Photocatalytic Reduction of CO₂ over Cu-TiO₂/Molecular Sieve 5A Composite

Abstract

TiO₂ and different Cu wt% loaded TiO₂ (TC_0.5–5.0), 10 wt% TC_2.0 supported on molecular sieve 5A (10 wt% TC_2.0/MS) were prepared by impregnation and solid-state dispersion methods. The photocatalysts prepared were characterized using XRD, SEM, and UV–Vis DRS, TEM, XPS spectroscopy techniques. Photocatalytic reduction of CO₂ in water and alkaline solution are investigated in a batch reactor. The yield of oxalic acid increased notably when TC was supported on molecular sieve. The Cu-TiO₂ supported on molecular sieve catalyst promotes the charge separation that leads to an increase in the selective formation of oxalic acid in addition to methanol, acetic acid and traces of methane. The product formation is due to the high adsorption of CO₂, water and product shape selectivity of the composite photocatalyst. The maximum yield of oxalic acid was found to be 65.6 μg h⁻¹ g⁻¹ per cat using 0.2 N NaOH containing solution over 10 wt% TC_2.0/MS photocatalyst. The difference in the photocatalytic activity is related to its physicochemical properties.