Effective Way to Remove Water through Desiccant Molecular Sieves

The most effective way to remove water is to run the solvent slowly through a column of the molecular sieves but, usually to remove most water; dried sieves are just positioned into the bulk solvent container (about 5%-10% by volume). Molecular sieves are available in market in the form of beads, pellets & powder.

They have a long list of advantages including of - their consistently high adsorption speed. They offer higher contamination resistance. They also have stronger crushing strength. Their increasing cyclic times which provide an extended product life are also an added advantage.

Typical application areas are: cracked gas drying, drying of highly polar compounds, such as methanol and ethanol, drying of unsaturated hydrocarbons, drying of liquid alcohol, drying of refrigerants, static, (non-regenerative) dehydration of insulating glass units. 3a molecular sieve can absorb unintended moisture, so put them in an air tight container until ready for use to avoid adsorption.

Molecular Sieve 3A Ethanol for Drying

 Molecular sieve 3a is an alkali metal alumina-silicate. It is of type 3A that means it is the potassium form of the type a crystal structure; it contains the effective pore opening of about 3 angstroms (0.3nm). This opening is large enough to allow the moisture inside it, but excludes molecules such as unsaturated hydrocarbons (unsaturated hydrocarbons can potentially form polymers) and this maximizes lifetime when dehydrating such molecules.

These molecular sieves are typically zeolite compounds, these compounds effectively adsorb water and have carefully controlled pore sizes. Both the solvent and the water will adsorb strongly to the molecular sieve surfaces. Smaller water molecules get access to the large surface area within the pores, so that they are successfully removed from the solvent. We can see from the table mentioned below that the water (1.93A) will enter the 3A pore size while acetone (3.08A) will mostly be excluded. Water will occupy the large surface area inside the pores and therefore be removed.  But if the solvent also enter the pores, it would struggle with water for the surface area and the removal of water becomes impossible. So Type 3A molecular sieve is effectively suitable for drying ethanol, methanol, or acetone. But type 4A sieve can fail to do the same since the pore size does not exclude these solvents.

Molecular Sieve 3A best use for Water Removal

When it comes at preserving their precious products, industrialists want to use the best method to get rid of such problem which can cause a major damage to them. Among the problems, moisture problem is the major one. Even a drop of moisture droplet can become a reason enough to demolish huge machinery. So, in order to get rid of moisture, effective moisture controlling technique is used that is desiccant. These desiccants absorb moisture and lock them inside and help to make the environment moisture free.

Considering molecular sieves desiccant exclusively it is used in various industries like oil and gas, petrochemicals, sugar and air Industries as well. In these industries they are used to perform various purposes like removal of water from various places and moisture removal as well. It is also used for drying natural as well as industrial gas drying. So basically we can say these desiccants are best for the protection against moisture and water. Although the manufacturers can give various different shape to the desiccant but they only choose to give beads and pellets shape because in this form the surface area for absorption increases. So, it can not only make the environment dry quickly but locks them inside.

Molecular Sieve Desiccant Packets for Formulation

Whenever it comes to protection against moisture, the first thing which comes in everyone’s mind is desiccants. Now desiccants are also of various types. Among all the most popular and the best is silica gel and molecular sieves beads. Although these desiccants are not much toxic unless it is consumed. But still some precautionary measures are taken and thus they comes sealed pack in breathing packets. Once these desiccants absorb moisture it locks them inside and makes the environment moisture free.

These molecular sieves beads are mostly used in pharmaceutical industries. As they help us to retain the originality of the product. Apart from this they are used in various other fields like food electronics, textile, stationary, leather and packaging industry. Whenever you buy any leather product, you must have seen a small packet with a do not eat tag and wondered what its use here is. It is very important at its own place. It not only controls moisture but also controls Odors. Many of the times these desiccants are used in breathers as well. That is because big machines perspire huge amount of moisture in the process of sudden cooling and heating. So, even a drop of moisture can be devastating. So apart from preventing the products from spoilage and fungus, bacterial growth it increases the life of machineries. As by using this product machines does not catch rust easily and thus increases its life. Desiccants have given a completely new phase to the food and packaging industry.

Elements of Ethanol Dehydration Process using 3A Molecular Sieves

Ethanol Drying is basically a process for removing water molecules or something equivalent to water molecules from any substance. Ethanol is drying to obtain ethylene and water when it is heated with catalyst of concentrated sulfuric acid. The ethane gas produced is collected over water and tests are done. This is to find out the typical properties possessed by the unsaturated hydrocarbon. For the dehydration of ethanol one likely product is ethane. In industry this term basically means removing water or moisture from the solution of ethanol which is a result of fragmentation. However, one of the most important dehydration is the dehydration of alcohol from phenyl ethanol.

