What is the pore size of molecular sieves?

The pore size of molecular sieves varies depending on the type. The following is a detailed introduction to the pore size of molecular sieves:

Small pore molecular sieves: usually surrounded by 8 TO4 tetrahedrons to form a channel window, with a pore size of about 4.0A (i.e. 0.4nm). For example, the effective pore size of 4A molecular sieve is about 0.42nm, which can adsorb molecules with polarity and molecular dynamics diameter less than 0.4nm, such as water, hydrogen sulfide, sulfur dioxide, carbon dioxide, etc.

Mesoporous molecular sieves: The pore size is about 5.5A, and the channel window is surrounded by 10 TO4 tetrahedrons. For example, the pore size of 5A molecular sieve is about 5×10^-7mm, which can adsorb water and carbon dioxide, and has a co-adsorption effect on hydrocarbons such as acetylene.

Large pore molecular sieves: The pore size is about 7.5A, and the channel window is surrounded by 12 TO4 tetrahedrons. For example, the pore size of 13X molecular sieve is about 10×10^-7mm, which can also adsorb water and carbon dioxide, and has a co-adsorption effect on hydrocarbons such as acetylene.

In addition, there are some molecular sieves with larger pore sizes, such as mesoporous molecular sieves (pore size between 50 and 100 nanometers) and large pore molecular sieves (pore size above 100 nanometers), which are usually used for specific adsorption and separation processes.

In summary, the pore size of molecular sieves is diverse, and the appropriate type of molecular sieve can be selected according to specific needs.