CHM 585490

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CHM 585/490

• Chapter 2

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Chapter 2

• Petroleum Cracking
• C4
• Methanol derivatives
• MTBE
• Formaldehyde
• Acetic Acid
• Ethylene, Chloroalkali and derivatives

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Major Petroleum Fractions
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Thermal Cracking

• Radical cleavage of hydrocarbons
• 400 500 ºC under pressure

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Example of Products from Naptha Cracking
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Typical C4 Composition
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MTBE Synthesis

• C4 raffinate is reacted with methanol at 30 -
  100ºC with an acid ion exchange resin
• Isobutene selectively reacts
• Methanol and MTBE form a pressure dependent
  azeotrope. Methanol removed either by a
  pressurized distillation or by pervaporation
  (membrane)

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Since 1995, the Clean Air Act requires
reformulated gasoline (RFG) year-round in cities
with the worst ground-level ozone (smog). RFG is
oxygenated gasoline (minimum of 2 percent oxygen
by weight) that is specially blended to have
fewer polluting compounds than conventional
gasoline. About 30 percent of this countrys
gasoline is reformulated gasoline, of which
87 contains MTBE.  Refiners have chosen MTBE as
the main oxygenate in RFG in cities outside of
the Midwest primarily for economic reasons and
its blending characteristics. Unlike ethanol,
MTBE can be shipped through existing pipelines,
and its volatility is lower, making it easier to
meet the emission standards.
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The majority of the human health-related research
conducted to date on MTBE has focused on effects
associated with the inhalation of the
chemical. When research animals inhaled high
concentrations of MTBE, some developed cancers or
experienced other non-cancerous health effects
EPA's Office of Water has concluded that
available data are not adequate to estimate
potential health risks of MTBE at low exposure
levels in drinking water but that the data
support the conclusion that MTBE is a potential
human carcinogen at high doses. EPA reviewed
available health effects information on MTBE in
its 1997 Drinking Water Advisory. The drinking
water advisory document indicates that there is
little likelihood that MTBE in drinking water
will cause adverse health effects at
concentrations between 20 and 40 ppb or below.
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EPA estimates that smog-forming pollutants are
being reduced annually by at least 105 thousand
tons, and toxics by at least 24 thousand tons.
http//www.epa.gov/mtbe
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MTBE U.S.Production

• 282,000 barrels per day (2001)
• 42 gallons per barrel gt 12 million gallons per
  day
• Density 0.74 1 gallon of water 8.3 lbs.
• 6.1 lb. MTBE per gallon
• 72 million pounds per day
• At 365 days gt 26 billion pounds per year

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• December 1998 underground storage tanks for
  gasoline were required to be double walled with a
  detection system between the inner and outer
  tanks.
• Cost penalty to the use of ethanol in place of
  MTBE about 5 cents per gallon even with
  government subsidies for ethanol.

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Formaldehyde

• 12.5 Billion Pounds per year U.S. capacity on a
  37 percent basis. ( Demand about 10 billion
  pounds)
• Commercial production is from methanol either by
  silver catalyst or metal oxide catalyst
  processes.
• Seventy to 80 percent of formaldehyde output is
  used captively.

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Formaldehyde Producers

• Borden, Georgia Pacific and Hoechst Celanese are
  major U.S. producers
• Wright Chemical has capacity of 160 million
  pounds ( Chem Expo report)

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Formaldehyde HCHO 3 Commercial Forms

• Aqueous solution ( 35-55)
• Cyclic trimer (trioxane)
• from the acid catalyzed reaction of formaldehyde
• Paraformaldehyde
• can be reversibly converted to the monomer by
  heat or acid

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Formaldehyde Uses

• 40 urea- and phenol-formaldehyde resins used in
  particleboard and plywood, respectively
• 13 polyacetal resins
• 11 1,4-butanediol

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Acetic Acid

• CH3OH CO CH3CO2H
• Catalyst developed by Monsanto is Rhodium (Rh) in
  the presence of I2
• The reaction involves CO insertion into a CH3-Rh
  bond
• Co and iridium based catalysts also known

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Acetic Acid

• 6 Billion pounds per year produced in the U.S.
• Celanese is the major producer
• 42 used to make vinyl acetate monomer

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Vinyl Acetate

• The dominant method of commercial production is
  by reaction of ethylene with acetic acid and
  oxygen in the presence of a palladium catalyst.
• About 2 billion pounds produced in North America
• Main use is for polymer manufacture

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Ethylene

• In terms of quantity produced, ethylene is the
  most important organic chemical
• Ranked 4 among all chemicals after
• 1. Sulfuric acid
• 2. Nitrogen
• 3. Oxygen

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Ethylene U.S. Production

• About 60 billion pounds made per year (2002)
• Major U.S. manufacturers (capacity lb.)
• Equistar ( 10B)
• Exxon Mobil ( 9B)
• Dow (8B)
• Chevron Phillips (8B)
• Shell(7B)

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Ethylene

• Steam cracking of hydrocarbons accounts for
  virtually all of the ethylene produced throughout
  the world. Hydrocarbons used as feedstocks range
  from natural gas liquids (ethane, propane and
  butane) to petroleum liquids (gas oils and
  naphtha).
• Roughly 70 percent of the US ethylene industry's
  production is used captively for downstream
  derivatives.

