Abstract
Our recent work has reported that higher propylene selectivity and improved stability can be achieved by combining redox-active VOx and basic In2O3 for CO2-assisted oxidative dehydrogenation of propane (CO2-ODHP). In the present work, we continued to explore the stability and regenerability of V/In catalysts. In particular, our interest lies in identifying the effect of mono- and polyvanadate on catalytic performance and regenerability. A V/In catalyst with an increased proportion of monovanadate was prepared using the Schlenk line under moisture-free conditions (V/In-S), while the fully polymerized vanadate catalyst was prepared through a regular impregnation (V/In) for comparison. The Schlenk-line-prepared catalyst, namely, V/In-S, not only exhibits a 17-30% enhanced propylene yield at high temperatures (500-540 °C) over V/In but also presents improved stability and regenerability with nearly 88% activity recovered after regeneration in O2. Detailed characterizations have been performed to reveal the catalyst structure-performance relationship, including chemisorption (NH3/CO2-temperature-programmed desorption, NH3/CO2-TPD), H2-temperature-programmed reduction (H2-TPR), and spectroscopic studies [Raman spectroscopy, UV-vis diffuse reflectance spectroscopy (UV-vis DRS), near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS), and high-sensitivity low-energy ion scattering (HS-LEIS)]. Characterization results demonstrate that compared with polyvanadates, monovanadates lead to strengthened interaction with In2O3 and a more stabilized V/In surface and subsurface, as well as improved redox properties of VOx. These advantages give rise to the observed enhancement in activity, stability, and regenerability. These findings advance the understanding of the relationship between the activity/stability and the molecular structure of surface oxide species (vanadia) and the interplay between acid-base interactions and redox properties of mixed metal-oxide catalysts for efficient CO2-ODHP.
| Original language | English |
|---|---|
| Pages (from-to) | 6311-6320 |
| Number of pages | 10 |
| Journal | Journal of Physical Chemistry C |
| Volume | 127 |
| Issue number | 13 |
| DOIs | |
| State | Published - Apr 6 2023 |
Funding
Notice: This manuscript has been authored by UT-Battelle, LLC, under contract no. DE-AC05-00OR22725, with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ). Acknowledgments This work was supported as part of the Center for Understanding and Control of Acid Gas-Induced Evolution of Materials for Energy (UNCAGE ME), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences at the under award no. DE-SC0012577. Part of the work including the synthesis, activity test, and characterization (chemisorption and in situ Raman spectroscopy) was done at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. In situ NAP-XPS and HS-LEIS were performed at the Operando Molecular Spectroscopy and Catalysis Research Laboratory of Lehigh University.