engleski

Photocatalytic oxidation of toluene in the gas phase: modelling of annular photocatalytic reactor

Photocatalytic oxidation of toluene in the gas phase over UV-illuminated thin layer of titanium dioxide was studied. The reaction was performed in the annular photocatalytic reactor at the room temperature and at various space times. The inlet reacting mixture consisted of air containing toluene and water vapours. Dependence of the reaction rate on various operating variables (water content, inlet toluene concentration and gas flow rate) was examined. The catalytic activity for toluene removal was evaluated by measuring the inlet and outlet toluene concentrations with GC/FID at the steady-state conditions. The additional RD and FTIR measurements were carried out to get better understanding of the catalytic properties. Modelling analysis was carried out to investigate effect of the key parameters on the reactor performance. To understand complex interaction between the chemical reaction and mass transfer phenomena, experimental data were analysed and compared with three different mathematical models (1-D model and 2-D models based on ideal flow and laminar flow conditions). The proposed models were verified by comparing the computer simulation data with the experimental laboratory results. Kinetic constant of the reaction rate, kA, was the adjustable reactor parameter in all models. The results revealed that the reaction rate constant, kA, decreased by increasing the inlet toluene concentrations. At relatively high inlet toluene concentrations the rate of its photocatalytic oxidation became independent of the total flow rate. Relative humidity of the contaminated gas stream had only negligible effect on toluene removal. It was found out that behaviour of the annular photocatalytic reactor was mainly limited by the interphase mass transfer. Finally, the 2-D heterogeneous model, based on the assumed laminar flow through the reactor, appeared to be the most suitable model for a detailed description of the annular photocatalytic reactor used for air pollution remediation.

annular photocatalytic reactor ; toluene oxidation ; TiO2 ; reactor modelling

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