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Title: Silica-Supported, Single-Site Sc and Y Alkyls for Catalytic Hydrogenation of Propylene

Abstract

Single site Sc and Y on silica catalysts have been prepared by aqueous and organometallic grafting methods. The former yields Y(III) ions with 5 bonds at an average bond distance of 2.31 Å by X-ray absorption spectroscopy. Although the aqueous synthesis gave single site Y with low coordination number, these were not catalytic for alkane dehydrogenation or olefin hydrogenation. Single site Sc(III) and Y(III) species were also prepared by grafting Sc(CH 2Si(CH 3) 3) 3(THF) 2 and Y(CH 2Si(CH 3) 3) 3(THF) 2, respectively and these are catalysts for olefin hydrogenation at temperatures from about 60 to 100°C; however, they were thermally unstable at higher temperatures necessary for alkane dehydrogenation. The structure of the grafted Y complex was determined by X-ray absorption spectroscopy, IR, and NMR. Grafting lead to protonolysis of 2 of the 3 CH 2Si(CH 3) 3 ligands. Additionally, there was loss of one THF ligand. The EXAFS indicated that there were 4 Y-ligand bonds in the surface species, 2 at 2.16 Å and 2 at 2.39 Å. The metal-alkyl ligand was thought to be necessary for catalytic activity and likely proceeds through a sigma bond metathesis mechanism. In the single site centers without alkyl bonds, Sc andmore » Y ions cannot generate metal-alkyl, or metal-hydride, moieties in situ. We conclude that this is likely due to the very high M-O-Si bond strengths, which must be broken through heterolytic dissociation of C-H bonds during alkane activation for either alkane dehydrogenation or olefin hydrogenation reactions. Lastly, this study demonstrates the importance of pre-catalyst choice versus in situ formation of reactive intermediates to produce active catalysts for alkane bond activation.« less

Authors:
 [1];  [2];  [3]; ORCiD logo [4]
  1. Argonne National Lab. (ANL), Lemont, IL (United States)
  2. Illinois Inst. of Technology, Chicago, IL (United States)
  3. Argonne National Lab. (ANL), Lemont, IL (United States); Purdue Univ., West Lafayette, IN (United States)
  4. Argonne National Lab. (ANL), Lemont, IL (United States); Illinois Inst. of Technology, Chicago, IL (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1400402
Grant/Contract Number:  
AC02-06CH11357
Resource Type:
Accepted Manuscript
Journal Name:
Organometallics
Additional Journal Information:
Journal Volume: 36; Journal Issue: 19; Journal ID: ISSN 0276-7333
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; single site Sc catalyst; grafted Sc(III) alkyl hydrogenation catalyst; grafted Y(III) alkyl hydrogenation catalyst; single site Y catalyst

Citation Formats

Getsoian, Andrew G. Bean, Hu, Bo, Miller, Jeffrey T., and Hock, Adam S. Silica-Supported, Single-Site Sc and Y Alkyls for Catalytic Hydrogenation of Propylene. United States: N. p., 2017. Web. doi:10.1021/acs.organomet.6b00623.
Getsoian, Andrew G. Bean, Hu, Bo, Miller, Jeffrey T., & Hock, Adam S. Silica-Supported, Single-Site Sc and Y Alkyls for Catalytic Hydrogenation of Propylene. United States. doi:10.1021/acs.organomet.6b00623.
Getsoian, Andrew G. Bean, Hu, Bo, Miller, Jeffrey T., and Hock, Adam S. Wed . "Silica-Supported, Single-Site Sc and Y Alkyls for Catalytic Hydrogenation of Propylene". United States. doi:10.1021/acs.organomet.6b00623. https://www.osti.gov/servlets/purl/1400402.
@article{osti_1400402,
title = {Silica-Supported, Single-Site Sc and Y Alkyls for Catalytic Hydrogenation of Propylene},
author = {Getsoian, Andrew G. Bean and Hu, Bo and Miller, Jeffrey T. and Hock, Adam S.},
abstractNote = {Single site Sc and Y on silica catalysts have been prepared by aqueous and organometallic grafting methods. The former yields Y(III) ions with 5 bonds at an average bond distance of 2.31 Å by X-ray absorption spectroscopy. Although the aqueous synthesis gave single site Y with low coordination number, these were not catalytic for alkane dehydrogenation or olefin hydrogenation. Single site Sc(III) and Y(III) species were also prepared by grafting Sc(CH2Si(CH3)3)3(THF)2 and Y(CH2Si(CH3)3)3(THF)2, respectively and these are catalysts for olefin hydrogenation at temperatures from about 60 to 100°C; however, they were thermally unstable at higher temperatures necessary for alkane dehydrogenation. The structure of the grafted Y complex was determined by X-ray absorption spectroscopy, IR, and NMR. Grafting lead to protonolysis of 2 of the 3 CH2Si(CH3)3 ligands. Additionally, there was loss of one THF ligand. The EXAFS indicated that there were 4 Y-ligand bonds in the surface species, 2 at 2.16 Å and 2 at 2.39 Å. The metal-alkyl ligand was thought to be necessary for catalytic activity and likely proceeds through a sigma bond metathesis mechanism. In the single site centers without alkyl bonds, Sc and Y ions cannot generate metal-alkyl, or metal-hydride, moieties in situ. We conclude that this is likely due to the very high M-O-Si bond strengths, which must be broken through heterolytic dissociation of C-H bonds during alkane activation for either alkane dehydrogenation or olefin hydrogenation reactions. Lastly, this study demonstrates the importance of pre-catalyst choice versus in situ formation of reactive intermediates to produce active catalysts for alkane bond activation.},
doi = {10.1021/acs.organomet.6b00623},
journal = {Organometallics},
number = 19,
volume = 36,
place = {United States},
year = {2017},
month = {9}
}

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