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Kinetics of phenol oxidation in supercritical water
Author(s) -
Thornton Thomas D.,
Savage Phillip E.
Publication year - 1992
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690380302
Subject(s) - supercritical fluid , supercritical water oxidation , phenol , chemistry , reaction rate constant , order of reaction , aqueous solution , reaction rate , oxygen , residence time (fluid dynamics) , kinetics , activation energy , chemical kinetics , inorganic chemistry , organic chemistry , catalysis , physics , quantum mechanics , engineering , geotechnical engineering
Abstract Aqueous solutions of phenol were oxidized in a flow reactor at temperatures between 300 and 420°C (0.89 ⩽ T r ⩽ 1.07) and pressures from 188 to 278 atm (0.86 ⩽ P r ⩽ 1.27). These conditions included oxidations in both near‐critical and supercritical water. Reactor residence times ranged from 1.2 to 111 s. The initial phenol concentrations were between 50 and 330 ppm by mass, and the initial oxygen concentrations ranged from 0 to 1,100% excess. The oxidation experiments covered essentially the entire range of phenol conversions. Analysis of the kinetics data for phenol disappearance using a combination of the integral method and the method of excess revealed that the reaction was first order in phenol and 1/2 order in oxygen, and influenced by pressure. The global reaction order for water was taken to be nonzero, and the global rate constant was assumed to be independent of pressure so that the only effect of pressure was to alter the water concentration and hence the reaction rate. This approach led to a global reaction rate law that was 0.7 order in water and had a rate constant with an activation energy of 12.4 kcal/mol. The implications of these rate laws to the design of a commercial supercritical water oxidation reactor are also explored.