Highly Active and Selective Sites for Propane Dehydrogenation in Zeolite Ga-BEA

Lingli Ni; Rachit Khare; Ricardo Bermejo-Deval; Ruixue Zhao; Lei Tao; Yue Liu; Johannes A Lercher

doi:10.1021/jacs.2c03810

Highly Active and Selective Sites for Propane Dehydrogenation in Zeolite Ga-BEA

J Am Chem Soc. 2022 Jul 13;144(27):12347-12356. doi: 10.1021/jacs.2c03810. Epub 2022 Jun 30.

Authors

Lingli Ni¹, Rachit Khare¹, Ricardo Bermejo-Deval¹, Ruixue Zhao¹, Lei Tao¹, Yue Liu^{1

2}, Johannes A Lercher^{1

3}

Affiliations

¹ Department of Chemistry and Catalysis Research Center, Technical University of Munich, Garching 85747, Germany.
² Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China.
³ Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States.

PMID: 35771043
DOI: 10.1021/jacs.2c03810

Abstract

A highly selective Ga-modified zeolite BEA for propane dehydrogenation has been synthesized by grafting Ga on Zn-BEA followed by removal of Zn in the presence of H₂. A propene selectivity of 82% at 19% propane conversion illustrates the high selectivity at 813 K. The kinetic model of the catalyzed dehydrogenation including the elementary steps of propane adsorption, first and second C-H bond cleavage, and propene and H₂ desorption demonstrates that the propane dehydrogenation rate is determined by the first C-H bond cleavage at low p_C₃H₈, while at high p_C₃H₈, the rate is limited by the desorption of H₂. The active sites have been identified as dehydrated and tetrahedrally coordinated Ga³⁺ in the *BEA lattice. The low selectivity toward aromatics is concluded to be associated with the high Lewis acid strength of lattice Ga³⁺ and the low Brønsted acid strength of the hydrated Ga sites.