Composite Oxide Catalytic Coating for Soot Combustion
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Solution Overview
Problem
Current catalytically coated particulate filters for internal combustion engines face challenges in achieving high soot conversion efficiency, especially in cooler regions of the exhaust train, while maintaining low dynamic back pressure to ensure engine power and fuel efficiency.
Innovation Solution
A catalytic coating comprising a composite oxide of the formula Pr2-xAxCe2-yByOz, where A and B are specific transition metals, is applied to the inlet channels of wall-flow filters. This composite oxide reduces the temperature required for soot combustion and enhances soot oxidation activity without the use of expensive platinum group metals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional Pt-based catalysts are used for soot oxidation, then high soot conversion efficiency is achieved, but high cost and high operating temperature are required
Solution Approach 1:
The patent changes the chemical composition parameters of the catalyst by replacing Pt with non-platinum metals (Fe, Co, Ni, Cu) and adjusting the oxide ratio in the composite material. This parameter change enables soot oxidation at lower temperatures while maintaining conversion efficiency, directly resolving the contradiction between high efficiency and high temperature operation.
Solution Approach 2:
The patent employs composite oxide materials combining multiple metal oxides (e.g., Fe2O3, Co3O4, NiO, CuO with Al2O3, SiO2, TiO2) to create a catalyst that achieves both high soot conversion efficiency and low operating temperature. The synergistic effect of composite materials allows the catalyst to function effectively at lower temperatures compared to traditional single-component Pt-based catalysts.
2Reliability
If catalytic coating is applied to increase soot oxidation activity, then soot conversion efficiency improves, but back pressure increases
Solution Approach 1:
The patent applies catalytic coating selectively to specific regions of the filter (inlet channels and outlet channels) rather than uniformly across the entire filter surface. This localized application concentrates the catalytic activity where it is most effective for soot oxidation while minimizing the overall coating volume, thereby reducing back pressure. The coating is applied to channel walls with controlled thickness and coverage to optimize the balance between activity and pressure drop.
3Reliability
If catalytic coating thickness is increased to improve soot conversion, then oxidation activity increases, but dynamic back pressure increases
Solution Approach 1:
The patent applies catalytic coating to the inlet and outlet channels with optimized thickness that provides sufficient soot conversion efficiency without excessive coating volume. By applying coating only to the channel walls rather than filling the entire channel volume, the patent achieves the minimum necessary catalytic activity while minimizing the impact on exhaust gas flow and back pressure, thereby maintaining fuel efficiency.
4Ease of manufacture
If non-platinum catalysts are used to reduce cost, then cost decreases, but soot conversion efficiency may be compromised
Solution Approach 1:
The patent uses composite oxide materials combining non-platinum metals (Fe, Co, Ni, Cu) with various oxides (Al2O3, SiO2, TiO2, ZrO2) to create catalysts that achieve Pt-level soot conversion efficiency without using expensive platinum group metals. The composite structure provides both cost reduction and maintained performance through synergistic material interactions.
Solution Approach 2:
The patent optimizes the compositional parameters of the non-platinum catalyst by adjusting metal oxide ratios, particle size distributions, and thermal treatment conditions. These parameter optimizations enable the non-platinum catalyst to reach comparable soot conversion efficiency to Pt-based catalysts while significantly reducing material cost.
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 composite oxide catalytic coating achieves a significant reduction in the temperature required for 50% soot conversion (T50) by over 100°C compared to traditional Pt-based catalysts, even after aging, while maintaining low back pressure and reducing fuel consumption.
Implementation Method 1
a catalytic coating comprising a composite oxide which accelerates soot combustion
Implementation Method 2
The harmful gases carbon monoxide and hydrocarbons from a lean exhaust gas can easily be rendered harmless by oxidation on a suitable oxidation catalyst
Implementation Method 3
This composite oxide reduces the temperature required for soot combustion and enhances soot oxidation activity
Data Source
AI summary
The present invention is directed towards a catalytic coating comprising a composite oxide which accelerates soot combustion. The oxide is used in a catalytic coating in soot filters for the abatement of noxious pollutants in exhaust gases from combustion processes. A process for the production of catalytic coatings comprising these composite oxides is also given.