Good Manufacturing Practice

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Lecture Topic 5 Inorganic Chemistry and
Industry Ref Inorganic Chemistry An Industrial
and Environmental Perspective by T. W. Swaddle
Premise Inorganic chemistry is extremely
important for many industries, but there are a
handful of reactions which are of primary
importance to the Chemical Industry. Goal St
udents should be able to 1) describe recovery
processes and uses of the most common
elements 2) discuss the chemistry of
atmospheric pollution 3) discuss the chemistry
of pulp and paper processing 4) describe the
synthesis of NH3 and H2SO4.
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Most Abundant Elements in the Earths Crust
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Oxygen

• Occurrence
• large amounts in Earths crust (oxides of other
  elements)
• 21 of atmosphere (as O2 and O3)
• Recovery
• by fractional distillation of air
• Industrial Uses

1) Sewage Treatment In the activated sludge
process, sludge is oxygenated and biodegraded by
aerobic bacteria. 2) Steelmaking Impurities are
removed by blowing O2 over molten iron to
generate slag, a layer of oxides that floats
atop the Fe(l). In the U.S., 3million metric
tons of O2 are used annually for this.
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Nitrogen

• Occurrence
• most abundant element in the atmosphere (N2)
• very low abundance in Earths crustal rocks
• Recovery
• by fractional distillation of air
• Industrial Uses
• fertilizers (nitrates, ammonia, ammonium salts,
  and urea)
• propellants and explosives (nitro-organics,
  nitrates, hydrazines)
• Most Important Industrial Reaction
• the Haber process for the production of ammonia
  (NH3)

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Nitrogen for Fertilizers
The relatively inert N2 of the atmosphere must be
fixed as soluble reactive compounds.bioavailabl
e compounds.
Ammonia (NH3) prepared using the Haber process
is 1) transported in liquid form by truck, barge
and pipeline 2) often injected directly into
soil (15-30 cm deep) 3) corrosive to the flesh 4)
explosive with air at a 16-25 NH3
concentration 5) commonly converted to ammonium
sulfate (NH4)2SO4, ammonium
nitrate NH4NO3, or urea (H2N)2CO
for safe shipment, storage and use.
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Nitrogen for Fertilizers
Urea 1) is made by reaction of ammonia and
the CO2 by-product of the water-gas shift
reaction. 2) can be produced in forms that
release nitrogen slowly to the soil a) SCU
fertilizers are urea pellets coated with 2
paraffin wax containing S8 that
oxidizes away slowly in the soil. b)
Urea-formaldehyde (UF) polymers decompose slowly
in the ground.
Ammonium sulfate is a safe form of ammonia for
shipping, storage and use.
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Nitrogen for Fertilizers
Nitric Acid and Ammonium Nitrate 1) The
catalytic oxidation of ammonia by air over Pt
gauze at 900C gives nitric oxide (NO2)
which is then converted to nitric acid by
air and H2O(l) to give the net reaction 2)
Nitric acid is converted on-site to ammonium
nitrate 3) NH4NO3 is potentially
explosive!! 4) Calcium carbonate CaCO3 (chalk,
limestone) can be added to solid NH4NO3 to
form a non-explosive product. 5) NH4NO3 can be
stored safely as a dilute aqueous solution. 6)
3 clay can be added as a drying agent to prevent
caking (34-0-0)
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Nitrogen for Explosives and Propellants

• Explosives and propellants are an important
  industrial technology for
• safety projects (airbags, ejector seats,
  avalanche control)
• civil engineering projects (highways, dams,
  waterways, etc.)
• mining and quarrying
• aerospace projects (launch technology)

