Borosilicate zeolite enriched in defect boron sites boosting the low-temperature oxidative dehydrogenation of propane

Borosilicate zeolites are the active catalysts in oxidative dehydrogenation of propane (ODHP), which provide an ideal platform to explore the origin of catalytic activity for boron-containing catalysts as well as the construction of highly active boron centers. Herein, we report that the incompletely crystallized MFI-type borosilicate zeolite catalyst displays extraordinary performance in ODHP, exhibiting an olefin productivity of 4.75 g(olefin) g(cat)(-1) h(-1) under low reaction temperature (445 & DEG;C) and high weight-hour-space-velocity (WHSV, 37.6 gC(3H8) g(cat)(-1) h(-1)). A combination of solid-state NMR, dual-beam FTIR, and in-situ DRIFT measurements reveal that the boron species are anchored to the zeolite matrix in the form of open coordination. Meanwhile, the ample Si-OH groups on the surface facilitate the formation of hydrogen bonds with the B-OH in defective boron species and inhibit the excessive leaching of boron. During the ODHP process, the isolated boron species would dynamically transform into aggregated ones, being closely related to the increased catalytic activity. The B-OH groups in aggregated BOx species that hydro-gen bond with adjacent Si-OH groups are identified as the active center and high efficiency in catalyzing ODHP reaction at low temperature. (C) 2022 Elsevier Inc. All rights reserved.

Automated summary

In this study, an incompletely crystallized borosilicate zeolite catalyst exhibited extraordinary performance in the oxidative dehydrogenation of propane. The boron species were found to be anchored to the zeolite matrix in the form of open coordination and formed hydrogen bonds with defective boron species, preventing excessive leaching of boron. The active center for catalyzing the reaction was identified as the B-OH groups in aggregated BOx species that formed hydrogen bonds with adjacent Si-OH groups.