Doped Perovskite Support for Rh Catalyst NOx Reduction
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Solution Overview
Problem
Current exhaust gas purification catalysts, particularly three-way catalysts, face a challenge in achieving sufficient catalytic activity for effective NOx reduction.
Innovation Solution
The catalysts are enhanced by using a metal oxide support doped with a cation having a higher oxidation number, such as SrTiO3 doped with Nb, ZrO2 doped with Nb, or Al2O3 doped with Ti, which supports Rh particles, reducing the adsorption energy of O atoms and increasing catalytic activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional alumina support particles with ZrO2 semiconductor particles are used, then the catalyst structure is stable, but the catalytic activity for NOx reduction is insufficient
Solution Approach 1:
The invention changes the chemical composition parameters of the support by doping metal elements (Nb, Ti, Ta) into perovskite structure oxides like SrTiO3. This doping introduces oxygen vacancies and modifies the electronic structure, transforming the support from conventional alumina to a highly active perovskite-based catalyst that significantly enhances NOx reduction activity while preserving structural stability through the robust perovskite framework.
Solution Approach 2:
The invention creates composite materials by combining Rhodium particles with doped perovskite oxide supports (e.g., Nb-doped SrTiO3, Ti-doped SrTiO3). This composite structure synergistically combines the high catalytic activity of Rh with the oxygen storage capacity and structural stability of the perovskite support, achieving superior three-way catalytic performance compared to conventional alumina-based catalysts.
2Productivity
If higher Rh loading is used to increase catalytic activity, then NOx reduction performance improves, but cost increases
Solution Approach 1:
The invention creates an active site-rich environment by doping the perovskite support with metal elements that generate oxygen vacancies. These vacancies act as additional active sites that can adsorb and activate reactant molecules, effectively multiplying the catalytic functionality per unit of Rhodium. The doped perovskite structure copies and amplifies the catalytic activity, reducing the need for large amounts of expensive Rhodium while maintaining high NOx reduction performance.
Solution Approach 2:
The doped perovskite oxide support acts as an intermediary that facilitates the interaction between Rhodium particles and exhaust gas components. The oxygen vacancies and modified electronic structure of the doped support enhance the spillover effect and improve the dispersion of Rhodium particles, maximizing their utilization efficiency. This intermediary effect allows much lower Rhodium loadings to achieve the same catalytic activity that would require higher loadings on conventional supports.
3Ease of manufacture
If conventional catalysts are used, then manufacturing is straightforward, but catalytic activity at low temperatures is insufficient
Solution Approach 1:
The invention modifies the thermal and chemical parameters of the support material by doping perovskite oxides with metal elements. This doping creates oxygen vacancies and alters the electronic band structure, which significantly lowers the temperature required for catalytic activation. The doped perovskite catalysts exhibit high catalytic activity at low temperatures, enabling effective exhaust gas purification in cold start conditions where conventional catalysts fail to activate.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration results in improved NOx reduction performance at lower temperatures, allowing for lower Rh usage and enhanced catalytic activity in exhaust gas purification.
Implementation Method 1
reducing the adsorption energy of O atoms and increasing catalytic activity
Implementation Method 2
exhaust gas purification catalyst comprising a metal oxide support and Rh particles supported on the metal oxide support
Data Source
AI summary
The present disclosure provides an exhaust gas purification catalyst with increased catalytic activity. The exhaust gas purification catalyst comprises a metal oxide support and Rh particles supported on the metal oxide support, wherein the metal oxide support is doped with a cation having a higher oxidation number than the cation of the metal oxide support. The metal oxide support may be a SrTiO3 support doped with greater than 0 mol % and 8 mol % or lower Nb, a ZrO2 support doped with 5 mol % to 20 mol % Nb, or an Al2O3 support doped with greater than 0 mol % and 7 mol % or lower Ti.