Zirconia Catalyst Support Doping for Exhaust Gas Treatment
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Solution Overview
Problem
Current three-way conversion (TWC) catalysts used in exhaust gas treatment systems are less effective at low temperatures and suffer from hydrothermal instability, particularly with zirconium oxide (ZrO2) supports, which degrade under harsh operating conditions, affecting NOx reduction efficiency.
Innovation Solution
The use of ZrO2-based support materials doped with BaO, SrO, Al2O3, and Nb2O5 improves the reducibility and dispersion of rhodium (Rh) species, enhancing the catalyst's performance for NOx, CO, and HC conversion, even at high temperatures, and allows for reduced Rh usage, thus improving hydrothermal stability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ZrO2 support material is used in TWC catalysts, then NOx reduction efficiency is improved, but hydrothermal stability deteriorates under harsh operating conditions
Solution Approach 1:
The patent uses composite support materials comprising ZrO2 combined with stabilizing dopants (La2O3, BaO, SrO, Al2O3, Nb2O5) to create a material that maintains both high NOx reduction efficiency and improved hydrothermal stability. The dopants form stable complexes with ZrO2 that resist degradation under harsh operating conditions while preserving catalytic activity.
Solution Approach 2:
The patent modifies the chemical composition parameters of ZrO2 by introducing dopants at specific concentrations (e.g., La2O3 at 1-20 wt%, BaO at 0.1-10 wt%) to change the material's hydrothermal stability properties while maintaining its catalytic performance for NOx reduction.
2Reliability
If Rhodium (Rh) is used as catalytic material, then NOx conversion performance is improved, but cost increases due to high Rh pricing
Solution Approach 1:
The patent optimizes the Rh loading parameters on the modified ZrO2 support to achieve the desired NOx conversion performance with reduced Rh quantities. The improved hydrothermal stability of the support allows for lower Rh loadings while maintaining catalytic effectiveness, thereby reducing cost.
3Use of energy by stationary object
If catalyst operates at low temperatures, then energy consumption is reduced, but catalytic activity deteriorates
Solution Approach 1:
The patent modifies the catalytic material composition and support properties to lower the light-off temperature and enhance low-temperature catalytic activity. The modified ZrO2 support with dopants provides better dispersion and reducibility of Rh species, enabling effective NOx reduction at lower operating temperatures.
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
The modified ZrO2-based support materials significantly enhance the light-off performance and NOx reduction efficiency of TWC catalysts, achieving better results than conventional catalysts while reducing the amount of Rh required, leading to cost savings and improved catalytic activity.
Implementation Method 1
catalyst compositions and catalytic articles for purifying exhaust gas emissions... catalysts... for reducing harmful components contained in the exhaust gas such as hydrocarbons (HCs), nitrogen oxides (NOx) and carbon monoxide (CO)
Implementation Method 2
the reduction of nitrogen oxides (NOx) to nitrogen... reduction of NOx occur substantially simultaneously
Data Source
AI summary
This disclosure is directed to catalyst compositions, catalytic articles for purifying exhaust gas emissions and methods of making and using the same. In particular, the disclosure relates to a catalytic article including a catalytic material on a substrate, wherein the catalytic material has a first layer and a second layer. The first layer includes a platinum group metal (PGM) component impregnated on a porous support material; and the second layer includes a rhodium component impregnated on a support material, wherein the support material is a composite material including zirconia doped with baria, alumina, or combinations thereof, wherein the zirconia-based support material includes zirconia in an amount from about 80 to about 99 wt. %.