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208604

Sigma-Aldrich

Molecular sieves, 4 Å

beads, 1.6-2.5 mm

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250 G
$94.40
1 KG
$206.00
5 KG
$484.00

About This Item

Linear Formula:
Na12[(AlO2)12(SiO2)12] · xH2O
CAS Number:
70955-01-0
MDL number:
MFCD00131613
UNSPSC Code:
23201100
eCl@ss:
32110204
NACRES:
NB.24

$94.40

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beads

Quality Level

100

particle size

1.6-2.5 mm

pore size

4 Å

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General description

Choosing a Molecular Sieve:
1. The preferential adsorption of one molecule over another depends upon pore diameter and mesh size.
2. The dynamic capacity of the silica gel for adsorbing a particular compound is governed by the internal surface area; the greater the surface area, the greater the dynamic capacity.
3. Rate of adsorption and sharpness of resolution are dependent chiefly on particle size and column packing; a fine particle size gives optimum sharpness of resolution.
4. Liquids are most readily adsorbed from solvents in which they are least soluble; a good solvent makes a good desorbing agent.
5. Highly polar liquids are readily adsorbed. Compounds having hydroxyl groups, or containing oxygen are strongly adsorbed.
6. For similar compounds, the higher the molecular weight the higher the selectivity.
7. For hydrocarbons of similar molecular weight, adsorptivity increases with the number of double bonds.
Molecular sieves are crystalline metal aluminosilicates having a three-dimensional interconnecting network of silica and alumina tetrahedra. Natural water of hydration is removed from this network by heating to produce uniform cavities which selectively adsorb molecules of a specific size. This 4A form with sodium ions has the effective pore opening of 4Å, thus excluding molecules of effective diameter >4Å (for example: propane). The 8 to 12-mesh type is common in liquid-phase applications. Molecular sieves are considered a universal drying agent in polar and nonpolar media.
Regeneration or Activation:
A saturated molecular sieve can be restored to its original capacity by regeneration, the principle of which involves changing the conditions surrounding the adsorbent to correspond to a very low equilibrium capacity. In general, the greater the difference between the equilibrium capacities of adsorption and regeneration, the more rapid and complete the regeneration.
The sieve may be regenerated in one of four ways:
1. Thermal reactivation –The maximum regeneration temperature for Silica is 300°C.
2. Pressure reactivation
3. Passing an appropriate fluid through the gel bed at normal temperature and pressure.
4. Displacement of adsorbates by passing a high concentration of molecules in a fluid through the bed.

Application

Molecular sieves, 4 Å may be used in the following processes:
  • Static dehydration in closed liquid or gas systems such as in packaging of drugs, electric components and perishable chemicals.
  • Water scavenging in printing and plastics systems.
  • Drying saturated hydrocarbon streams by adsorbing gases such as sulfur dioxide, carbon dioxide, hydrogen sulfide, ethene, ethane and propene.
The product (Molecular sieves, 4 Å) has been used for the removal of all traces of water from various solvents (methanol, methanol-acetone and acetone).[1] Also, they have been used for drying during the preparation of solutions of N-hydroxysuccinimide (NHS) and biotin-NHS esters (1gL-1) in dried ACN (acetonitrile).[2]

Storage Class

11 - Combustible Solids

wgk_germany

WGK 3

flash_point_f

Not applicable

flash_point_c

Not applicable

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Certificates of Analysis (COA)

Lot/Batch Number
MKCX0068
MKCV5834
MKCQ2993
MKCP9811
MKCP8053

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Evgeny Pavlov et al.
Biophysical journal, 88(4), 2614-2625 (2005-02-08)
We examined ion channels derived from a chloroform extract of isolated, dehydrated rat liver mitochondria. The extraction method was previously used to isolate a channel-forming complex containing poly-3-hydroxybutyrate and calcium polyphosphate from Escherichia coli. This complex is also present in
Quantification of N-hydroxysuccinimide and N-hydroxysulfosuccinimide by hydrophilic interaction chromatography (HILIC).
Klykov O and Weller MG.
Analytical Methods : Advancing Methods and Applications, 7(15), 6443-6448 (2015)

Questions

1–7 of 7 Questions  

  1. How is shipping temperature determined? And how is it related to the product storage temperature?

    1 answer

    1. Products may be shipped at a different temperature than the recommended long-term storage temperature. If the product quality is sensitive to short-term exposure to conditions other than the recommended long-term storage, it will be shipped on wet or dry-ice. If the product quality is NOT affected by short-term exposure to conditions other than the recommended long-term storage, it will be shipped at ambient temperature. As shipping routes are configured for minimum transit times, shipping at ambient temperature helps control shipping costs for our customers. For more information, please refer to the Storage and Transport Conditions document: https://www.sigmaaldrich.com/deepweb/assets/sigmaaldrich/marketing/global/documents/316/622/storage-transport-conditions-mk.pdf

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  2. How can I determine the shelf life / expiration / retest date of this product?

    1 answer

    1. If this product has an expiration or retest date, it will be shown on the Certificate of Analysis (COA, CofA). If there is no retest or expiration date listed on the product's COA, we do not have suitable stability data to determine a shelf life. For these products, the only date on the COA will be the release date; a retest, expiration, or use-by-date will not be displayed.
      For all products, we recommend handling per defined conditions as printed in our product literature and website product descriptions. We recommend that products should be routinely inspected by customers to ensure they perform as expected.
      For products without retest or expiration dates, our standard warranty of 1 year from the date of shipment is applicable.
      For more information, please refer to the Product Dating Information document: https://www.sigmaaldrich.com/deepweb/assets/sigmaaldrich/marketing/global/documents/449/386/product-dating-information-mk.pdf

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  3. For how long the new molecular sieves can be used after the activation? How do we know when the used molecular sieves need to be re-activated?

    1 answer

    1. This material does not have an expiration date. Like the 3A sieve, the 4A type can also be reused and regenerated. First, you will want to remove the absorbed moisture and other materials, and then heat it to 250 to 450 degrees Fahrenheit. Then store the sieve in an airtight container until ready to use again to avoid any unintentional moisture absorption.

      Activating the sieves dries the sieves, you would need to reactivate the sieves before use if they contain absorbed moisture. Once activated, the sieves can be stored in a glass container with a double wrapped parafilm. This will keep them activated for up to six months.

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  4. How do Molecular sieves, 4 Å, Product 208604, work?

    1 answer

    1. A nominal pore diameter of 4 Å means that molecules with a smaller effective diameter will be absorbed, such as H2O, NH3, ethanol, CO2, H2S, SO2, ethylene, ethane and propylene. Conversely, it will exclude molecules with effective diameters greater than 4 Å, such as propane. Hence, it enjoys wide utility for drying solvents

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  5. Are Molecular sieves, 4 Å, Product 208604, pre-activated?

    1 answer

    1. No. They should be activated by purging with a Bunsen burner, or by drying in an oven at 350-400°F for a few hours.

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  6. What is the Department of Transportation shipping information for this product?

    1 answer

    1. Transportation information can be found in Section 14 of the product's (M)SDS.To access the shipping information for this material, use the link on the product detail page for the product.

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  7. What is the capacity of the Molecular sieves, 4 Å, Product 208604?

    1 answer

    1. The capacity of these sieves is approximately 20% by weight.

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