Abstract
Direct oxidation of methane to value-added C1 chemicals (e.g. HCHO and CO) provides a promising way to utilize natural gas sources under relatively mild conditions. Such conversions remain, however, a key selectivity challenge, resulting from the facile formation of undesired fully-oxidized CO2. Here we show that B2O3-based catalysts are selective in the direct conversion of methane to HCHO and CO (~94% selectivity with a HCHO/CO ratio of ~1 at 6% conversion) and highly stable (over 100 hour time-on-stream operation) conducted in a fixed-bed reactor (550 °C, 100 kPa, space velocity 4650 mL gcat−1 h−1). Combined catalyst characterization, kinetic studies, and isotopic labeling experiments unveil that molecular O2 bonded to tri-coordinated BO3 centers on B2O3 surfaces acts as a judicious oxidant for methane activation with mitigated CO2 formation, even at high O2/CH4 ratios of the feed. These findings shed light on the great potential of designing innovative catalytic processes for the direct conversion of alkanes to fuels/chemicals.
Highlights
Direct oxidation of methane to value-added C1 chemicals (e.g. HCHO and CO) provides a promising way to utilize natural gas sources under relatively mild conditions
Our results show that B2O3-based catalysts are highly selective in the direct conversion of methane to HCHO and CO, and these selectivities are unexpectedly insensitive to the O2/CH4 ratios
Structural characterization, kinetic measurements, and isotopic labeling experiments are combined to discern that molecular O2 bonded to coordinately unsaturated BO3 centers on the B2O3 surfaces is the crucial oxidant that accounts for the selective methane oxidation
Summary
Direct oxidation of methane to value-added C1 chemicals (e.g. HCHO and CO) provides a promising way to utilize natural gas sources under relatively mild conditions Such conversions remain, a key selectivity challenge, resulting from the facile formation of undesired fully-oxidized CO2. Kinetic studies, and isotopic labeling experiments unveil that molecular O2 bonded to tri-coordinated BO3 centers on B2O3 surfaces acts as a judicious oxidant for methane activation with mitigated CO2 formation, even at high O2/CH4 ratios of the feed. These findings shed light on the great potential of designing innovative catalytic processes for the direct conversion of alkanes to fuels/chemicals. The mechanistic understanding of methane oxidation on the unique B2O3 surfaces would inspire the design of the generation of heterogeneous catalysts for selective oxidation of hydrocarbons
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
