acetic acid

1. Definition of The Project
A Methane to Acetic acid plant is to be set up at Brammanbaria in Bangladesh having a capacity
of 300 ton 99% Acetic Acid per day, corresponding to 109500 ton of 99%Acetic Acid per
year, and an intermediate capacity of 450 ton of 91.5% Methanol per day corresponding to ton
of 16500 tons 91.5% of Methanol per year including all offsites, auxiliaries, utilities and
supporting facilities using Industrial Grade Methane (96.48% CH4) fromTitas Gas Field as
raw material.

2. Product & Raw material
Specifications
Acetic Acid, CH3COOH:
Acetic acid,systematically named ethanoic acid,is an organic compound.It is a colourless liquid
that when undiluted is also called glacial acetic acid. Acetic acid has a distinctive sour taste and
pungent smell.
Liquid acetic acid is a hydrophilicprotic solvent, similar to ethanol and water. It dissolves not
only polar compounds such as inorganic salts and sugars, but also non-polar compounds such as
oils and elements such as sulfur and iodine. It readily mixes with other polar and non-polar
solvents such as water, chloroform, and hexane. With higher alkanes (starting with octane),
acetic acid is not completely miscible anymore, and its miscibility continues to decline with
longer n-alkanes. This dissolving property and miscibility of acetic acid makes it a widely used
industrial chemical, for example, as a solvent in the production of dimethyl
terephthalate.Although it is classified as a weak acid, concentrated acetic acid is corrosive and
can attack the skin.
Table 1.1:Properties of CH3COOH:
Molecular formula CH3COOH
Molar mass 60.05 g·mol−1
Appearance Colourless liquid
Odor Pungent/Vinegar-like
Density 1.049 g cm−3
Melting point 16 °C; 61 °F; 289 K
Boiling point 118 °C; 244 °F; 391 K
Solubility in water Miscible
log P -0.322
Acidity (pKa) 4.76
Basicity (pKb) 9.198 (basicity of acetate ion)
Refractive index (nD) 1.371
Viscosity 1.22 mPa s
Dipole moment 1.74 D
Specific
heat capacity (C)
123.1 J K−1
mol−1

3. Std molar
entropy (So
298)
158.0 J K−1
mol−1
Std enthalpy of
formation (ΔfHo
298)
-483.88--483.16 kJ mol−1
Std enthalpy of
combustion (ΔcHo
298)
-875.50--874.82 kJ mol−1
Methanol, CH3OH:
Methanol, also known as methyl alcohol,wood alcohol, wood naphtha or wood spirits. It is
the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a pleasant smell . It
is highly toxic and unfit for consumption. At room temperature, it is a polar liquid, and is used as
an antifreeze, solvent, fuel, and as a denaturant for ethanol.
Table 1.2: Properties of Methanol
Molecular formula CH3OH
Molar mass 32.04 g·mol−1
Appearance Colorless liquid
Density 0.7918 g·cm−3
0.7925 g·cm−3
@20°C
Melting point −97.6 °C (−143.7 °F; 175.6 K)
Boiling point 64.7 °C (148.5 °F; 337.8 K)
log P -0.69
Vapor pressure 13.02 kPa (at 20 °C)
Acidity (pKa) 15.5[3]
Refractive index (nD) 1.33141[4]
Viscosity 0.545 mPa×s (at 25°C) [5]
Dipole moment 1.69 D
Flash point 11 to 12 °C (52 to 54 °F; 284 to 285 K)
Autoignition
temperature
385 °C (725 °F; 658 K)
Explosive limits 6%-36%

4. Availability of Raw Materials:
 CH4: Bought from Titas Gas Field, Brammanbaria
 H2O (cooling, treated, DM water, etc.): Available in Bangladesh.
Raw material specification
Natural Gas from Titas Gas Fiel

5. Process Selection
Methane to Methanol conversion process
Catalytic Conversion
Features:
 Conversion of methane to methanol with an economic yield of 10%
 In most experiments with solid catalysts, selectivities to methanol fell rapidly as methane
conversions exceeded 59%
 complete oxidation of methane to carbon dioxide (ΔH = -877 kJ/mol) is highly favored
over partial oxidation of methane to methanol (ΔH = -200 kJ/mol)
 A noticeable progress, however, has been made in the field of molecular catalysis by
Periana et al., who demonstrated the selective conversion of methane to methanol at
temperatures around 473 K over platinum bipyrimidine complexes. According to their
experiment, 81% selectivity to methyl bisulfate, a methanol derivative, was reached at
methane conversion of 90% in concentrated sulfuric acid
 Although these results are promising, commercial applications are hampered by difficult
separation and recycling of the molecular catalyst.
Thermal Cracking
 Methane is converted to methanol by partial oxidation to hydrogen gas and carbon
monoxide (synthesis gas or syngas) at high temperatures normally several hundred
degrees celsius
 Syngas is then catalytically converted to methanol over a copper or platinum surface, also
at a couple hundred degrees Celsius
 It is only around five or ten percent efficient due to accidental total oxidation to carbon
dioxide and water.
Photo-Catalytic Conversion
 Ultraviolet light breaks water into a hydrogen and hydroxyl free radical, which are highly
reactive. When a hydroxyl radical reacts with a methane molecule, a hydrogen is
displaced and methanol is produced.

6.  With the use of tungsten oxide or a similar semiconductor, photons of lower energy than
ultraviolet (down to blue) can be used.
 Using Of WO₃ as photo-catalyst visible laser light can be used in room temperature
 It is highly energy inefficient (only 2-3% efficiency)
 The process is not out in commercial production yet
Biological conversion
 Conversion combines both methane and ammonia streams using methane-oxidizing
bacteria and ammonia-oxidizing bacteria, in both wild type and genetically modified
forms
 Can convert heterogeneous methane feedstocks, unlike existing commercial process
 Does not require a pure source of methane
 It does not require expensive chemical catalysts
 Cleanup and dehumidification processes not required
 Widely applicable to digester gas, landfill gas, peatbogs, marshes, and wastewater
treatment facilities
 Conversion process is time consuming
ICI process
 Catalyst: Copper-Zinc oxide catalyst
 Temperature: 200-30000
C
 Pressure: 5-10 MPa
 Activity of this catalyst is more sensitive to impurities (poisoning)
 Reduced manufacturing costs.

7. Methanol to Acetic acid
Cativa Process
 Process developer: BP chemicals
 Catalyst: Iridium/iodide catalyst
 Improved catalyst stability
 Allowing operation at low water concentrations
 High reaction rates
 Reduced formation of liquid by-products
 Improved yield on carbon monoxide
 Temperature:
 Pressure:
Monsanto process
 Process developer: Monsanto
 Temperature: 150-2000
C
 Pressure: 30-60 bar
 Catalyst: rhodium/iodide catalyst
 Selectivity: 99%
 To prevent rhodium loss the reactor composition is maintained within limits on water,
methyl acetate, methyl iodide and rhodium concentrations
 High H2O concentrations to prevent catalyst precipitation and maintain high reaction
rates
BASF process
 Catalyst: cobalt /iodide catalyst
 Temperature: 2500
C
 Pressure: 680 bar
 Selectivity: 90% (based upon methanol)