There are 2 requirements for a material to be an
explosive 1. Decomposition or combustion must
be highly exothermic. 2. Hot reaction products
must be gaseous. The high bond energy of the N?N
triple bond explains the tendency of N-containing
compounds to decompose exothermically to
N2(g). Airport security units use Neutron
Activation Analysis to detect high nitrogen
content.
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Nitrogen for Explosives and Propellants
Ammonium Nitrate 1) is the most commonly used
blasting explosive 2) gentle heating to its
melting point (170C) gives nitrous oxide 3)
_at_ Tgt250C, or when shocked, violent decomposition
to N2 4) is commonly mixed with an oxidizable
substance (fuel oil) for legitimate use as a
relatively safe and inexpensive explosive.
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Nitrogen for Explosives and Propellants
Potassium Nitrate, KNO3 (Saltpeter) Used for
black powder (41 KNO3, 29.5 C, 29.5 S)
for firearms (before guncotton) (75 KNO3 15
C, 10 S) for fireworks, time fuses etc.
Hydrazine, H2NNH2, and dimethylhydrazine,
(CH3)2NNH2 Used for rocket propellants
The hydrazine is oxidized by H2O2, O2(l), or
F2(l).
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Nitrogen for Explosives and Propellants
Nitro-containing organic compounds R-NO2 1)
are the most common commercial high
explosives 2) Nitro groups can oxidize the C
content to CO or CO2 and the H content to
H2O.increases exothermicity and gas
volume.
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A Word on Nitrogen Oxides
Nitrogen oxides are widely implicated as air
pollutants.
Nitrous oxide, N2O 1) is a colourless,
odourless, non-toxic gas 2) is produced a) by
degradation of nitrate fertilizers b) as a
by-product of nylon production 3) is used as an
anaesthetic (laughing gas) and as a
propellant (whipped-cream spray cans) 4) is
implicated in greenhouse warming.has a residence
time in the atmosphere of 150 years and
could contribute up to 10 of the
anticipated greenhouse warming. 5) in the
stratosphere, reacts with the 1D excited state of
atomic oxygen to generate nitric oxide.
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A Word on Nitrogen Oxides
NOx NO, NO2, N2O4 1) NO.Nitric oxide is a
toxic, colourless gas. Very
endothermic (?H 180.6 kJ/mol),
BUT equilibrium rapidly established. When
air is heated to very high T, small amount of NO
is made. If it is then quenched to Tlt1000K,
the NO is frozen in. This is what happens
in combustion engines! 2) NO2.Nitrogen dioxide
is a toxic, brown gas. NO reacts rapidly
with O2 from air. 3) N2O4.Dinitrogen
tetroxide is a yellow liquid (b.p. 21C
_at_1bar) Dimerization of NO2.
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A Word on Nitrogen Oxides
NOx NO, NO2, N2O4 4) Acid precipiation
NO2 in the troposphere reacts with
hydroxyl radicals (OH, produced
indirectly from ozone pollution) to
form nitric acid. 5) Photochemical smog a
white aerosol that is intensely
irritating to eyes and
mucous membranes. The chemistry of
photochemical smog is complex (gt50
rxns!) Involves photochemical reaction of NOx
with unburned hydrocarbons to generate peroxyacyl
nitratrate (PAN), aldehydes, hydroperoxides and
peroxynitrates. 6) How to reduce NOx
emissions. i) reduce combustion T (by
lowering compression ratio) ii) lower
post-combustion conc. of O2 (fuel-rich
mixtures) iii) use catalytic converter to remove
NO and unburnt fuel
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Silicon

• Occurrence
• most important element in igneous and many
  sedimentary rocks
• SiO2 (quartz, silica), aluminosilicates
  (feldspar, etc.), .
• Recovery
• reduction of silica sand with coke (furnace) ?
  crude Si
• chlorination of silica and reduction with Mg ?
  high purity Si
• Industrial Uses
• ferrosilicon alloys for acid-resistant metal
  (chemical reactors)
• organosiloxane (silicone) polymers
• electronic chips
• SiO2 (fiber optics)

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Organopolysiloxanes (Silicones)
1) .are made by the hydrolysis of
organochlorosilanes RnSiCl4-n
Rochow process Inclusion of RSiCl3 will
Inclusion of R3SiCl will lead to chain
branching. cause chain termination. 2)
.can be oils, waxes, rubbers 3) .have high
thermal stabilities, resistance to oxidation,
electrical insulation, water repellency,
good biocompatibility, low chemical
reactivity.
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Aluminum

• Occurrence
• in combination with Si and O as
  aluminosilicates in rocks
• or as its ore, bauxite essentially AlO(OH)
  with Fe contaminants
• Recovery
• Al(III) is leached out from bauxite using
  NaOH(aq) and the
• resulting gibbsite a-Al(OH)3 is
  dehydrated to a-Al2O3.
• a-Al2O3 is dissolved in molten Na3AlF6 / CaF2
  (91) and
• reduced electrolytically using
  graphite electrodes (consumed).
• Industrial Uses
• Al(m) is used in vehicles, aircraft, packaging,
  construction, etc.
• Aluminosilicates are used as catalysts (e.g.,
  zeolites)

