As a porous material, an industrial catalyst or carrier is a collection of particles having a developed pore system. Generally, a certain atom (molecular) or ion forms a nanoporous crystal containing micropores according to the crystal structure rule; and due to the preparation of chemical conditions and chemical composition, several crystal grains can be aggregated into micron-sized particles of different sizes. And then industrially shaped into larger agglomerates or aggregates of particles with different geometric shapes. ?
Different preparation methods produce different pore structures. For example, the pore structure of a high-temperature sintered or extruded porous solid is irregular; and the colloid precipitates, shrinks, and ages in the water-filled primary structure, producing a characteristic microporous structure (typical examples such as cement and gypsum). ). ?
Zeolites and molecular sieves have a stable crystal structure, and the pores inside thereof have a uniform size and a regular shape composed of pores, slits or cages in the crystal. Inside the zeolite, the cage is connected by a window of 0.4?–?1 nm in diameter. A cage can be thought of as a spherical hole. ?
Therefore, the pore structure in the actual volume is complex and consists of different types of pores. At the molecular level, the inner surfaces of the pores are almost all matte. However, we can start with a few basic types (pictured) and then build various combinations of them. ?
The most typical is a cylindrical hole (cylindrical hole), which is a basic model for the calculation of the hole distribution. ?
Spherical or polyhedral particles that are extrusion cured but not yet sintered are mostly tapered holes (wedge holes, pyramidal spaces). ?
A fracture hole is a space formed by contact or stacking between particles. This model is also the basis for the calculation of swelling and agglomeration. ?
The ink bottle holes have a neck. The aperture is the neck of the larger aperture, so the ink bottle aperture can also be seen as a combination of a spherical aperture and a cylindrical aperture. The pores of the zeolite type are stable, but are controlled by the "neck", which can be regarded as an intermediate state between the cylindrical hole and the ink bottle hole.
Makeup Remover,Lipstick Makeup,Pink Lips,Shine Loud Liquid Lipstick
Guangzhou Boxuanya Cosmetics Co., Ltd. , https://www.bxycosmetic.com