Removal of Heteroatoms from Organic Compounds by Supercritical Water

Kinetics and reaction pathways of pyridine oxidation in supercritical water

“…In a preliminary study involving a laboratoryscale, batch reactor system, pyridine was found to be highly refractory even at temperatures near 500 °C (Lee et al, 1991). This finding was in agreement with the observations reported by other researchers (Townsend et al, 1988;Houser et al, 1991) about the refractory nature of unsubstituted aromatic compounds in supercritical water. Following the preliminary tests, more detailed kinetic and mechanistic studies were conducted using a laboratoryscale, continuous-flow reactor system.…”

Reactions at supercritical conditions: Applications and fundamentals

“…Their research program focused on the removal of heteroatoms, especially nitrogen, from model compounds thought to be representative of structures found in coal. Compounds investigated include quinoline and isoquinoline (Houser et al, 1986;Li and Houser, 1992); tetrahydroquinoline, benzylamine and bibenzyl (Houser et al, 1989); benzaldehyde, benzylidenebenzylamine, benzyl alcohol, and benzoic acid (Tsao et al, 1992); and l-chlorohexane, ethyl benzilate, trihexylamine, quinuclidine, phenylpiperidine, and phenylpyridine (Houser et al, 1993). Several of the compounds in this most recent report mimic structures in chemical weapons rather than coal.…”

Wet Air Oxidation

“…Modell (1982) demonstrated >99.9% destruction efficiency in less than 1 min for feed mixture (27 000-33 000 mg/L organic carbon) prepared from different combinations of DDT, methyl ethyl ketone, 1,1,1 -trichloroethane, benzene; PCB 1234, PCB 1254, 2,4-dinitrobenzene, o-xylene, hexachlorocyclopentadiene, etc. Houser et al (1991) studied supercritical water oxidation of nitrogencontaining compounds while Lee et al (1991) studied supercritical water oxidation of hazardous compounds including pyridine. Takahashi et al (1989) studied oxidation of Controlled Ecological Life Support Systems (CELSS) model waste comprising ammonium hydroxide, acetic acid, and a slurry of human urine, feces, and wipes, in the temperature range of 200-500 °C.…”