Currently, low intimacy between hydrogenation sites and acidic sites causes unsatisfactory catalytic activity and selectivity for the synthesis of 2,5-hexanedione from C 6 furan aldehydes (5methylfurfural, 5-hydroxymethylfurfural). Herein, iodine(I) modification of Pd-supported catalysts (such as PdI/Al 2 O 3 and PdI/ SiO 2 ) was investigated to modulate the hydrogenation sites and acidic sites. Unlike Pd catalysts that produced 71.4 % yield of 2hydroxymethyl-5-methyl tetrahydrofuran via an overhydrogenation route of 5-methylfurfural, PdI catalysts showed a high efficiency for 2,5-hexanedione with 93.7 % yield by a hydro-genative ring-opening route. More importantly, the selective synthesis of 2,5-hexanedione from 5-hydroxymethylfurfural with a high yield of 50.2 % by the hydrogenolysis and subsequent ring-opening route was reported for the first time. I-modified Pd nanoparticles produced in-situ hydrogen spillover, which promoted the selective C=O hydrogenation and ring-opening steps by regulating the adsorption configuration of the reactants and the transformation of Lewis to Brønsted acidity, respectively.
One pot synthesis of 2,5‐dimethylfuran (2,5‐DMF) from saccharides under mild conditions is of importance for the production of biofuel and fine chemicals. However, the synthesis requires a multitude of active sites and suffers from slow kinetics due to poor diffusion in most composite catalysts. Herein, a metal‐acid functionalized 2D metal‐organic framework (MOF; Pd/NUS‐SO3H), as an ultrathin nanosheet of 3–4 nm with Lewis acid, Brønsted acid, and metal active sites, was prepared based on the diazo method for acid modification and subsequent metal loading. This new composite catalyst gives substantially higher yields of DMF than all reported catalysts for different saccharides (fructose, glucose, cellobiose, sucrose, and inulins). Characterization suggests that a cascade of reactions including polysaccharide hydrolysis, isomerization, dehydration, and hydrodeoxygenation takes place with rapid molecular interactions.
Developing
an efficient and selective catalyst for C–O hydrogenolysis
of biomass-derived aromatic aldehydes, such as 5-methylfurfural (MF),
5-hydroxymethylfurfural (HMF), and vanillin (VA), is highly significant
for the synthesis of biofuel and fine chemicals. Herein, metal–organic
framework (MOF)-encapsulating metal–acid interfaces (Pd@UiO–CH2SO3H, Pd@UiO–PhSO3H) were first
reported. Compared with traditionally supported catalysts (Pd/UiO–SO3H, Pd/UiO–NH2), Pd–acid-interface-encapsulated
MOFs show much higher activity and selectivity for MF to 2,5-dimethylfuran
(DMF), HMF to DMF, and VA to 2-methoxy-4-methylphenol (MMP) reactions.
In particular, Pd@UiO–SO3H shows the best catalytic
performance with 89.0 and 86.0% DMF yield from MF and HMF and a 99.4%
MMP yield from VA based on its suitable hydrophilicity, high hydrogen
activation ability, and abundant Pd–SO3H interface
active sites. According to the catalytic performance of Pd/UiO–NH2 and the results of an ATR-IR test, the acidic sites on the
Pd–acid interface can accelerate the activation of the hydroxyl
group for these hydrogenolysis reactions. This work provides an effective
design strategy for the preparation of MOF-encapsulating metal–acid
interfaces and shows the powerful synergistic effect of hydrogenation
and acid catalysis.
Longitude/Latitude map of base stations (* and O) at Greenville, SC, using DCCH 786 on Dec. 14, 2004. The thick path is a single drive-test route through the test area. 83 xii Longitude/Latitude map of base stations (* and O) at Greenville, SC, using DCCH 512 on Dec.
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