Chemical industry
History of chemical industry
Sulfuric
Acid
sulfuric
acid, chemical compound, H2SO4, colorless, odorless,
extremely corrosive, oily liquid. It is sometimes called oil of
vitriol.
1749: The
Sulfuric Acid began to be produced and manufactured with the use and
application of the Leaden Condensing Chambers.
In
1746 John Roebuck developed the lead
chamber process
for the manufacture of sulfuric acid. Prior to this time, sulfuric
acid had been produced in glass bottles several pounds at a time. But
the lead chamber process could produce sulfuric acid by the ton.
In
the original lead chamber process, sulfur and potassium nitrate are
ignited in a room lined with lead foil. Potassium nitrate, or
saltpeter
is
an oxidizing agent oxidizes the sulfur to sulfur trioxide according
to the reaction:
6
KNO3(s) + 7 S(s) -----> 3 K2S + 6 NO(g) + 4
SO3(g)
The
floor of the room was covered with water. When the sulfur trioxide
reacted with the water, sulfuric acid was produced:
SO3(g)
+ H2O(l) -----> H2SO4(aq)
This
process was a batch process and resulted in the consumption of
potassium nitrate
In
1835, Joseph Gay-Lussac invented a process for recovering the
nitrogen in nitrogen monoxide and recycling it to replace the
saltpeter as a source of nitrogen.
4
NO(g) + O2(g) + 2 H2O(l) -----> 4 HNO2(l)
4
HNO2(l) + 2 SO2(g) -----> 2 H2SO4(aq)
+ 4 NO(g)
This
accomplished two things simultaneously: it reduced the dependence on
expensive saltpeter and at the same time sharply reduced nitrogen
monoxide emissions. The only
requirement
now for saltpeter was to make up for the lost nitrogen monoxide.
Lead
Chamber Process
In
the lead chamber process hot sulfur dioxide gas enters the bottom of
a reactor called a Glover tower where it is washed with nitrous
vitriol (sulfuric acid with nitric oxide, NO, and nitrogen dioxide,
NO 2, dissolved in it) and mixed with nitric oxide and nitrogen
dioxide gases; some of the sulfur dioxide is oxidized to sulfur
trioxide and dissolved in the acid wash to form tower acid or Glover
acid (about 78% H 2SO 4). From the Glover tower a mixture
of gases (including sulfur dioxide and trioxide, nitrogen oxides,
nitrogen, oxygen, and steam) is transferred to a lead-lined chamber
where it is reacted with more water. The chamber may be a large,
boxlike room or an enclosure in the form of a truncated cone.
Sulfuric acid is formed by a complex series of reactions; it
condenses on the walls and collects on the floor of the chamber.
There may be from three to twelve chambers in a series; the gases
pass through each in succession. The acid produced in the chambers,
often called chamber acid or fertilizer acid, contains 62% to 68%
H 2SO 4. After the gases have passed through the chambers
they are passed into a reactor called the Gay-Lussac tower where they
are washed with cooled concentrated acid (from the Glover tower); the
nitrogen oxides and unreacted sulfur dioxide dissolve in the acid to
form the nitrous vitriol used in the Glover tower. Remaining waste
gases are usually discharged into the atmosphere.
Contact
Process
In
the contact process, purified sulfur dioxide and air are mixed,
heated to about 450°C, and passed over a catalyst; the sulfur
dioxide is oxidized to sulfur trioxide. The catalyst is usually
platinum on a silica or asbestos carrier or vanadium pentoxide on a
silica carrier. The sulfur trioxide is cooled and passed through two
towers. In the first tower it is washed with oleum (fuming sulfuric
acid, 100% sulfuric acid with sulfur trioxide dissolved in it). In
the second tower it is washed with 97% sulfuric acid; 98% sulfuric
acid is usually produced in this tower. Waste gases are usually
discharged into the atmosphere. Acid of any desired concentration may
be produced by mixing or diluting the products of this process.
1791:
Nicolas
LeBlanc patented the Leblac process, which was an industrial process
for the production of soda ash (sodium carbonate) from sea salt
(sodium chloride). In 1823, production of Soda Ash was started by a
British Entrepreneur.
- 2
NaCl
+
H2SO4
→
Na2SO4
+
2HCl
This
chemical reaction had been discovered in 1772 by the Swedish chemist
Carl
Wilhelm Scheele.
Leblanc's contribution was the second step, in which the salt cake
was mixed with crushed limestone
(calcium
carbonate)
and coal and fired. In the ensuing chemical reaction, the coal
(carbon)
was oxidized
to
carbon
dioxide,
reducing
the
sulfate
to
sulfide and leaving behind a solid mixture of sodium carbonate and
calcium sulfide, called black
ash.
- Na2SO4
+
CaCO3
+
2 C
→
Na2CO3
+
CaS + 2 CO2
Because
sodium carbonate is soluble in water, but neither calcium carbonate
nor calcium sulfide is, the soda ash was then separated from the
black ash by washing it with water. The wash water was then
evaporated to yield solid sodium carbonate. This extraction process
was termed lixiviation.
