Because there are uniform small internal pores in the molecular sieve structure, Powdered activated carbon Ji'an When the molecular linear degree of reactants and products is close to the pore size of the crystal, the selectivity of catalytic reaction often depends on the corresponding size of the molecule and pore size. This selectivity is called shape selective catalysis. There are two mechanisms leading to shape selectivity. One is caused by the difference of diffusion coefficient of molecules participating in the reaction in the pore cavity, which is called mass transfer selectivity; The other is caused by the space limitation of the transition state of the catalytic reaction, which is called transition state selectivity. Molecular sieve has clear pore cavity distribution, extremely high internal surface area (600m2/s), good thermal stability (1000 ℃), and adjustable acid site center. The acidity of molecular sieve mainly comes from three coordinated aluminum atoms and aluminum ions (AlO)+on the framework and in the pores. The OH based acid sensitive site center on the molecular sieve HY obtained by ion exchange, and the aluminum ion outside the framework will strengthen the acid site, forming the L acid site center. Polyvalent cations such as Ca2+, Mg2+and La3+can show the acid site center after exchange. The reduction of transition metal ions such as Cu2+and Ag+can also form acid site centers. In general, the higher the Al/Si ratio, the higher the specific activity of OH group. The modification of zeolite acidity can introduce protons through direct exchange of dilute hydrochloric acid. Powdered activated carbon major This method often leads to dealumination of molecular sieve framework. So NaY will become NH4Y and then HY.

Powdered activated carbon major The highly effective selective adsorption is due to the fact that the alumina tetrahedron of zeolite has a negative charge, while the skeleton hole contains cations, which forms a strong electric field around the cations. Therefore, the adsorption force of zeolite not only has a strong dispersion force, but also has a large electrostatic force. It is precisely because of this electrostatic relationship that zeolites have preferential selective adsorption on polar, unsaturated and polarizable molecules. It can strongly adsorb molecules containing polar groups such as hydroxyl ion, ammonium ion and other polarizable groups, especially water, which can form hydrogen bonds with aluminum silicon skeleton, so zeolite has strong water absorption. It can still adsorb even under low relative humidity and concentration, and its water absorption is higher than that of silica gel and activated alumina. The adsorption capacity of zeolite for organic pollutants mainly depends on the polar size and molecular diameter of organic molecules. Small molecules are easier to be adsorbed than large molecules, while polar molecules are easier to be adsorbed than non-polar ones. Different substances (such as organic molecules, metal ions and water molecules) exist in water, Powdered activated carbon manufactor Their polarity and molecular size are different, and competition will occur during adsorption.

Powdered activated carbon major Because the silicon (aluminum) oxygen tetrahedron of natural zeolite crystal has many holes and channels, which occupy cations and water molecules. When some other goods are completely dehydrated after baking, the crystal skeleton is not damaged, but forms large holes on the inner surface, which can absorb and store a large number of molecules, so it has the characteristics of large adsorption capacity and high selectivity. There are cavities and channels in the crystal structure of zeolite with large adsorption capacity, whose volume accounts for more than 50% of the total volume of zeolite crystals. Moreover, the micropores of zeolite are evenly distributed, and the pore size is small, which is equivalent to the molecular size of general substances. The internal surface area of zeolite crystals can reach more than 1000 square meters. Therefore, the adsorption capacity of zeolite is particularly large. Powdered activated carbon manufactor In different zeolite minerals, the proportion of silicon and aluminum is different, and the different proportion will cause some characteristics of zeolite changes, such as ion exchange and acid resistance.

High silica zeolite type molecular sieves, this kind of zeolite has a series, and ZSM-5 is widely used, with ZSM-8 and ZSM-11 having the same structure; The other group is ZSM-21, ZSM-35 and ZSM-38. ZSM-5 is often called high silica zeolite, with the Si/Al ratio up to 50 and ZSM-8 up to 100. This group of molecular sieves also shows hydrophobic characteristics. Powdered activated carbon manufactor Their structural units are similar to those of mordenite, consisting of pairs of five membered rings, with no cage like cavities and only channels. ZSM-5 has two sets of cross channels, one is straight through, the other is zigzag perpendicular to each other, both formed by ten yuan rings. The channel is oval and its window diameter is (0.55-0.60) nm. Powdered activated carbon major Zeolites belonging to the high silicon group also have silicalite-1 of all silicon type, which has the same structure as ZSM-5, and silicalite-2 is the same as ZSM-11.

The main material of honeycomb zeolite adsorbent is natural zeolite. The zeolite manufacturer is an inorganic microporous material composed of sio2, al_2o_3 and alkaline metal or alkaline earth metal, Powdered activated carbon major Its inner pore volume accounts for 40-50% of the total volume, and its specific surface area is 100-500 m2/g. It is characterized by high temperature resistance, non flammability, good thermal stability and hydrothermal stability. It is an efficient molecular sieve carrier with good adsorption performance, no secondary pollution, and can be regenerated at high temperature. Compared with honeycomb activated carbon, its performance is about 25% of its efficiency, but it has high temperature resistance and is not easy to ignite Catalysis and environment are widely used, which is more suitable for the treatment of organic waste gas with large air volume and low concentration. Zeolite adsorbent products include microporous adsorbent and mesoporous adsorbent. Powdered activated carbon manufactor (1) Microporous molecular sieves with molecular pore size below 2 nm and mesoporous molecular sieves with molecular pore size between 2-50 nm (50 nm The above are macroporous molecular sieves), mesoporous molecular sieves have high specific surface area, regular and orderly pore structure, narrow pore size distribution, continuous and adjustable pore size and other characteristics, which make it play an important role in the adsorption, separation and catalytic reaction of macromolecules that are difficult for many microporous molecular sieves to complete. (2) Therefore, molecular sieve materials with different properties and pore sizes shall be configured according to the different components of organic waste gas during selection, so as to achieve targeted organic waste gas treatment, meet the design requirements and emission standards.

Honeycomb zeolite molecular sieve has the crystal structure and characteristics, the surface is a solid skeleton, and the internal holes can play the role of adsorption molecules. There are channels between the holes to connect with each other, and molecules pass through the channels. Due to the crystalline nature of the pores, the pore size distribution of the molecular sieve is very uniform. Molecular sieves selectively adsorb molecules according to the size of holes in their crystals, that is, they adsorb molecules of a certain size and repel molecules of larger substances, so they are vividly called "molecular sieves". The adsorption or repulsion function of molecular sieves is affected by the molecular electricity. Synthetic zeolite has the special function of selective adsorption according to molecular size and polarity, Powdered activated carbon manufactor Therefore, gas or liquid can be dried or purified, which is also the basis for molecular sieve separation. Synthetic zeolite can meet the extensive demand of industry for adsorption and selective products, Ji'an Powdered activated carbon It is also widely used in industrial separation to synthesize zeolite molecular sieves. Advantages of UOP molecular sieve