Rh/CeO2 Catalyst for Low-Temp N2O Decomposition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current catalyst systems for internal combustion engines are inadequate in efficiently removing nitrous oxide (N2O) emissions, which are a significant greenhouse gas, especially under transient conditions encountered in stoichiometric and lean operations with periodic rich excursions, and existing solutions are not optimized for low-temperature exhaust conditions.
Innovation Solution
A nitrous oxide removal catalyst composite comprising a platinum group metal (PGM) component, such as rhodium, palladium, or platinum, supported on a ceria-containing support with a single phase cubic fluorite crystal structure, effective for decomposing N2O to nitrogen and oxygen or reducing it to nitrogen, water, and carbon dioxide, even at temperatures below 500°C, suitable for use in stoichiometric and lean conditions with periodic rich transients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If industrial N2O decomposition catalysts are used, then N2O removal efficiency is improved, but operating temperature requirement increases to >550°C which is incompatible with typical automotive exhaust conditions
Solution Approach 1:
The patent modifies the catalyst composition by using Rh supported on CeO2 with specific promoters (Ba, Sr, Ca, or Pb) at optimized loadings. This changes the physical and chemical parameters of the catalyst to achieve high N2O decomposition activity at lower temperatures (200-500°C) compared to industrial catalysts requiring >550°C
Solution Approach 2:
The patent creates a composite catalyst system combining Rh metal particles with ceria-based support and alkaline earth metal promoters. This composite structure synergistically enhances low-temperature N2O decomposition activity while maintaining stability under automotive exhaust conditions
2Reliability
If conventional catalyst systems optimized for NOx reduction are used, then NOx conversion is improved, but N2O emission control is worsened due to lack of N2O decomposition activity
Solution Approach 1:
The patent designs a multi-functional catalyst that simultaneously performs NOx reduction and N2O decomposition. The Rh/CeO2-based catalyst with promoter metals exhibits dual activity: reducing NOx to N2 under rich conditions and decomposing N2O to N2 and O2 under lean conditions, making it suitable for both functions in a single catalyst system
Solution Approach 2:
The patent utilizes the dynamic oscillating conditions in three-way catalyst operation (alternating between rich and lean phases) to enable the catalyst to perform different functions at different times. During rich phases, NOx reduction occurs; during lean phases, N2O decomposition occurs, allowing the same catalyst to handle both pollutants effectively
3Productivity
If existing N2O decomposition catalysts (supported Rh, metal oxides, ion exchanged zeolites) are used, then N2O removal capability is improved, but catalyst form and support structure are worsened (powder or pelleted form not supported on ceramic carrier)
Solution Approach 1:
The patent merges the active N2O decomposition catalyst (Rh/CeO2 with promoter) with a monolithic ceramic carrier structure. This combines the high N2O removal activity of the catalyst material with the practical advantages of monolithic supports (low pressure drop, high thermal stability, ease of integration into exhaust systems), creating a unified catalyst assembly suitable for automotive applications
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 achieves over 90% N2O conversion under lean conditions following transient rich exposure, making it suitable for integration into existing catalyst systems to meet stringent emission regulations and minimize tailpipe emissions in various engine applications.
Implementation Method 1
a nitrous oxide (N2O) removal catalyst composite comprising a platinum group metal (PGM) component, such as rhodium, palladium, or platinum, supported on a ceria-containing support... effective for decomposing N2O to nitrogen and oxygen or reducing it to nitrogen, water, and carbon dioxide
Data Source
AI summary
A nitrous oxide (N2O) removal catalyst composite is described, which includes: a N2O removal catalytic material on a carrier, wherein the catalytic material comprises a platinum group metal (PGM) component on a ceria-containing support having a single phase, cubic fluorite crystal structure. The catalytic material is effective to decompose nitrous oxide (N2O) to nitrogen (N2) and oxygen (O2) and/or to reduce N2O to N2 and water (H2O) and/or (CO2) under conditions of an exhaust stream of an internal combustion engine operating under conditions that are stoichiometric or lean with periodic rich transient excursions. Methods of making and using the same are also provided.