Monoclinic Zirconia-Ag Catalyst for Low-Temperature Soot Oxidation
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Solution Overview
Problem
Existing diesel particulate filter regeneration systems require expensive noble metals and are sensitive to NOx concentrations, making them costly and inefficient for low-temperature soot oxidation.
Innovation Solution
A particulate combustion catalyst using monoclinic zirconium oxide as a carrier with supported metallic Ag or Ag oxide, within specific concentration and surface area ranges, facilitates low-temperature soot oxidation without noble metals, utilizing only oxygen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If expensive noble metal catalysts (Pt) are used for soot oxidation, then catalytic activity is improved, but cost increases significantly
Solution Approach 1:
The patent replaces expensive noble metal catalysts (Pt) with a cheaper alternative catalyst system based on zirconium oxide carrier and Ag or Ag oxide catalyst component. This substitution maintains catalytic functionality while significantly reducing material cost, directly addressing the contradiction between catalytic activity and cost.
Solution Approach 2:
The patent optimizes specific parameters including the amount of catalyst component (0.1-10 mass% Ag equivalent), BET specific surface area (5-50 m²/g), and carrier particle size (0.1-10 μm) to achieve effective soot oxidation without requiring expensive noble metals. These parameter adjustments enable the cheaper catalyst system to match the performance of Pt-based catalysts.
2Reliability
If NO2-based regeneration method is used, then soot oxidation is enhanced, but system complexity and restrictions increase
Solution Approach 1:
The patent extracts the NO2 oxidation step from the regeneration system by using a catalyst that directly oxidizes soot with available oxygen. This eliminates the need for upstream oxidation catalysts to convert NO to NO2, simplifying the overall system while maintaining soot oxidation efficiency.
Solution Approach 2:
The catalyst system enables the DPF to perform self-regeneration using oxygen already present in the exhaust gas or ambient air, without requiring external NO2 generation systems or complex control mechanisms. The catalyst component (Ag/Ag oxide) facilitates direct oxidation of trapped soot, making the system self-sufficient.
3Reliability
If high temperature oxidation is used for DPF regeneration, then soot removal is effective, but energy consumption increases
Solution Approach 1:
The patent changes the temperature parameter by enabling soot oxidation to proceed at lower temperatures through the use of the zirconium oxide carrier and Ag/Ag oxide catalyst component. The optimized catalyst parameters (surface area 5-50 m²/g, catalyst component 0.1-10 mass%) facilitate low-temperature oxidation, reducing the energy input required for regeneration compared to high-temperature thermal oxidation.
Solution Approach 2:
The patent replaces thermal oxidation (heat-driven) with catalytic oxidation (catalyst-driven) for soot removal. The catalyst component provides an alternative pathway with lower activation energy, substituting the need for high thermal energy input and reducing overall energy consumption while maintaining effective soot removal.
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 effective soot oxidation at low temperatures, regardless of NOx concentration, with improved durability and heat resistance, reducing costs and operational constraints.
Implementation Method 1
a particulate combustion catalyst including a carrier formed of monoclinic zirconium oxide particles, and metallic Ag or Ag oxide, which serves as a catalyst component and is supported on the carrier
Implementation Method 2
removal of soot through oxidation at low temperature without employment of an expensive noble metal, and which enables oxidation reaction to proceed with the aid of only oxygen
Data Source
AI summary
Provided is a particulate combustion catalyst including a carrier formed of monoclinic zirconium oxide particles, and metallic Ag or Ag oxide, which serves as a catalyst component and is supported on the carrier, wherein the amount of the catalyst component is 0.5 to 10 mass%, as reduced to metallic Ag, on the basis of the mass of the carrier, and preferably, the catalyst has a BET specific surface area of 8 to 21 m2/g. Also provided are a particulate filter coated with the particulate combustion catalyst; and an exhaust gas cleaning apparatus including a particulate filter coated with the particulate combustion catalyst.