Gas Adsorption Measurement Using Reference Tube Volume Correction
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Solution Overview
Problem
Existing gas adsorption amount measurement methods face challenges in accurately measuring the reference volume of free space in sample tubes without using helium, which is becoming scarce, and struggle with measurement accuracy for materials with micropores like zeolite or activated carbon.
Innovation Solution
A gas adsorption amount measurement apparatus and method that uses a reference tube to measure the reference volume of free space with an adsorption gas like nitrogen, eliminating the need for helium and allowing for accurate gas adsorption amount calculations by calculating volume changes and using these volumes to determine the gas adsorption amount.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If helium is used to measure the reference volume of free space, then measurement accuracy is maintained, but helium availability decreases due to increasing demand and resource depletion
Solution Approach 1:
The patent replaces expensive and scarce helium with readily available adsorption gases (nitrogen, argon, carbon dioxide) that can be easily obtained from atmospheric air or commercial sources. This substitution eliminates dependency on depleted helium resources while maintaining measurement functionality through the use of these abundant alternative gases for determining reference volumes.
Solution Approach 2:
The patent changes the fundamental parameter used for volume measurement from helium (which does not adsorb significantly) to adsorption gases (which do adsorb). By measuring pressure changes during adsorption processes and using these changes to calculate reference volumes, the system transforms the measurement approach from non-adsorbing gas volume displacement to adsorption-based volume determination, enabling accurate measurements without helium.
2Stability of the object's composition
If liquid nitrogen level is maintained to prevent volume changes, then reference volume stability is improved, but measurement time increases due to stage-wise raising operations
Solution Approach 1:
The patent employs pressure sensors to continuously monitor pressure changes in the reference volume and uses this feedback information to detect liquid nitrogen level variations. By measuring pressure changes that correspond to volume changes, the system can track reference volume stability in real-time without requiring manual intervention or stage-wise adjustments, thereby reducing measurement time while maintaining accuracy.
Solution Approach 2:
The patent replaces the mechanical liquid level sensor and stage-wise raising mechanism with a pressure-based detection system. Instead of mechanically monitoring liquid level and physically adjusting the Dewar bottle position, the system uses pressure measurements to detect volume changes and calculates reference volumes computationally, eliminating mechanical complexity and reducing measurement time.
3Ease of operation
If reference volume is measured before adsorption amount measurement, then measurement procedure is simplified, but accuracy decreases for materials with micropores due to liquid nitrogen vaporization
Solution Approach 1:
The patent performs preliminary measurement of the reference volume using adsorption gas at room temperature before cooling the system for actual adsorption measurements. This preliminary reference volume measurement, conducted before liquid nitrogen is introduced, establishes a baseline that is not affected by subsequent liquid nitrogen vaporization. The system then uses this stable reference value in conjunction with pressure change measurements during the cooled adsorption process to calculate accurate gas adsorption amounts, thereby maintaining both procedural simplicity and measurement accuracy for microporous materials.
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
Enables highly accurate gas adsorption amount measurements without helium, reduces measurement time, and prevents decreases in accuracy associated with helium use, especially for materials with micropores.
Implementation Method 1
measuring the adsorption isotherms of materials by the constant volume method... supplying the sample tube with nitrogen, and measuring the pressure change in the sample tube
Implementation Method 2
If the liquid nitrogen in the Dewar bottle vaporizes during the measurement of the adsorption characteristics and the liquid level gradually decreases
Data Source
AI summary
A gas adsorption amount measurement device, which is an example of an embodiment of the present invention, comprises at least one sample tube, a reference tube, and a control unit. The control unit is configured to measure, using adsorption gas, reference volumes Vdst,ads of a free space of the sample tube not having a sample and reference volumes Vdref,ads of a free space of the reference tube, respectively and to calculate a gas adsorption amount of the sample using the reference volumes Vdst,ads, Vdref,ads.