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Ethylene Uses

• Polyethylene 54
• Ethylene dichloride, 18
• Ethylene oxide 12
• Ethylbenzene, 6

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Chloralkali

• Chlorine / Caustic
• Cl2 / NaOH
• 13 million tons of chlorine
• 15 million tons of NaOH
• Coproduced by the electrolysis of NaCl

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U.S. Chlorine Producers

• Dow 4 billion tons per year
• OxyChem 3 billion tons per year
• PPG 2 billion tons per year
• These three are also the top caustic producers

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• Manufacture The process of manufacture uses
  electricity and salt. In manufacture, for every
  80 tonnes of caustic soda, 71 tonnes of chlorine
  and 2 tonnes of hydrogen are co-produced. Each
  tonne of caustic soda requires around 2200 kWh of
  electricity and 1.55 tonnes of salt.

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Chlorine / Caustic

• Three processes of manufacture.
• Mercury cell - the oldest technology employed
  which has been largely closed down around the
  world being less efficient and polluting.
  (HoltraChem)
• Diaphragm cell - the dominant technology.
• Membrane cell - preferred technology for new
  plants

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Diaphragm Cell
2 Mole NaOH produced for each mole of Cl2 80
grams NaOH produced for each 71 grams of Cl2 80
tons NaOH produced for each 71 tons of Cl2
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Chlorine / Caustic

• Diaphragm acts to separate the anode and cathode
  to prevent mixing of chlorine with NaOH or
  hydrogen
• The effluent cell liquor contains about 14 NaCl
  and 12 NaOH. This is passed though an
  evaporation train where NaCl is removed by
  crystallization and returned as a feed material

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NaOH Use

• 54 direct application (pulp and paper, soaps
  and detergents, alumina, petroleum, textiles,
  water treatment)
• 35 organic chemicals (propylene oxide,
  polycarbonate,ethyleneamines, epoxy resins,
• 11 inorganic chemicals (sodium/calcium
  hypochlorite, sulfur-containing compounds, sodium
  cyanide).

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Chlorine Use

• 36 Polyvinyl chloride (ethylene dichloride and
  vinyl chloride monomer)
• 41 Other organic chemicals
• 15 inorganic chemicals
• 4 water treatment
• 1 pulp and paper
• 3 miscellaneous

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Ethylene Dichloride

• About 16 billion pounds produced in U.S.
• 94 goes to PVC manufacture
• OxyVinyls (JV between OxyChem and Geon) number 1
  manufacturer
• Dow 2
• Formosa 3

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EDC Synthesis

• Direct Chlorination
• C2H4 Cl2 à C2H4Cl2
• liquid phase FeCl3 or CuCl2 catalysts
• Oxychlorination
• C2H4 2HCl ½O2 à C2H4Cl2 H2O
• Gas phase CuCl2 catalyst

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VCM Synthesis
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Balanced VCM Process

• Chlorination of ethylene
• C2H4 Cl2 à C2H4Cl2
• Cracking to make vinyl chloride
• 2C2H4Cl2 à 2C2H3Cl 2HCl
• OxyChlorination
• C2H4 2HCl ½O2 à C2H4Cl2 H2O
• Overall
• 2C2H4 Cl2 ½O2 à 2C2H3Cl H2O

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Ethylene Oxide
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Ethylene Oxide

• 9 Billion lbs in U.S.
• Dow/Union Carbide, Shell, Huntsman and Equistar
  are some of the major producers
• 57 used for ethylene glycol
• Source for various ethers and alcohols

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Ethylene glycol
Typically uses a ten fold excess of water if
lower water ratio is used, di, tri, and
polyethylene glycols are formed Product ethylene
glycol is concentrated by evaporation and then
fractionally vacuum distilled
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Ethylene Glycol Uses

• 58 for Polyester (PET)
• 26 for antifreeze

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Ethylbenzene
Friedel-Crafts catalysts or zeolites(Al2O3.SiO2)
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Ethylbenzene U.S. Production

• 14 billion pounds annually
• Lyondell, Sterling, Cos-Mar (Ato-Fina GE), Dow
  and Chevron are among the major producers
• Used for styrene production

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Styrene
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Styrene

• 12 Billion pounds
• Same producers as ethylbenzene
• Used for polystyrene production