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The Role of Ru and RuO 2 in the Catalytic Transfer Hydrogenation of 5‐Hydroxymethylfurfural for the Production of 2,5‐Dimethylfuran
Author(s) -
Jae Jungho,
Zheng Weiqing,
Karim Ayman M.,
Guo Wei,
Lobo Raul F.,
Vlachos Dionisios G.
Publication year - 2014
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201300945
Subject(s) - catalysis , chemistry , hydrogenolysis , bifunctional , ruthenium , reactivity (psychology) , transfer hydrogenation , yield (engineering) , heterogeneous catalysis , furan , selectivity , inorganic chemistry , organic chemistry , materials science , medicine , alternative medicine , pathology , metallurgy
We have previously shown that 2,5‐dimethylfuran (DMF) can be produced selectively from 5‐hydroxymethylfurfural in up to 80 % yield via catalytic transfer hydrogenation with 2‐propanol as a hydrogen donor and Ru/C as a catalyst. Herein, we investigate the active phase of the Ru/C catalyst by using extended X‐ray absorption fine structure, X‐ray photoelectron spectroscopy, and high‐resolution TEM analyses. The results reveal that RuO 2 is the dominant phase in the fresh (active) catalyst and is reduced to metallic Ru during the reaction with the hydrogen produced in situ from 2‐propanol. The deactivation of the catalyst is correlated with the reduction of the surface of RuO 2 . Reactivity studies of individual phases (bulk RuO 2 and reduced Ru/C catalysts) indicate that RuO 2 mainly catalyzes the Meerwein–Ponndorf–Verley reaction of 5‐hydroxymethylfurfural that produces 2,5‐bis(hydroxymethyl)furan and the etherification of 2,5‐bis(hydroxymethyl)furan or other intermediates with 2‐propanol and that the reduced Ru/C catalyst has moderate hydrogenolysis activity for the production of DMF (30 % selectivity) and other intermediates (20 %). In contrast, a physical mixture of the two phases increases the DMF selectivity up to 70 %, which suggests that both metallic Ru and RuO 2 are active phases for the selective production of DMF. The oxidation of the reduced Ru/C catalyst at different temperatures and the in situ hydrogen titration of the oxidized Ru/C catalysts were performed to quantify the bifunctional role of Ru and RuO 2 phases. The mild oxidation treatment of the Ru/C catalyst at 403 K could activate the catalyst for the selective production of DMF in up to 72 % yield by generating a partially oxidized Ru catalyst.