Hydrodynamics, mass transfer, and photocatalytic phenol selective oxidation reaction kinetics in a fixed TiO2 microreactor

• Published in: AIChE journal Vol. 61; no. 2; pp. 572 - 581
• Main Authors: Krivec, Matic, Pohar, Andrej, Likozar, Blaž, Dražić, Goran
• Format: Journal Article
• Language: English
• Published: New York Blackwell Publishing Ltd 01-02-2015; American Institute of Chemical Engineers
• Subjects: catalysis; mass transfer; mathematical modeling; microfluidics; photochemical reactions
• ISSN: 0001-1541; 1547-5905
• DOI: 10.1002/aic.14648

Photocatalytic phenol dissociation was studied in a microreactor, with a TiO2 layer immobilized on the reactor inner walls. Experiments were conducted for various residence times, initial concentrations, pH values, and UV light irradiation intensities. The intermediates and products (catechol, hydroquinone, and resorcinol) were quantitatively investigated to determine the predominant reaction pathways for the investigated anatase catalyst. A three‐dimensional mathematical model was used to simulate the heterogeneous photocatalysis reaction conditions with Langmuir–Hinshelwood mechanism, considering the adsorption/desorption thermodynamic equilibria, and for kinetic parameter estimation via regression analysis. The effectiveness factor, Thiele modulus, and the correction function were calculated to determine the pore diffusion effects. The value of pH had the dramatic effect of lowering the reaction rate due to the competitive adsorption of hydroxide ions and protons on the catalyst surface. A phenol conversion of 79.5% was achieved at the residence time of 7.22 min, but without total mineralization. © 2014 American Institute of Chemical Engineers AIChE J, 61: 572–581, 2015