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Download fileAerobic Oxidation of 5‑Hydroxymethylfurfural to High-Yield 5‑Hydroxymethyl-2-furancarboxylic Acid by Poly(vinylpyrrolidone)-Capped Ag Nanoparticle Catalysts
journal contribution
posted on 2019-02-28, 00:00 authored by Jiahuan An, Guohan Sun, Haian XiaAn
efficient method for the catalytic aerobic oxidation of 5-hydroxymethylfurfural
(HMF) to 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) was developed
using size-controlled Ag nanoparticles (NPs) in an aqueous solution.
A series of AgNPs catalysts stabilized by poly(vinylpyrrolidone) (PVP)
supported on ZrO2with different Ag loadings were prepared.
XRD, TEM, XPS, and FT-IR techniques were used to characterize the
nature of these catalysts. The impact of the Ag loading, the molar
ratio of PVP to Ag, the reaction temperature and time, and the base
type on the conversion of HMF and yield of HMFCA was investigated.
The reaction results show that Ag–PVP/ZrO2 catalysts
with a bigger particle size (>10 nm) exhibited superior catalytic
activity and HMFCA selectivity compared to Ag/ZrO2 with
a smaller particle size (ca. 8.5 nm), indicating that the addition
of PVP has a promoting effect on the aerobic oxidation of HMF into
HMFCA. The 2.5%Ag–PVP/ZrO2(1:1) catalyst presents
an excellent activity with 100% conversion of HMF and 98.2% yield
of HMFCA in oxygen flow at 20 °C for 2 h.The basicity is also
very critical to obtain a high HMFCA yield, especially for the use
of high concentration of HMF; i.e., Ca(OH)2 afforded a
higher selectivity toward HMFCA compared to the use of NaOH or Na2CO3 under an identical reaction condition. It is
revealed for the first time that the presence of a capping agent (PVP)
can effectively modulate the metal–support interaction. Interestingly,
it is found that the relatively weak interaction between Ag NPs and
the ZrO2 support has a beneficial effect on the conversion
of HMF. This work provides new insights into the relationship between
the metal–support interaction mediated by PVP molecule and
the activity and selectivity of the oxidation reaction.
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Keywords
5- hydroxymethyl -2-furancarboxylic acidZrO 2 supportFT-IR techniquesXPSsize-controlled Ag nanoparticlesbase typeXRD2 h.The basicityreaction results showPVP moleculeoxidation reactionTEMAg loadingreaction temperatureAgNPs catalystsparticle sizereaction conditionNa 2 CO 3Aerobic OxidationZrO 2Ag NPsHMFCA selectivitymolar ratiooxygen flow5- hydroxymethylfurfuralAg loadings