Direct conversion of methane to formaldehyde and CO on B<sub>2</sub>O<sub>3</sub> catalysts.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 33173054.
- Also identified by DOI 10.1038/s41467-020-19517-y and PMC identifier 7655938.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Direct oxidation of methane to value-added C<sub>1</sub> 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 CO<sub>2</sub>. Here we show that B<sub>2</sub>O<sub>3</sub>-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 g<sub>cat</sub><sup>-1</sup> h<sup>-1</sup>). Combined catalyst characterization, kinetic studies, and isotopic labeling experiments unveil that molecular O<sub>2</sub> bonded to tri-coordinated BO<sub>3</sub> centers on B<sub>2</sub>O<sub>3</sub> surfaces acts as a judicious oxidant for methane activation with mitigated CO<sub>2</sub> formation, even at high O<sub>2</sub>/CH<sub>4</sub> 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.