Abstract
Recently metal carbide catalysts have attracted attention as alternatives to pure metals for the conversion of syngas to higher oxygenates, a process which could enable the sustainable production of fuels, polymers, and chemicals. Although Mo and Co carbides have both shown promise for higher oxygenate production, they have not achieved the requisite activity and selectivity for practical implementation. In this work we synthesize and characterize a binary Mo and Co carbide catalyst that exhibits improved activity and oxygenate selectivity relative to either pure metal carbide. We apply a combination of advanced electron microscopy and X-ray diffraction to show that the binary Mo/Co carbide catalyst forms uniformly mixed amorphous nanoparticles. Through in situ X-ray absorption spectroscopy studies, we determine that the structure of the mixed metal carbide catalyst under reaction conditions consists of both carbidic and bimetallic components. By testing the catalytic properties of a series of Mo/Co carbide catalysts prepared by different synthesis methods, we find that the Mo and Co sites must be in close contact to achieve improved syngas conversion to higher alcohols. Through in situ DRIFTS measurements, both Mo and Co atoms at the surface of the catalyst are identified as adsorption sites for reactive species.
Original language | English |
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Pages (from-to) | 446-458 |
Number of pages | 13 |
Journal | Journal of Catalysis |
Volume | 391 |
DOIs | |
State | Published - Nov 2020 |
Funding
We gratefully acknowledge the SUNCAT Center for Interface Science and Catalysis, supported by the U.S. Department of Energy , Office of Science , Office of Basic Energy Sciences , Chemical Sciences, Geosciences, and Biosciences Division , Catalysis Science Program. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory is supported by the U.S. Department of Energy , Office of Basic Energy Sciences under Contract N. DE-AC02-76SF00515 . Co -ACCESS is supported by the U.S. Department of Energy , Office of Science , Office of Basic Energy Sciences , Chemical Sciences, Geosciences, and Biosciences. STEM -EDS was conducted at the Center for Nanophase Materials Science, which is a DOE Office of Science User Facility. Part of this work was performed at the Stanford Nano Shared Facilities ( SNSF ), supported by the National Science Foundation under award ECCS - 1542152 . The authors would like to thank Josiah Yarbrough for assisting in reviewing and editing this manuscript. We gratefully acknowledge the SUNCAT Center for Interface Science and Catalysis, supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division, Catalysis Science Program. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory is supported by the U.S. Department of Energy, Office of Basic Energy Sciences under Contract N. DE-AC02-76SF00515. Co-ACCESS is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences. STEM-EDS was conducted at the Center for Nanophase Materials Science, which is a DOE Office of Science User Facility. Part of this work was performed at the Stanford Nano Shared Facilities (SNSF), supported by the National Science Foundation under award ECCS-1542152. The authors would like to thank Josiah Yarbrough for assisting in reviewing and editing this manuscript.
Keywords
- Amorphous catalysts
- In situ DRIFTS
- In situ XAS
- Metal carbides
- Syngas conversion