4a molecular sieve activation

4a molecular sieve, can adsorb water, methanol, ethanol, hydrogen sulfide, sulfur dioxide, carbon dioxide, ethylene, propylene and other low-molecular compounds pore molecular sieve 4A, does not adsorb any molecular diameter greater than 4A (including propane), high selective adsorption for water any other molecules, is one of the largest industrial use of molecular sieve varieties of. 110 ° C for moisture evaporation large space is possible, but it is impossible to sieve pore water rush out. Thus, in general laboratory muffle furnace drying can be activated by dehydration at a temperature of 350 ° C, dried 8 hours at atmospheric pressure (vacuum pump, if there is, can be dried for 5 hours at 150 ° C exhaust case). Activated molecular sieve in air cooled to 200 ° C (about 2 minutes), and immediately stored in a desiccator. If the conditions applied during cooling and preservation of dry nitrogen to prevent moisture in the air is absorbed again. Old sieve contaminants after use, when activated not only up to a temperature of 450 ° C, but also to pass into the steam or inert gas (nitrogen) to substitute other substances out of zeolite adsorbent

Zeolite drying technology

Conventional molecular sieve drying technique commonly used hot air natural gas dryingtechnology, and microwave drying technology to solve the traditional dry sieve drying slow, energy loss, poor product quality problems, in particular in: 1, microwave drying fast molecular sieve, generally a few minutes 2 can achieve the purpose of microwave drying, microwave drying sieve evenly to achieve the depth of dry, good product quality; 3, still dry, do not burn with less dust; 4, microwave drying molecular sieve process safety, energy conservation, environmental protection and the use of electricity, dry inside and outside at the same time, electric drying than saving more than 50%; 5, shorten the production cycle, greatly reducing the production of working capital; 6, microwave drying equipment cabinet temperature below 40 ℃, improve workers' working environment.

Introduction of Zeolite

molecular sieve is a cubic lattice of an aluminosilicate compound having. Molecular sieve has a uniform porous structure, the diameter of its pores of uniform size, these cavities can adsorb molecules smaller diameter than the internal bore, and an unsaturated polar molecules and molecules having a preferential adsorption capacity, and thus able to very different degree, different degree of saturation, and boiling points of different molecular sizes of different molecules separated, that has the effect of "screening" elements, so called molecular sieves. Since the molecular sieve adsorbent have a high adsorption capacity, high thermal stability other adsorbents that are not so widely applied molecular sieve.
In the field of biological macromolecules, a common bio-rad SEC sieve prepacked columns.
US scientists have found that by adjusting the temperature, to precisely control one titanium silicate material pore size, to create a sophisticated molecular sieve. Some internal crystal material has a large number of uniform pore size smaller than the molecules can pass through the holes, while large molecules can not pass through, and thus serves to separate different molecules, such materials are known as molecular sieve.
In fact, in 2001, scientists in the UK "Nature" magazine reported that they had discovered a titanium silicate material known as ETS-4 can be used as a good molecular sieve. When the temperature rises, ETS-4 will gradually dehydrated, pore size decreases. Finely adjust the pore size in the use of this method, (1 angstrom equals one billion of a meter) in the 3-4 Angstroms range. Scientists say some common elements such as nitrogen, methane, oxygen, argon and water molecules are about the size of 3-4 Å, another is almost the same size, molecular sieve made with ETS-4 can effectively separate them. Researchers have experimented with ETS-4 from the nitrogen content in the mixture of nitrogen and methane, from 18% to 5%, and in the separation of argon and oxygen, nitrogen and oxygen experiments have been successful. It is believed that this technology will have important commercial applications

Performance and structure of molecular sieve

Performance: zeolite powdery crystals with metallic luster, hardness of 3 to 5, the relative density of 2 to 2.8, color natural zeolite, synthetic zeolite powder obtained as a white, water-insoluble, heat stability and acid resistance as SiO2 / Al2O3 composition ratio increases and improved. Molecular sieves have a great specific surface area, up to 300 ~ 1000m2 / g, the inner surface of the crystal highly polarized, as a class of highly efficient adsorbents, also a type of solid acid, the surface has a high acid concentration and acid strength, can cause carbonium catalytic ionic reactions. When the composition of the metal ions and other ions in solution were exchanged, adjustable aperture, changes its absorption properties and catalytic properties, which molecular sieve catalyst prepared with different properties.

