Catalytic supercritical water oxidation of coke works waste with manganeseoxide

Heterogeneous catalysis in supercritical water oxidation (SCWO) is a new ap proach to improve the reaction efficiency of the treatment of hazardous was te water. In this study, the kinetic analysis of catalytic SCWO of coke wor ks waste with manganese oxide (MnO2) was performed to obtain fundamental da ta for the reactor design, as well as information about interactions affect ing the reaction rate between the reaction species. The major component of the coke works waste is NH3. Catalytic SCWO of NH3 solution confirmed that MnO2 is a good catalyst for the complete oxidation of NH3. SCWO of an aqueo us mixture of phenol and NH3 was examined as a model solution of the real w aste. The oxidation rate of NH3 in the model solution was lower than that o f an aqueous solution of NH3. The presence of NH3 in the model solution did not affect the phenol conversion, but strongly suppressed the decompositio n of total organic carbon (TOC). These inhibition effects between NH3 and p henol are explainable by a Langmuir-type model, in which all corresponding species are assumed to adsorb competitively on the same catalytic site. Cat alytic SCWO of diluted real waste showed a similar inhibition effect especi ally with shorter contact times of less than 0.5 s. However, very high conv ersions of both NE3 and TOC were achieved within 2 s of contact time at 500 degreesC. These experimental results suggest that catalytic SCWO is a prom ising technique for the complete decomposition of coke works waste.