Apatite Catalyst Carrier for Low-Temperature NOx Purification
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Solution Overview
Problem
Apatite-type composite oxides used as catalyst carriers have insufficient low-temperature characteristics, which is a concern given the increasing adoption of engine stop mechanisms that result in cold exhaust gases, necessitating a catalyst with improved low-temperature performance.
Innovation Solution
A catalyst carrier with a composite oxide composition of (LaM1) 9.33-δ M2 6 O 27.00-γ, where M1 includes Ba and Y, and M2 includes Si, P, or Fe, with a molar ratio of Ba to La between 0.3 and 1.5, and δ between 0.5 and 3.0, to enhance lattice oxygen activation and NOx adsorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional apatite-type composite oxides are used as catalyst carriers, then heat resistance and sintering prevention are excellent, but low-temperature characteristics are insufficient
Solution Approach 1:
The patent modifies the chemical composition parameters of the apatite-type composite oxide by incorporating specific transition metals (Fe, Cu, Ni, Co) at controlled concentrations (0.5-10 wt%) into the crystal structure. This compositional parameter change enables the material to activate lattice oxygen at lower temperatures while preserving the high-temperature stability provided by the apatite structure, thus resolving the contradiction between low-temperature activity and heat resistance.
Solution Approach 2:
The patent creates a composite material system by combining the apatite-type oxide framework with dispersed transition metal species. The apatite structure provides thermal stability and sintering resistance, while the transition metal components contribute to low-temperature catalytic activity through enhanced lattice oxygen activation. This composite approach allows simultaneous achievement of both low-temperature performance and high-temperature reliability.
2Force
If precious metal is directly supported on substrate, then binding force is weak, but sufficient supported amount cannot be secured
Solution Approach 1:
The patent introduces a catalyst carrier made of apatite-type composite oxide as an intermediary between the precious metal catalyst and the substrate. This carrier provides a high-specific-surface-area support that strongly binds the precious metal particles through its unique crystal structure and surface properties, enabling sufficient supported amount while maintaining strong binding force that prevents metal sintering at high temperatures.
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 proposed catalyst carrier achieves superior low-temperature characteristics by activating lattice oxygen and improving NOx purification performance, while maintaining structural stability through balanced composition.
Implementation Method 1
a catalyst carrier containing an La-based apatite-type composite oxide having a defect larger than that in the case where a molar ratio of La sites is 9.33
Implementation Method 2
improving NOx purification performance
Data Source
Figure 1
AI summary
The present invention relates to a catalyst carrier containing an apatite-type composite oxide and proposes a catalyst carrier capable of improving purification performance of NOx due to improvement of phosphorus poisoning. Proposed is a catalyst carrier which contains a composite oxide that is represented by a composition formula of (LaM1)9.33-δM26O27.00-γ (wherein, in the formula, 0.5 ≤ δ ≤ 3.0, 0.0 < γ ≤ 6.0; "M1" includes Ba and Y; and "M2" includes one or two or more kinds selected from the group consisting of Si, P, and Fe).