In general, disclosed herein are methods for forming hydrogen by use of an ammonia decomposition catalyst system. For instance, a method can include contacting a catalyst system with an ammonia source at a temperature of about 450? C. or lower. The catalyst systems can include a support material and a trimetallic catalyst component carried on the support material and within a reactor. Disclosed catalyst systems can decompose ammonia at relatively low temperatures and can provide an efficient and cost-effective route to utilization of ammonia as a carbon-free hydrogen storage and generation material.

A method for making a catalyst comprises providing an initial compound having a perovskite lattice structure according to formula I

M.sup.1M.sup.2M.sup.3O.sub.3 FORMULA I,

where M.sup.1 is about 1 relative elemental ratio strontium (Sr); M.sup.2 is from greater than 0 to 0.7 relative elemental ratio and is selected from cobalt (Co), scandium (Sc), iron (Fe), nickel (Ni), and titanium (Ti); and M.sup.3 is 0.3 to 0.6 relative elemental ratio iridium (Ir). Initial exemplary compounds include SrSc.sub.0.5Ir.sub.0.5O.sub.3 (SSI) and SrCo.sub.0.5Ir.sub.0.5O.sub.3 (SCI). M.sup.1 and/or M.sup.2 cations are selectively leached from the initial compound to produce a catalyst having substantially increased catalytic performance. Cycling SSI or SCI in an acid produces SSI-H or SCI-H; cycling SSI or SCI in a base produces SSI-OH or SCI-OH. Dual-site metal leaching induced catalytic activity improvement by about 2 orders of magnitude, making reconstructed SrCo.sub.0.5Ir.sub.0.5O.sub.3 among the best-known catalysts for water oxidation in an acidic condition.

A method for making a catalyst comprises providing an initial compound having a perovskite lattice structure according to formula I

M.sup.1M.sup.2M.sup.3O.sub.3 FORMULA I,

where M.sup.1 is about 1 relative elemental ratio strontium (Sr); M.sup.2 is from greater than 0 to 0.7 relative elemental ratio and is selected from cobalt (Co), scandium (Sc), iron (Fe), nickel (Ni), and titanium (Ti); and M.sup.3 is 0.3 to 0.6 relative elemental ratio iridium (Ir). Initial exemplary compounds include SrSc.sub.0.5Ir.sub.0.5O.sub.3 (SSI) and SrCo.sub.0.5Ir.sub.0.5O.sub.3 (SCI). M.sup.1 and/or M.sup.2 cations are selectively leached from the initial compound to produce a catalyst having substantially increased catalytic performance. Cycling SSI or SCI in an acid produces SSI-H or SCI-H; cycling SSI or SCI in a base produces SSI-OH or SCI-OH. Dual-site metal leaching induced catalytic activity improvement by about 2 orders of magnitude, making reconstructed SrCo.sub.0.5Ir.sub.0.5O.sub.3 among the best-known catalysts for water oxidation in an acidic condition.

A process for producing methyl methacrylate, the process comprising contacting reactants comprising methacrolein, methanol and an oxygen-containing gas, under reaction conditions in the presence of a solid catalyst comprising palladium, bismuth and at least one third element X, where X is selected from the group consisting of P, S, Sc, V, Ga, Se, Y, Nb, Mo, La, Ce, and Nd, wherein the solid catalyst further comprises a support selected from at least one member of the group consisting of silica, alumina, calcium carbonate, active carbon, zinc oxide, titanium oxide and magnesium oxide.

A process for producing methyl methacrylate, the process comprising contacting reactants comprising methacrolein, methanol and an oxygen-containing gas, under reaction conditions in the presence of a solid catalyst comprising palladium, bismuth and at least one third element X, where X is selected from the group consisting of P, S, Sc, V, Ga, Se, Y, Nb, Mo, La, Ce, and Nd, wherein the solid catalyst further comprises a support selected from at least one member of the group consisting of silica, alumina, calcium carbonate, active carbon, zinc oxide, titanium oxide and magnesium oxide.

The present invention provides a catalyst for producing hydrogen and a preparing method thereof. The method includes the steps of adding a first metal source, a second metal source, a third metal source and a cerium source into a first organic solvent containing a surfactant to form a colloidal mixture, wherein a metal of the first metal source is a Group IIIB metal; a metal of the second metal source is selected from the group consisting of alkali metals, alkaline earth metals and Group IIIB metals, and a metal of the third metal source is a transition metal; calcining the colloidal mixture to form a metal solid solution; and allowing the metal solid solution to be carried on a carrier to obtain the catalyst. When the catalyst of the present invention is used for an ethanol oxidation reformation, the reaction temperature of the ethanol oxidation reformation can be significantly decreased. After the catalyst is used for long periods of time, the ethanol oxidation reformation still has high ethanol conversion ratio and hydrogen selection ratio.

The present invention provides a catalyst for producing hydrogen and a preparing method thereof. The method includes the steps of adding a first metal source, a second metal source, a third metal source and a cerium source into a first organic solvent containing a surfactant to form a colloidal mixture, wherein a metal of the first metal source is a Group IIIB metal; a metal of the second metal source is selected from the group consisting of alkali metals, alkaline earth metals and Group IIIB metals, and a metal of the third metal source is a transition metal; calcining the colloidal mixture to form a metal solid solution; and allowing the metal solid solution to be carried on a carrier to obtain the catalyst. When the catalyst of the present invention is used for an ethanol oxidation reformation, the reaction temperature of the ethanol oxidation reformation can be significantly decreased. After the catalyst is used for long periods of time, the ethanol oxidation reformation still has high ethanol conversion ratio and hydrogen selection ratio.

A composite oxygen transport membrane having a dense layer, a porous support layer and an intermediate porous layer located between the dense layer and the porous support layer. Both the dense layer and the intermediate porous layer are formed from an ionic conductive material to conduct oxygen ions and an electrically conductive material to conduct electrons. The porous support layer has a high permeability, high porosity, and a microstructure exhibiting substantially uniform pore size distribution as a result of using PMMA pore forming materials or a bi-modal particle size distribution of the porous support layer materials. Catalyst particles selected to promote oxidation of a combustible substance are located in the intermediate porous layer and in the porous support adjacent to the intermediate porous layer. The catalyst particles can be formed by wicking a solution of catalyst precursors through the porous support toward the intermediate porous layer.

A composite oxygen transport membrane having a dense layer, a porous support layer and an intermediate porous layer located between the dense layer and the porous support layer. Both the dense layer and the intermediate porous layer are formed from an ionic conductive material to conduct oxygen ions and an electrically conductive material to conduct electrons. The porous support layer has a high permeability, high porosity, and a microstructure exhibiting substantially uniform pore size distribution as a result of using PMMA pore forming materials or a bi-modal particle size distribution of the porous support layer materials. Catalyst particles selected to promote oxidation of a combustible substance are located in the intermediate porous layer and in the porous support adjacent to the intermediate porous layer. The catalyst particles can be formed by wicking a solution of catalyst precursors through the porous support toward the intermediate porous layer.

Methods and systems are provided for an emissions aftertreatment device. In one example, the emissions aftertreatment device may include a catalyst and a high entropy oxygen storage material formed of at least five metal oxides in equal molar proportions. The at least five metal oxides includes one or more rare earth metals as well as other metals with similar chemical properties as the rare earth metals.