Acetic Acid Manufacturing Process

Reaction

  RAW MATERIAL REQUIREMENT TO MAKE 1 METRIC TON ACETIC ACID

Acetaldehyde                    : 1100 kg

Manganous Acetate       : 3.3 kg

Air                                          : 233 Cubic meter

PROCESS

99-99.8% concentrated Acetaldehyde solution is introduced into a stainless steel Reaction vessel in which air at 70 to 75 psi (480 kPa to 520 kPa) bubbles through the liquid 955 to 65 degree C) which contains 0.1 to 0.5% Manganous Acetate used to decompose the explosive intermediate Peraacetic Acid. In batches 4085 kg Acetaldehyde can be completely Oxidized in 12 hours. The gases leaving the reactor are scrubbed with water, releasing Nitrogen and decomposition products to the Atmosphere. The dilute Acetaldehyde solution leaving the bottom of the scrubber is sent to a column for recovery. The crude Acetic Acid (94 to 96%) is Discharged frm the reactor and continuously rectified to yield 99% Glacial Acetic Acid.

In some modern plants the oxidation is carried out continuously rather than in batches. The catalyst in this case is Cobalt Acetate dissolved in Acetic Acid. The reactor is operated at 15 psi (100 kPa) and 70 to 80 degree C. Approximately 4 moles of air enter the converter per mole of Acetaldehyde.

Conversions of 20 to 30% per pass and yields of 95 to 96% of theory may be obtained. If Oxygen is used in place of Air, the pressure in system may be reduced to 30 psi or 210 kPa and good recovery obtained.

An alternative vapor phase oxidation process currently in use employs a mixture of Alcohol and Acetaldehyde, which on catalytic Air oxidation yields both Acetaldehyde and Acetic acid as products. By recycling the Acetaldehyde, adding only Alcohol to the system as makeup, and removing only Acetic acid, the process becomes essentially a catalytic vapor phase Alcohol oxidation to Acetic acid.

PROPERTIES

(Glacial Acetic acid) Colorless liquid with pungent odor and sharp acid taste.

Molecular Weight            : 60.05

Specific Gravity                 : 1.0492, 20 degree C/4

Weight per gallon            : 8.64 lb (20 degree C)

Melting Point                     : 16.6 degree C

Boiling Point                       : 118.1 degree C

Flash Point (open cup)   : 39 degree C

Ignition Temperature     : 516 degree C

Vapor Density (air = 1)   : 2.07

Explosive Limits % by volume in air           : Lower 6.6 and Upper 19.9

Threshold Limit value in ppm      : 10

Soluble in all proportions with water, ethanol, glycerin, and ether at room temperature. Insoluble in carbon disulfide.

Dangerous fire hazard in contact with chromic acid, sodium peroxide, or nitric acid.

Containers & Regulations – Tank cars, tank trucks, tight barrels, Aluminum drum, carboys, and bottles. Glacial Acetic Acid expands on solidification and may burst the container unless stored at a temperature above 16 degree C. and requires a White DOT shipping label.