The choice of adsorbed gas for surface area analysis depends on the specific purpose of the test. While certain gases may be ideal for characterizing surface properties, they might not always be the best option for studying adsorption behavior. When choosing between helium and nitrogen, it's important to consider the material being analyzed. For instance, materials with very low surface areas—such as organic compounds or metal powders—adsorb only small amounts of gas. In such cases, using a gas that provides a larger difference between the amount adsorbed and the residual gas after equilibrium can improve measurement accuracy.
At liquid nitrogen temperature, the saturation pressure of helium is roughly 1/300 that of nitrogen (helium: ~2.5 torr; nitrogen: ~760 torr). This means that at the same relative pressure, there are about 300 times more nitrogen molecules in free space compared to helium. However, when a monolayer is formed, the number of helium and nitrogen molecules becomes similar, which leads to a significant increase in the measured gas uptake relative to nitrogen. Therefore, helium is often preferred for low-surface-area samples.
For microporous analysis, the choice between nitrogen and argon also plays a key role. Argon is an inert, spherical monoatomic gas, while nitrogen is a non-spherical diatomic molecule. The quadrupole moment of nitrogen may cause localized adsorption, especially on polar surfaces. However, both gases have similar molecular sizes and heat of adsorption. Argon has a higher boiling point (87.29 K) than nitrogen (77.35 K), which makes it more suitable for microporous analysis at liquid argon temperatures. This allows for faster equilibration and better resolution of small pores. Additionally, argon’s higher filling pressure makes it easier to measure accurately, especially for ultra-microporous materials.
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High Precision Three-Station Side-by-Side Automatic Mesoporous Micropore Analyzer
The JW-BK300 series is a state-of-the-art, fully automatic mesoporous and microporous analyzer designed for high-precision surface area and pore size analysis. Built on the foundation of the JW series, this instrument integrates advanced hardware and software technologies to deliver accurate, reliable results comparable to imported systems at a much lower cost. It is particularly well-suited for analyzing materials like activated carbon, activated alumina, molecular sieves, zeolites, MOFs, and nano-powder materials.
**Key Features:**
- **Three independent analysis stations** for simultaneous testing and degassing
- **Advanced vacuum system** with turbomolecular pump and multi-channel parallel pumping
- **Multi-point BET surface area analysis** with high accuracy and repeatability
- **Supports multiple gases**, including nitrogen, argon, helium, and COâ‚‚
- **Comprehensive pore size distribution** analysis using NLDFT, BJH, HK, SF, and other models
- **Real-time Pâ‚€ monitoring** and intelligent pressure control for enhanced precision
- **User-friendly software** with remote control capabilities and Ethernet data acquisition
**Technical Specifications:**
- **Test range**: Surface area from 0.0005 m²/g to unlimited, pore size from 0.35 nm to 5000 nm
- **Repeatability**: Specific surface area ≤ ±1.0%, pore size ≤ 0.2 nm
- **Degassing capacity**: Up to 400°C with programmable temperature steps
- **Pressure sensors**: 1000 Torr, 10 Torr, 1 Torr (upgradable to 0.1 Torr)
- **Vacuum level**: Ultimate vacuum up to 10â»â¶ Pa
**Applications:**
- Catalysts (e.g., activated alumina, molecular sieve, zeolite)
- Environmental materials (e.g., activated carbon)
- Nanomaterials (e.g., nano-ceramics, metal powders, carbon nanotubes)
- Coal and mining industry (e.g., coal, shale gas, coalbed methane)
- Composite and porous materials
This analyzer is ideal for research labs, quality control departments, and industrial applications where precise and fast pore structure analysis is required. For more technical details, visit our website.
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