Wet oxidation kinetics of refractory low molecular mass carboxylic acids

Journal Article · Fri Oct 01 04:00:00 UTC 1999 · Industrial and Engineering Chemistry Research

DOI:https://doi.org/10.1021/ie9902028· OSTI ID:20000991

Shende, R V; Levec, J

Wet oxidation kinetics of aqueous solutions of formic, acetic, oxalic, and glyoxalic acids was studied in a titanium autoclave at a temperature range of 150--320 C and oxygen partial pressures between 8 and 60 bar. Oxidation reactions obeyed a first-order kinetics with respect to concentration of all substrates. On the basis of acid concentration decay, the activation energy for acetic, oxalic, and glyoxalic acid oxidation was 178, 137, and 97 kJ/mol, respectively; whereas on the total organic carbon (TOC) conversion basis, these values were slightly higher, namely 182, 141, and 104 kJ/mol. The activation energy for formic acid took a unique value of 149 kJ/mol regardless of the type of concentration used. The rate of oxidation was proportional to a square root of oxygen concentration (partial pressure) for acetic, formic, and oxalic acids, whereas it was linearly proportional for glyoxalic acid. When sufficiently high oxygen partial pressure was applied ({ge}22 bar), the individual acid conversion in a mixture of these acids was well predicted by the rate expression derived for that acid. The lumped TOC concentration of mixtures did not obey a first-order kinetic behavior, although underlying TOC kinetics for each individual acid was linear. The oxidation results are also discussed in a view of speculated reaction pathways and the reactor material.

• Research Organization: National Inst. of Chemistry, Ljubljana (SI)
• OSTI ID: 20000991
• Journal Information: Industrial and Engineering Chemistry Research, Journal Name: Industrial and Engineering Chemistry Research Journal Issue: 10 Vol. 38; ISSN IECRED; ISSN 0888-5885
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
ACETIC ACID
ACTIVATION ENERGY
CHEMICAL REACTION KINETICS
DICARBOXYLIC ACIDS
FORMIC ACID
WASTE WATER
WATER TREATMENT
WET OXIDATION PROCESSES