Catalytic wet air oxidation of phenol in a trickle bed reactor: kinteics and reactor modelling.
Wastewater treatment and re-use of industrial process water is a critical issue for the suitable development of human activities. The need for effective water recycling has reinforced the research on tailored low cost pollution abatement since the existing solutions are not longer universal. In part...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2003 |
| País: | España |
| Institución: | CBUC, CESCA |
| Repositorio: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/8517 |
| Acceso en línea: | http://www.tdx.cat/TDX-1103103-094925 http://hdl.handle.net/10803/8517 |
| Access Level: | acceso abierto |
| Palabra clave: | active carbon parameeter estimation trickle bed reactor catalytic wet aire oxidation simulated annealing phenol kinetics 00 62 |
| Sumario: | Wastewater treatment and re-use of industrial process water is a critical issue for the suitable development of human activities. The need for effective water recycling has reinforced the research on tailored low cost pollution abatement since the existing solutions are not longer universal. In particular, the emerging Catalytic Wet Air Oxidation (CWAO) process is one of the most promising technologies for the remediation of moderately concentrated and/or biotoxic water pollutants, when a stable and active catalyst can be provided. To this purpose, the catalytic activity and stability of active carbon was tested in the CWAO of the target compound, phenol, at mild conditions of temperature and pressure. The active carbon, which is a relatively inexpensive catalytic material is shown to be stable and to yield higher phenol destruction and less toxic partial mineralisation products, compared to a widely used copper oxide catalyst. During the CWAO of phenol, numerous partial oxidation products appeared and the knowledge of the kinetics that control their oxidation process is fundamental for the design, modelling and scale up of CWAO pilot plant or industrial units. Complex kinetic modelling was undertaken using both the classical gradient based method and a stochastic algorithm termed Simulated Annealing (SA). SA was shown to perform better in the identification of multiparameter kinetic reaction schemes, allowing to improve the kinetic modelling of CWAO beyond the actual state of art in this field. Detailed kinetic analysis of CWAO is scarce in the literature and the same situation holds for engineering studies. There is a clear need for the simultaneous development of process chemistry and engineering aspects. Consequently, we parallely focused on the state of art modelling of a Trickle Bed Reactor (TBR), being the priority candidate of best performing CWAO reactor. First, the ability of TBR in CWAO was affirmed by appropriate experimental comparison of batch slurry reactor and continuous fixed bed reactors operating either in the cocurrent downflow mode (TBR), or upflow mode (FBR) of the gas and liquid flow. A phenomenological transport-reaction model of the TBR was then developed and programmed. The TBR model implements the previously obtained oxidation kinetics and emphasis on important aspects of TBR, namely catalyst wetting, and mass transfer between the phases. Non-isothermal operation is also accounted for to face the need for autothermal operation, lowering the global process costs. The validation of the model was successfully done with the available experimental data from the laboratory TBR and thus provided a reliable tool for the scale up study of the CWAO process. The outcomings of this model aided scale up, allow to give recommendation on the design and operation of industrial units, thereby making more reliable the implementation of CWAO units on an industrial level. |
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