Aluminophosphate HC Adsorbent Catalyst for Cold-Start Durability
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Solution Overview
Problem
Conventional exhaust gas purifying catalysts experience a significant decrease in hydrocarbon (HC) purifying performance at cold start after prolonged exposure to high-temperature exhaust gas containing water, primarily due to the transfer of silicon (Si) from zeolite-based molecular sieves affecting the catalyst metal, leading to reduced efficiency.
Innovation Solution
Employing an aluminophosphate molecular sieve with a 12-membered ring and a crystallite diameter of 360 Å to 700 Å as the HC adsorption material, which minimizes the adverse effects of Si on the catalyst metal, thereby enhancing HC purifying performance at cold start after hydrothermal enduring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If zeolite-based molecular sieve is used as HC adsorption material, then HC purifying performance at cold start is improved, but HC purifying performance deteriorates after hydrothermal enduring due to Si transfer affecting catalyst metal
Solution Approach 1:
The patent changes the chemical composition parameters of the molecular sieve by using aluminophosphate (ALPO) instead of conventional zeolite. This substitution eliminates silicon from the molecular sieve structure, preventing Si transfer to the catalyst metal during hydrothermal enduring, thereby maintaining both cold start performance and long-term durability.
Solution Approach 2:
The patent creates a composite structure combining aluminophosphate molecular sieve with catalyst metal layers. This composite material design ensures that the molecular sieve provides HC adsorption capability while the absence of silicon prevents harmful interactions with the catalyst metal, resolving the contradiction between initial performance and durability.
2Reliability
If aluminophosphate molecular sieve with crystallite diameter of 360 Å to 700 Å is used, then HC purifying performance at cold start after hydrothermal enduring is significantly improved
Solution Approach 1:
The patent specifies a precise crystallite diameter range (360-700 Å) for the aluminophosphate molecular sieve to optimize both HC adsorption capacity and catalyst protection. This parameter control ensures that the molecular sieve particles are small enough to provide high surface area for adsorption while being large enough to maintain structural integrity during hydrothermal enduring.
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 use of aluminophosphate molecular sieves with specified crystallite diameters significantly improves HC purifying performance at cold start by maintaining catalyst efficiency and adsorption capacity post-hydrothermal exposure.
Implementation Method 1
an HC adsorption type exhaust gas purifying catalyst in which a catalyst layer containing a catalyst metal is stacked on an HC adsorption layer containing an HC adsorption material has been developed
Implementation Method 2
a catalyst layer containing a catalyst metal such as platinum (Pt), palladium (Pd), or rhodium (Rh) is formed on a base material with high heat resistance
Data Source
Figure 1~2
Figure 3~4(B)
Figure 5(A)~5(B)
AI summary
According to the present invention, an exhaust gas purifying catalyst with high HC purifying performance at cold start after hydrothermal enduring is provided. The exhaust gas purifying catalyst disclosed herein includes a base material and an exhaust gas purifying layer provided on the base material. The exhaust gas purifying layer includes a catalyst metal and a molecular sieve that does not substantially contain Si as a hydrocarbon adsorption material. The molecular sieve that does not substantially contain Si is an aluminophosphate molecular sieve including a 12-membered ring. The crystallite diameter of the aluminophosphate molecular sieve that is determined by X-ray diffraction measurement is 360 Å to 700 Å.