Insights into the active sites of ordered mesoporous cobalt oxide catalysts for the total oxidation of o-xylene

• Published in: Journal of catalysis 2017-08, Vol.352, p.282-292
• Main Authors: Xie, Shaohua, Liu, Yuxi, Deng, Jiguang, Yang, Jun, Zhao, Xingtian, Han, Zhuo, Zhang, Kunfeng, Dai, Hongxing
• Format: Article
• Language: English
• Subjects: Cobalt monoxide; Divalent cobalt species; Mesoporous transition metal oxides; O-xylene oxidation; Oxygen activation ability
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2017.05.016

[Display omitted] •Ordered mesoporous Co3O4 (meso-Co3O4) is prepared via the KIT-6-templating route.•meso-CoO and meso-CoOx are fabricated from meso-Co3O4 via a reduction process.•meso-CoOx with the largest surface Co2+ amount performs best for o-xylene oxidation.•Surface Co2+ species are beneficial for oxygen activation.•Active oxygen species formed in the Co2+ sites are mainly O2− and/or O22−. Cobalt oxide is a typical transition metal oxide that exhibits high catalytic activity for the total oxidation of volatile organic compounds. In this study, a reduction process in a glycerol solution was adopted to generate mesoporous CoO (meso-CoO) or CoOx (meso-CoOx) from mesoporous Co3O4 (meso-Co3O4). The obtained samples were rich in Co2+ species and exhibited high catalytic activity for o-xylene oxidation. The meso-CoOx sample with the largest surface Co2+ amount performed the best: The o-xylene conversion at 240°C was 83%, and the reaction rate over meso-CoOx was nine times higher than that over meso-Co3O4. It is found that the samples with more surface Co2+ species possessed better oxygen activation ability, and the Co2+ species were the active sites that favored the formation of highly active O2− and O22− (especially O2−) species.