Covalency triggers high catalytic activity of amorphous molybdenum oxides for oxidative desulfurization

作者：Zou, Juncong; Lin, Yan^*; Yang, Chunping^*

来源：Science China Chemistry, 2023, 66(4): 1211-1220.

DOI：10.1007/s11426-022-1534-8

• amorphous
• molybdenum oxide
• oxidative desulfurization
• covalency

Oxidative desulfurization (ODS) is a promising technology to produce clean fuel with requiring superior catalysts to lower kinetic barriers. Although most ODS catalysts are based on crystalline transition-metal oxides (TMOs), extraordinary activity also can be achieved with amorphous TMOs. However, the origin of the remarkable catalytic activity of the amorphous TMOs remains greatly ambiguous. Here, we found the crucial role of Mo-O covalency in ruling the intrinsic catalytic activity of amorphous molybdenum oxides (MoOx). Experimental and theoretical analysis indicated that the nonequivalent connectivity in the amorphous structure strongly enhanced Mo-O covalency, thereby increasing the content of electrophilic oxygen and nucleophilic molybdenum to favor the MoOx-H2O2 interaction. With the boosted Mo-O covalency to improve the flexibility of the charge state, the amorphous MoOx-based composite catalyst (PE-MoOx/S-0.05) exhibited outstanding catalytic activity for ODS of fuel oil. The turnover frequency (TOF) value of the catalyst (18.63 h(-1)) was almost an order of magnitude higher than that of most reported crystalline MoOx/molecular sieve composite catalysts. The in-depth understanding of the origin of the amorphous TMOs activity for ODS provides a valuable reference for developing ODS catalysts.

• 单位
  南昌航空大学; 茂名学院; y