Synergetic effects of surface free Co₃O₄ species on catalytic oxidation of NO over cerium-cobalt solid solution

Abstract

The xCo₃O₄/Ce_0.85Co_0.15-3xO_2-δ catalyst was prepared by a sol-gel method for selective catalytic oxidation of NO. The experimental results showed that the highest catalytic activity reached 60.2% at 300 °C. In addition, the Raman spectra and XPS results confirmed that the Ce-Co catalyst contained surface free Co₃O₄ species and Co ions in the Ce_0.85Co_0.15-3xO_2-δ solid solution. Surface free Co₃O₄ species could be removed by hydrochloric acid, leading to decrease of the catalyst activity. For the xCo₃O₄/Ce_0.85Co_0.15-3xO_2-δ catalyst, the surface free Co₃O₄ species and the Ce_0.85Co_0.15-3xO_2-δ solid solution enhanced catalytic performance, and the former provided the adsorption sites of NO and the latter promoted the activation of oxygen. This research studied the synergetic effects of Co₃O₄ species and Ce_0.85Co_0.15-3xO_2-δ solid solution on the process of NO oxidation. For the xCo₃O₄/Ce_0.85Co_0.15-3xO_2-δ catalyst, the enhanced catalytic performance was due to the synergy between the surface Co₃O₄ species and the Ce_0.85Co_0.15-3xO_2-δ solid solution, as the former provided the sites for NO chemisorption and the latter promoted the activation of oxygen.

Graphical Abstract

Keywords:

• Selective catalytic oxidation
• NO
• ceria-cobalt solid solution
• synergetic effects

Additional information

Funding

This work was financially supported the National Natural Science Foundation of China (51578288), Jiangsu Province Scientific and Technological Achievements into a Special Fund Project (BA2016055 and BA2017095), Top-notch Academic Programs Project of Jiangsu Higher Education Institutions.