A novel suspended/supported photoreactor design for photocatalytic decomposition of acetic acid with simultaneous production of useful hydrocarbons

This study reports the generation of combustible C1–C4 hydrocarbons and hydrogen via photocatalytic decomposition of acetic acid in N2 atmosphere. A new photoreactor design based on a hybrid suspended/supported photocatalytic system was proposed. The TiO2 photocatalyst was immobilized on a glass fabric which was mounted in the photoreactor containing additionally TiO2 suspended in the reaction solution. The photodecomposition took place in both liquid and gaseous phases. The configuration allowed for the diffusion of CH3COOH molecules from the reaction solution to the upper part of the fabric where the photoreaction proceeded. Moreover, decomposition of acetic acid molecules which evaporated from the solution took place. An improvement of the effectiveness of methane generation for about 90% compared to the suspended system and for about 50% in comparison with the immobilized system alone was observed. The amounts of the gases evolved after 27 h of the process conducted in the novel photoreactor were equal to 1.95, 1.66, 0.304, 0.059, 0.0014 and 0.007 mmol (5.57, 4.74, 0.87, 0.17, 0.004 and 0.02 mmol/mol CH3COOH) for CH4, CO2, C2H6, C3H8, C4H10 and H2, respectively. The observed improvement of the process efficiency was attributed to: (i) simultaneous CH3COOH decomposition in liquid and gaseous phases and (ii) photoreduction of CO2 to CH4.

► A new hybrid suspended/supported photocatalytic system design.
► A 90% improvement of efficiency of hydrocarbons photogeneration from CH3COOH.
► Simultaneous CH3COOH decomposition in liquid and gaseous phases.
► CH4 formation by CO2 photoreduction in the gas phase.