Aerobic Oxidation of 5-Hydroxymethylfurfural to High-Yield 5-Hydroxymethyl-2-furancarboxylic Acid by Poly(vinylpyrrolidone)-Capped Ag Nanoparticle Catalysts

Abstract

An efficient method for the catalytic aerobic oxidation of 5hydroxymethylfurfural (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 ZrO 2 with 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/ZrO 2 catalysts with a bigger particle size (>10 nm) exhibited superior catalytic activity and HMFCA selectivity compared to Ag/ZrO 2 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/ZrO 2 (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 Na 2 CO 3 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 ZrO 2 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.

Influence of the Capping Agent PVP of the Outer Layer of Pd Nanocubes Surface on the Catalytic Hydrogenation of Unsaturated C−C Bonds

“…Increasing the number of washes, the N 1s peak position slowly approaches of free PVP (399.9 eV). 18 Comparing relative areas, it is clear that N/Pd ratio progressively changed upon treatment, which agrees with the removal of PVP. The signal-to-noise quality of N 1s peak progressively decreases with the number of washes, contrary to Pd region of spectra.…”

“…400 eV ascribed to pyrrolidone group. 17,18 At higher energies, N 1s can be attributed to decreased electron density of the N group, when PVP chemisorb on metal surface through the N and O atom. Increasing the number of washes, the N 1s peak position slowly approaches of free PVP (399.9 eV).…”

Selective Oxidation of 5‐Hydroxymethylfurfural to 2,5‐Furandicarboxylic Acid over MnOx‐CeO2 Supported Palladium Nanocatalyst under Aqueous Conditions

“…because the use of renewable oxygen/air and recyclable heterogeneous catalysts follows the concept of "green and sustainable chemistry". [23,24] Noble metal catalysts including Pt, Pd, Au, Ru, Ag, and the bimetallic nanoparticles [20,[25][26][27][28][29][30][31] usually exhibit better catalytic activity and FDCA selectivity under mild reaction conditions. Zhang immobilized Pa nanoparticles on the core-shell structure of C@Fe 3 O 4 and prepared FDCA at 80°C.…”

“…However, in the absence of liquid base additive, base sites or carriers are effective for the aerobic oxidation of HMF to FDCA. [28,[48][49][50] It is very necessary to develop a versatile method for synthesizing supported noble metal catalyst under mild conditions, which is used for the tandem reaction of catalytic oxidation of HMF to FDCA.…”

Spontaneous Growth of 3D Silver Mesoflowers on Poly(4‐vinylpyridine) Brushes‐Grafted‐Graphene Oxide Films and Facile Creation of Nanoporosities over their Surface

“…Ah igh-resolution transmission electron microscopy (HRTEM) image is shown in Figure 1(F), where metallic Ag is detected by the reflection of (111)w ith al attice spacing of d = 0.234 nm. [25] The chemical compositions of the GO film, P4VP-g-GO film, and P4VP-g-GO/Ag MFs film were characterizedb yX -ray photoelectron spectroscopy (XPS). In Figure 1(G), the XPS survey spectrum of the GO film showst wo predominant peaks at 286.4 eV and 532.4 eV,w hicha re assignedt oC1s and O1s, respectively.T he peak-fitted C1sc oreline spectrumo ft he GO film is shown in Figure 1(H), which displays the presence of C=C/CÀC( 284.6 eV), CÀO( 286.5 eV), C=O( 288.3 eV), andO ÀC=O( 290.3 eV) groups.…”