A molecular sieve is a material containing tiny pores of a precise and uniform size that is used as an adsorbent for gases and liquids. Adsorption is a process that occurs when a gas or liquid Solute accumulates on the surface of a solid or a liquid (adsorbent forming a film of molecules or atoms (the This page is about the physical properties of gas as a state of matter Liquid is one of the principal States of matter. A liquid is a Fluid that has the particles loose and can freely form a distinct surface at the boundaries of
Molecules small enough to pass through the pores are adsorbed while larger molecules are not. In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by Adsorption is a process that occurs when a gas or liquid Solute accumulates on the surface of a solid or a liquid (adsorbent forming a film of molecules or atoms (the It is different from a common filter in that it operates on a molecular level. For instance, a water molecule may be small enough to pass through while larger molecules are not. Because of this, they often function as a desiccant. A Desiccant is a Hygroscopic substance that induces or sustains a state of dryness ( Desiccation) in its local vicinity in a moderately-well sealed container A molecular sieve can adsorb water up to 22% of its own weight. [1]
Often they consist of aluminosilicate minerals, clays, porous glasses, microporous charcoals, zeolites, active carbons, or synthetic compounds that have open structures through which small molecules, such as nitrogen and water can diffuse. Aluminosilicate Minerals are minerals composed of Aluminium, Silicon, and oxygen A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific Clay is a naturally occurring material composed primarily of fine-grained Minerals which show plasticity through a variable range of Water content, and Glass in the common sense refers to a Hard, Brittle, transparent Solid, such as that used for Windows many Charcoal' is the blackish residue consisting of impure Carbon obtained by removing water and other volatile constituents from Animal and Vegetation Zeolites (Greek zein, "to boil" lithos, "a stone" are hydrated Aluminosilicate Minerals and have a micro-porous structure Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6
Molecular sieves are often utilized in the petroleum industry, especially for the purification of gas streams and in the chemistry laboratory for separating compounds and drying reaction starting materials. Petroleum ( L petroleum, from Greek πετρέλαιον, lit The mercury content of natural gas is extremely harmful to the aluminum piping and other parts of the liquefaction apparatus - silica gel is used in this case. Mercury (ˈmɜrkjʊri also called quicksilver or hydrargyrum, is a Chemical element with the symbol Hg ( Latinized hydrargyrum Silica gel is a granular porous form of Silica made synthetically from Sodium silicate.
Methods for regeneration of molecular sieves include pressure change (as in oxygen concentrators), heating and purging with a carrier gas (as when used in ethanol dehydration), or heating under high vacuum. Ethanol fuel is Ethanol (ethyl alcohol the same type of Alcohol found in Alcoholic beverages.
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Adsorption capabilities[2][3]
- 3A (pore size 3 Å): Adsorbs NH3, H2O, (not C2H6), good for drying polar liquids.
- 4A (pore size 4 Å): Adsorbs H2O, CO2, SO2, H2S, C2H4, C2H6, C3H6, EtOH. Will not adsorb C3H8 and higher hydrocarbons. Good for drying nonpolar liquids and gases.
- 5A (pore size 5 Å): Adsorbs normal (linear) hydrocarbons to n-C4H10, alcohols to C4H9OH, mercaptans to C4H9SH. Will not adsorb isocompounds or rings greater than C4.
- 10X (pore size 8 Å): Adsorbs branched hydrocarbons and aromatics. Useful for drying gases.
- 13X (pore size 10 Å): Adsorbs di-n-butylamine (not tri-n-butylamine). Useful for drying HMPA. Hexamethylphosphoramide (abbreviated HMPA is a colorless organic liquid with the formula 3PO
See also
Some of the many types of molecular sieves are:
References
- ^ Molecular sieve,and molecular sieves study
- ^ Feiser and Feiser, Reagents for Organic Synthesis, Vol. Activated carbon, also called activated charcoal or activated coal, is a form of Carbon that has been processed to make it extremely porous and thus to A Desiccant is a Hygroscopic substance that induces or sustains a state of dryness ( Desiccation) in its local vicinity in a moderately-well sealed container Lime is a general term for various naturally occurring Minerals and materials derived from them in which Carbonates Oxides and Hydroxides of Silica gel is a granular porous form of Silica made synthetically from Sodium silicate. Zeolites (Greek zein, "to boil" lithos, "a stone" are hydrated Aluminosilicate Minerals and have a micro-porous structure 1, Wiley, New York, 1967, p. 703
- ^ Breck, D. W. J. Chem. Ed. , 41, 678 (1964)
External links
- Sieves put a lid on greenhouse gas
- molecular sieve patents
- Molecular sieve faq.
- An Open Cycle Molecular Sieve Dehydration System.
- Sigma-Aldrich