3A Zeolite Adsorbent for Nitrogen-Free Gas Purity
Solution Overview
Problem
Existing gas supply systems, particularly those using pressurized cylinders, often contaminate gases with excess nitrogen despite initial low nitrogen content due to nitrogen-adsorbing adsorbents like Type 4A zeolite accidentally absorbing nitrogen during assembly and filling processes, leading to contamination during customer use.
Innovation Solution
Employing a 3A zeolite with a potassium exchange level of at least 15% and being free from nitrogen-adsorbing components, such as UOP XH-11 and UOP EPG, to adsorb water while minimizing nitrogen adsorption, ensuring the adsorbent is inert to atmospheric nitrogen, thus preventing contamination in gas supply systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Type 4A zeolite is used as the adsorbent in the gas supply system, then water adsorption capacity is improved, but nitrogen adsorption capacity increases causing gas contamination
Solution Approach 1:
The invention changes the chemical composition parameters of the zeolite by specifying a silicon-to-aluminum ratio between 2.5:1 and 3.0:1, and requiring potassium content of at least 15% by atomic percentage. These parameter changes modify the pore structure and adsorption properties to preferentially adsorb water while excluding nitrogen, resolving the contradiction between water removal efficiency and nitrogen contamination prevention
Solution Approach 2:
The invention uses a composite zeolite structure combining specific ratios of silicon, aluminum, and potassium elements. This composite material approach creates a synergistic effect where the specific composition (3A zeolite with high potassium content) provides both high water adsorption capacity and low nitrogen adsorption capacity, simultaneously addressing both requirements
2Ease of manufacture
If adsorbent is exposed to atmosphere during assembly and filling, then assembly process is simplified, but nitrogen is accidentally adsorbed leading to gas contamination
Solution Approach 1:
The invention specifies using 3A zeolite with very low nitrogen adsorption capacity (less than 0.01 mgmole/g at 23°C and 101 kPa), which can be exposed to atmosphere during assembly without significant nitrogen uptake. This allows the adsorbent to be handled more freely during manufacturing while still preventing nitrogen contamination in the final gas product
Solution Approach 2:
The invention creates an effectively inert environment for the gas supply by selecting an adsorbent (3A zeolite with specific composition) that does not react with or adsorb nitrogen under normal operating conditions. This inert behavior towards nitrogen allows atmospheric exposure during assembly without compromising gas purity
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 high-potassium-exchange 3A zeolite effectively prevents nitrogen contamination in gases with low nitrogen content, maintaining the purity of the gas supply by minimizing nitrogen adsorption, as demonstrated by tests showing no detectable nitrogen uptake in UOP EPG and UOP XH-11 adsorbents, thereby ensuring the gas quality meets stringent industry standards.
Implementation Method 1
contacting the gas with an adsorbent having a capacity to adsorb water from said gas, said adsorbent having a nitrogen adsorption capacity below 0.01 mgmole/g
Implementation Method 2
being a 3A zeolite having a potassium exchange level of not less than 15%, with the balance of the cations being sodium
Data Source
Figure 1
Figure 2~3
AI summary
A built in purifier for a cylinder of essentially nitrogen free gas having a low water content is provided with a molecular sieve 3A adsorbent to adsorb water from the gas, the 3A adsorbent having a particularly low adsorption capacity for nitrogen.