Title: Mechanistic Insights into the Hydrogenolysis of Levoglucosanol over Bifunctional Platinum Silica–Alumina Catalysts

Abstract

In this paper, we report on the hydrogenolysis of the biorenewable intermediate levoglucosanol (Lgol) over bifunctional platinum catalysts supported on silica–alumina in tetrahydrofuran solvent. ¹³C radiolabeling is used to confirm the ring rearrangement forming tetrahydrofurandimethanol. The reaction rate and product selectivity are comparable between 1.1 and 5.3 wt % Pt loadings, indicating that, at these metal loadings, the rate-limiting step is acid catalyzed. The measured zero-order dependence in hydrogen indicates that a non-rate-determining hydrogenation step follows an acid-catalyzed irreversible rate-determining step. The measured first-order dependence in Lgol indicates that the acid sites are not highly covered by Lgol. A physical mixture of Pt/SiO₂ and SiAl catalysts displayed product selectivity similar to that of the Pt/SiAl catalyst, indicating that nanoscale proximity of metal and acid sites is not required to carry out Lgol hydrogenolysis selectively. As the Pt loading in Pt/SiAl catalysts is decreased, or when the bare SiAl support is separated from a Pt/SiO₂ catalyst in a dual-layer configuration, the selectivity toward identified products decreases. These results suggest that degradation reactions are avoided when the reactive intermediates formed over acid sites are rapidly hydrogenated over metal sites. First-principles simulations are performed to investigate the energetics of the proposed reaction pathway.more » A detailed reaction mechanism for Lgol hydrogenolysis is proposed on the basis of a combination of the experimental and computational results. Our findings provide a fundamental understanding of the catalytic conversion of levoglucosanol over bifunctional metal–acid catalysts, facilitating rationally designed processes to produce renewable chemicals from biomass-derived levoglucosenone.« less

Authors:

Krishna, Siddarth H. ^[1]; Assary, Rajeev S.  ^[2];

• Search DOE PAGES for author "Assary, Rajeev S."
• Search DOE PAGES for ORCID "0000-0002-9571-3307"

Rashke, Quinn A. ^[1]; Schmidt, Zachary R. ^[1]; Curtiss, Larry A.  ^[2];

• Search DOE PAGES for author "Curtiss, Larry A."
• Search DOE PAGES for ORCID "0000-0001-8855-8006"

Dumesic, James A.  ^[1];

• Search DOE PAGES for author "Dumesic, James A."
• Search DOE PAGES for ORCID "0000-0001-6542-0856"

Huber, George W.  ^[1]

• Search DOE PAGES for author "Huber, George W."
• Search DOE PAGES for ORCID "0000-0002-7838-6893"

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+ Show Author Affiliations

1. Univ. of Wisconsin, Madison, WI (United States). Department of Chemical and Biological Engineering
2. Argonne National Lab. (ANL), Lemont, IL (United States). Materials Science Division

Publication Date:

Fri Mar 23 00:00:00 EDT 2018

Research Org.:

Univ. of Wisconsin, Madison, WI (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Energy Efficiency and Renewable Energy (EERE)

Contributing Org.:

University of Wisconsin-Madison Department of Chemistry; University of Wisconsin-Madison Department of Civil and Environmental Engineering; Consortium for Computational Physics and Chemistry (CCPC); Laboratory Computing Resource Center at Argonne National Laboratory

OSTI Identifier:

1477855

Grant/Contract Number:  

EE0006878; AC02-06CH11357; AC02-05CH11231

Resource Type:

Accepted Manuscript

Journal Name:

ACS Catalysis

Additional Journal Information:

Journal Volume: 8; Journal Issue: 5; Journal ID: ISSN 2155-5435

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; bifunctional; biomass; catalysis; heterogeneous; kinetics; levoglucosenone; mechanism