Tuesday, 30 September 2014

Ethanol Dehydration Process with Molecular Sieves

These sieves are made available in the form of beads, pellets and powder foam that can be used for ethanol dehydration, natural gas adsorption and purification process. When we talk about high water adsorption capacity, strong crushing structure, high mass transmission efficiency, these sieves are the best choice. These adsorbents have more than one cyclic process times and more durability involving regeneration features improves more efficiency and longtime adsorption capacity with having more effective then activated alumina and silica gel.

Molecular Sieves for Ethanol Dehydration Process
These desiccants have a high adsorption quality. This quality is bought by the intricate network of pores and also empty cavities in which moisture can be absorbed. These sieves are available in various configurations like 3X, 4X, 5X, 10X. The higher the numerical value, the better is the moisture absorbing capacity. Molecular sieve 3a is the potassium based molecules having opening pore size about 3Ao of “A” type crystalline structure and also it cannot absorb any molecules more than its pore size. The chemical name of this desiccant is synthetic sodium potassium or calcium aluminosilicate.

These desiccants find extensive use in various commercial and industrial processes. Molecular sieves are used in dehydration of many kinds of liquids like ethanol. It is also used in the separation and purification of these liquids. Oil purification is another such area where these sieves are used extensively. These are also used in olefin drying. The feed that comes from polymer plant is also dried using molecular sieves. It is also recommended for drying unsaturated hydrocarbons and highly polar compounds such as methanol and ethanol. The molecular sieve 3a structure is particularly effective in dehydrating the inner space of insulating glass windows as well as refrigerant gases. The moisture absorbing property of these sieves is also very effective in dehydration of cracked gas, ethylene, ethyne, propylene, butadiene, natural gas or methane, oxygen remove from air and also the air itself. It is also used in drying N2-H2 mixtures made by cracking of ammonia.

Tuesday, 23 September 2014

Characteristics & Uses of Molecular Sieves

Molecular sieve is a porous solid, usually a synthetic or a natural zeolite derived from alumina silicates with a different attachments of compounds like sodium, Calcium, Potassium that separates particles of molecular dimension which are defined to its pore diameter openings like 3A,4A,5A,10A. A true Molecular sieves are hydrated metal alumino-silicate compounds with well-defined crystalline structures. 

The silicate and aluminates groupings form three-dimensional crystal lattices surrounding cavities in which the metal ions and the water molecules are loosely held. Channels run through the entire crystal, interconnecting the cavities and terminating at the crystal surface. Upon heating above 200 deg C, the zeolites lose their inbound water content with little or no change in their crystal structure. The dehydrated Molecular sieves can reversibly absorb water or other molecules that are small enough to pass through the channels or pores. The metal ions are also readily replaceable by oterionic units of similar charge and size..

Molecular Sieves
Molecular Sieves

 The sizes of a 4 to 8-mesh sieve is normally used in gas phase applications, while the 8 to 12-mesh type is common in liquid phase applications. The powder forms of the 3A, 4A, 5A and 13X Molecular sieves are suitable for specialized applications. Long known for their drying capacity (even to 90°C), molecular sieves have recently demonstrated utility in synthetic organic procedures, frequently allowing isolation of desired products from condensation reactions that are governed by generally unfavorable equilibria. These synthetic zeolites have been shown to remove water, alcohols (including methanol and ethanol), and HCl from such systems as ketamine and enamine syntheses, ester condensations, and the conversion of unsaturated aldehydes to polyenals.

Molecular sieves are used for drying gases and liquids and for separating molecules on the basis of their sizes and shapes. When two molecules are equally small and can enter the pores, separation is based on the polarity (charge separation) of the molecule, the more polar molecule being preferentially adsorbed.

3A type with potassium base is widely used in commercial dehydration of unsaturated hydrocarbon streams, including cracked gas, propylene, butadiene, acetylene; drying polar liquids such as methanol and ethanol. Adsorption of molecules such as NH3 and H2O from a N2/H2 flow. Considered a general-purpose drying agents in polar and nonpolar media.

Type 4A Molecular Sieve is most preferred for static dehydration in closed liquid or gas systems, e.g., in packaging of drugs, electric components and perishable chemicals; water scavenging in printing and plastics systems and drying saturated hydrocarbon streams. Adsorbed species include SO2, CO2, H2S, C2H4, C2H6, and C3H6. Generally considered a universal drying agent in polar and nonpolar media.

Commercial gas drying, air plant-feed purification (simultaneous H2O and CO2 removal) and liquid hydrocarbon/natural gas sweetening (H2S and mercaptan removal- sweet smell ) which is well taken care by 13X type.

If you plan to remove or separation of normal paraffin’s from branched-chain and cyclic hydrocarbons; removal of H2S, CO2 and mercaptans from natural gas. Molecules adsorbed include nC4H10, nC4H9OH, C3H8 to C22H46, and di-chlorodifluoro-methane (Freon 12®) then the most recommended product is a 5A type. Which is widely accepted.

