Abstract: Methods of making an iron based catalyst using microwave hydrothermal synthesis are provided. The methods include dissolving iron(III) nitrate, Fe(NO3)3, in an organic solvent to form a solution. Once dissolved, the methods include a step of neutralizing the solution with an alkaline mineralizing agent to obtain a precipitate. The solution with the precipitate is then subjected to microwave radiation to cause a temperature gradient and a hydrothermal crystallization process to form a synthesized product. The synthesized product is subsequently separated from the mineralizing agent. The method includes washing and drying the synthesized product to obtain particles of sodium iron oxide (NaFeO2) catalyst that can be used as a composition for a passive NOx adsorber. A two-stage NOx abatement device for removal of NOx from an exhaust gas stream during a cold start operation of an internal combustion engine is also provided.

Abstract: A co-catalyst system for the removal of NOx from an exhaust gas stream has a layered oxide and a spinel of formula Ni0.15Co0.85CoAlO4. The system converts to nitric oxide to nitrogen gas with high product specificity. The layered oxide is configured to convert NOx in the exhaust gas stream to an N2O intermediate, and the spinel is configured to convert the N2O intermediate to N2.

Abstract: Passive NOx adsorption (PNA) compositions have a formula Pd—NiFe2O4 wherein Pd represents a palladium component, such as palladium oxide, that is adsorbed on surfaces of the nickel ferrite. Such compositions can be synthesized by wet impregnation of nickel ferrite with a palladium salt, and exhibit efficient NOx adsorption at low temperature, with NOx desorption occurring predominantly at high temperature. Two-stage NOx abatement catalysts, effective under engine cold start conditions, include a PNA composition upstream from an NOx conversion catalyst.

Abstract: NOx abatement compositions include cobalt oxide (Co3O4) doped with cerium, and having an overall formula Co3-xCexO4, with cerium occupying tetrahedral and/or octahedral sites in the spinel structure. The NOx abatement compositions possess NOx storage and NOx direct decomposition activity. Dual stage NOx abatement devices include an upstream portion having the NOx abatement composition to adsorb and store NOx at low temperature, and then release the NOx at higher temperature to a downstream catalytic conversion portion.

Abstract: NOx abatement compositions have a formula MxCu1-xFe2O4, wherein M is a substitution metal cation that can be any of cobalt, nickel, and zinc; and x is greater than zero and less than one. Such compositions can serve as direct decomposition catalysts and/or passive adsorption/storage components. Methods for synthesizing the compositions include alkaline precipitation of solutions containing nitrate salts of copper, iron, and at least one of cobalt, nickel, and zinc.

Abstract: Active catalysts for the treatment of a low temperature exhaust gas stream are provided containing copper oxides dispersed on a spinel oxide for the direct, lean removal of nitrogen oxides from the exhaust gas stream. The low temperature, direct decomposition is accomplished without the need of a reductant molecule. In one example, CuOx may be dispersed as a monolayer on a metal oxide support, such as Co3O4 spinel oxide, synthesized using an incipient wetness impregnation technique. The CuOx/Co3O4 catalyst system converts nitric oxide to nitrogen gas with high product specificity, avoiding the production of a significant concentration of the undesirable N2O product.

Abstract: A co-catalyst system for the removal of NOx from an exhaust gas stream has a layered oxide and a spinel of formula Ni0.15Co0.85CoAlO4. The system converts to nitric oxide to nitrogen gas with high product specificity. The layered oxide is configured to convert NOx in the exhaust gas stream to an N2O intermediate, and the spinel is configured to convert the N2O intermediate to N2.

Abstract: A co-catalyst system for the removal of NOx from an exhaust gas stream has a layered oxide and a spinel of formula Ni0.15Co0.85CoAlO4. The system converts to nitric oxide to nitrogen gas with high product specificity. The layered oxide is configured to convert NOx in the exhaust gas stream to an N2O intermediate, and the spinel is configured to convert the N2O intermediate to N2.

Abstract: A nitrogen oxide (NOx) reduction catalyst that includes a transition metal tungstate having the formula: MWO4 wherein M is selected from the group consisting of Mn, Fe, Co, Ni, and Cu. The catalyst may be utilized in various environments including oxygen rich and oxygen deficient environments.

Abstract: Active catalysts for the treatment of a low temperature exhaust gas stream are provided containing palladium oxides dispersed on a spinel oxide for the direct, lean removal of nitrogen oxides from the exhaust gas stream. The low temperature (from about 400° C. to about 650° C.), direct decomposition is accomplished without the need of a reductant molecule. In one example, PdO may be dispersed on a surface of a metal oxide support, such as Co3O4 spinel oxide, synthesized using wet impregnation techniques. The PdO/Co3O4 catalyst system converts nitric oxide to nitrogen gas with high product specificity, avoiding the production of a significant concentration of the undesirable N2O product.

Abstract: Active catalysts for the treatment of a low temperature exhaust gas stream are provided containing potassium (K) dispersed on a spinel oxide for the direct, lean removal of nitrogen oxides from the exhaust gas stream. The low temperature (from about 400° C. to about 650° C.), direct decomposition is accomplished without the need of a reductant molecule. In one example, K may be dispersed on a surface of a metal oxide support, such as NiFe2O4 spinel oxide, synthesized using wet impregnation techniques. The K/NiFe2O4 catalyst system converts nitric oxide to nitrogen gas with high product specificity, up to 100%, avoiding the production of a significant concentration of the undesirable N2O product.

