TY - JOUR
T1 - Structure and Mechanism of Titania-Supported Platinum-Molybdenum Catalyst for Hydrodeoxygenation of 2-Furancarboxylic Acid to Valeric Acid
AU - Asano, Takehiro
AU - Nakagawa, Yoshinao
AU - Tamura, Masazumi
AU - Tomishige, Keiichi
N1 - Funding Information:
This work is supported by JSPS KAKENHI Grant Number 18H05247. XAFS experiments at the BL14B2 station of SPring-8 were performed with the approval of the Japan Synchrotron Radiation Research Institute (JASRI; Proposal Nos. 2017B1839, 2018A1754, and 2018B1805). We thank the Technical Division of the School of Engineering, Tohoku University, for TEM measurement.
Publisher Copyright:
Copyright © 2019 American Chemical Society.
PY - 2019/5/20
Y1 - 2019/5/20
N2 - Selective hydrodeoxygenation of 2-furancarboxylic acid, which can be a relatively stable platform chemical from hemicellulose, to valeric acid was investigated in detail, and the reaction has been reported to be specifically promoted by supported Pt-MoOx catalysts. The dependence of catalytic performance of Pt-MoOx/TiO2 on loading amounts of Pt and Mo showed that the highest activity is obtained at around Mo ∼0.5 wt % when the Pt loading amount is fixed. With enough of the catalyst that can minimize the effect of deactivation, ∼60% yield of valeric acid was obtained over all Pt-MoOx/TiO2 catalysts with Pt ≥ 1 wt % and 0.5 wt % Mo loadings. Characterization results of Pt-MoOx/TiO2 catalysts with XRD and CO adsorption showed that the Pt particles (3-5 nm, depending on Pt loading amount) were not covered with MoOx species, suggesting that MoOx species were mainly located on the TiO2 support surface. Mo K-edge XAFS results suggest that the MoOx species in Pt-MoOx/TiO2 have a Mo(IV) valence state and some of the MoIVOx species have direct bonds with the Pt atom on Pt metal particles. The number of the direct Pt-Mo bonds became smaller after catalytic use, which can be related to the deactivation. Therefore, the Pt-Mo bimetallic site can be the catalytically active site. Based on the solvent effect, reactivity trends of related substrates, and reaction orders in kinetics, a reaction mechanism is proposed where the ring is opened after addition of one hydrogen atom to the 2-position of the furan ring.
AB - Selective hydrodeoxygenation of 2-furancarboxylic acid, which can be a relatively stable platform chemical from hemicellulose, to valeric acid was investigated in detail, and the reaction has been reported to be specifically promoted by supported Pt-MoOx catalysts. The dependence of catalytic performance of Pt-MoOx/TiO2 on loading amounts of Pt and Mo showed that the highest activity is obtained at around Mo ∼0.5 wt % when the Pt loading amount is fixed. With enough of the catalyst that can minimize the effect of deactivation, ∼60% yield of valeric acid was obtained over all Pt-MoOx/TiO2 catalysts with Pt ≥ 1 wt % and 0.5 wt % Mo loadings. Characterization results of Pt-MoOx/TiO2 catalysts with XRD and CO adsorption showed that the Pt particles (3-5 nm, depending on Pt loading amount) were not covered with MoOx species, suggesting that MoOx species were mainly located on the TiO2 support surface. Mo K-edge XAFS results suggest that the MoOx species in Pt-MoOx/TiO2 have a Mo(IV) valence state and some of the MoIVOx species have direct bonds with the Pt atom on Pt metal particles. The number of the direct Pt-Mo bonds became smaller after catalytic use, which can be related to the deactivation. Therefore, the Pt-Mo bimetallic site can be the catalytically active site. Based on the solvent effect, reactivity trends of related substrates, and reaction orders in kinetics, a reaction mechanism is proposed where the ring is opened after addition of one hydrogen atom to the 2-position of the furan ring.
KW - Carboxylic acid
KW - Furan
KW - Hydrodeoxygenation
KW - Molybdenum
KW - Platinum
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U2 - 10.1021/acssuschemeng.9b01104
DO - 10.1021/acssuschemeng.9b01104
M3 - Article
AN - SCOPUS:85066141663
SN - 2168-0485
VL - 7
SP - 9601
EP - 9612
JO - ACS Sustainable Chemistry and Engineering
JF - ACS Sustainable Chemistry and Engineering
IS - 10
ER -
