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Photocatalytic NOx abatement: Mathematical modeling, CFD validation and reactor analysis

de O.B. Lira, Jéssica, Padoin, Natan, Vilar, Vítor J.P., Soares, Cíntia
Journal of hazardous materials 2019 v.372 pp. 145-153
light intensity, mathematical models, nitric oxide, nitrogen dioxide, photocatalysis, prediction, relative humidity
A 2D CFD model was implemented for the numerical simulation of NOx abatement in a photocatalytic reactor, considering the effect of relative humidity (10–60%), light intensity (0.3–13 W⋅m−2) and inlet NO concentration (0.1–1.0 ppm). Significant differences of NOx concentration at the catalytic surface and bulk gas were found (Δmax of ∼12% and ∼16% for NO and NO2, respectively) and corrections were proposed to achieve intrinsic rate laws from a model available in the literature. An analysis of the reactor performance was conducted and a nonlinear behavior was observed when the channel height (H) was varied. A point of maximum for the integral rate of NO and NO2 consumption as a function of H was found (ΔNO of ∼2% and ∼-1% for H→2H→4H; ΔNO2 of ∼46% and -8.5% for H→2H→4H). Additionally, the NO conversion decreased from ∼29% to ∼7% and the selectivity decreased from ∼85% to ∼80% (passing through a point of minimum at 2H) when the height was varied in the range H-4H. When comparing the results from the CFD simulations and the predictions of a plug flow model, deviations for NO conversion and selectivity increased with H (Δmax of ∼2% and ∼45%, respectively).