High pressure gas adsorption instrumentIt is a professional analytical equipment used to accurately determine the gas adsorption performance of solid materials (such as activated carbon, molecular sieves, metal organic framework materials MOFs, porous polymers, etc.) under high pressure environment. It is widely used in materials science, energy storage (such as hydrogen/methane storage), environmental governance (such as CO ₂ capture), catalytic research and other fields. Its core function is to monitor the pressure, temperature and gas consumption changes during the adsorption process, obtain key data such as adsorption isotherms, adsorption kinetics, pore size distribution of materials, and provide scientific basis for material performance evaluation and application development.
From the perspective of working principle, high-pressure gas adsorbents are mainly designed based on the "volume method" or "weight method". The volumetric method calculates the amount of gas adsorbed by the material by accurately controlling and measuring the volume and pressure changes of the sample tank and reference tank, and is suitable for most gas adsorption tests at medium and high pressures (usually up to 1-30MPa); The weight rule uses a high-precision electronic balance to directly measure the weight change of the sample after adsorbing gas, which can avoid the error of dead volume calibration in the volume method and is more suitable for adsorption testing of ultra-high pressure (up to 100MPa) or low boiling point gases (such as hydrogen).
High pressure gas adsorption instrumentIntroduction to Technical Features:
1. Wide range high voltage operation
Characteristic: The core capability is the ability to perform precise measurements under vacuum to high pressure (usually up to 200 bar, and some research grade equipment can reach 300 bar or even higher).
Advantages: It can simulate real application scenarios (such as ANG storage tank pressure of 160-250 bar, hydrogen storage tank pressure of 350-700 bar), obtain the adsorption isotherms of materials under actual working pressure, and the data is more practical.
2. High precision and high sensitivity
Pressure measurement:
Adopting high-precision, full range pressure sensors (such as quartz resonance and capacitive), the accuracy can reach ± 0.01% FS or higher.
Equipped with pressure sensors of different ranges, ensuring high accuracy throughout the full pressure range through automatic switching.
Temperature control:
Real time monitoring of sample temperature using high-precision platinum resistance thermometer (PT100).
Equipped with high-performance constant temperature systems (such as circulating oil baths and electric heating furnaces), the temperature control accuracy can reach ± 0.1 ° C, ensuring that the adsorption process is carried out under isothermal conditions, which is a prerequisite for obtaining accurate data.
Volume measurement (volumetric method):
Accurately calibrate the volume of the reference chamber and sample chamber.
Accurately calculate the quantity change of gas substances using the ideal gas state equation or the real gas state equation (such as NIST REFPROP).
3. Advanced measurement methods
Manometric/Volumetric Method:
The most mainstream technology. By measuring the pressure changes of a reference chamber and a sample chamber with a known volume before and after gas expansion equilibrium, combined with temperature and volume, the amount of adsorbed gas is calculated.
Advantages: The principle is direct and applicable to various gases and a wide pressure range.
Gravimetric Method:
Use a microbalance to directly measure the mass change of the sample before and after gas adsorption.
Advantages: Fast measurement speed, independent of gas state equations.
Challenge: Complex buoyancy correction is required (especially under high pressure), and it is extremely sensitive to vibration. The high-pressure weight method has high technical difficulty and expensive equipment.
Modern trend: High precision instruments often combine two methods or use more complex calibration algorithms.
4. Automation and Intelligent Control
Fully automatic operation: From vacuum pumping, temperature rise and degassing, cooling, air intake, balancing to data acquisition, the entire process is automatically controlled by software to reduce human error.
Dynamic balance judgment: The software automatically judges whether the adsorption/desorption process has reached equilibrium based on the rate of pressure change, and decides whether to proceed to the next step to improve efficiency and accuracy.
Multi point isotherm measurement: The pressure point sequence can be pre-set to automatically complete the measurement of the entire adsorption/desorption isotherm.
5. Powerful data processing and analysis capabilities
Real gas correction: The software has a built-in high-precision real gas state equation (such as NIST REFPROP), which accurately corrects the non ideal behavior of gases under high pressure, which is the key to obtaining accurate adsorption capacity.
Dead volume correction: Accurately deducting the impact of "dead volume" in sample tubes, valves, pipelines, etc. on measurement results.
Buoyancy correction (weight method): Accurately calculate and deduct the buoyancy effect of high-pressure gas on the sample and suspension rod.
Isothermal analysis: provides various model fitting and analysis tools:
Excess adsorption capacity vs. absolute adsorption capacity: can be calculated and converted.
Isothermal models: Langmuir, Freundlich, Toth, D-A (Dubinin Astakhov), etc.
Pore analysis: For ultra-high pressure CO ₂ adsorption, micropore analysis can be performed by combining NLDFT (non local density functional theory) or GCMC (grand canonical Monte Carlo) simulations.
6. Multifunctionality and flexibility
Multi gas compatibility: Different gas paths can be configured for easy replacement and testing of various gases (CH ₄, CO ₂, H ₂, N ₂, Ar, etc.), commonly used for studying the selective adsorption of materials.
Variable temperature test: The adsorption isotherm can be measured at different temperatures to calculate the adsorption heat.
Dynamics research: Some instruments can perform temperature dependent programmed desorption (TPD) or measure adsorption rates.
7. High security design
High pressure safety: All pressure bearing components (pipelines, valves, compartments) are designed and manufactured according to high pressure vessel standards, using high-strength stainless steel (such as 316SS).
Multiple protections:
Equipped with a safety valve (bursting disc or spring type) to prevent overpressure.
Pressure interlock: When the pressure exceeds the set value, the gas source will be automatically cut off or pressure relief will be activated.
Gas leakage monitoring: optional sensors can be used to monitor combustible gas leaks such as H ₂ and CH ₄.
Durable protective cover: protects operators.
8. Modularity and Scalability
Characteristics: The system often adopts modular design (such as independent vacuum system, pressure system, temperature control system, gas path module).
Advantages: Easy to maintain, upgrade, and customize (such as adding more gas channels, upgrading to higher pressure).