Molybdenum Oxide, Oxycarbide, and Carbide: Controlling
the Dynamic Composition, Size, and Catalytic Activity of Zeolite-Supported
Nanostructures
Posted on 2019-08-27 - 18:40
Molybdenum nanostructures
are promising catalysts for a single-step
methane conversion into aromatic hydrocarbons and for multiple other
hydrocarbon reactions. Dynamic transformations of catalytic zeolite-supported
Mo structures from an oxide to an oxycarbide and then to a carbide
in methane dehydroaromatization were studied with in situ X-ray absorption
spectroscopic measurements and density functional theory calculations.
After a treatment in the presence of gas-phase oxygen, Mo is present
in the form of isolated oxide structures. Under reaction conditions
with methane, these initial oxide structures become carbided and catalyze
methane conversion to aromatic hydrocarbons. As the reaction progresses,
the Mo carbide structures agglomerate and accumulate excess carbon,
leading to catalyst deactivation. Although the initial oxide structures
and catalytic activity can be restored by reversing the agglomeration
and coking with periodic oxygen regeneration treatments, it is desirable
to continuously control the dynamic composition, size and catalytic
activity of Mo structures under hydrocarbon reaction conditions. This
objective can be accomplished by co-feeding an oxygen-containing molecule,
such as CO2, that transforms Mo structures into an oxycarbide
and slows the undesirable agglomeration and coking. It is, therefore,
preferable for preserving catalytic activity to prevent full carburization
of Mo and, instead, maintain the Mo structures in an oxycarbide form,
an intermediate between an oxide and a carbide.
CITE THIS COLLECTION
DataCiteDataCite
3 Biotech3 Biotech
3D Printing in Medicine3D Printing in Medicine
3D Research3D Research
3D-Printed Materials and Systems3D-Printed Materials and Systems
4OR4OR
AAPG BulletinAAPG Bulletin
AAPS OpenAAPS Open
AAPS PharmSciTechAAPS PharmSciTech
Abhandlungen aus dem Mathematischen Seminar der Universität HamburgAbhandlungen aus dem Mathematischen Seminar der Universität Hamburg
ABI Technik (German)ABI Technik (German)
Academic MedicineAcademic Medicine
Academic PediatricsAcademic Pediatrics
Academic PsychiatryAcademic Psychiatry
Academic QuestionsAcademic Questions
Academy of Management DiscoveriesAcademy of Management Discoveries
Academy of Management JournalAcademy of Management Journal
Academy of Management Learning and EducationAcademy of Management Learning and Education
Academy of Management PerspectivesAcademy of Management Perspectives
Academy of Management ProceedingsAcademy of Management Proceedings
Academy of Management ReviewAcademy of Management Review
Zheng, Yiteng; Tang, Yadan; Gallagher, James R.; Gao, Jie; Miller, Jeffrey T.; Wachs, Israel E.; et al. (2019). Molybdenum Oxide, Oxycarbide, and Carbide: Controlling
the Dynamic Composition, Size, and Catalytic Activity of Zeolite-Supported
Nanostructures. ACS Publications. Collection. https://doi.org/10.1021/acs.jpcc.9b05449