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Methanol conversion on borocarbonitride catalysts: Identification and quantification of active sites
Xuefei Zhang1, Pengqiang Yan2, Junkang Xu1
1State Key Laboratory of Photocatalysis on Energy and Environment, College of Chemistry, Fuzhou University, Fuzhou 350016, China.
Science Advances
|July 9, 2020
Summary
Borocarbonitrides (BCNs) are selective catalysts for oxidative dehydrogenation (ODH). This study elucidates their methanol conversion mechanism, revealing key active sites for formaldehyde production.
Area of Science:
- Heterogeneous Catalysis
- Materials Science
- Surface Chemistry
Background:
- Borocarbonitrides (BCNs) show promise as selective catalysts for oxidative dehydrogenation (ODH).
- The precise catalytic mechanisms of BCNs, particularly concerning surface oxygen functional groups, remain poorly understood.
- Understanding these mechanisms is crucial for optimizing BCN performance in chemical conversions.
Purpose of the Study:
- To synthesize BCN nanotubes with multiple active sites for oxygen-assisted methanol conversion.
- To elucidate the catalytic mechanism and identify key active sites responsible for methanol conversion and formaldehyde selectivity.
- To provide fundamental insights into the functional mechanisms of BCN catalysts for nonmetallic catalytic systems.
Main Methods:
- Synthesis of BCN nanotubes with diverse active sites.
- Catalytic testing for oxygen-assisted methanol conversion.
- Kinetic measurements, in situ infrared spectroscopy, X-ray absorption spectroscopy, and density functional theory (DFT) calculations.
Main Results:
- Achieved a 29% improvement in methanol conversion with 54% selectivity to formaldehyde using BCN nanotubes.
- Identified carboxylic acid groups as responsible for dimethyl ether formation.
- Determined that ketonic carbonyl and boron hydroxyl (B─OH) sites are crucial for redox catalysis to formaldehyde, with the B─OH pathway elucidated.
Conclusions:
- BCN nanotubes exhibit significant activity and selectivity in methanol conversion to formaldehyde.
- Specific surface functional groups (carboxylic acid, ketonic carbonyl, B─OH) play distinct roles in the catalytic pathways.
- This research offers critical physical-chemical insights into BCN catalytic mechanisms, advancing nonmetallic catalyst development.
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