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US 10,201,804 B2Granted
Platinum group metal (PGM) catalysts for automotive emissions treatment
AssigneesBASF SE, Georgia Tech Research Corporation
InventorsAndrey Karpov, David Preli, Knut Wassermann, Andreas Sundermann, Sang-IL Choi, Ping Lu, Younan Xia
Life of this patent
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Abstract
Catalytic materials for exhaust gas purifying catalyst composites comprise platinum group metal (PGM)-containing catalysts whose PGM component(s) are provided as nanoparticles and are affixed to a refractory metal oxide, which may be provided as a precursor. Upon calcination of the catalysts, the PGM is thermally affixed to and well-dispersed throughout the support. Excellent conversion of hydrocarbons and nitrogen oxides can advantageously be achieved using such catalysts.
Claims21
A catalytic material comprising:
- a porous refractory metal oxide support, wherein the support is in particulate form and has an average primary particle size of about 1 nm to about 100 nm as measured by Transmission Electron Microscopy (TEM);
- and
- a platinum group metal (PGM) component in nanoparticle form dispersed throughout the support;
- wherein the average primary particle size of the PGM component is about 10 nm to about 92 nm as measured by TEM, and
- wherein the catalytic material exhibits one or more of the following features:
- a) a BJH desorption average pore radius of about 3 to about 20 nanometers as measured by nitrogen-pore size distribution (N2-PSD);
- b) a BET surface area greater than or equal to about 30 m2/g as measured by nitrogen adsorption isotherm;
- and
- c) an aged PGM component average primary particle size that remains about 10 nm to about 92 nm as measured by Transmission Electron Microscopy (TEM) after calcination at 550° C. for two hours in air of the catalytic material starting in a fresh state.
6 more elements
A catalytic material comprising:
- a porous refractory metal oxide support, wherein the support is in particulate form and has an average primary particle size of about 1 nm to about 100 nm as measured by Transmission Electron Microscopy (TEM);
- and
- a platinum group metal (PGM) component in nanoparticle form dispersed throughout the support,
- wherein the average primary particle size of the PGM component is about 10 nm to about 92 nm as measured by TEM, and
- wherein:
- the refractory metal oxide optionally comprises up to about 30% of a promoter, a stabilizer, or both a promoter and a stabilizer, and the catalytic material BJH desorption average pore radius is about 3 to about 30 nanometers as measured by nitrogen-pore size distribution (N2-PSD);
- and
- the platinum group metal (PGM) component comprises colloidally-delivered palladium that is affixed to the support to form the catalytic material.
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A method of making a catalytic material, the method comprising:
- (a) obtaining PGM nanoparticles;
- (b) obtaining nanoparticles of a refractory metal oxide support or a precursor of a refractory metal oxide support;
- (c) preparing an aqueous colloidal solution of the PGM nanoparticles of step (a) and the nanoparticles of step (b) to form a catalytic material solution;
- and
- (d) drying and calcining the catalytic material solution of step (c) to form the catalytic material, wherein the PGM component is dispersed throughout the support and thermally affixed to the support, wherein step (a) comprises:
- forming an aqueous solution of a salt of a platinum group metal (PGM) component, a reducing agent, and a surfactant;
- mixing and heating the aqueous solution, thereby reducing at least a portion of the metal to a zero valance form by the reducing agent in the presence of the surfactant and forming an aqueous solution of colloidal PGM nanoparticles;
- and
- optionally, purifying and/or concentrating the nanoparticles,
- wherein the surfactant is selected from the group consisting of poly(vinylalcohol), poly(vinylpyrrolidone), poly(ethyleneimine), poly(acrylic acid), carbohydrates, alkali metal citrates, and combinations thereof.
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A method of making a catalytic material, the method comprising:
- (a) obtaining PGM nanoparticles;
- (b) obtaining nanoparticles of a refractory metal oxide support or a precursor of a refractory metal oxide support;
- (b) preparing an aqueous colloidal solution of the PGM nanoparticles of step (a) and the nanoparticles of step (b) to form a catalytic material solution;
- and
- (c) drying and calcining the catalytic material solution of step (c) to form the catalytic material, wherein the PGM component is dispersed throughout the support and thermally affixed to the support, wherein
- step (a) comprises:
- forming an aqueous solution of a salt of a platinum group metal (PGM) component, a reducing agent, and a surfactant;
- mixing and heating the aqueous solution, thereby reducing at least a portion of the metal to a zero valance form by the reducing agent in the presence of the surfactant and
- forming an aqueous solution of colloidal PGM nanoparticles;
- and
- optionally, purifying and/or concentrating the nanoparticles, and
- wherein upon calcination, the refractory metal oxide support comprises a high surface area gamma alumina having a surface area of at least about 60 square meters per gram (m2/g).
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Dependencies are inferred from the claim text.