A method for preparing an active catalyst for high-efficiency denitration is disclosed. The method includes: a catalyst raw material is charged into a denitration reactor, NH.sub.3 and an inert gas are introduced and then heating is performed, and the temperature is held and then natural cooling is performed, thereby obtaining the catalyst. The active catalyst can greatly improve the denitration activity in low temperature range, and can not only improve the denitration efficiency under the condition without SO.sub.2 and H.sub.2O, but also can improve the denitration efficiency under the condition with both SO.sub.2 and H.sub.2O. The service life of the catalyst is prolonged under the premise of not changing the existing catalyst preparation process, and the economic benefit is significant. The denitration efficiency of a powder catalyst can be increased by 25%, and the denitration efficiency of a honeycombed catalyst or a corrugated catalyst can be increased by 20%.

Provided is a composition comprising alumina, the alumina being surface-modified with a perovskite type compound of formula (I); wherein formula (I) is defined by A.sub.x-yA′.sub.yB.sub.1. .sub.zB′.sub.zO.sub.3; where: A is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd; A′ is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd; B is an ion of a metal selected from the group consisting of Cu, Mn, Mo, Co, Fe, Ni, Cr, Ti, Zr, Al, Ga, Sc, Nb, V, W, Bi, Zn, Sn, Pt, Rh, Pd, Ru, Au, Ag, and Ir; B′ is an ion of a metal selected from the group consisting of Cu, Mn, Mo, Co, Fe, Ni, Cr, Ti, Zr, Al, Ga, Sc, Nb, V, W, Bi, Zn, Sn, Pt, Rh, Pd, Ru, Au, Ag, and Ir; x is from 0.7 to 1; y is from 0 to 0.5; and z is from 0 to 0.5.

Provided is a composition comprising alumina, the alumina being surface-modified with a perovskite type compound of formula (I); wherein formula (I) is defined by A.sub.x-yA′.sub.yB.sub.1. .sub.zB′.sub.zO.sub.3; where: A is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd; A′ is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd; B is an ion of a metal selected from the group consisting of Cu, Mn, Mo, Co, Fe, Ni, Cr, Ti, Zr, Al, Ga, Sc, Nb, V, W, Bi, Zn, Sn, Pt, Rh, Pd, Ru, Au, Ag, and Ir; B′ is an ion of a metal selected from the group consisting of Cu, Mn, Mo, Co, Fe, Ni, Cr, Ti, Zr, Al, Ga, Sc, Nb, V, W, Bi, Zn, Sn, Pt, Rh, Pd, Ru, Au, Ag, and Ir; x is from 0.7 to 1; y is from 0 to 0.5; and z is from 0 to 0.5.

Provided is a composition comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite type compound of formula (I); wherein formula (I) is defined by A.sub.x-yA′.sub.yB.sub.1-zB′.sub.zO.sub.3; where: A is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd; A′ is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd; B is an ion of a metal selected from the group consisting of Cu, Mn, Mo, Co, Fe, Ni, Cr, Ti, Zr, Al, Ga, Sc, Nb, V, W, Bi, Zn, Sn, Pt, Rh, Pd, Ru, Au, Ag, and Ir; B′ is an ion of a metal selected from the group consisting of Cu, Mn, Mo, Co, Fe, Ni, Cr, Ti, Zr, Al, Ga, Sc, Nb, V, W, Bi, Zn, Sn, Pt, Rh, Pd, Ru, Au, Ag, and Ir; x is from 0.7 to 1; y is from 0 to 0.5; and z is from 0 to 0.5.

