Pd-Pr Complex Exhaust Catalyst Thermal Durability
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Solution Overview
Problem
Existing exhaust gas purifying catalysts face issues with maintaining high catalyst activity over time due to sintering of precious metal particles at high temperatures and insufficient activity, particularly in catalysts without a chemical bond between praseodymium oxide and palladium, and insufficient detection of PdO in XRD patterns.
Innovation Solution
An exhaust gas purifying catalyst containing a Pd-Pr complex and PdO, where the Pd-Pr complex is represented by Pr a Pd b O c, with a specific intensity ratio of X-ray diffraction angles, inhibiting Pd particle aggregation and maintaining high adsorption capacity even at high temperatures, and further including oxygen storage materials, refractory inorganic oxides, and alkaline-earth metal compounds supported on a three-dimensional structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If praseodymium oxide and palladium are used without chemical bonding, then oxygen storage capability is maintained, but precious metal particles sinter at high temperature causing insufficient catalyst activity
Solution Approach 1:
The patent combines Pd and Pr into a Pd-Pr complex where the metals are chemically bonded together, merging their functions to prevent sintering while maintaining oxygen storage capability. The complex structure ensures Pd particles remain dispersed even at high temperatures.
Solution Approach 2:
The invention creates a composite material system with Pd-Pr complex, PdO, and oxygen storage materials working together. The composite structure provides both thermal stability through the complex and catalytic activity through PdO and oxygen storage components.
2Reliability
If PdO particles are used with small diameter, then catalyst activity is improved, but PdO is not detected in XRD patterns indicating insufficient structure
Solution Approach 1:
The patent maintains small PdO particle diameter (1-50 nm) for high catalyst activity while allowing the bulk structure to contain detectable PdO phases. The local nanoscale particles provide activity while the overall composition shows detectable XRD patterns.
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 catalyst maintains high activity and adsorption capacity over a long period by inhibiting Pd particle aggregation, achieving effective purification of nitrogen oxide, carbon monoxide, and hydrocarbon in high-temperature exhaust gases, with improved thermal durability and oxidizing performance.
Implementation Method 1
praseodymium oxide and palladium do not have a chemical bond with each other
Implementation Method 2
precious metal particles (platinum, rhodium, and palladium) may be sintered
Implementation Method 3
maintaining high adsorption capacity
Data Source
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AI summary
The present invention provides an exhaust gas purifying catalyst which can maintain high catalyst activity even after the exhaust gas purifying catalyst is exposed to an exhaust gas at a high temperature for a long period of time. The exhaust gas purifying catalyst contains a Pd-Pr complex and PdO, and the Pd-Pr complex is represented by PraPdbOc, where a = 1 to 3, b = 1 to 10, and c = 1 to 6.