Nitrogen adsorptionBETSpecific surface area tester

JW-BK222The dual station fully automatic specific surface area tester is a continuation ofBK112Another classic, practical, and efficient physical adsorption instrument that operates independently in parallel with two stations. All important hardware of the instrument adopts first-line brands, and the comprehensive performance of the product is complete. The accuracy, precision, and stability of the test results fully reach the level of imported equivalent instruments, with high cost-effectiveness, suitable for rapid detection of mesoporous and macroporous materials in enterprises, institutions, research institutes, and universities.

Performance parameters of specific surface area tester:

Instrument model:JW-BK222Specific surface area tester

Principle and method: gas adsorption method, static capacity method;

Test function: isothermal adsorption desorption curve; Single point, multi-pointBETSpecific surface area;LangmuirSpecific surface area; External surface area（STSA）； Single point adsorption total pore volume and average pore size;BJHAnalysis of mesoporous macropore volume and pore size distribution;t-plotLawas- plotLawDRLawMPConventional analysis of micropores; Estimation of average particle size; Special Features:NLDFTAnalysis of aperture distribution using the method; Accurate testing of true density; Gas adsorption capacity and adsorption heat testing; Quality input method testing;

Test gases: nitrogen, oxygen, hydrogen, argon, krypton, carbon dioxide, methane, etc;

Test scope: up to surface area testing0.0005m2/g, aperture: 3.5 nm - 5000 nm；

Scope of pore volume testing: 0.0001cc/gUp to no limit;

Repeatability accuracy: specific surface area≤± 1.0%, aperture≤0.2 nm；

Test efficiency: Average specific surface area per sample15 minMean mesoporous and macroporous analysisEach one2-3Hour;

Analysis Station:2A completely independent sample analysis station, capable of simultaneous degassing;

P0Position: Real time and accurate measurement of the saturated vapor pressure of nitrogen;

Lifting system:2A sample analysis site is set up in situ2Set up an independent lifting system, electrically controlled and automatically controlled, and do not interfere with each other;

Vacuum system: Multi channel parallel vacuum pumping system, modular modular design, vacuum pumping speed fine adjustment valve system * * technology, can be used in2-200ml/sAutomatic adjustment within the range;

Vacuum pump: Original imported mechanical vacuum pump, with a vacuum capacity of up to6.7* 10^-2Pa；

Degassing system: Modular design of vacuum degassing pretreatment system for same position and different position. Standard configuration2Install a same position degassing system,2An independent heating package,2A set of independent temperature controllers, both capable of programmable temperature control, with up to several heating steps10Step; Optional external ectopic placement4Vacuum degassing system;

Degassing temperature: room temperature—400℃, accuracy±1℃；

Pressure sensor: imported with original packaging,1000torr, accuracy≤± 0.15%(Read value);

Voltage division range:P/P0 10^-4-0.998；

Pressure control: Balanced pressure intelligent control method, pressure controllable interval<0.1KPaThe adsorption pressure point can be automatically controlled;

Data collection: Ethernet data collection, fast collection speed, high accuracy, compatibleWindows 7/XP 32/64Positional system;

Product features of specific surface area tester:

●Completely independent two station parallel analysis, capable of simultaneously conducting pore size analysis of two samples, with high testing efficiency;
●Two co located degassing stations, with a degassing temperature of up to400℃； Optional at the same timeJWExternal four station vacuum degassing machine greatly improves degassing efficiency;
●Multiple points of two samplesBETCompared to surface testing,30It can be automatically completed within minutes;
●Adopting a liquid nitrogen surface control comprehensive system and software compensation technology to ensure a relatively constant non-uniform temperature field in the sample chamber throughout the entire testing process, in order to ensure the accuracy of analysis, suitable for various cold baths such as liquid nitrogen, liquid argon, ice water, etc;
●Introducing advanced constant temperature clamp technology from abroad, equipped with large capacity vacuum glass inner Dewar flasks and anti liquid nitrogen volatilization units to ensure the sustainability of experiments72Hour;
●Self controlled adjustable multi-channel parallel vacuum pumping system, built-in anti splash unit, and“Ladder style”Anti splash program, effectively preventing ultrafine powder from flying and completely avoiding instrument contamination;
●The instrument control panel is equipped with valve position control indicator lights, allowing experimenters to more intuitively and clearly see the working status of the control valve, with a user-friendly design;
●Non local density function theoryNLDFTAnalyze the standard configuration of the model to achieve international standards;
●Balanced pressure intelligent control technology, sample suction/Automatic determination and data collection of desorption equilibrium pressure, and automatic control of the number of testing points for isothermal adsorption desorption curves;
●Ethernet data acquisition and processing software, guided operation, one set of software can control multiple instruments simultaneously, and can be remotely controlled;

