Micropores, mesopores, macropores how to distinguish - Database & Sql Blog Articles

微盟ME2188A33PG

Kaixin micro test ESD18VB03-0201

Brand AVX TPSE226M035R0125 Low impedance tantalum capacitor AVX 22

Electronic scale crystal oscillator 3.2*2.5mm 3225 16M (16.000MHZ) 12PF 10PPM 20PPM 30PPM

Excellent micro led manufacturers high power led lamp beads 1W green light Sanan 30mil chip

The pore size refers to the shape and size of the pores in the porous solid, which is extremely irregular, and is generally regarded as a cylinder and its radius is used to indicate the size of the pore. The pore size distribution is often related to the adsorption capacity of the adsorbent and the activity of the catalyst. The pore size distribution with pore radius below 10 nm can be determined by gas adsorption method, and the pore size distribution of some mesopores and macropores can be determined by mercury intrusion method.
When the measured value of the pore size is small, it is usually made up of "A" (10 minus ten square meters) (usually used in the adsorption process). The surface of many ultrafine powder materials is not smooth, even designed to be porous, and the size, shape, and number of pores are closely related to some of its properties, such as catalysts and adsorbents. Therefore, it is important to determine the pore volume and pore size distribution on the surface of the powder material. The so-called pore volume and pore size distribution refer to the change rate of the pore volume of different pore sizes with the pore size.
Internationally, these pores are generally classified into three types according to their size: pore size ≤ 2 nm for micropores, pore size in the range of 2-50 nm for mesopores, and pore diameter ≥ 50 nm for macropores, of which mesopores have the most general significance.
The determination of the pore size distribution in the micropore by nitrogen adsorption is a relatively mature and widely used method. It is an extension of the BET specific surface area measured by nitrogen adsorption. Both are the isothermal adsorption characteristics of nitrogen: at liquid nitrogen temperature, The amount of nitrogen adsorbed on the solid surface depends on the relative pressure of nitrogen (P/P0), P is the partial pressure of nitrogen, P0 is the saturated vapor pressure of nitrogen at liquid nitrogen temperature; when P/P0 is in the range of 0.05-0.35, the sample The adsorption characteristics accord with the BET equation; when P/P0 ≥ 0.4, due to the phenomenon of capillary condensation, that is, nitrogen begins to coagulate in the pores of the particles, the pore volume and pore size distribution can be determined through experimental and theoretical analysis.