Propene and 1,3-butadiene are important building-block chemicals that can be produced by dehydrogenation of propane and butane on Pt catalysts. A challenge is to develop highly active and selective catalysts that are resistant to deactivation by Pt sintering and coke formation. We have recently shown (Qi , J. Am. Chem. Soc. 2021, 143, 21364−21378) that these objectives can be met for propane dehydrogenation (PDH) using atomically dispersed Pt anchored to neighboring ≡SiOZn-OH groups bonded to the framework of dealuminated zeolite BEA. In the present study, we demonstrate that significantly superior performance can be achieved using self-pillared pentasil (SPP) zeolite nanosheets as supports. Following catalyst reduction in H2, atomic resolution, scanning transmission electron microscopy (STEM), and X-ray absorption spectroscopy (XAS) indicate that Pt is stabilized in structures well approximated as (≡Si-O-Zn)4-5Pt. These species are highly active, selective, and stable for PDH to give propene and for n-butane dehydrogenation (BDH) to give 1,3-butadiene. No catalyst deactivation was observed after 12 days of time on stream, and the selectivity remained at nearly 100% for PDH conducted at 823 K and a weight hourly space velocity (WHSV) of 1350 h–1. The apparent rate coefficient for PDH on this catalyst is significantly higher than that reported previously for Pt-containing catalysts. For BDH at 823 K and a WHSV of 3560 h–1, the selectivity to butene isomers and 1,3-butadiene is 98.9%, and the selectivity to 1,3-butadiene is 45%. We propose that the high catalyst stability observed during PDH and BDH is a consequence of a large fraction of the Pt-containing centers being located on the external surface of the zeolite nanosheets, where nascent coke precursors can desorb before condensing to form coke.
KAUST Repository Item: Exported on 2022-09-14
Acknowledgements: A.T.B., L.Q., and Y.Z. acknowledge the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy (DOE) under Contract No. DE-AC02-05CH11231 for providing support to this work. B.C.G. and M.B. acknowledge DOE, BES, under Contract DE-SC0012702 (an Energy Frontier Research Center supporting the Inorganometallic Catalyst Design Center) for the contributions to this work. M. T. and P. L. acknowledge SPP zeolite synthesis under DOE, BES, Grant DE-SC0001004 (an Energy Frontier Research Center supporting the Catalysis Center for Energy Innovation). The authors acknowledge use of the Stanford Synchrotron Radiation Light Source (SSRL), SLAC National Accelerator Laboratory, which is supported by the DOE, BES, under Contract No. DE-AC02-76SF00515. Additional support by the Consortium for Operando and Advanced Catalyst Characterization via Electronic Spectroscopy and Structure (CoACCESS) at SLAC is acknowledged. Co-ACCESS is supported by DOE, BES, Chemical Sciences, Geosciences and Biosciences, under Contract DE-AC02-76SF00515. L.Q. also acknowledges the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, People’s Republic of China. The authors thank Dr. Xinglong Dong of KAUST and Jia Lv of Chongqing University for assistance in acquiring STEM images.