Molecular Sieve Pellets/Beads for Effective Solvent Drying

Molecular Sieve- A Brief Introduction

Molecular Sieves, like Silica Gel, are well-known desiccants used mainly for removing vapour molecules from oil, liquid and natural gas streams. Available in balls, beads and pellet form, these desiccants are nowadays more preferred to Silica Gel and Activated Alumina because they can absorb humidity molecules in a better manner. Molecular Sieves are also economically viable as they can take in more moisture molecules in lesser period of time and this helps in saving money.

Molecular Sieves are much in demand due to their uniform pore crystalline structure. This added with their large surface area speeds up the absorption process to a large extent. Molecular Sieves work by using the size exclusion principle. When water molecules come in contact with the Molecular Sieve, only those molecules which fit into the pores are absorbed while the larger molecules pass through. The pore size of Molecular Sieves are in the range of 3,4,5 and 10 Angstroms. When the absorption process is going on depending on the pore size, the water molecules will be absorbed or move forward. This is one of the biggest benefits of using Molecular Sieves as desiccants for removing water vapour.

The main difference while using Molecular Sieve and other desiccants like Silica Gel and Activated Alumina is that in Molecular Sieves, the absorbed molecules get trapped while in the others, the absorbed molecules are free to move away. This is why when Molecular Sieves are used, the water molecules are retained in the pores, freeing the remaining area of moisture. 

Molecular Sieves pellets are widely used in drying oil and liquid gas streams and solvent drying because this desiccant can hold 22% of its own weight in water. Molecular Sieve beads also witness much demand because their absorption qualities are much superior to other desiccants. These qualities include adsorption possible based on molecular size, molecular affinity for the sieve crystal surface and finally the shape of the molecule.

Molecular Sieve Beads/Pellets in Solvent Drying

Among all the Molecular Sieves beads in use, the Molecular Sieve type 3A is generally used to dry dehydration solvents for electron microscopy. The solvents, which are generally made free from moisture molecules are the most commonly used ones like acetone, ethanol, and methanol. They are generally used in electron microscopy embedding work using epoxy resins, so it becomes very important that they have no traces of moisture in them. This is where the role of Moisture Sieve Beads and Pellets become crucial as they will remove all the traces of humidity from the solvents. What better way of solvent drying that Moisture Sieve beads and pellets.

When the bottles containing the solvents are opened, there are chances that they will pick up moisture from the surroundings so that is why Molecular Sieves are used to dry up the solvents. These dried solvents are used in the final stages of dehydration and embedding. The solvent and the water will be quickly adsorbed onto the molecular sieve surfaces as the small pores can only access the smaller water molecules.

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Molecular Sieve Adsorbents for Effective CO2 Removal

What are Molecular Sieve Adsorbents?

When we think of adsorbents, the first thing that comes to mind is Silica Gel. This, however, is not the only adsorbent being used by companies to remove moisture from closed spaces. Molecular Sieve Adsorbents are high-quality desiccants, which are equally effective in maintaining optimum humidity levels. Molecular Sieve Adsorbents are basically crystalline alumino-silicates, commonly known as zeolites.

They are manufactured in such a manner that they have a porous crystalline structure. These pores can re-adsorb water or other polar molecules. With the help of strong ionic forces or electrostatic fields (which are due to the presence of cations such as sodium, calcium and potassium) and with enormous internal surface area of around 1‘000 m2 /g, molecular sieves can take in a large amount of water or other compounds. If the fluid, which is to be adsorbed is a polar compound, it can be adsorbed with high loading, even during very low concentrations of the contaminants. Molecular sieves adsorbents are therefore capable of removing many gas or liquid impurities to very low levels (ppm or less). Another popular positive factor about Molecular Sieve Adsorbents is that they can separate gases or liquids by molecular size or polarity. This is largely made possible by the fact that the pore openings of the Molecular Sieve Adsorbents have the same size as a wide range of products. As the water molecule size is smaller than the Molecular Sieve Adsorbents size, they will be easily absorbed thus maintaining optimum moisture levels.

Molecular Sieve Adsorbents for Carbon Dioxide Adsorption

One may think that Molecular Sieve Adsorbents are only used for water vapour adsorption. That is, however, not the only thing it is used for. Molecular Sieve Adsorbents are utilized for adsorption of other compounds as well. One of them is Carbon Dioxide. Molecular Sieve for CarbonDioxide removal is very common among companies.

For obtaining an adsorbent with typical molecular sieve properties one makes use of thermal processing of granulated carbonaceous material at temperatures of 970-980 degree Celsius. This is usually done in the presence of gases to prevent the oxidation of the carbon material. At temperatures of around −196° C, the adsorption takes place in its micro-pores, whereas nitrogen and argon are taken in at the same temperature at the surface of transitional pores and macro-pores only.

It is mainly oil and natural gas companies, which make use of Molecular Sieve Adsorbents to remove carbon dioxide. It is mainly used to remove CO2 from stream cracked gas, Liquid Petroleum Gas and different atmospheric gases. Mainly, Molecular Sieve 3A and 4A is preferred for the above mentioned purposes.

There are many reasons why Adsorbents 3A and 4A are widely used for carbon dioxide removal. The first being these adsorbents have a high and very rapid adsorption rate. Another factor is that molecular sieve adsorbents are known to have a consistent adsorption speed and have a higher contamination resistance. All these factors make Molecular Sieve adsorbents the ideal substance for removing carbon dioxide from oil and natural gas industries. 

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Molecular Sieve for Naphtha Drying

Naphtha is a hydrocarbon distillate which is the remaining from the process of coal tar or refining petroleum. It is a multifaceted mixture of chemicals that is broken down and converted into other chemicals from catalytic reforming or steam cracking.

Molecular Sieves

Molecular sieves are defined as a material that comprises very minute pores that have a similar size and shape. Because of this property, the smaller molecules of another material can easily pass through, but the larger molecules are blocked just like a sieve. This uniformity in its structure makes this material a great desiccant. In fact, some common examples of this would be activated charcoal/carbon or silica gel. These materials are used as desiccants for gases and liquids adsorbents that have tremendous capacity of adsorption than activated alumina and silica gel desiccant. It is extremely effective at removing water from liquid and gases. 

molecular sieve offers a variety of adsorption capacity based on molecular size, sieve crystal surface and shape of the molecule. It is most popular moisture adsorbing solution in industries because of superior adsorption efficiency compared to other moisture adsorption system.

Molecular sieve for naphtha drying are desorbed and hydrocarbons are dehydrogenated and used as desorbing agents.

The present invention relates to the preparation of high octane motor fuel sand more particularly relates to an improved process for upgrading naphtha for use as a blending stock in the preparation of high octane gasoline.

Present octane levels require the use of large quantities of relatively high octane blending stocks such as catalytic naphtha, polymer gasoline, hydrogenate and the like and permit the inclusion of much lesser amounts of light virgin naphtha than were formerly used in gasoline blending. This trendy away from the use of light virgin naphtha as a blending stock has created surpluses of such naphtha at many refineries.

The process of the invention may be further said -by considering a typical application of the process in a commercial refinery processing

The product naphtha fraction obtained from the process has the following composition and octane values:

• Table II Component B./D. Vol. RON RON-H5 Percent Clear cc. TEL

• Isoparains and Cyclics- 6, 200 72 87. 1 100 Olenn 2, 424 28 96. 7 100. 3 8, 624 100 90. 5 100. 1