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Sulfur

• Occurrence
• native, i.e., elemental sulfur (S8 and other
  allotropes)
• sulfates (SO42-) and sulfides (S2-)
• hydrogen sulfide (H2S)
• Recovery
• elemental S used to be mined using the Frasch
  process
• now, so much H2S is recovered as a by-product
  from natural gas
• and refinery operations that mining
  is obsolete!
• Highly toxic H2S is converted to solid S by the
  Claus process
• Industrial Uses
• H2SO4 is the 1 synthetic chemical in terms of
  tonnage
• H2SO4 used mostly to make fertilizers, but also
  for ClO2
• Kraft and Sulfite processes for wood pulping
  (paper)

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Sulfur from H2S Claus Process
Hydrogen Sulfide H2S 1) is a highly toxic gas
that occurs in Albertan sour natural gas

(gt30 H2S content) 2) H2S is scrubbed
out of natural gas by absorption in aqueous
monoethanolamine (MEA, HOCH2CH2NH2) or
diethanolamine (DEA, (HOCH2CH2)2NH). The
aqueous base is then stripped off to recover
the H2S. 3) Claus Process H2S is burnt
partially to SO2 in air unburnt H2S and SO2
react (catalyzed by Fe2O3 or ?-Al2O3)
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Sulfuric Acid
Sulfuric acid H2SO4 1) generally is produced
by the contact process a) exothermic air
oxidation of SO2 (V2O5 or Pt catalyst) b) SO3
is absorbed into 100 H2SO4 to give a mixture
disulfuric and sulfuric acids, known
as oleum c) oleum is hydrolyzed to H2SO4
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Sulfuric Acid
2) 90 of the sulfur produced industrially is
converted to H2SO4!! 3) 2/3 of the H2SO4
produced is consumed in fertilizer manufacture,
to make ammonium sulfate (NH4)2SO4 or
superphosphate 32 CaHPO4/Ca(H2PO4)2H2O
3 H3PO4
50 CaSO4
or potassium sulfate K2SO4 (Mannheim
process) 4) H2SO4 is also used to make chlorine
dioxide ClO2 for bleaching paper pulp and
for sterilizing water. i) Mathieson process
ii) Solvay process
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Sulfur Chemicals Pulp Paper Industry
Wood pulping is a process in which lignin is
broken down without excessive damage to the
cellulose. The the Kraft and Sulfite processes
are chemical pulping processes.
Kraft Process (or Sulfate process) 1) An alkaline
process resulting in strong, brown, acid-free
paper. 2) Wood chips are digested at 800C (800
kPa) for 1 to3 hours in aqueous
NaOH/Na2S/Na2CO3 converting the lignin to soluble
alcohols, anions, mercaptans (RSH) and
organic sulfides (R2S). 3) Once the pulp is
collected, tall oil (for soaps) is removed from
the spent aqueous solution by centrifugation,
then the water is removed and the remaining
residue is ignited, converting the organic
content to C. Finally, the NaOH, Na2S, Na2CO3 are
regenerated by the addition of Na2SO4 and
Ca(OH)2.
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Sulfur Chemicals Pulp Paper Industry
Sulfite Process 1) An acidic process yielding
weaker, white paper. 2) Uses a buffered aqueous
sulfurous acid solution (HSO3/H2SO3). 3) SO2 is
passed over wet limestone CaCO3 to produce the
solution. 4) This solution is used to digest
wood chips at 130C for 24h. 5) SO2 is recovered
from relief gases and CaSO3 is recovered by
evaporation of the spent liquor and addition of
slaked lime Ca(OH)2.
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Sulfur Compounds and Air Pollution

• Sulfur dioxide SO2
• 1) is a moderately toxic, pungent, colourless gas
  (b.p. -10C)
• 2) is produced in large amounts by burning fossil
  fuels (coal!),
• roasting sulfide ores (pyrite, FeS2), pulp
  paper mill discharges,
• and natural volcanic activity 21
  anthropogenic to natural
• 3) Acid Precipitation
• mostly H2SO4 from
• wet clouds
• or dry air
• also some H2SO3 from

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Sulfur Compounds and Air Pollution
How to minimize SO2 emissions 1)
Desulfurization of fuels difficult and
expensive e.g. Battelle hydrothermal coal
process 2) Scrubbing of stack gases with wet
limestone Fuels are burnt as
received and resulting SO2 is removed in the
stack. 3) Recovery of SO2 as H2SO4 The stack
is scrubbed with a cool spray of an
organic amine solution which absorbs the SO2.
The resulting complex is then heated in a
separate column to release SO2 which
is then converted to H2SO4.
(Union Carbide
CanSolv process)
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Sulfur Compounds and Air Pollution