1804:
St. Rollox Chemical Works produced almost 10,000 tons of bleaching
powder, improving exponentially its production of 52 tons in 1799.
Created by Charles Tennant (who discovered the bleaching powder), it
was considered as the first biggest chemical enterprise in the world.
The
most common chlorine-based bleaches are:
Sodium
hypochlorite
(NaClO), usually as a 3–6% solution in water, usually called
"liquid bleach" or just "bleach". Historically
called "Javel water". It is used in many households to
whiten laundry, disinfect hard surfaces in kitchens and bathrooms,
treat water for drinking and keep
swimming pools free of infectious agents.
Bleaching
powder
(formerly known as "chlorinated lime"), usually a mixture
of calcium
hypochlorite(Ca(ClO)
2),
calcium
hydroxide
(lime,
Ca(OH)
2), and calcium
chloride
(CaCl
2)
in variable amounts.
Sold
as a white powder or in tablets, is used in many of the same
applications as sodium hypochlorite, but is more stable and contains
more available chlorine.
1859: The first oil well is drilled successfully
near Titusville, Pennsylvania. This oil well of 70 feet marked the
beginning of the Petroleum Industry.
1855:
BejamÃn Silliman, from New Haven, Conneticut, obtained
valuable products from the destillation of petroleum. Between these
valuable products were the naphthalene, gasoline, tar and other
solvents.
1918:
Fritz Haber won and received the Nobel Prize for his work in the
synthesis of ammonia. Nevertheless, this method was adapted for
its commercial use until 1930 by the german chemist Carl Bosh
1931:
First appearance of the first synthetic rubber.
1933: The
Imperial Chemical Industries, England, discovered the polyethylene.
1935:
Wallace H. Carothers, Du Pont, discovered the nylon.
1937: Dow
Chemical began to commercialize the polystyrene
1940: In
United States the first synthetic rubber tire was produced
1943: USA
produced the DDT (dichlorodiphenyltrichloroethane), which was used
for its insecticidal properties
Sulfuric
acid is by far the largest single product of the chemical industry.
When
sulfur is burned in air, sulfur
dioxide
is
formed, and this, when combined with water,
gives sulfurous acid. To form sulfuric acid, the dioxide is combined
with oxygen
to
form the trioxide,
which is then combined with water. A technique to form the trioxide,
called the chamber process, developed in the early days of the
operation of the Leblanc process. In this technique the reaction
between sulfur dioxide and oxygen takes place in the presence of
water and of oxides of nitrogen. Because the reaction is rather slow,
sufficient residence time must be provided for the mixed gases to
react. This gaseous mixture is highly corrosive, and the reaction
must be carried out in containers made of lead.
SO
2 + NO 2 + H 2 O → H 2 SO 4 + NO
NO
+ 1/2 O 2 →
NO2
In
1775 the French Academy of Sciences offered an award for a practical
method for converting common salt, sodium chloride, into sodium
carbonate, a chemical needed in substantial amounts for the
manufacture of both soap
and
glass.
Nicolas
Leblanc,
a surgeon with a bent for practical chemistry, invented such a
process. His patron, the duc d’Orléans, set up a factory for the
process in 1791, but work was interrupted by the French
Revolution.
The process was not finally put into industrial operation until 1823
in England, after which it continued to be used to prepare sodium
carbonate for almost 100 years.
The
first step in the Leblanc process was to treat sodium chloride with
sulfuric
acid.
This treatment produced sodium sulfate and hydrogen chloride. The
sodium sulfate was then heated with limestone and coal to produce
black ash, which contained the desired sodium carbonate, mixed with
calcium sulfide and some unreacted coal. Solution of the sodium
carbonate in water
removed
it from the black ash, and the solution was then crystallized. From
this operation derives the expression soda ash that is still used for
sodium carbonate.
2
NaCl + H 2 SO 4 →
Na
2 SO 4 + 2 HCl
followed
by conversion of the sulfate to soda with charcoal and chalk
Na
2 SO 4 + 2 C + CaCO 3 →
Na
2 CO 3 + CaS + 2 CO2
It
was soon found that when hydrogen
chloride
was
allowed to escape into the atmosphere, it caused severe damage to
vegetation over a wide area. To eliminate the pollutionproblem,
methods to convert the dissolved hydrogen chloride to elemental
chlorine
were
developed. The chlorine, absorbed in lime, was used to make bleaching
powder,
for which there was a growing demand.
Because
calcium
sulfide
contained
in the black ash had a highly unpleasant odour, methods were
developed to remove it by recovering the sulfur, thereby providing at
least part of the raw material for the sulfuric acid required in the
first part of the process. Thus the Leblanc process demonstrated, at
the very beginning, the typical ability of the chemical industry
to
develop new processes and new products, and often in so doing to turn
a liability into an asset.
