Phosphorus-BEA Zeolite Exhaust Purification
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Solution Overview
Problem
Conventional exhaust gas purifying compositions face challenges in achieving high hydrocarbon adsorbability, especially at low exhaust gas temperatures and in high-temperature environments, due to insufficient hydrothermal stability and adsorption of toluene, a major hydrocarbon species, using proton zeolite and Cu 2+ exchange CHA zeolite, and phosphorus-containing zeolites are not effectively utilized for high-temperature exhaust gas purification.
Innovation Solution
A composition containing BEA zeolite with phosphorus and zirconium, where the SiO2/Al2O3 molar ratio is between 25 and 600, and the P/Al molar ratio is between 0.5 and 8, providing high hydrocarbon adsorbability and thermal resistance up to 1000°C, maintaining the BEA structure and specific surface area through specific production methods and heat resistance testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If proton zeolite is used as HC adsorbent, then HC adsorbability is improved, but hydrothermal stability deteriorates
Solution Approach 1:
The patent uses BEA-type zeolite as a composite material that combines high hydrothermal stability with effective HC adsorbability. The specific crystal structure of BEA zeolite provides both the stability needed to withstand hydrothermal conditions and the pore structure necessary for adsorbing hydrocarbons, thereby resolving the contradiction between adsorbability and stability.
Solution Approach 2:
The patent optimizes the Si/Al ratio parameter of the BEA zeolite to achieve the desired balance between hydrothermal stability and HC adsorbability. By controlling this compositional parameter, the zeolite maintains structural integrity under hydrothermal conditions while preserving the active sites necessary for hydrocarbon adsorption.
2Reliability
If Cu 2+ exchange CHA zeolite is used, then HC adsorbability is improved, but toluene adsorption deteriorates
Solution Approach 1:
The patent utilizes the porous structure of BEA-type zeolite with specific pore dimensions and channel intersections that enable effective adsorption of toluene molecules. The pore size and topology of BEA zeolite are particularly suited for capturing aromatic hydrocarbons like toluene, which were not effectively adsorbed by CHA zeolite structures.
3Productivity
If phosphorus-containing zeolite is used for cracking, then hexane cracking is improved, but exhaust gas purification deteriorates
Solution Approach 1:
The patent employs BEA-type zeolite that performs multiple functions simultaneously: it maintains structural stability under exhaust gas conditions, adsorbs various hydrocarbon species including toluene, and provides catalytic activity. This multi-functional zeolite replaces the need for separate cracking catalysts and adsorbents, enabling effective exhaust gas purification in a single material.
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 composition effectively maintains high hydrocarbon adsorbability and structural integrity at high temperatures, achieving efficient exhaust gas purification in internal combustion engines by ensuring the BEA zeolite structure's stability and adsorption capacity for toluene and other hydrocarbons.
Implementation Method 1
the use of Cu 2+ exchange CHA zeolite, toluene, which is contained in a particularly large amount among the HC molecular species in the emission, cannot be adsorbed
Implementation Method 2
providing high hydrocarbon adsorbability and thermal resistance up to 1000°C, maintaining the BEA structure and specific surface area through specific production methods and heat resistance testing
Data Source
Figure 1(a)~1(b)
AI summary
The present invention provides an exhaust gas purifying composition containing BEA zeolite containing phosphorus, wherein an amount of phosphorus is such that a molar ratio thereof with respect to Al in the zeolite is 0.5 or greater, and a maintaining factor RS of a specific surface area of the exhaust gas purifying composition after heating at 980°C for 25 hours is 35% or greater. Furthermore, the present invention also provides an exhaust gas purifying composition containing phosphorus-containing zeolite, wherein an amount of phosphorus is such that a molar ratio thereof with respect to Al in the zeolite is from 0.5 to 8, and a maintaining factor Rd of a crystallite diameter after heating at 980°C for 25 hours is 50% or greater. The exhaust gas purifying composition of the present invention has excellent HC purifiability for exhaust gas purification in internal combustion engines such as gasoline engines.