Provided is a composition comprising a ceria-zirconia mixed oxide, the ceria-zirconia mixed oxide being surface-modified with a perovskite type compound of formula (I); wherein formula (I) is defined by A.sub.x-yA′.sub.yB.sub.1-zB′.sub.zO.sub.3; where: A is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd; A′ is an ion of a metal selected from the group consisting of Li, Na, K, Cs, Mg, Sr, Ba, Ca, Y, La, Ce, Pr, Nd, and Gd; B is an ion of a metal selected from the group consisting of Cu, Mn, Mo, Co, Fe, Ni, Cr, Ti, Zr, Al, Ga, Sc, Nb, V, W, Bi, Zn, Sn, Pt, Rh, Pd, Ru, Au, Ag, and Ir; B′ is an ion of a metal selected from the group consisting of Cu, Mn, Mo, Co, Fe, Ni, Cr, Ti, Zr, Al, Ga, Sc, Nb, V, W, Bi, Zn, Sn, Pt, Rh, Pd, Ru, Au, Ag, and Ir; x is from 0.7 to 1; y is from 0 to 0.5; and z is from 0 to 0.5.

A nanocomposite catalyst includes a support, a multiplicity of nanoscale metal oxide clusters coupled to the support, and one or more metal atoms coupled to each of the nanoscale metal oxide clusters. Fabricating a nanocomposite catalyst includes forming nanoscale metal oxide clusters including a first metal on a support, and depositing one or more metal atoms including a second metal on the nanoscale metal oxide clusters. The nanocomposite catalyst is suitable for catalyzing reactions such as CO oxidation, water-gas-shift, reforming of CO.sub.2 and methanol, and oxidation of natural gas.

Methods of depolymerizing polyolefin-based material into useful petrochemical products using supported metal oxides and heat are described. The supported metal oxides improve the depolymerization reaction by decreasing the half time for the depolymerization, which results in a higher depolymerization rate and a shorter residence time in the depolymerization unit, allowing for a predictable depolymerization reaction, and decreasing the branching or aromatic formations in the product.

A high-adsorption-performance nanofiber filter medium includes a support material and a composite nanofiber filtration layer that includes multiple nanometer composite nanofiber layers deposited and stacked on the support material. The nanometer composite nanofiber layer includes first, second, and third nano-powder composite nanofibers, which are uniformly mixed by means of an airflow or are sequentially laminated to form the nanometer composite nanofiber layer. The nanometer composite nanofiber layer formed through sequential lamination includes first, second, and third nanofiber layers. The first nanofiber layer includes multiple first nano-powder composite nanofibers. The second nanofiber layer is stacked on the first nanofiber layer and includes multiple second nano-powder composite nanofibers. The third nanofiber layer is stacked on the second nanofiber layer and includes multiple third nano-powder composite nanofibers. The composite nanofiber filtration layer is formed of multiple nanometer composite nanofiber layers, so that the high-adsorption-performance nanofiber air filter medium shows improved performance.

A high-adsorption-performance nanofiber filter medium includes a support material and a composite nanofiber filtration layer that includes multiple nanometer composite nanofiber layers deposited and stacked on the support material. The nanometer composite nanofiber layer includes first, second, and third nano-powder composite nanofibers, which are uniformly mixed by means of an airflow or are sequentially laminated to form the nanometer composite nanofiber layer. The nanometer composite nanofiber layer formed through sequential lamination includes first, second, and third nanofiber layers. The first nanofiber layer includes multiple first nano-powder composite nanofibers. The second nanofiber layer is stacked on the first nanofiber layer and includes multiple second nano-powder composite nanofibers. The third nanofiber layer is stacked on the second nanofiber layer and includes multiple third nano-powder composite nanofibers. The composite nanofiber filtration layer is formed of multiple nanometer composite nanofiber layers, so that the high-adsorption-performance nanofiber air filter medium shows improved performance.

A catalyst system includes an oxygen storage and release material that has at least one compound of the structure YMO.sub.3+δ, where M is selected from Mn, Co, Cu, Ce, Ti, Ni, Zn, Fe and any combination thereof, and where δ is ≥0. The oxygen storage and release material is configured to allow absorption and release oxygen depending on the conditions of a reagent stream such that sufficient oxygen is maintained for the catalytic removal of at least one of incompletely combusted hydrocarbons, CO, and NO. The catalyst system is useful in a catalytic converter such that oxygen is supplied under rich combustion conditions in an engine upstream of the catalytic converter inlet and oxygen is adsorbed and absorbed under lean rich combustion conditions in the engine.