Structure: proteoglycan thus formed polymer tortuous coiled, forming a sieve-like microporous structure, known as molecular sieves. Microporous molecular sieve which only allows material through is less than, greater than the pores of macromolecular substances, bacteria and the like having a barrier function is. The matrix becomes the limiting diffusion of harmful substances such as bacteria defensive barrier. Hemolytic streptococcus and cancer cells can produce hyaluronidase, the decomposition of proteoglycan, destruction of the matrix structure, to be spread. On binding proteoglycan aggregate also many hydrophilic groups, capable of binding water molecules, forming extracellular "reservoirs"

Principles and types of Zeolite

Absorption features: molecular sieve adsorption material from physical adsorption (van der Waals forces), which has a strong internal crystal cavities polarity and Coulomb field of polar molecules (such as water) and unsaturated molecules show a strong adsorption capacity.
Screening function: very uniform pore size distribution of the molecular sieve, only molecular diameter smaller than the diameter of the hole before substance may enter bughole internal molecular sieves.
By order of priority and size to distinguish molecular adsorption of different substances, so the image is called "molecular sieve."
Type: synthetic zeolite molecular sieve zeolite and two natural. Most ① natural zeolite formed by volcanic tuffs occur and tuffaceous sedimentary rocks in marine or lacustrine environment reaction. Have been found to have more than 1000 kinds of zeolite mineral, the more important ones are 35 kinds, often with clinoptilolite, mordenite, erionite and chabazite, etc. Mainly in the United States, Japan, France and other countries, China also found that a large number of mordenite and clinoptilolite deposits, Japan is the largest country in the natural zeolite mined. ② due to natural zeolite subject to resource constraints, from the beginning of the 1950s, a large number of synthetic zeolites.
Goods zeolite crystal structure common prefixes Digital classify the different molecular sieves, such as type 3A, 4A type, 5a zeolite molecular sieves. 4A Class A type that table, aperture 4Å ;. A type of zeolite containing Na +, referred to as Na-A, if one is Na + K + replacement, pore size of about 3Å ;, is the 3A molecular sieve; Na-A if there is more than one third of the Na + Ca2 + exchange, aperture is about 5Å ;, is the 5A molecular sieve.

functions and features of Molecular sieve

The porous material has been widely used in many fields, such as the main catalytic microporous molecular sieve material, adsorption and ion exchange material separation materials plays an increasingly important role in oil processing, petrochemicals, fine chemicals, and household chemicals .
molecular sieves(also known as a synthetic zeolite) is a microporous aluminosilicate crystalline silicon. It is made of silicon oxide, aluminum oxide tetrahedra basic skeleton structure, there is a metal cation in the crystal lattice (such as Na +, K +, Ca2 +, Li +, etc.), in order to balance the negative charge excess crystals. According to their type of zeolite crystal structure is divided into: A type, X-type, Y type.
Zeolite relevant standards:
"3a molecular sieve" "4A molecular sieve" "5a molecular sieve and test methods" "13X molecular sieve"
"Water assay method static sieve" "sieve dynamic water assay method"
"Granular sieve size determination," "Determination of bulk density of molecular sieve" "sieve crush strength test method", "Standard Test Method for molecular sieve desiccant cooling systems with anti-wear performance," "Determination of dynamic zeolite adsorption of carbon dioxide."
"Industrial activated alumina," "air separation plant with activated alumina acceptance technical conditions"

Application of molecular sieves 4A

Detergent additives: zeolite 4a as a detergent additive main function is to produce calcium ion exchange water softening, remove dirt and prevent redeposition. 4A Zeolite is currently applied on behalf of the largest builders of phosphorus and most mature product. 4A Zeolite replace sodium tripolyphosphate as detergent additives to solve the environmental pollution has a major role. 4A Zeolite forming agent can also be used soap, toothpaste friction agent.
Sewage: 4A molecular sieve can remove sewage NH3-N, and Pb2 +, Cu2 +, Zn2 + ,, Cd2 + and so on. Industry, agriculture, animal husbandry and aquatic civilian discharged wastewater containing ammonia nitrogen, not only endanger the survival of fish, in the farming environment pollution, and promote algae growth, leading to blockage of rivers and lakes. 4A molecular sieve due to high selectivity of NH4 + exchangeable, has been successfully applied in the field. Sewage from metal mines, smelters, metal surface treatment and chemical emissions from industry and other sectors, which contains heavy metal ions harmful to human health. 4a zeolite molecular sieves with sewage in addition to those qualified to ensure the water quality, but also the recovery of heavy metals.
Other uses:
(1) Water ---- hard water softener, can replace the current widespread use of sulfonated coal, thereby reducing costs;
(2) Metallurgical Industry ---- separating agent, separation, extraction of brine potassium, rubidium, and cesium. In industry for the enrichment, separation and extraction of metals and other processes;
(3) petrochemical industry ---- catalysts, desiccants, adsorbents;
(4) ---- agricultural soil conditioner;
(5) Pharmaceutical ---- silver zeolite antimicrobial agent.

