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Ru/ZrO 2 Catalysts for Transfer Hydrogenation of Levulinic Acid with Formic Acid/Formate Mixtures: Importance of Support Stability
Author(s) -
Gao Yanxiu,
Zhang Hongwei,
Han Aijuan,
Wang Jie,
Tan HuiRu,
Tok EngSoon,
Jaenicke Stephan,
Chuah GaikKhuan
Publication year - 2018
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201702152
Subject(s) - levulinic acid , catalysis , formic acid , monoclinic crystal system , leaching (pedology) , cubic zirconia , ruthenium , inorganic chemistry , tetragonal crystal system , x ray photoelectron spectroscopy , materials science , methanol , chemistry , nuclear chemistry , chemical engineering , crystal structure , organic chemistry , metallurgy , ceramic , environmental science , soil science , engineering , soil water
The transfer hydrogenation of levulinic acid to γ‐valerolactone using an equimolar mixture of formate/formic acid in water was investigated using Ru/ZrO 2 catalysts. Ru/ZrO 2 with < 3 wt. % loading were more active than those with higher loadings. The stability of the catalysts is of concern as the reaction occurs under acidic and hydrothermal conditions. To minimize metal leaching, the Ru/ZrO 2 catalysts were prepared by a sol‐gel process to entrap the ruthenium nanoparticles within the support. Despite insignificant leaching of Ru, the used catalyst was deactivated after the first run. No agglomeration of Ru particles could be observed by TEM and XRD. However, the zirconia support had transformed from a predominantly tetragonal crystal phase to the monoclinic form. X‐ray photoelectron spectroscopy revealed a decrease in the surface Ru/Zr ratio. Doping with 0.1 wt. % SiO 2 successfully stabilized the tetragonal phase of zirconia and the recycled catalyst maintained its high activity in reuse.