Cerium Oxide Catalyst for Low-Temperature PM Combustion
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Solution Overview
Problem
Conventional filter catalysts face challenges in efficiently burning particulate matter (PM) at low temperatures and preventing thermal runaway, leading to decreased fuel consumption and potential filter damage due to high temperatures required for complete PM removal.
Innovation Solution
A particulate matter purifying material comprising cerium oxide with a specific metal content (zirconium, yttrium, praseodymium, or neodymium) and a controlled degree of crystallinity, supported on a porous ceramic filter substrate with a noble metal catalyst layer, allowing for effective PM burning at temperatures below 800°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the filter is heated to high temperatures (600-650°C or more) to quickly burn and remove deposited PM, then the PM removal efficiency is improved, but fuel consumption increases and thermal runaway may occur
Solution Approach 1:
The patent changes the chemical composition parameters of the catalyst by incorporating specific metal elements (Fe, Co, Ni, Cu, or Mn) in controlled amounts (0.1-10 wt%) into the cerium oxide structure. This compositional parameter change enables the catalyst to function effectively at lower temperatures, allowing PM combustion to occur below 600°C without requiring excessive heating that would consume more fuel or cause thermal runaway.
2Productivity
If a large amount of catalyst is supported on the filter to promote PM burning, then the PM combustion rate is improved, but pores of the filter are blocked and pressure loss increases
Solution Approach 1:
The patent optimizes the catalyst composition parameters by using cerium oxide as the base material with small amounts of specific metal elements (0.1-10 wt%). This parameter optimization achieves high catalytic activity with minimal catalyst loading, preventing pore blockage and pressure loss while maintaining effective PM combustion rates.
Solution Approach 2:
The patent creates a composite catalyst material by combining cerium oxide with specific metal elements (Fe, Co, Ni, Cu, or Mn). This composite structure enhances the catalytic activity per unit mass, allowing effective PM combustion with reduced catalyst quantity, thereby avoiding filter pore blockage and excessive pressure loss.
3Reliability
If the filter is heated to high temperatures to ensure complete PM removal, then the PM purification efficiency is improved, but the filter may be damaged due to thermal runaway
Solution Approach 1:
The patent modifies the catalyst's chemical composition parameters by incorporating specific metal elements into cerium oxide, enabling effective catalytic activity at lower temperatures (below 600°C). This parameter change ensures complete PM removal at temperatures that do not cause thermal runaway or damage the filter structure, thereby maintaining both purification efficiency and filter reliability.
4Device complexity
If conventional three-way catalyst is used in exhaust gas with high oxygen content, then the catalyst structure is simple, but the catalyst cannot effectively reduce and purify nitrogen oxide (NOx)
Solution Approach 1:
The patent develops a composite catalyst material by combining cerium oxide with specific metal elements (Fe, Co, Ni, Cu, or Mn). This composite structure provides both the simplicity of a single-component system and the enhanced functionality of multi-component catalysts, enabling effective NOx reduction in high-oxygen exhaust gas environments while maintaining structural simplicity.
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 solution enables efficient PM burning at lower temperatures, preventing thermal runaway and maintaining catalyst effectiveness, thus reducing fuel consumption and extending filter lifespan.
Implementation Method 1
a mixture of 25 to 100 g/L of the particulate matter purifying material and 0.25 to 1.0 g/L of a noble metal, per unit volume of the filter substrate
Implementation Method 2
a filter substrate made of porous ceramics having continuous fine pores
Implementation Method 3
unburned fuel is discharged from the internal combustion engine to be burned by an oxidation catalyst provided in the front portion of the filter
Implementation Method 4
the deposited PM is burned in a self chain reaction at such a high temperature
Data Source
Figure 1~2
Figure 3(A)~3(D)
Figure 4~5
AI summary
A particulate matter purifying material is used for a filter catalyst for purifying particulate matter that is disposed in an exhaust gas flow path of an internal combustion engine, traps the particulate matter in exhaust gas generated in the internal combustion engine, and burns the particulate matter to be deposited, so as to be regenerated. The particulate matter purifying material includes an oxide containing cerium (Ce) having an oxygen storage-release capacity, and at least one metal (Me) selected from the group consisting of Zr, Y, La, Pr, Sr, Nb and Nd, wherein a content ratio (Ce:Me) of cerium to the metal is 6:4 to 9:1 in terms of an atomic ratio, and a degree of crystallinity (CR) represented by the following formula (1) is within a range of 25 to 60%: Degree of crystallinityCR=I/I0×100% wherein I represents an X-ray diffraction peak intensity with regard to a (111) plane of a CeO2 phase in the particulate matter purifying material, and I0 represents the X-ray diffraction peak intensity with regard to the (111) plane of the CeO2 phase after the particulate matter purifying material is baked in air at 1000 °C.