EPR and magnetic studies on the regeneration of cobalt-molybdenum catalysts for coal liquefaction

Mehandjiev, D.; Zhecheva, E.; Aleksić, Bogdan R.; Aleksić, Bojana; Marković, Branislav; Bogdanov, S. V.

doi:10.1007/bf02075404

Cited by 6 publications

(2 citation statements)

References 9 publications

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“…The magnetic property of Co sensitively reflects the chemical state of Co atoms and their mutual interactions. The magnetic study of Co−Mo catalysts has been conducted by several groups in oxidic , and sulfided − states. In their magnetic study, Topsøe et al , reported that the effective magnetic moment of Co decreased as the temperature decreased for an unsupported Co−MoS 2 catalyst (Co/Mo = 0.0625) in which all the Co atoms were present as the Co−Mo−S phase according to MES measurements.…”

Section: Introductionmentioning

confidence: 99%

Structure of the Active Sites of Co−Mo Hydrodesulfurization Catalysts as Studied by Magnetic Susceptibility Measurement and NO Adsorption

et al. 2004

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The elucidation of a molecular structure of the active sites (i.e., the Co−Mo−S phase) of Co−Mo hydrodesulfurization catalysts has received extensive attention. In the present study, we unambiguously determined, for the first time, the NO adsorption behavior and magnetic property of the Co−Mo−S phase by preparing unique Co−Mo/Al2O3 catalysts (CVD−Co/MoS2/Al2O3), in which all the Co atoms are present as the Co−Mo−S phase. The catalysts were characterized by NO adsorption (pulse technique and FTIR), Co K-edge XANES, and the magnetic susceptibility and effective magnetic moment of Co. Nitric oxide molecules were adsorbed on 33% of the Co atoms in CVD−Co/MoS2/Al2O3 after sulfidation and on only half of the Co atoms even after an H2-treatment of the sulfided catalyst at 573−673 K. The Co atoms in CVD−Co/MoS2/Al2O3 exclusively exhibited an antiferromagnetic property, indicating that even-numbered Co atoms are interacting with each other in the Co−Mo−S phase. A Co−Mo/Al2O3 catalyst, prepared by a conventional impregnation technique, was composed of the antiferromagnetic Co sulfide species as observed in CVD−Co/MoS2/Al2O3 in addition to Co9S8. On the basis of the NO adsorption behavior and magnetic property, it is empirically proposed that the structure of the Co−Mo−S phase is represented as a Co sulfide dinuclear cluster located on the edge of MoS2 particles. The magnetic property of Co/Al2O3 sulfide catalysts depended on the preparation method.

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Section: Introductionmentioning

confidence: 99%

Structure of the Active Sites of Co−Mo Hydrodesulfurization Catalysts as Studied by Magnetic Susceptibility Measurement and NO Adsorption

et al. 2004

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“…The sulfur vacancy strength of MoS 2 –Mo 2 N and MoS 2 –MoC was obviously stronger than that of MoS 2 , indicating that MoS 2 –Mo 2 N and MoS 2 –MoC contain more S vacancies. At the same time, for MoS 2 –MoC, the parameter center signals showed axial anisotropy, g = 2.0508 and 1.9804, which were related to the bulk defects in MoS 2 …”

Section: Resultsmentioning

confidence: 88%

Mo-Based Heterogeneous Interface and Sulfur Vacancy Synergistic Effect Enhances the Fenton-like Catalytic Performance for Organic Pollutant Degradation

Zhang

et al. 2022

ACS Appl. Mater. Interfaces

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Heterogeneous Fenton-like reactions (HFLRs) based on the in situ electrochemical generation of hydrogen peroxide (H 2 O 2 ) are one of the green methods to remediate organic pollutants in wastewater. However, the design of Fenton-like catalysts with specific active sites and high pollutant degradation rate is still challenging. Here, MoS 2 −MoC and MoS 2 −Mo 2 N catalytic cathodes with heterojunctions were successfully prepared, and the mechanism by which hydroxyl radicals and singlet oxygen ( 1 O 2 ) were generated cleanly without adding chemical additives other than oxygen was clarified. The composite catalysts contained more sulfur vacancies, and the catalytic cathode achieved a high paracetamol pollutant degradation efficiency with 0.17 kWh g −1 TOC specific energy consumption. And almost 5 times higher activity was achieved compared to a pure MoS 2 catalytic cathode. Experimental studies confirmed that the production of 1 O 2 was based on the transformation of superoxide radicals by Mo 6+ , and 1 O 2 accounted for approximately 66% of the total degradation and enhanced the nonradical behavior in the reaction. This work provides a sustainable strategy for pollutant utilization, which is valuable for solving the difficult problems of HFLRs and developing new environmental remediation technologies.

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Molybdenum-promoted cobalt supported on SBA-15: Steam and sulfur dioxide stable catalyst for CO oxidation

Lima

Macedo

Silva

et al. 2020

Applied Catalysis B: Environmental

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EPR and magnetic studies on the regeneration of cobalt-molybdenum catalysts for coal liquefaction

Cited by 6 publications

References 9 publications

Structure of the Active Sites of Co−Mo Hydrodesulfurization Catalysts as Studied by Magnetic Susceptibility Measurement and NO Adsorption

Structure of the Active Sites of Co−Mo Hydrodesulfurization Catalysts as Studied by Magnetic Susceptibility Measurement and NO Adsorption

Mo-Based Heterogeneous Interface and Sulfur Vacancy Synergistic Effect Enhances the Fenton-like Catalytic Performance for Organic Pollutant Degradation

Molybdenum-promoted cobalt supported on SBA-15: Steam and sulfur dioxide stable catalyst for CO oxidation

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