In the process of ethanol dehydration using molecular sieves 3A Zeolite molecular sieves is used to absorb the water content from ethanol. This absorbent is crystalline form of amino silicates. It has a unique structure which allows crystallized water to be removed and end the end left is a porous crystalline structure. If a polar compound fluid has to be absorbed it can easily be absorbed with the help of low concentration fluid. Molecular sieves have strong absorptive force which allows it to easily remove impurities from gasses or liquids. Having strong ionic forces which is a result of the presence of cations like calcium, sodium and potassium.

Molecular Sieves for Ethanol Dehydration

Before understanding the process of ethanol drying with the help of molecular sieves it is important to understand what is a molecular sieve. It is that material which is used for absorption and has selective properties. These properties are important for the purpose of separating different mixture. It depends on the type of mixture that which size and shape of molecular sieves has to be used. Molecular sieves can be used in any form that is in pelleted, beaded or in powdered form. Molecular sieves are a result of the composition of three dimensional material that is micro porous material, macro porous material and meso porous material. A single bead of molecular sieves is made with the blend of all the three. Molecular sieves are used as absorbents for various other industrial applications. According to the requirement and size molecular sieves are of various types that is 13x, 3A, 4A and 5A. So, now with the help of these efficient absorbents it is now possible to extract moisture from oils to gasses. This is the most reliable source of moisture absorbent in oil and electronic industry.

Dehydration of Ethanol Using Molecular Sieves

For the catalytic reaction crystalline aluminosilicate salts of the molecular sieve family is used. Now let’s we look how molecular sieve will help in the dehydration of the ethanol.

The rectified spirit which is produced in the rectifier is superheated with steam in feed super- heater. After following this stage the super heated rectified spirit from the feed super heater is passes to one of the pair of molecular sieve bed for many times. Later by time the superheated rectified spirit vapor is poured or moved to another pair of bed. The loaded bed is regenerated by using a small portion of the anhydrous ethanol vapor leaving the fresh adsorption bed. Following this process a moderate vacuum pump operating after the condensation of the regenerated ethanol water mixture. The condensate is then transferred from recycle drum to the rectified column in the hydrous distillation plant by recycle pump. The remaining anhydrous absolute alcohol draw is again condensed in product condenser and passed to product storage.one of the main advantage of using this process is it cost less and also normally the molecular sieve has a life span of around five to seven years. While comparing azeotropic distillation this process cost very low.

Molecular Sieve for Ethanol Dehydration Explored

Now a days  most of the countries are facing a great problem in the production of anhydrous ethanol due to the great efforts directed to use biofuels and diminishment in pollution and environmental problems of fossil fuels, So because of this many countries arising this issue as their main problems. Usually the extraction of anhydrous alcohol production comprises three main steps: fermentation distillation and dehydration. The ethanol quantity will be determined purely based on the last step that is the final dehydration step which depends on the operating conditions and the technology used.

 

It was found to be more time consuming and costly, because of this a new catalyst called molecular sieve beads is introduced for the production of anhydrous ethanol. Absolute alcohol is an important product required by industry. Many countries depends the production of high standard alcohol for their economic uplifting.

As per IS specification alcohol should be nearly 100% pure or water free alcohol. Rectified spirit, which is 94.68% alcohol, and the rest contained with water is currently available in market. Practically it is not possible to remain the water content from the rectified spirit by straight distillation as the compound; ethyl alcohol forms a constant boiling mixture with water at this stage to form a product known as azeotrope. Therefore special extraction process is needed for the removal of water for the manufacture of absolute alcohol. So the manufactures of absolute alcohol or for the dehydration of the alcohol we use molecular sieve process.

Molecular Sieves are used in Desiccant Packets

Another important desiccant is molecular sieves. These are also available in form of granules but are assumed to be little less effective than silica gel. It is used to absorb moisture. Next is activated carbon. These are the odor absorbing specialist. The last one is clay. It is also used for absorbing odor as well as some amount of moisture. Although, clay is not used widely! Reason is that once a bag of clay has fully absorbed moisture it has to be changed immediately as it starts to leak water droplets. And absolutely fails to trap moisture inside. Still it is considered as the cheapest way for absorbing moisture.

Many people use a single desiccant at a time but as per the requirement a combination of more than one desiccant can also be used. Suppose, using silica gel and activated carbon in a same packet can help you to get rid of moisture and odor at the same time. As the product does not release any toxins it is safe to use with eatable items. These desiccants are mostly used at the time of packaging of dry food items, shoe boxes, vitamins medicines and many more.