Building Materials Encyclopedia: Analysis of Using Kaolin to Produce Zeolite Molecular Sieves
The article "Study on the Production of Zeolite Molecular Sieves from Kaolin" was published on July 4 last year, which aroused the interest of many ceramic companies. They also want to know about application issues.
For this reason, we wrote this article as a sister article for the production of zeolite molecular sieves from kaolin.
Zeolite molecular sieve is the only adsorption and catalytic material with shape selectivity. It is not only expected to reduce the generation of by-products and increase the utilization rate of reaction raw materials through selective catalysis, but also can form the necessary production by means of structural adjustment and load modification. Functional catalytic materials are therefore more and more researched and utilized in many fields and used more and more widely.
The zeolite molecular sieve represented by Type A has a silicon-to-aluminum ratio close to 1, and has the highest cation content, large pore volume, large specific surface area and smaller pore size. It is mainly used for purification, drying, separation and ion exchange processes. Such as ethylene dehydration, air oxygen production, and ion exchange during washing. The medium silica series zeolite molecular sieves are represented by X and Y molecular sieves. They are mainly used as catalysts and catalyst carriers. They have the dual function of solid acid and metal; and because of their unique uniform pore size system, they can react to the reactants and react in the catalytic process. The product plays a role in shape-selective catalysis, so it has higher activity and selectivity. It has been widely used in industries such as petroleum cracking, hydrocracking, isomerization, reforming, and toluene disproportionation. The high-silicon series zeolite molecular sieve is represented by ZSM-5 type, with high silicon-to-aluminum ratio, good thermal stability and acid resistance, and because of its high-density framework structure and straight-tube pore system, it is not easy to form carbon during the catalytic reaction. And lose activity. It has been used in methanol-to-gasoline and hydrocarbon isomerization, and its application range is expanding. Except for the similar pore structure of ZSM-5 molecular sieve, the all-silicon molecular sieve has almost no hydrocarbon groups on its surface, and has good hydrophobic and lipophilic properties. It can be used to separate water and organic phases, especially to adsorb trace organic matter from the water phase. , Pollution prevention and purification have special effects.
Recent studies have shown that zeolite molecular sieves also have properties such as acid resistance, high temperature resistance, and radiation resistance. These physical and chemical properties endow the zeolite molecular sieve with unique functions.
The adsorption capacity of zeolite for organic pollutants mainly depends on the polarity and size of organic molecules. Organic molecules containing polar groups can strongly adsorb on the surface of zeolite molecular sieve. Using this principle, we can decolorize garbage wastewater, aquaculture wastewater, aniline-containing wastewater, slaughter wastewater, papermaking wastewater, printing and dyeing wastewater, remove trace phenol and benzene, remove radioactive substances from water and remove radioactive substances from solids, and industrial and industrial Removal of ammonia nitrogen, arsenic, phosphorus, aluminum from domestic wastewater and treatment of heavy metals (lead, nickel, zinc, cadmium, copper, iron, manganese, mercury), etc., such as high-concentration wastewater discharged from papermaking wastewater, can make CODCR from 2800~3500mg /l is reduced to 450~960mg/l. Aniline is an important intermediate in the production of dyes, pesticides and medicines. However, aniline is a toxic substance that is difficult to biodegrade. It is very toxic. It is quickly absorbed by the human body through the skin and inhaled steam. It will cause purpura. Use zeolite molecular sieve The maximum adsorption capacity of aniline can reach 10mg/g, and the adsorption rate can reach 93%.
The ammonia nitrogen in natural water mainly comes from the decomposition of protein, or the formation of ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen caused by the conversion of ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen under certain conditions due to nearby pollution sources. It is harmful to the human body. Ammonia nitrogen enters the human body to synthesize nitroso compounds. Inducing cancer. Therefore, measures must be taken to remove ammonia nitrogen to improve the quality of drinking water. In addition, industrial and mining wastewater and urban domestic wastewater also have greater possibilities for removing ammonia nitrogen.
Hydrocarbons, carbon monoxide, hydrogen sulfide, etc. emitted from chemical, light industry and other industries are the main harmful gases that pollute the atmosphere. Zeolite molecular sieves have good adsorption and purification functions for these gases, especially in the low temperature range with other adsorbents. Without the adsorption capacity, using the adsorption performance, acid resistance and high temperature resistance of zeolite molecular sieve, it can adsorb SO2 in factory waste gas, the adsorption capacity can reach 100~120mg/g, and the removal rate can reach more than 90%.
When recovering ammonia from synthetic ammonia waste gas and recovering CO, NO and other nitrogen oxide compounds for use in automobile exhaust gas treatment agents, harmful gases can be absorbed and environmental pollution can be reduced. Zeolite molecular sieves have a good adsorption effect on sulfur oxygen, nitrogen oxygen, hydrogen sulfide and ammonia, and are widely used as deodorizing adsorbents. NH3 and H2S are the main odorous gases in the refrigerator. Zeolite molecular sieve can make the removal rate of NH3 and H2S reach 90%.