Spinel Oxide Phosphorus Collection Layer for Exhaust Catalysts
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Solution Overview
Problem
Exhaust gases contain phosphorus compounds that adhere to precious metals in exhaust gas purification catalysts, leading to phosphorus poisoning and reduced catalytic activity, which existing materials like hydrotalcite cannot effectively prevent.
Innovation Solution
Incorporating a phosphorus collection layer with a composite oxide having a cubic spinel structure belonging to the space group Fd-3m, containing Al and an alkaline earth metal element like Mg, arranged upstream or on top of the catalyst layer, to adsorb phosphorus compounds and prevent poisoning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sulfur oxide (SOx) absorption layer containing MgO or hydrotalcite is provided to suppress sulfur oxide poisoning, then sulfur oxide poisoning is suppressed, but phosphorus poisoning cannot be suppressed
Solution Approach 1:
The invention divides the protective function into separate layers: a sulfur oxide absorption layer containing MgO or hydrotalcite for sulfur oxide poisoning suppression, and a phosphorus collection layer containing a specific composite oxide for phosphorus poisoning suppression. This segmentation allows each layer to specialize in its respective function without interference.
Solution Approach 2:
The invention uses a composite oxide material containing alkaline earth metal element Ma and aluminum with a cubic spinel structure (space group Fd-3m) and specific Ma/Al molar ratio (0.02-0.60) in the phosphorus collection layer. This composite material provides superior phosphorus poisoning suppression capability compared to single materials.
2Quantity of substance
If phosphorus compounds are deposited on the catalyst layer, then phosphorus compounds are removed from exhaust gas, but catalytic activity of precious metals decreases
Solution Approach 1:
The phosphorus collection layer is positioned upstream or on the upper layer side relative to the catalyst layer, allowing it to intercept and collect phosphorus compounds from the exhaust gas before they can reach and deposit on the precious metals in the catalyst layer. This preliminary action prevents phosphorus poisoning of the catalyst.
3Quantity of substance
If phosphorus compounds are deposited on the oxygen storage/release substance, then phosphorus compounds are removed from exhaust gas, but oxygen storage/release function is inhibited
Solution Approach 1:
The phosphorus collection layer is positioned to intercept phosphorus compounds upstream or on the upper layer side relative to the catalyst layer containing oxygen storage/release substances. This preliminary collection prevents phosphorus compounds from reaching and reacting with the oxygen storage/release substances, thereby preserving their oxygen storage and release functions.
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 phosphorus collection layer effectively suppresses phosphorus poisoning, enhancing the long-term durability of the catalyst by trapping phosphorus compounds before they reach the catalyst layer, thereby maintaining catalytic activity.
Implementation Method 1
the phosphorus collection layer contains a composite oxide containing Al and an alkaline earth metal element Ma that includes Mg... the composite oxide has a cubic spinel structure... the composite oxide has a molar ratio (Ma/Al molar ratio) of the Ma element to the Al element in a range of 0.02 or more and 0.60 or less
Data Source
AI summary
Provided is an exhaust gas purification catalyst that suppresses phosphorus poisoning and improves long-term durability. The exhaust gas purification catalyst includes a phosphorus collection layer and a catalyst layer containing at least one precious metal element Mp selected from the group consisting of Pt, Pd, and Rh, wherein the phosphorus collection layer is arranged on the upper layer side and/or the upstream side with respect to the catalyst layer; the phosphorus collection layer contains a composite oxide containing Al and an alkaline earth metal element Ma that includes Mg and that may include at least one selected from the group consisting of Ca, Sr, and Ba, and having a cubic spinel structure belonging to the space group Fd-3m; the composite oxide has a Ma/Al molar ratio in a range of 0.02 or more and 0.60 or less; and the composite oxide has a peak derived from the cubic spinel structure belonging to the space group Fd-3m of the composite oxide between a diffraction angle 2θxMaO that is a position of a peak derived from an alkaline earth metal oxide MaO and a diffraction angle 2θxAl2O3 that is a position of a peak derived from an aluminum oxide Al2O3 in an X-ray diffraction spectrum.