Base‐Free Aqueous‐Phase Oxidation of 5‐Hydroxymethylfurfural over Ruthenium Catalysts Supported on Covalent Triazine Frameworks

Abstract

The base-free aqueous-phase oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxilic acid (FDCA) was performed at 140 °C and 20 bar of synthetic air as the oxidant. Ru clusters supported on covalent triazine frameworks (CTFs) enabled superior conversion (99.9%) and FDCA yields in comparison to other support materials such as activated carbon and γ-Al2O3 after only 1 h. The properties of the CTFs such as pore volume, specific surface area, and polarity could be tuned by using different monomers. These material properties influence the catalytic activity of Ru/CTF significantly as mesoporous CTFs showed superior activity compared to microporous materials, whereas high polarities provide further beneficial effects. The recyclability of the prepared Ru/CTF catalysts was comparable to that of Ru/C at high conversions and product yields. Nevertheless, minor deactivation in five successive recycling experiments was observed.

One‐Pot Transformation of Carbohydrates into Valuable Furan Derivatives via 5‐Hydroxymethylfurfural

“…Ru‐based heterogeneous catalysts on various supports have been reported to catalyze the oxidation of HMF selectively to DFF, FFCA, or FDCA in organic solvents or water under neutral or basic conditions. In parallel to our studies on the direct one‐pot inulin transformation to FDCA by Pt/C, we performed similar experiments in which Ru/C was used as an oxidation catalyst in the presence of NaHCO 3 (Table ).…”

“…A decrease of the reaction time from 14 to 10 h increased the FFCA yield to 61 % because of the diminished exposure time to oxidation. As expected, an increase in the reaction temperature from 80 to 140 °C accelerated the FFCA oxidation rate and increased the FDCA yield to 44 % . These results emphasize the utility of Ru/C as a convenient catalyst for the oxidation of HMF, as the product distribution can be tuned, even with crude HMF, simply by adjusting the reaction conditions, such as the initial pH, temperature, and reaction time.…”

Advances in Porous Organic Polymers for Efficient Water Capture

“…Although bipy-CTF500 showedagraduali ncrease in water uptake at low pressure, the profile of pym-CTF500 steeply increased at low pressure, whichi ndicates its higher hydrophilicity.W ater uptake capacitieso f4 5a nd 22 wt %w ereo bserved at P/P 0 = 0.9 for bipy-CTF500 and pym-CTF500, respectively.A round the same time, Palkovits and co-workersu sed 1,3-dicyanobenzene (1,3-DCB), 2,6-pyridinedicarbonitrile (2,6-DCP), 1,4-DCB, and 4,4biphenyldicarbonitrile monomerst os ynthesize CTF-a, CTF-b, CTF-c, and CTF-d, respectively. [59] Although the purpose of this study was to utilize the CTF backbone as at emplate for ruthenium catalysts in the oxidationo f5 -hydroxymethylfurfural, the authors also carried out water adsorption experiments (Figure 9c)t op robe the hydrophilicity of the CTF template. CTF-a to -d showed good affinity towards water vapor along with high water uptake capacities compared with the control sample, Ru/C.…”

“…Water vapor adsorption/desorption isotherms of covalent triazinef rameworks, (a) bipy-CTF-500, (b) pym-CTF-500, (c) CTF-atoC TF-d, and (d) CTF-TPC/FL (closed symbols, adsorption; open symbols, desorption). Reprinted with permission from Refs [58],[59]. and[60],r espectively.…”

Pt Nanoparticles Supported on Nitrogen‐Doped‐Carbon‐Decorated CeO2 for Base‐Free Aerobic Oxidation of 5‐Hydroxymethylfurfural

“…Conversely, due to the formation of acidic FDCA in the absence of a homogeneous base in the reaction medium, the easy leaching of active metal components can result in rapid deactivation in the case of LDH‐supported catalysts . Although Ru clusters supported on covalent triazine frameworks exhibited good stability in the above reaction, low FDCA yields (<90 %) were obtained. Therefore, the design of new stable support materials for the catalytic base‐free aerobic oxidation of HMF is greatly desirable for highly efficient production and environmental protection.…”