The
ammonia-soda (Solvay) process
The
Leblanc process was eventually replaced by the ammonia-soda
process
(called
the Solvay process), which was first practiced successfully in
Belgium
in
the 1860s. In this process, sodium chloride as a strong brine is
treated with ammonia
and
carbon
dioxide
to
give sodium bicarbonate and ammonium
chloride.
The desired sodium carbonate is easily obtained from the bicarbonate
by heating. Then, when the ammonium chloride is treated with lime, it
gives calcium
chloride
and
ammonia. Thus, the chlorine that was in the original sodium chloride
appears as calcium chloride, which is largely discarded (among the
few uses for this compound
is
to melt snow and ice from roads and sidewalks). The ammonia thus
regenerated is fed back into the first part of the process. Efficient
recovery of nearly all the ammonia is essential to the economic
operation of the process, the loss of ammonia in a well-run operation
being no more than 0.1 percent of the weight of the product.
NH
3 + H 2 O + CO 2 →
NH
4 HCO 3
NaCl
+ NH 4 HCO 3 →
NaHCO
3 + NH 4 Cl
2
NaHCO 3 →
Na
2 CO 3 + H 2 O + CO2
Later
in the 19th century the development of electrical power generation
made possible the electrochemical
industry.
This not clearly identifiable branch of the chemical industry
includes a number of applications in which electrolysis, the breaking
down of a compound in solution into its elements by means of an
electric
current,
is used to bring about a chemical change. Electrolysis of sodium
chloride
can
lead to chlorine and either sodium
hydroxide
(if
the NaCl was in solution) or metallic sodium (if the NaCl was fused).
Sodium hydroxide, an alkali like sodium carbonate, in some cases
competes with it for the same applications, and in any case the two
are interconvertible by rather simple processes. Sodium chloride can
be made into an alkali by either of the two processes, the difference
between them being that the ammonia-soda process gives the chlorine
in the form of calcium chloride, a compound of small economic value,
while the electrolytic processes produce elemental chlorine, which
has nearly innumerable uses in the chemical industry, including the
manufacture of plastic
polyvinyl
chloride,
the plastic material produced in the largest volume. For this reason
the ammonia-soda process, having displaced the Leblanc process, has
found itself being displaced, the older ammonia-soda plants
continuing to operate very efficiently but no new ammonia-soda plants
being built.
Lead
is a material awkward to use in construction,
and the process cannot deliver acid more concentrated than about 78
percent without special treatment. Therefore, the chamber process has
been largely replaced by the contact process, in which the reaction
takes place in a hot reactor, over a platinum or vanadium compound
catalyst,
a substance that increases the speed of the reaction without becoming
chemically involved.
Sulfuric
acid is manufactured in three stages
2
SO 2 + O 2 →
2SO
3
SO
3 + H 2 O → H 2 SO 4
Since
the reaction of sulfur with dry air is exothermic, the sulfur dioxide
must be cooled to remove excess heat and avoid reversal of the
reaction
Carbon
disulfide is made by the reaction of carbon and sulfur. Carbon comes
from natural
gas,
and the sulfur may be supplied in the elemental form, as hydrogen
sulfide, or as sulfur dioxide. The chief uses of carbon disulfide are
for the manufacture of rayon and for regenerated cellulose film.
These two products are made in such large quantity that carbon
disulfide is a heavy chemical, by any standard.
By
far the most important use of ammonia within the chemical industry is
to produce nitric acid (HNO3). Nitrogen and oxygen
can
be made to combine directly with one another only with considerable
difficulty. A process based on such a direct combination, but
employing large quantities of electrical power, was in use in the
1920s and 1930s in Norway, where hydroelectric
power
is
readily available. It has not proved economical in modern conditions.
Ammonia
burns in air, or in oxygen, causing the hydrogen atoms to burn off,
forming water and leaving free nitrogen. With the aid of a catalyst,
platinum with a small percentage of the related metal rhodium,
ammonia is oxidized to oxides of nitrogen that can be made to react
with water to form nitric acid.
Nitric
acid treated with ammonia gives ammonium
nitrate,
a most important fertilizer. Ammonium nitrate, moreover, is also an
important constituent
of
many explosives.
Three fundamental explosive
materials
are obtained by nitrating (treating with nitric acid, often in a
mixture with sulfuric acid): cellulose, obtained from wood,
gives cellulose nitrate (formerly called nitrocellulose); glycerol
gives glyceryl
trinitrate
(formerly
called nitroglycerin); and toluene
gives
trinitrotoluene, or TNT. Another explosive ingredient is ammonium
picrate,
derived from picric
acid,
the relationship of which appears more clearly in its systematic
name, 2,4,6-trinitrophenol.
A
minor but still important segment of the explosives industry is the
production of detonating
agents,
or such priming compositions
as
lead azide [Pb(N3)2], silver azide (AgN3), and mercury
fulminate
[Hg(ONC)2].
These are not nitrates or nitro compounds,
although some other detonators are, but they all contain nitrogen,
and nitric acid is involved in their manufacture.
