Abstract

Background: Microreactor devices have attracted increasing attention over the last years due to their high surface-to-volume ratio, which ensures a high heat and mass transfer, short molecular diffusion distance and greater spatial illumination homogeneity compared to the traditional reactors.

Objective: The aim of this study was to model the kinetics of photo-degradation of 2-propanol over TiO₂-based thin films in a gas-phase batch-reactor and simulate their performance in a microreactor device.

Methods: The reaction was carried out in a gas-phase batch-reactor, assessing the reactivity of singlelayer nitrogen (N)-doped TiO₂ and a bilayer consisting of N-doped TiO₂ as a bottom layer and copper (Cu)-doped TiO₂ as a top layer. The kinetics of the photocatalytic process was modelled by Langmuir– Hinshelwood (LH) model. The constants obtained from the LH model were used to simulate the performance of the photocatalysts in a microreactor, operating in a continuous flow mode and investigating the effect of the volumetric flow rate (Q), initial concentration of pollutant (C_o), number of microchannels (n) and microchannel length (l) on the photo-degradation of 2-propanol.

Results: N-Cu-TiO₂ exhibited a higher reactivity but a lower adsorption ability towards the target pollutant compared to N-TiO₂. To maximize and leverage the advantages of a microreactor, optimal operating conditions for a continuous flow mode, at a steady-state, should be moderately low Q and C_o, long l and n that minimizes flow maldistribution in parallel.

Conclusion: The findings in this work could serve as a basis to design and fabricate efficient microreactors for the removal of VOC in air purification applications.

Keywords: Photocatalysis, microreactor, VOCs, bilayer thin-film structure, TiO₂, nitrogen and copper doping.

Graphical Abstract