Validation of a two-dimensional modeling of an externally irradiated slurry photoreactor

Heterogeneous photocatalysis: Light-matter interaction and chemical effects in quantum efficiency calculations

“…A second effect of the light-matter interaction usually dismissed is the fact that in a powdered, nanostructured material, even in the form of a thin film, shadowing effects take place [5][6][7][8][9][10][11][12][13][14]. Such effects are controlled or driven by the morphological properties of the catalyst and, as we will show, are dominated by the secondary particle size and porosity.…”

“…applicable to most common rector configurations) formulations to obtain quantum efficiency values [5][6][7][8][9][12][13][14][41][42][43][44][45]. Among light-matter and chemical parameters or effects influencing efficiency calculations, the most salient studies focussed on the following: (i) obtaining accurate measurements and modeling, with explicit consideration of all optical events, of the photon handling capability of photoactive catalytic surfaces or bodies [6,9,14,42,[44][45][46]; or (ii) accounting for the influence of the selectivity in the spectral dependence of the quantum efficiency [47].…”

“…To evaluate the denominator of Eq. (1), we need to calculate the average superficial rate of photon absorption for the catalyst with consideration of the number of charge carrier species involved in generating chemistry, as described in next sections [5][6][7][8][9][12][13][14][41][42][43][44]. The same equation can be used to determinate the apparent efficiency (g app ) using as denominator the total radiation flux of the lamp or, more properly and according to the IUPAC suggestions [44], the net radiation flux reaching the internal surface of the irradiation window and thus, in a gas-phase reaction (with negligible light adsorption by reactants/products), impinging on the catalytic film (hqi sup ).…”

“…The classical formulation of the quantum efficiency requires the calculation of the ratio between the number of molecules reacting by the number of photons interacting with the catalyst [5][6][7][8][9][12][13][14][41][42][43][44].…”

“…In the absence of mass transfer limitations, the intrinsic photocatalytic efficiency of a reaction is measured by the ratio between the rate of the photoreaction and the rate of photon absorption by the photocatalyst at a set of well defined conditions. The difficulty in measuring this observable has led, as above mentioned, to alternative formulations and/or simplifications, particularly in use is the apparent photonic efficiency which considers all available photons instead of the fraction absorbed by the catalyst [5][6][7][8][9][11][12][13][14][15].…”