Abstract
Silica-supported Pd and PdZn nanoparticles of a similar size were evaluated for neopentane hydrogenolysis/isomerization and propane hydrogenolysis/ dehydrogenation. Monometallic Pd showed high neopentane hydrogenolysis selectivity. Addition of small amounts of Zn to Pd lead Pd-Zn scatters in the EXAFS spectrum and an increase in the linear bonded CO by IR. In addition, the neopentane turnover rate decreased by nearly 10 times with little change in the selectivity. Increasing amounts of Zn lead to greater Pd-Zn interactions, higher linear-to-bridging CO ratios by IR and complete loss of neopentane conversion. Pd NPs also had high selectivity for propane hydrogenolysis and thus were poorly selective for propylene. The PdZn bimetallic catalysts, however, were able to preferentially catalyze dehydrogenation, were not active for propane hydrogenolysis, and thus were highly selective for propylene formation. The decrease in hydrogenolysis selectivity was attributed to the isolation of active Pd atoms by inactive metallic Zn, demonstrating that hydrogenolysis requires a particular reactive ensemble whereas propane dehydrogenation does not.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 75-84 |
| Number of pages | 10 |
| Journal | Journal of Catalysis |
| Volume | 318 |
| DOIs | |
| State | Published - Oct 2014 |
Funding
JTM and NS were supported as part of the Institute for Atom-Efficient Chemical Transformations (IACT), an Energy Frontier Research Center funded by the United States Department of Energy , Office of Science, Office of Basic Energy Sciences. R.J.M. and D.C. gratefully acknowledge funding for this work from the National Science Foundation (CBET Grant No. 0747646 ). Partial funding for DC was provided by the Chemical Sciences and Engineering Division at Argonne National Laboratory and the Office of the Vice Chancellor for Research at the University of Illinois at Chicago. S.M.K.S. and R.M.R. acknowledges funding from the Department of Energy , Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division , Catalysis Sciences Program under Grant No. DE-FG02-12ER16364 . R.M.R. acknowledges financial support provided through a 3M Non-Tenured Faculty Grant (NTFG). The STEM work was performed at the UIC Research Resource Center. Use of the Advanced Photon Source was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. MRCAT operations are supported by the Department of Energy and the MRCAT member institutions. The CleanCat Core facility acknowledges funding from the Department of Energy (DE-FG02-03ER15457 and DE-AC02-06CH11357) used for the purchase of the DRIFTS system and the AMI-200, respectively.
Keywords
- CO calorimetry
- CleanCat
- DRIFTS
- EXAFS
- Intermetallic PdZn
- Neopentane conversion
- Propane dehydrogenation
- Structure-sensitive reaction
ASJC Scopus subject areas
- Catalysis
- Physical and Theoretical Chemistry