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[Display omitted] • Dopant of Ag on MnCeO x promotes the catalytic activity for propane oxidation. • Ag dopant increases Mn4+ and Ce3+ concentrations. • Ag dopant enhances surface oxygen migration capability. • Ag dopant leads to a novel carboxylate formation path. The development of highly active catalysts for eliminating volatile organic compounds (VOCs) at low temperature is desirable but remains challenging. In this study, a series of Ag-loaded MnCeO x catalysts were fabricated. Catalysts with an Ag loading of 5 wt% exhibited the highest catalytic activity (T 90 = 242 °C) and excellent stability in H 2 O, NO 2 , and CO atmosphere. Characterization results revealed that the introduction of Ag increased Mn4+ and Ce3+ concentrations and enhanced surface oxygen migration capability, which is conducive to the adsorption and dissociation of propane and O 2. Combining in-situ diffuse reflectance infrared Fourier transform and discrete Fourier transform calculation revealed a novel propane oxidation pathway on MnCeO x and Ag/MnCeO x. The addition of Ag species can convert propane into propylene in the initial stage and reduce the activation energy. This study supplied a novel insight into Ag-doped catalysts catalytic mechanism for VOCs oxidation reaction. [ABSTRACT FROM AUTHOR]

A single-molecule confinement-sulfurization strategy was proposed to construct ultrafine Co-MoS 2 monolayer catalysts, employing oil-soluble POMs as precursors. Well-defined Co 2 Mo 10 -POMs were introduced for regulating CoMoS sites at atomic scale, exhibiting high intrinsic activities in VR HCK. [Display omitted] • Ultrafine Co-MoS 2 monolayer catalysts were controllably fabricated from the oil-soluble polyoxometalate (POM) precursors. • The POM anions were encapsulated and confined by organic surfactant cations at single-molecule level. • Well-defined Co 2 Mo 10 POMs were introduced for regulating CoMoS active sites at atomic scale. • CoMoS active sites show excellent catalytic performance for slurry phase hydrocracking of vacuum residue. • The structures and catalytic mechanisms of CoMoS sites were revealed by coupling XAFS with DFT calculations. Herein, a novel single-molecule confinement-sulfurization strategy was proposed to construct ultrafine Co-MoS 2 monolayer catalysts by using oil-soluble single-molecule polyoxometalates (POMs), (DODA) 6 Co 2 Mo 10 , as precursors. Well-defined Co 2 Mo 10 -POM, acting as molecular pre-assembling platform, is introduced for the atomically precise construction of bimetallic sites. Highly efficient conversion of VR under severe condition is realized with (DODA) 6 Co 2 Mo 10. The origin of prominent catalytic performance can be attributed to the in-situ formation of ultrafine single-layered Mo-based nanosheets with abundant exposed CoMoS active sites. By combining synchrotron radiation-based X-ray absorption spectroscopy and density functional theory calculations, we further discover that there is clearly intimate interaction between Mo and Co atoms and the dissociation of molecular hydrogen at CoMoS phases is energetically preferred, leading to remarkable hydrogenation and coke suppression activity. This work highlights an idea on the rational design and targeted synthesis of ultrafine bimetallic catalysts for slurry phase HCK with dramatically synergistic catalysis. [ABSTRACT FROM AUTHOR]