Effect of Co doping on active oxygen species of CoxCe1-xOy mixed oxide catalysts derived from MOF materials for soot combustion

Abstract

Background

Cerium-based materials have the potential to be used as catalysts for diesel particulate filters. The development of Cerium-based MOF derived catalysts is an important way to explore these materials for DPF applications.

Methods

In this work, Co_xCe_1-xO_y catalysts were synthesized by calcining cobalt-cerium bimetallic MOF precursors. The prepared catalysts were characterized using XRD, Raman, SEM, N₂ adsorption-desorption, XPS, H₂-TPR, and O₂-TPD, and tested for soot oxidation activity and performed DFT calculations.

Significant findings

Raman spectra analysis revealed that Co_0.2Ce_0.8O_y catalyst had a larger maximum half-width and was more likely to form oxygen defects. Compared with CeO₂ catalyst, N₂ adsorption-desorption results demonstrated that Co_0.2Ce_0.8O_y catalyst possessed a larger specific surface area (61.4 m²·g⁻¹). XPS, H₂-TPR, and O₂-TPD characterizations indicated that Co_0.2Ce_0.8O_y catalyst possessed a higher content of active oxygen (45.2 %), a greater consumption amount of hydrogen (7.5 mmol·g⁻¹), and a larger total desorption amount of oxygen species (1.16 mmol·g⁻¹). Catalytic activity test results showed that Co_0.2Ce_0.8O_y catalyst exhibited better soot oxidation activity (T₉₀ = 406 °C). DFT calculations demonstrated that Co_0.2Ce_0.8O_y catalyst had a larger surface energy (0.44 J/m²) and a smaller oxygen vacancy formation energy (2.26 eV).