; wherein the catalytic activity of the catalyst in the first reaction zone is higher than the catalytic activity of the catalyst in the second reaction zone, and the catalytic activity of the catalyst is gradually increased from the second reaction zone to the last reaction zone; and n is an integer between 3 to 10.

Abstract: Disclosed is a method for preparing a heteropolyacid salt catalyst, comprising dissolving the lead compounds for each element to prepare a suspension and dispersion slurry of catalyst precursor, which comprises all of the catalyst components; drying the catalyst precursor, mixing them with an organic compound, molding, and calcining to produce the catalyst.

Abstract: A method for preparing methacrolein from t-butanol, specifically a method for preparing methacrolein by using t-butanol as a starting material, is disclosed, comprising passing the starting material through a fixed bed reactor filled with catalyst, wherein the fixed bed reactor is divided to n reaction zones from the inlet of the starting material to the outlet of the starting material and each zone is filled with catalysts of different catalytic activities; wherein the catalytic activity of the catalyst in the first reaction zone is higher than the catalytic activity of the catalyst in the second reaction zone, and the catalytic activity of the catalyst is gradually increased from the second reaction zone to the last reaction zone; and n is an integer between 3 to 10.

Abstract: Disclosed are a ferrite catalyst, its preparation method and use. The catalyst has a formula of FeAaDbOc, wherein A is Mg atom, Zn atom or a mixture of these two atoms in any ratio; D is one or more atoms elected from the group consisting of Ni, Co, Mn, Ca, Mo or V; a=0.01˜0.6; b=0˜0.30; c is a number satisfying the valence. The catalyst is prepared by a method comprising mixing the metal oxide precursors according to the chemical ratios and grinding by ball milling to obtain the ferrite catalyst. The catalyst exhibits excellent activity and selectivity when used in a reaction for preparing butadiene by oxidative dehydrogenation of butene. The preparation of the catalyst is simple, controllable and well repeatable, with reduced waste water and waste gas during preparation.

Abstract: Disclosed are a molybdenum based composite oxide catalyst, its preparation method and use. The catalyst has the following general formula: BiMoxMyNzOa; wherein M is one of V, Cr, Mn, Fe, Co, Ni and Cu, or a mixture of two or more of V, Cr, Mn, Fe, Co, Ni and Cu in any ratio; N is one of Na, K, Cs, Ca and Ba, or a mixture of two or more of Na, K, Cs, Ca and Ba in any ratio; x=0.5˜20; y=0.05˜20; z=0.0˜15; a is a number satisfying the valance of each atom. The catalyst is prepared by the following method: firstly mixing a certain amount of the lead metal oxides according to the chemical proportion and then grinding the mixture with high-energy ball milling for a period of time to obtain the molybdenum based composite oxide catalyst. The catalyst exhibits excellent performance when using for preparation of butadiene by oxidative dehydrogenation of butene, and the preparation process is simple, controllable, and repeatable.