Aggressive Moisture Control Desiccant – Molecular Sieves

Basically Molecular Sieves are used in industrial or commercial applications; this desiccant is aggressive in nature for absorbing moisture. If this desiccant used in proper quantity, then this is a powerful desiccants can be used in the right order to remove moisture from environment. Some general example of a desiccant would be in electronic items and pharmaceutical products when any drops of moisture harm their circuits.
Aggressive Moisture Control Desiccant
This desiccant has high adsorption quality in their pores and empty hollows where moisture or vapors can be adsorbed. Molecular sieves are accessible in versions such as 3a, 4a, 5a, 10a etc. The higher the numerical value, the better are the adsorption abilities.

Applications of Molecular sieves 3a

Applications of Molecular sieves 3a

An Ideal Moisture Absorption Solution with Molecular Sieve Desiccant

Molecular sieves provide moisture removal to extremely low levels with high adsorption capacity. Common applications using molecular sieves include dehydration of moisture sensitive formulations, Air dryers for plastics, air conditioning & refrigeration systems, air brake systems, environmental pollution control, oxygen concentrators, insulating glass, package dehydration & deodorization, natural gas, petroleum & petrochemical drying & purification.

Moisture Absorption Solution with Molecular Sieve Desiccant
Moisture Absorption Solution

Featuring innumerable empty cavities, which is what endows it with the highest adsorption capacity in comparison with other desiccants; these adsorbents are a synthetically manufactured form of zeolite. However, one of the most expensive adsorbents available today is this very quality.

Molecular sieve desiccant provides a wide range of adsorption potential based on molecular size, sieve crystal area and shape of the molecule. It is most popular wetness adsorbing solution in industries because of excellent adsorption efficiency in comparison to other moisture adsorption system.

There are many types of sizes available like 3A, 4A, 5A and 13X molecular sieves based on industrial requirement and adsorption capacity of moisture..Molecular sieves are available with micropores in a number of sizes ranging in the nanometer ranges. Typical micropore sizes range from 3 to 10 Angstroms contained in beads measuring 1.5mm to 5mm.

This desiccant is based on ingredients such as calcium alumina silicate. Most manufacturers provides conventional prepackaged molecular sieves for industrial use. However, if you need personalized alternatives, these can be acquired too. For this you would need to solicit the services of a reputable desiccant manufacturer company. Here are some other significant features of these desiccants.

• They can either be used individually or custom blended with some other desiccants to give you an optimal adsorption solution. 

 • Different desiccants have different adsorption capacities. In the case of a molecular sieve, you can expect it to adsorb moisture or gas up to 20 times its own weight.

 • Since it is one of the most aggressive desiccants available in the market today, it costs significantly more than its other counterparts.

 • Especially during the transportation and warehousing stages of the distribution cycle, a number of pharmaceutical companies make use of molecular sieve to protect packaged drugs and antibiotics from humidity. 

So, there are several industrial applications in which this desiccant is commonly used, right from protecting costly artwork to pre-purification of water to absorbing co2. It can also be used with drug products, since this desiccant is odorless. Moreover, molecular sieves are very appropriate for use in high temperature applications, with a melting point that is slightly less than 2900 degrees Fahrenheit. They are also used in chemical reactions since they are stable. However, one should always wear a dust mask and gloves while handling it, as safe as this desiccant is.

Information on Molecular Sieve Desiccant

Molecular Sieves are synthetic crystalline zeolites in which the atoms are organized in a certain pattern. Internally, the structure has many oral cavities inter-connected by small pores of a consistent dimension. These pores are only able to accept and pass to the cavities molecules of the same and small dimension, hence the name molecular filter.

The water fumes adsorption features are very different from those of silica gel. Molecular sieves can absorb up to approximately 20% by weight of water before the comparative moisture of the air improves significantly. Any further increase causes a large rise in comparative moisture.

molecularsieve desiccants
Molecularsieve Desiccants
These features allow molecular sieves to sustain very low dew points (-50°C for 10% by weight of adsorbed water). The content also has the ability to quickly adsorb water fumes and is capable of keeping high adsorption performance at high temperature ranges of up to 90°C.

Molecular Sieves are available in four main general types, 3A, 4A, 5A and 13X. Each type has its own specific qualities and applications, and all maintain a complete choice for adsorption of water.

• 3A Molecular sieve is the preferred Molecular Sieves adsorbent for the commercial dehydration of unsaturated hydrocarbon streams.

• 4A Molecular sieve is the preferred Molecular Sieves adsorbent for the static dehydration in a closed gas or liquid drying system.

• 5A Molecular sieve is the preferred Molecular Sieves adsorbent for the separation of normal paraffin's from hydrocarbons.

 13X Molecular sieve is used commercially for general gas drying, air plant feed purification and liquid hydrocarbon and natural gas sweetening.