Ecology & Safety, Volume 15, 2021

Abstract: Nowadays many researchers are focused on catalytic oxidation as one of the most efficient ways to reduce the harmful emissions from various chemical industries. The use of appropriate highly active catalysts could decrease the operational costs by significantly lowering the temperature for total oxidation of volatile organic compounds (VOCs). The object of the present study is the complete benzene oxidation, used as a probe reaction for the VOCs abatement, over Co3O4 – CeO2 mixed oxides synthesized via mechanical mixing of cerium hydroxide and cobalt hydroxycarbonate precursors at different time of treatment. The CeO2 content was 20, 30 and 40 wt.%. All materials were characterized using Brunauer-Emmet-Teller (BET) method, X-ray Diffraction (XRD), and Temperature Programmed Reduction (H2 –TPR). The mixed oxides exhibited much better catalytic activity in comparison with Co3O4. 100% benzene conversion was reached in the relatively very low temperature range 200 – 250oC, thus confirming the promotional role of ceria. The optimal composition was 70 wt.% Co3O4 – 30 wt.% CeO2. The catalyst prepared by 1 min mechanical mixing exhibited the best performance, a slightly lower activity was established in the case of 5 min precursors’ grinding. Both catalysts with this best composition reached 100% benzene conversion at 200oC, maintaining stable activity at this temperature without any products of incomplete benzene oxidation. The important role of mechanochemical treatment was evidenced by the significantly worst catalytic behavior over the sample with this optimal composition but prepared by manual mixing. The results showed the promising oxidation activity of low-cost noble metal-free composites synthesized by simple method of mechanochemical mixing for effective VOCs elimination.