VOCs Photothermo-Catalytic Removal on MnOx-ZrO2 Catalysts

Abstract

Solar photothermo-catalysis is a fascinating multi-catalytic approach for volatile organic compounds (VOCs) removal. In this work, we have explored the performance and the chemico-physical features of non-critical, noble, metal-free MnOx-ZrO2 mixed oxides. The structural, morphological, and optical characterizations of these materials pointed to as a low amount of ZrO2 favoured a good interaction and the ionic exchange between the Mn and the Zr ions. This favoured the redox properties of MnOx increasing the mobility of its oxygens that can participate in the VOCs oxidation through a Mars-van Krevelen mechanism. The further application of solar irradiation sped up the oxidation reactions promoting the VOCs total oxidation to CO2. The MnOx-5 wt.%ZrO2 sample showed, in the photothermo-catalytic tests, a toluene T90 (temperature of 90% of conversion) of 180 °C and an ethanol T90 conversion to CO2 of 156 °C, 36 °C, and 205 °C lower compared to the thermocatalytic tests, respectively. Finally, the same sample exhibited 84% toluene conversion and the best selectivity to CO2 in the ethanol removal after 5 h of solar irradiation at room temperature, a photoactivity similar to the most employed TiO2-based materials. The as-synthetized mixed oxide is promising for an improved sustainability in both catalyst design and environmental applications.

Abatement of Volatile Organic Compounds Employing a Thermoplastic Nano‐Photocatalyst Layered on a Glass Reactor

“…The photodegradation of VOCs is usually performed using a powdered photocatalyst placed in a suitable photoreactor [27–29] . However, this approach requires the use of a large amount of photocatalyst, affecting the cost of the overall process and also limiting its industrial scalability.…”

“…The photodegradation of VOCs is usually performed using a powdered photocatalyst placed in a suitable photoreactor. [27][28][29] However, this approach requires the use of a large amount of photocatalyst, affecting the cost of the overall process and also limiting its industrial scalability. Furthermore, the influence of internal diffusion related to the different grain sizes of the powders can strongly affect the absorption of incident photons, leading to an important decrease in photoactivity over time.…”

Emerging high-prospect applications in photothermal catalysis

“…This concerns the valorization of bio-resource, the activation of methane, the synthesis 3 of ammonia and the activation of molecular oxygen for selective oxidations. The reader can refer to recent updates on already well-reviewed applications from both environmental and energy fields, like the degradation of pollutants in water and air, the production of H2 by oxygenate photoreforming, as well as CO2 and CO conversion reactions, including artificial photosynthesis (CO2 + H2O) [2,4,[8][9][10][11].…”

Editorial: Photocatalysts for Air Purification: Design, Synthesis, and Mechanism Investigations

“…Among various technologies, photocatalysis is particularly suitable for removing low-concentration air pollutants (e.g., VOCs) at sub-ppm or ppb levels because the conventional adsorption technologies are not very efficient ( Boonen and Beeldens, 2014 ; Yu et al, 2010 ; Hay et al, 2015 ; Boyjoo et al, 2017 ; Ren et al, 2017 ; Schreck and Niederberger, 2019 ; Weon et al, 2019 ). In recent years, much effort has been made to improve the applicability of photocatalytic air purification, such as developing novel photocatalysts for air purification, increasing the optical absorption and charge generation to enhance the photocatalytic activity, and understanding of mechanisms and reactions ( Wu and van de Krol, 2012 ; Dong et al, 2014 ; Weon and Choi, 2016 ; Huang et al, 2017 ; Zhu et al, 2017 ; Li et al, 2018 ; Liu et al, 2020 ; Fiorenza et al, 2022 ).…”