Application areas of specific surface area tester:

●Rubber materials: carbon black, white carbon black, calcium carbonate, zinc oxide, silicone Chemical raw materials such as silicon oxide;
●Battery materials: lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, graphite, ternary materials Positive and negative electrode materials such as separators;
●Catalyst materials: activated alumina, molecular sieve, zeolite, etc;
●Materials for desulfurization and denitrification: denitrification catalysts, etc;
●Food additives: starch, activated clay, bentonite, etc;
●Magnetic materials: iron oxide, ferrite, manganese oxide, etc;
●Environmental protection field: adsorbents such as activated carbon;
●Nanomaterials: Nanoceramic powders (alumina, zirconia, yttrium oxide, silicon nitride, etc.) Silicon carbide, nano metal powders (silver powder, iron powder, copper powder, tungsten powder, nickel powder, etc.) Nano polymer materials, carbon nanotubes, etc;
●Coal mining industry: coal, ore, rock, shale gas, coalbed methane, etc;
●Other materials: ultrafine fibers, porous fabrics, composite materials, soil, etc.

Technical Tips:

Introduction to Practical Techniques for Specific Surface Area Analysis:

There are several factors that have a significant impact on the testing process and results of gas adsorption method, such as surface area and pore size distribution (porosity). Effective analysis of test results requires consideration of these factors. These factors include: sample processing conditions, characteristics of adsorbate gases, different testing methods, etc., which will be described in detail below.

Sample processing conditions

Due to the close relationship between the determination of specific surface area and porosity and the outer surface of particles, and the key to adsorption method determination is the adsorbate gas molecules“Effectively”Adsorbed on the surface of the tested particles or filled in the pores, therefore, whether the surface of the sample particles is“clean”crucial. The main purpose of sample processing is to release the surface occupied by non adsorbate molecules as much as possible, in order to facilitate the surface adsorption of adsorbate molecules during the testing process. Generally, pre-treatment is required before sample determination, and the treatment method is selected according to the characteristics of the measured sample. In general, most samples need to remove the water molecules adsorbed on their surface, so it is higher than100℃ (usually taken as105℃-120Drying at normal pressure (℃) can achieve this goal, which is beneficial for simplifying the operation process. For samples containing micropores or with strong adsorption characteristics, impurity molecules are easily adsorbed at room temperature and pressure, or many other molecules are adsorbed on the surface during the manufacturing process. It is usually necessary to perform degassing treatment under vacuum conditions, and sometimes an inert protective atmosphere must be introduced during the pretreatment process to facilitate the desorption of impurities on the sample surface. In summary, the purpose of sample pretreatment is to make the surface of the sample clean, in order to ensure accurate and effective measurement results of specific surface area and pore size (porosity).

Characteristics of adsorbate gas

In the analysis and testing of surface area and pore size distribution by gas adsorption method, the basic requirement for the adsorbate gas is that its chemical properties are stable, the adsorption process will not have any impact on the performance and surface adsorption characteristics of the sample itself, and it must be reversible physical adsorption. Nitrogen is a commonly used adsorbate, and practice has shown that the vast majority of substances are determined using nitrogen as the adsorbate, resulting in ideal accuracy and repeatability of the test results. For samples containing micropores, if the micropore size is very small, close to the diameter of nitrogen molecules, on the one hand, nitrogen molecules are difficult or impossible to enter the micropores, resulting in incomplete adsorption; On the other hand, the adsorption characteristics of gas molecules in pores with diameters equivalent to their own are very complex and are influenced by many additional factors, so the adsorption capacity cannot fully reflect the size of the sample surface area. For such samples, argon or krypton with smaller molecular diameters are generally used as adsorbents to facilitate sample adsorption and ensure the validity of test results.

Testing method factors

Different testing methods also have a significant impact on the test results, and each testing method has its own advantages and disadvantages. In the continuous flow method, due to the use of“contrast”The principle of the method can effectively reduce the impact of sample processing on test results compared to the capacity method. By comparing, to some extent, the errors caused by imperfect processing between the standard sample and the tested sample can be offset, provided that the surface structure and adsorption characteristics of the two samples are similar and the processing conditions are the same. This is very valuable for testing used for on-site product quality control purposes, reducing sample processing time and greatly improving testing efficiency. If the same substance is used as the standard sample and the tested sample, due to the similar surface structure and adsorption characteristics, the specific surface area test result will be insensitive to the sample processing conditions, in other words, the error will be offset. Therefore, the continuous flow method is very suitable for on-site inspection of product quality. On the contrary, the volumetric method can be said to be very sensitive to sample processing, as it uses the principle of adsorption capacity measurement. Any surface impurities or other factors that affect the adsorption process of adsorbates will directly affect the measurement results of the product.