The function of 4A molecular sieve properties

 Water softening ion exchange performance features: 4a molecular sieveframework are each oxygen atom is shared by two adjacent tetrahedra, this structure which may be occupied by cations and water molecules large bugholes, and these cations and water molecules have a greater mobility, cation exchange and reversible dehydration. 4A zeolite is ion exchange with aluminum ions in the framework carried a negative charge carried by each of the aluminum ions, may be not only sodium ions, may also be combined with other cations. Calcium and magnesium ions can enter the original sodium ions occupy a large crystal cave, the 4A Zeolite replace sodium ions 4A Zeolite down ---- that sodium ions can be exchanged with hard water Ca2 + ,, Mg2 + ions exchange, so as to achieve the purpose to soften water.
Combined with calcium and magnesium ions in zeolite 4a speed slower than sodium tripolyphosphate, and with the ability to bind magnesium ions is weak. But 4a molecular sieve can be a small amount of water in harmful heavy metal ions (such as Pb2 +, Cd2 +, Hg2 +) can be very easily and quickly removed to purify water has very important significance.
---- Carrier liquid of adsorptive functional surfactant: As 4a molecular sieve crystals of the hole structures, plus fine particles having a large specific surface area, so the strong adsorption performance of 4A molecular sieve.
Adsorption of non-ionic surfactants, 4A molecular sieves 3 times NTA (nitrilo-triacetate) and sodium carbonate, five times the sodium tripolyphosphate (STPP) and sodium sulfate, and the nature of the molding for the agglomeration production of high-concentrated detergent formulated with more surfactants, washing and flow properties obtained good product makes sense. Through the experiment, liquid Zeolite 4A carrying capacity ≥30%,4a molecular sieve in the detergent production process, increase the mobility of the material, to adjust the viscosity, obtained product appearance, sexual fluidity and anti-caking good product.
Detergency: experiments with different additives on the same formula, changing its detergency aid comparison, found 20% of the STPP, 20% of the molecular sieve, 4% polymer and 40% of the decontamination effect STPP rather, in 20% of non-phosphorus zeolite added 10% sodium carbonate and 4.5% of the polymer obtained very good detergency products.
Redeposition properties: 4a molecular sieve with good adhesion of oil, when sodium carbonate, CMC, sodium silicate and sodium and other additives added zeolite adsorption decreased nylon fabric for oil pollution. Particle size of the zeolite at 0.4-1.0μm, better dispersibility can be prevented from adhering on the fabric.
Although not as good as 4a molecular sieve dispersing ability STPP, but with sodium polyacrylate dispersion can solve complex problems of dirt.
Compatibility with other additives: 4A Zeolite proper performance and other additives can make it complementary, 4a molecular sieve dirt dispersion and hardness ions chelating inferior STPP, but 4A Zeolite mix with STPP, detergency can STPP reached with a single effect. This is because since the solid surface can quickly STPP complex calcium and magnesium ions, and passed through an aqueous medium 4A molecular sieves. 4A Zeolite magnesium ion binding ability, can be obtained by molecular sieve complex silicates, carbonates be compensated.
PH buffer: 4a molecular sieve alkaline PH 1% aqueous solution at 11.0, and therefore has a certain buffer alkalinity.
Safety: 4A Zeolite non-toxic, safe to human height. Eyes, skin irritation, does not cause allergies, safety and reliability. After washing deposited in the soil, does not cause pollution, but also can improve soil, 4A Zeolite no adverse impact on the ecology

Some catalytic behavior of molecular sieve dehydration in ethanol amination reaction

Aliphatic amines is an important raw material of pesticides, pharmaceuticals, dyes and other industries. Its main synthetic methods ammoniated alcohol dehydration and alcohol dehydrogenation amination, an AI:. O, as a catalyst since production has since been put in since the early 1960s. Its alcohol conversion rate is acceptable, but a less selective amine. Binary and ternary metal oxide catalytic systems studied many reports ['', due to poor performance, the industry .zSM a selective 5 zeolite came after an attempt to take advantage of its role in improving the shape-selective primary amine has not been adopted Research work has been reported ['a 6'. Selective dehydration of methanol amination reaction of methylamine is indeed improved. For alcohol-containing C-C bond, 3a zeolite molecular sieves dehydration amination reaction catalyst as a research work has not yet commenced. This article focuses on the study of various zeolite acidity, pore structure on ethanol dehydration amination. Got some interesting results. Experiment 1 reagent and preparing zeolite powder original NaY (Wenzhou Chemical), NaM (Nanjing plant 5a zeolite molecular sieves  and NaZSM a 5 (Nankai Chemical) were treated with 10% NH; NO. Solution, 1 mol / L and 0.1 mol L hydrochloric acid solution / Maid change at a certain temperature for several hours to obtain sodium hydrogen zeolite washing, suction filtration, drying, take part NaHY, NaHM, NaHzSM a 5 respectively 5% LaC13, La 10% MgclZ solution obtained corresponding exchange, Mg · zeolite, washing, suction filtration, dried and set aside. Pu 2 test zeolite catalyst