Abstract: Active catalysts for the treatment of a low temperature exhaust gas stream are provided containing potassium (K) dispersed on a spinel oxide for the direct, lean removal of nitrogen oxides from the exhaust gas stream. The low temperature (from about 400° C. to about 650° C.), direct decomposition is accomplished without the need of a reductant molecule. In one example, K may be dispersed on a surface of a metal oxide support, such as NiFe2O4 spinel oxide, synthesized using wet impregnation techniques. The K/NiFe2O4 catalyst system converts nitric oxide to nitrogen gas with high product specificity, up to 100%, avoiding the production of a significant concentration of the undesirable N2O product.

Abstract: A process of forming a direct NOx catalyst includes the steps of providing a palladium salt, providing a silicon oxide support material, mixing the palladium salt and silicon oxide support material in an aqueous solution, evaporating the aqueous solution forming a solid, calcining the solid, and then exposing the calcined solid to a pretreatment gas at a specified temperature to form a desired direct NOx catalyst. When the process includes exposing the calcined solid to helium gas at a temperature of from 650 to 1000° C. the catalyst may include a mixture of palladium and palladium oxide having a particle size of from 5 to 150 nm where the palladium particles are discrete particles without sintering and the mixture may include 41% by weight palladium oxide and 51% by weight palladium metal.

Abstract: Active catalysts for the treatment of a low temperature exhaust gas stream are provided containing palladium oxides dispersed on a spinel oxide for the direct, lean removal of nitrogen oxides from the exhaust gas stream. The low temperature (from about 400° C. to about 650° C.), direct decomposition is accomplished without the need of a reductant molecule. In one example, PdO may be dispersed on a surface of a metal oxide support, such as Co3O4 spinel oxide, synthesized using wet impregnation techniques. The PdO/Co3O4 catalyst system converts nitric oxide to nitrogen gas with high product specificity, avoiding the production of a significant concentration of the undesirable N2O product.

Abstract: Active catalysts for the treatment of a low temperature exhaust gas stream are provided containing copper oxides dispersed on a spinel oxide for the direct, lean removal of nitrogen oxides from the exhaust gas stream. The low temperature, direct decomposition is accomplished without the need of a reductant molecule. In one example, CuOx may be dispersed as a monolayer on a metal oxide support, such as Co3O4 spinel oxide, synthesized using an incipient wetness impregnation technique. The CuOx/Co3O4 catalyst system converts nitric oxide to nitrogen gas with high product specificity, avoiding the production of a significant concentration of the undesirable N2O product.

Abstract: A co-catalyst system for the removal of NOx from an exhaust gas stream has a layered oxide and a spinel of formula Ni0.15Co0.85CoAlO4. The system converts to nitric oxide to nitrogen gas with high product specificity. The layered oxide is configured to convert NOx in the exhaust gas stream to an N2O intermediate, and the spinel is configured to convert the N2O intermediate to N2.

Abstract: Active catalysts for the treatment of a low temperature exhaust gas stream are provided for the direct decomposition removal of NOx from an exhaust gas stream. The catalyst system may include a mixed oxide composition including cerium oxide and nickel oxide CeO2—NiO. The exhaust gas stream may be provided at a temperature of from about 400° C. to about 650° C. Methods for making the catalyst include co-precipitation techniques, using KOH as a precipitating agent. The catalyst system is configured to catalyze a decomposition of the NOx to generate N2 without the presence of a reductant. The catalyst may be a cubic structure, with nickel incorporated in a cubic lattice of cerium. The catalyst composition may be represented as Ce0.5Ni0.5O2.

Abstract: A nitrogen oxide (NOx) reduction catalyst that includes a transition metal tungstate having the formula: MWO4 wherein M is selected from the group consisting of Mn, Fe, Co, Ni, and Cu. The catalyst may be utilized in various environments including oxygen rich and oxygen deficient environments.

Abstract: A noble metal-free lanthanum transition metal perovskite catalyst material. The noble metal-free lanthanum transition metal perovskite catalyst material may include a two phase mixture of a lanthanum transition metal perovskite with an alkali or alkaline earth metal carbonate, a lanthanum transition metal perovskite doped with an alkali or alkaline earth metal, or a combination thereof. The lanthanum transition metal perovskite catalyst material provides direct decomposition of NOx into N2 and O2 without the presence of a noble metal and in the presence of excess O2.

Abstract: A process of forming a direct NOx catalyst includes the steps of providing a palladium salt, providing a silicon oxide support material, mixing the palladium salt and silicon oxide support material in an aqueous solution, evaporating the aqueous solution forming a solid, calcining the solid, and then exposing the calcined solid to a pretreatment gas at a specified temperature to form a desired direct NOx catalyst. When the process includes exposing the calcined solid to helium gas at a temperature of from 650 to 1000° C. the catalyst may include a mixture of palladium and palladium oxide having a particle size of from 5 to 150 nm where the palladium particles are discrete particles without sintering and the mixture may include 41% by weight palladium oxide and 51% by weight palladium metal.