Desulfurization or desulphurisation is a chemical process for the removal of
sulfur
Sulfur ( American spelling and the preferred IUPAC name) or sulphur ( Commonwealth spelling) is a chemical element; it has symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms ...
from a material. The term usually refers to the removal of sulfur from a molecule or a material by
hydrogenolysis
Hydrogenolysis is a chemical reaction whereby a carbon–carbon or carbon–heteroatom single bond is cleaved or undergoes lysis (breakdown) by hydrogen.Ralph Connor, Homer Adkins. Hydrogenolysis Of Oxygenated Organic Compounds. J. Am. Chem. Soc. ...
:
:
Hydrogen is the ultimate sulfur acceptor. As applied to
oil refinery
An oil refinery or petroleum refinery is an industrial processes, industrial process Factory, plant where petroleum (crude oil) is transformed and refining, refined into products such as gasoline (petrol), diesel fuel, Bitumen, asphalt base, ...
streams, the conversion is known as
hydrodesulfurization
Hydrodesulfurization (HDS), also called hydrotreatment or hydrotreating, is a catalytic chemical process widely used to desulfurization, remove sulfur (S) from natural gas and from oil refinery, refined petroleum products, such as gasoline, g ...
. These processes are of industrial and environmental importance as they provide the bulk of sulfur used in industry (
Claus process
The Claus process is the most significant gas desulfurizing process, recovering elemental sulfur from gaseous hydrogen sulfide. First patented in 1883 by the chemist Carl Friedrich Claus, the Claus process has become the industry standard.
Th ...
and
Contact process
The contact process is a method of producing sulfuric acid in the high concentrations needed for industrial processes. Platinum was originally used as the catalyst for this reaction; however, because it is susceptible to reacting with arsenic impu ...
), sulfur-free compounds that could otherwise not be used in a great number of
catalytic
Catalysis () is the increase in reaction rate, rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst ...
processes, and also reduce the release of harmful sulfur compounds into the environment.
A laboratory scale hydrogenolysis is the desulfurization of thioketals by
Raney nickel
Raney nickel , also called spongy nickel, is a fine-grained solid composed mostly of nickel derived from a nickel–aluminium alloy. Several grades are known, of which most are gray solids. Some are pyrophoric, but most are used as air-stable s ...
. In such cases, the hydrogen is contained within the reagent.
Desulfurization without hydrogenolysis
Desulfurization without hydrogenolysis is uncommon. Some trithiocarbonates can be coupled by desulfurization with
phosphite
The general structure of a phosphite ester showing the lone pairs on the P
In organic chemistry, a phosphite ester or organophosphite usually refers to an organophosphorous compound with the formula P(OR)3. They can be considered as esters of ...
s or phosphines as S-atom acceptors. This approach has been described by the following equation:
:
Other
Other processes used for desulfurization include
hydrodesulfurization
Hydrodesulfurization (HDS), also called hydrotreatment or hydrotreating, is a catalytic chemical process widely used to desulfurization, remove sulfur (S) from natural gas and from oil refinery, refined petroleum products, such as gasoline, g ...
, the
SNOX process and the
wet sulfuric acid process (WSA process).
See also
*
Shell–Paques process
*
Flue-gas desulfurization
Flue-gas desulfurization (FGD) is a set of technologies used to remove sulfur dioxide () from exhaust flue gases of fossil-fuel power plants, and from the emissions of other sulfur oxide emitting processes such as waste incineration, petroleum ...
*
Biodesulfurization
References
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