Kinetics of carbon dioxide formation from the oxidation of phenols in supercritical water

Li, Ruokang; Thornton, Thomas D.; Savage, Phillip E.

doi:10.1021/es00036a009

Cited by 51 publications

(53 citation statements)

References 13 publications

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“…These observations for o-cresol are entirely consistent with our previous work with phenol and 2-chlorophenol (Li et al, 1992). In contrast with the earlier work, however, we observe that the water density influences the rate of COZ production for o-cresol oxidation.…”

Section: Kinetics Of O-cresol Oxidation In Supercritical Watersupporting

confidence: 91%

Kinetics and Products from o-Cresol Oxidation in Supercritical Water

Martino

Savage

Kasiborski

1995

Ind. Eng. Chem. Res.

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Dilute aqueous solutions of o-cresol(2-methylphenol) were oxidized in a tubular flow reactor at near-critical and supercritical conditions. The power-law rate expression that best correlates the kinetics of o-cresol disappearance is rate = 105.7 exp(-29700/RT)[o-creso11°~57[0210~22[H~011~44.The power-law rate expression that best correlates the experimental results for the conversion of organic carbon to C02 is rate = 106.8 exp(-34000/RT)[TOClo~34[O~lo~'3[H~O11~18. All concentrations are in moles per liter, the activation energy is in calories per mole, and the rate is in moles per liter per second. The most abundant products from o-cresol oxidation were typically phenol, 2-hydroxybenzaldehyde, 1,3-benzodioxole, indanone, CO, and C02. 2-Hydroxybenzaldehyde was the major primary product. A reanalysis of published kinetics data for the oxidation of two other ring-containing compounds (pyridine and 4-chlorophenol) in supercritical water revealed that the rate laws previously reported for these two compounds do not provide the best correlation of the experimental data. We report the new rate laws, which are similar to those for o-cresol, 2-chlorophenol, and phenol in that the global reaction orders are between 0.55 and 0.9 for the organic compounds and between 0.2 and 0.5 for oxygen.

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Section: Kinetics Of O-cresol Oxidation In Supercritical Watersupporting

confidence: 91%

Kinetics and Products from o-Cresol Oxidation in Supercritical Water

Martino

Savage

Kasiborski

1995

Ind. Eng. Chem. Res.

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“…These figures show that for all three cresols, the yield of CO 2 always exceeded the yield of CO. This behavior has also been observed for the SCWO of phenol and o-chlorophenol (Li et al, 1992). The yield of CO 2 consistently exceeding the yield of CO for all phenolic compounds studied to date, even at low conversions, indicates that CO is not an important intermediate in the reaction network for CO 2 production from phenolic compounds.…”

Section: Reaction Products and Pathwayssupporting

confidence: 58%

Supercritical Water Oxidation Kinetics, Products, and Pathways for CH₃- and CHO-Substituted Phenols

Martino

Savage

1997

Ind. Eng. Chem. Res.

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Phenols bearing -CH 3 and -CHO substituents were oxidized in supercritical water at 460°C and 250 atm. Experiments with each compound explored the effects of the reactor residence time and the concentrations of the phenolic compound and oxygen on the reaction rate. These experimental data were fit to global, power-law rate expressions. The resulting rate laws showed that the reactivity of the different isomers at 460°C was in the order of ortho > para > meta for both compounds. Moreover, the CHO-substituted phenol was more reactive than the analogous CH 3 -substituted phenol, and all of these substituted phenols were more reactive than phenol itself under supercritical water oxidation conditions. Identifying and quantifying the products of incomplete oxidation allowed us to assemble a general reaction network for the oxidation of cresols in supercritical water. This network comprises three parallel primary paths. One path leads to phenol, a second path leads to a hydroxybenzaldehyde, and the third path leads to ring-opening products. The hydroxybenzaldehyde reacts through two parallel paths, which lead to phenol and to ring-opening products. Phenol also reacts via two parallel paths, but these lead to phenol dimers and ring-opening products. The dimers are eventually converted to ring-opening products, and the ring-opening products are ultimately converted to CO 2 . The relative rates of the different paths in the reaction network are strong functions of the location of the substituent on the phenolic ring.

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“…These studies have focused primarily on determining global rate laws for the disappearance of the organic compound. Departing from this trend, Li et al (1992) obtained global rate laws for the formation of CO, from the oxidation of phenol and o-chlorophenol. Thornton et al (1991) identified several multiring products (such as dibenzofuran, 2and 4-phenoxypheno1, dibenzo-pdioxin, and 2,2'-biphenol) from the oxidation of phenol in supercritical water at 380°C.…”

Section: Introductionmentioning

confidence: 99%

A reaction network model for phenol oxidation in supercritical water

1995

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Kinetics of carbon dioxide formation from the oxidation of phenols in supercritical water

Cited by 51 publications

References 13 publications

Kinetics and Products from o-Cresol Oxidation in Supercritical Water

Kinetics and Products from o-Cresol Oxidation in Supercritical Water

Supercritical Water Oxidation Kinetics, Products, and Pathways for CH₃- and CHO-Substituted Phenols

A reaction network model for phenol oxidation in supercritical water

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Kinetics of carbon dioxide formation from the oxidation of phenols in supercritical water

Cited by 51 publications

References 13 publications

Kinetics and Products from o-Cresol Oxidation in Supercritical Water

Kinetics and Products from o-Cresol Oxidation in Supercritical Water

Supercritical Water Oxidation Kinetics, Products, and Pathways for CH3- and CHO-Substituted Phenols

A reaction network model for phenol oxidation in supercritical water

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Supercritical Water Oxidation Kinetics, Products, and Pathways for CH₃- and CHO-Substituted Phenols