Evidence of Synergy Effects between Zinc and Copper Oxides with Acidic Sites on Natural Zeolite during Photocatalytic Oxidation of Ethylene Using Operando DRIFTS Studies

• Published in: Catalysts 2023-03, Vol.13 (3), p.610
• Main Authors: Abreu, Norberto J, Valdés, Héctor, Zaror, Claudio A, de Oliveira, Tatianne Ferreira, Azzolina-Jury, Federico, Thibault-Starzyk, Frédéric
• Format: Article
• Language: English
• Subjects: Absorption spectra; Acidic oxides; Adsorption; Catalysts; Catalytic activity; Chemical reactions; Chemical Sciences; Conversion; Copper; Copper oxide; Copper oxides; Cuprite; Diffuse reflectance spectroscopy; Electromagnetic absorption; Ethylene; Fourier transforms; Fruits; Methylene blue; Nanoparticles; natural zeolite support; Oxidation; Oxidation-reduction reaction; Photocatalysis; Protection and preservation; Semiconductors; Silica; Silica fume; single and double metal oxide catalysts; Surface chemistry; Surface properties; synergistic mechanism; Transition metal oxides; Zeolites; Zinc; Zinc oxides
• ISSN: 2073-4344; 2073-4344
• DOI: 10.3390/catal13030610

In this article, the role of surface sites of modified zeolites with semiconductor nanoparticles as alternative photocatalyts for protecting post-harvest foodstuff from the detrimental effects of ethylene is addressed. Two single and one double catalyst based on zinc and copper oxides supported over modified zeolite samples were prepared. Physical, chemical, and surface properties of prepared materials were studied by several characterization methods. UV-Vis absorption spectra show that the applied modification procedures increase the optical absorption of light in the UV and visible regions, suggesting that an increase in the photocatalytic activity could take place mainly in the obtained co-impregnated catalyst. An ethylene conversion around 50% was achieved when the parent natural zeolite support was modified with both transition metal oxides, obtaining higher removal efficiency in comparison to single oxide catalysts. Adsorption and photocatalytic oxidation experiments were also performed using single and double catalysts supported over fumed silica, attaining lower ethylene conversion and thus highlighting the role of zeolite surfaces as adsorption sites for ethylene during photocatalytic reactions. Operando diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) studies reveal that a synergistic mechanism occurs, involving ethylene adsorption at acidic sites of zeolite and its photocatalytic oxidation due to the generation of radicals by the light activation of nanoparticles of zinc and copper oxides.