Author: Publisher:
ISBN:
Category : Coal
Languages : en
Pages : 97
Book Description
Evaluation of Wet Oxidation Technology for the Treatment of Coal Conversion Wastewater
Energy Research Abstracts
Author: Fossil Energy Update
Author: Coal Conversion Wastewater Treatment by Catalytic Oxidation in Supercritical Water
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 26
Book Description
Wastewaters from coal-conversion processes contain phenolic compounds in appreciable concentrations. These compounds need to be removed so that the water can be discharged or re-used. Catalytic oxidation in supercritical water is one potential means of treating coal-conversion wastewaters, and this project examined the reactions of phenol over different heterogeneous oxidation catalysts in supercritical water. More specifically, the authors examined the oxidation of phenol over a commercial catalyst and over bulk MnO2, bulk TiO2, and CuO supported on Al2O3. They used phenol as the model pollutant because it is ubiquitous in coal-conversion wastewaters and there is a large database for non-catalytic supercritical water oxidation (SCWO) with which they can contrast results from catalytic SCWO. The overall objective of this research project is to obtain the reaction engineering information required to evaluate the utility of catalytic supercritical water oxidation for treating wastes arising from coal conversion processes. All four materials were active for catalytic supercritical water oxidation. Indeed, all four materials produced phenol conversions and CO2 yields in excess of those obtained from purely homogeneous, uncatalyzed oxidation reactions. The commercial catalyst was so active that the authors could not reliably measure reaction rates that were not limited by pore diffusion. Therefore, they performed experiments with bulk transition metal oxides. The bulk MnO2 and TiO2 catalysts enhance both the phenol disappearance and CO2 formation rates during SCWO. MnO2 does not affect the selectivity to CO2, or to the phenol dimers at a given phenol conversion. However, the selectivities to CO2 are increased and the selectivities to phenol dimers are decreased in the presence of TiO2, which are desirable trends for a catalytic SCWO process. The role of the catalyst appears to be accelerating the rate of formation of phenoxy radicals, which then react in the fluid phase by the same mechanism operative for non-catalytic SCWO of phenol. The rates of phenol disappearance and CO2 formation are sensitive to the phenol and O2 concentrations, but independent of the water density. Power-law rate expressions were developed to correlate the catalytic kinetics. The catalytic kinetics were also consistent with a Langmuir-Hinshelwood rate law derived from a dual-site mechanism comprising the following steps: reversible adsorption of phenol on one type of catalytic site, reversible dissociative adsorption of oxygen on a different type of site, and irreversible, rate-determining surface reaction between adsorbed phenol and adsorbed oxygen.
Energy Research Abstracts
Author: Coal Conversion Wastewater Treatment by Catalytic Oxidation in Supercritical Water. Technical Progress Report, July 1, 1995 - June 30, 1996
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 9
Book Description
The overall objective of this research project is to obtain the reaction engineering information required to evaluate the utility of catalytic supercritical water oxidation (SCWO) for treating wastes arising from coal conversion processes. Our more specific objectives for this first phase of the project were: 1. to recruit and train a graduate student to work on this project 2. to construct a reactor system for the experimental studies 3. to initiate catalytic SCWO experiments and identify an active catalyst. Each of these three objectives has been met. The literature search revealed that both CuO and Mno2 are effective catalysts for the oxidation of organics (including phenol) in aqueous streams. Recently, these materials have also shown promise in catalytic supercritical water oxidation. Accordingly, our initial experiments have employed CuO and MhO2 catalysts that are commercially available. The catalyst we used in these initial studies, CARLITE 150 from Carus Chemical Company, has been commercially used in treating volatile organic compounds generated in various chemical processes. It contains MnO2 and CuO supported on Al2O3. The commercial catalyst pellets were ground to powders and separated by size before use. We used phenol as the first model pollutant to study because it is ubiquitous in wastewaters and there is a large data base for non- catalytic SCWO with which we can contrast results from catalytic SCWO.
Computer-aided Design of a Combined Phenosolvan--Wet Air Oxidation Treatment Process to Treat Contaminated Wastewater
Author: Dale R. HeronPublisher:
ISBN:
Category : Phenols
Languages : en
Pages : 464
Book Description
Journal
Author: Coal Conversion Wastewater Treatment Technology
Author: W. B. KindzierskiPublisher:
ISBN:
Category : Coal
Languages : en
Pages : 312
Book Description
Author: