Preparation of P-doped spherical bimetallic oxides by co-immobilization of acids for sustainable oxidative desulfurization

Background

The catalytic oxidative desulfurization of sulfide from fuel oil is significant in producing clean energy. However, traditional catalysts face some bottleneck problems, such as improving accessible area, balancing electronic effects, and adjusting surface acidity.

Methods

This study reveals a designed P-doped transition-metal-oxides (P-TMOs(Ce/Mo)). Its spherical structure and surface acidity are obtained under regulations of acetic acid and phosphate. Self-directional migration of phosphate is achieved through a temperature-programmed method.

Significant findings

These procedures alter oxygen bridge-bondings between Ce-Mo to improve the mobility of excited oxygen atoms. Phosphate migrated to the surface creates Mo-O-P electron channels, facilitating reversible metal valence switching. The intricate processes of mass and electron transfer enhance the functionality of the metal sites, resulting in a synergistic acid-metal capability. ODS rate of 99.67 % is achieved under the mild reaction conditions (V(ILs)/V(oil)=0.02; n(O)/n(S)=2.8; m(catalyst)/V(oil)=0.005/5 (g/mL); 50 °C). The low activation energy (46.4 kJ/mol) and the dual-pathway synergistic catalytic reaction mechanism involving •OH and •O₂⁻ were verified by experiments and analyses (UV–Vis, XPS, EPR, etc.). Catalysts maintain stable ODS performance after multiple recycling processes. A novel catalyst recovery pathway has been identified, thereby enhancing the application potential of P-TMOs(Ce/Mo) across various dimensions.