• How to minimize SO2 emissions
• 4) Fluidized bed combustion _at_ T 820 - 870C,
  limestone reacts
• 
  with SO2 and air to give CaSO4
• CaSO4 (gypsum) is non-toxic and useful (roadbed
  cement)
• unlike CaSO3 which is toxic to plants (hard to
  dispose of)
• 5) Use of low-sulfur fuels e.g. Coal from
  western Canada
• transportation costs and politics are
  the major concerns

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Chlorine

• Occurrence
• as chloride ion Cl, the most abundant anion in
  seawater
• as rocksalt NaCl
• Recovery
• Chloralkali process electrolysis of brine
  NaCl(aq)
• by-product of
• NaOH synthesis
• Industrial Uses
• 67 to organic chemicals industry (25 for EDC
  alone!)
• 30 to pulp paper mills, and 5 to water
  treatment

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Chlorine
Hypochlorite ion OCl and Hypochlorous acid HOCl
1) Cl2 disproportionates when dissolved in
water 2) HOCl decomposes slowly releasing
oxygen Since HOCl is a powerful
disinfectant, Cl2 is used to treat water. 3) Cl2
dissolved in cold, dilute aqueous NaOH generates
kinetically stable solutions of OCl.
HOUSEHOLD BLEACH!
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Chlorine
Chlorate ion ClO3 1) Cl2 dissolved in hot,
concentrated aqueous NaOH forms ClO3 2)
Chlorate salts are strong oxidizing agents.KClO3
can be used in place of KNO3 as an oxidant
for C and S in black powder. 3) Chlorate salts
can be used as an unselective herbicide. 4)
Chlorate salts are mainly used as a source of
ClO2 for bleaching paper pulp and for
sterilizing water. Recall Mathieson process and
Solvay process
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Chlorine
Chlorine dioxide ClO2 and the Chlorite ion ClO2
1) ClO2 is an orange-yellow gas, explosive in
high concentrations. 2) ClO2 is often converted
to sodium chlorite NaClO2 for safer shipping
and handling.there is still a friction explosion
hazard!
Perchloric acid HClO4 and the Perchlorate ion
ClO4 1) Electrolysis of chlorate ClO3
solutions gives perchlorate ClO4. 2) ClO4(aq)
is often used to adjust acidity / ionic
strength. 3) Perchlorates are explosive!
e.g., Solid Rocket Fuel NH4ClO4 is used to
oxidize Al powder. e.g., A single drop of
conc. HClO4 in DMSO ? BOOM!
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Chlorine and Industrial Chemistry
VCM, vinyl chloride monomer H2CCHCl 1) VCM
is made almost exclusively by thermal cleavage of
EDC, ethylene dichloride (or
1,2-dichloroethane) ClCH2CH2Cl. 2) EDC is formed
by chlorinating ethylene.Cl2 H2CCH2 3) 95
of the VCM produced is used to make polymers
e.g. PVC, poly(vinyl chloride) -CH2-CHCl-n
Hydrochloride HCl salts as pharmaceuticals A
common technique used to stabilize
amine-containing drugs is to synthesize the HCl
salt. e.g., US 2003125336 patented the
HCl and HBr salts of this HIV protease
inhibitor
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Chlorine and Environmental Concerns
Chlorofluorocarbons CFCs e.g., CF2Cl2 and
CFCl3 1) Were widely used as refrigeration
fluids, cleaning fluids for electronics
manufacture, aerosol propellants, and plastic
foam blowing agents. 2) Were thought to be
inert, but now are known to be the major
factor in the destruction of the stratospheric
ozone layer! 3) Montréal Protocol (1988)
phase-out of CFC production by 1995.
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Chlorine and Environmental Concerns
Chlorinated organic compounds 1) DDT,
dichlorodiphenylchloroethane An insecticide
still used in the tropics to combat the
anopheles mosquito (carriers of malaria). 2)
TCDD, tetrachlorodibenzo-p-dioxin A potent
toxin and carcinogen, this dioxin is a
byproduct of Cl2 bleaching of pulp and paper. 3)
PCBs, polychlorobiphenyls Once used as
electrical transformer oils. Mimic natural
hormones disrupt endocrine systems of
animals. 4) Chlorinated solvents such as
chloroform CHCl3, carbon tetra- chloride
CCl4, etc. carcinogenic and threaten ozone pool.