Cerium Zirconium Catalyst Porosity via Supercritical Drying
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Cerium and zirconium oxide-based materials used in catalytic applications face challenges in maintaining structural integrity under severe conditions, leading to diminished catalyst activity and increased precious metal usage due to sintering and occlusion of active sites, necessitating the development of materials with high surface area, stable porosity, and enhanced oxygen storage and release capabilities.
Innovation Solution
The development of compositions comprising zirconium, cerium, optionally yttrium, and rare earths, synthesized using a process involving mixing of salt solutions, precipitation, dewatering, addition of mesitylene, supercritical drying, and calcination, which results in materials with improved mercury intrusion volumes and surface areas, maintaining stability under oxidizing, reducing, and hydrothermal conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional synthesis methods are used for CeO2-ZrO2 materials, then the production process is simpler, but the materials exhibit lower surface area and diminished stability under severe conditions
Solution Approach 1:
The invention applies preliminary action by incorporating a drying step before calcination to remove pore-blocking species. This preliminary removal of contaminants ensures that the subsequent calcination process produces materials with stable porosity and high surface area, resolving the contradiction between structural stability and synthesis complexity
Solution Approach 2:
The invention utilizes parameter changes by optimizing calcination temperature and atmosphere conditions. By carefully controlling these parameters, the process achieves both high structural stability and maintained porosity, overcoming the typical trade-off between stability and complexity
2Area of stationary object
If conventional synthesis methods are used, then the manufacturing process is less complex, but the materials exhibit lower surface area and reduced catalytic activity
Solution Approach 1:
The drying step performed before calcination serves as a preliminary action that removes organic pore-blocking species. This ensures that the calcination process can proceed to form high-surface-area materials without being hindered by residual organics, thereby achieving both high surface area and reasonable process complexity
3Quantity of substance
If conventional synthesis methods are used, then the process is simpler, but the materials exhibit lower mercury intrusion volume and reduced oxygen storage capacity
Solution Approach 1:
The pre-calcination drying step acts as a preliminary action that removes pore-blocking species, ensuring that the subsequent calcination produces materials with optimized pore structures. This leads to enhanced oxygen storage capacity while keeping the overall process complexity manageable
Solution Approach 2:
By optimizing calcination parameters such as temperature, atmosphere, and duration, the invention achieves materials with superior oxygen storage capacity. These parameter optimizations resolve the contradiction between enhanced performance and process complexity
4Productivity
If conventional synthesis methods are used, then the manufacturing process is less complex, but the materials exhibit higher mass transfer resistance and lower redox activity
Solution Approach 1:
The drying step before calcination serves as a preliminary action that eliminates pore-blocking species, ensuring optimal pore accessibility. This results in lower mass transfer resistance and higher catalyst activity while maintaining reasonable process complexity
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 resulting compositions exhibit high and stable mercury intrusion volumes, surface areas, and redox activities at lower temperatures, with reduced mass transfer resistance and enhanced oxygen storage and release characteristics, improving catalyst activity and heat resistance while minimizing precious metal usage.
Implementation Method 1
adding mesitylene to the precipitate; supercritically drying the precipitate
Implementation Method 2
calcining the precipitate to provide a composition comprising zirconium, cerium
Implementation Method 3
adding the mixture to basic solution to form a precipitate
Data Source
AI summary
Disclosed herein are catalyst compositions having improved mercury intrusion volume and surface areas and processes for making these compositions. The enhanced compositions disclosed herein contain zirconium, cerium, optionally yttrium, and optionally one or more rare earths other than cerium and yttrium. Further disclosed are processes of producing these compositions involving supercritical drying after addition of mesitylene. The compositions can be used as a catalyst and/or as part of a catalyst system in an automobile exhaust system.