What is Desulfurization

1. What Is Desulfurization?
Desulfurization is the process of removing sulfur from
something to prevent contamination. Also known as
hydrodesulphurization or HDS, this chemical process reduces the
sulfur dioxide emissions and converts them to sulfuric acid. The
sulfuric acid is then used in car batteries and fertilizer. The most
commonly required desulfurization process is in natural gas.
Additional desulfurizing is required for flue gas, coal, and oil.
Natural gas desulfurization is typically accomplished by
adsorption. A bed of activated carbon is used as the filter for
natural gas pipelines. As the natural gas runs through the
pipeline, it runs through the activated carbon at an established
interval. The sulfur is left behind and adsorbed into the activated
carbon. Tests are performed regularly to ensure the levels of
sulfur remain in the acceptable level.
Flue gas is the byproduct of power plants and refers to the
exhaust from burning fossil fuels. Flue gas desulfurization is
required to reduce the amount of sulfur dioxide getting into the
air. It is a large factor in the formation of acid rain.

2. Most Common Methods Of Removal
Of Sulphur:
I.Hydrodesulfurization.
II.Chemical Desulphurization.
III.Physical Adsorption Of Sulphur Oxide.
IIII.Wet Sulfuric acid process.
IV. Spray dry scrubbing using similar
sorbent slurries.

3. I.Hydrodesulfurization:
In the hydrodesulfurization process, a mixture of the oil-based raw
material and hydrogen gas is heated to 300-400°C and pumped under a
pressure of up to 130 atmospheres into a hydrodesulfurization reactor.
Here, the mixture passes over a catalyst which breaks the sulfur-carbon
bonds, allowing the sulfur to react with the hydrogen to form hydrogen
sulfide. There are a number of hydrodesulfurization catalysts, but the one
most commonly used consists of molybdenum sulfide, which contains cobalt
on an aluminum oxide base.
The H2S flows out of the reactor, along with excess hydrogen, and into a
treatment unit where it is separated out, allowing the hydrogen to be
recycled through the process. Several cycles may be required to reduce the
sulfur content to the required level.
The hydrogen sulfide produced by HDS is converted to elemental sulfur
by a procedure known as the Claus Process — refineries generally have a
Claus unit for this purpose. Much of the sulfur recovered in this way is used in
the production of sulfuric acid. Although sulfur deposits are still mined, most
sulfur production today is from petroleum via the HDS and Claus processes.

4. II.Physical Adsorption Of Sulphur Oxide:
Macrotyloma uniflorum Lam. is commonly known as horse gram,
which belongs to the family Fabaceae. Polyphenols present in seed
extract of M. uniflorum were water soluble, heat stable, polar, non-tannin
and nonprotein in nature. Taking all these factors into
consideration M. uniflorum seed powder was selected as an
adsorbent.
We tried to examine the possibility of using a well-known
physicochemical method as adsorption for the removal of SO2 from
aqueous SO2 solution.
The initial screening study has been carried by mixing a known
amount of M. uniflorum adsorbent into the aqueous solution of SO2
(Angold, 1997).
The adsorption experiment is carried out with respect to contact
time between aqueous solution and adsorbent, with respect to effect
of aqueous SO2 concentration, and with respect to adsorbent dosage.

5. III.Chemical Desulphurization:
Chemical desulphurization and microwave-chemical desulphurization was
employed to remove sulfur in crude oil. Several desulfurizing agents have been
selected and investigated.
Among these desulfurizing agents, DCP, BPO, BBPV, and BPMC are organic
peroxides, while the active oxygen content of organic peroxides is increasing,
the oxidation effects become better and the desulfurizing efficiency of crude oil
is increasing.
BBPV and BPMC are compared with other organic desulfurizing agents,
which perform better. Various influencing factors such as dosage of desulfurizer,
investigated temperature, and optimum reacting conditions were obtained.
The optimized dosage of BBPV, BPMC, and formylhydroperoxide is 1%, 2%,
and 15%, respectively. The optimized temperature should be 80–90°C.
Microwave inducement can improve the effect of chemical desulphurization
and better desulfurizing results were gained.
The desulfurizing efficiencies of peroxy acetic acid, BBPV, and BPMC
increased from 18.6%, 21.8%, 28.5%, and 24.3% to 34.7%, 33.3%, 34.5%, and
43.3%, respectively. The microwave inducement can decompose sulfone to
water-soluble sulfate and sulfite. Thus, organic sulfur was transformed into
inorganic sulfur and then removed.