Highly Efficient Oxidation of Biomass Xylose to Formic Acid with CeO_x-Promoted MnO_x Catalyst in Water

Abstract

Formic acid is a versatile chemical, which is industrially produced from fossil resources. In this work, biomass-derived xylose was used as a potential feedstock to synthesize formic acid with Mn−Ce oxides as the catalyst in water. Among the Mn−Ce oxides with different molar ratios, Mn 4 Ce 0.05 O x showed the best catalytic activity, offering a formic acid yield up to 65.1% at 160 °C with 3 MPa of O 2 , which was much higher than that using pristine MnO x (40.5%) and CeO x (9.9%). In addition, Mn 4 Ce 0.05 O x was shown to be tolerant to a higher xylose concentration. The introduction of CeO x into MnO x increased the total surface area (55.8 vs 33.7 m 2 g −1 ), gave a higher ratio of (Mn 2+ +Mn 3+ )/Mn 4+ (1.94 vs 1.54), and produced more surface adsorbed oxygen (39.0% vs 26.0%). The DFT calculations revealed that the adsorption energy of xylose on the Ce site (−1.231 eV) was much lower than that on the Mn site (−0.884 eV), thus facilitating the binding of xylose on the catalyst. Mechanism studies of xylose−catalyst−water reaction systems indicated that glyceric acid and glycolic acid were the main intermediates, while CO 2 was cogenerated with the formic acid.

Manganese oxide-based catalysts for the sustainable synthesis of value-added chemicals through oxidation processes: a critical review and perspectives for the future

“…Formic acid (FA), being the most basic carboxylic acid, holds significant value as a chemical compound and has the potential to serve as an energy carrier. 113 It is highly desirable for FA to be derived from renewable sources such as biomass, as opposed to the current method reliant on fossil fuels. Guo et al 114 obtained a FA yield of 79% from glucose over Mo–MnO x at 160 °C in 90 min (Scheme 20).…”

Toward Value-Added Chemicals from Carbohydrates via C–C Bond Cleavage and Coupling Transformations

“…This work highlights the great potential of the Fenton reaction as a powerful and alternative tool for C−C bond cleavage. 163 Shen's group further investigated a series of Mn-based catalysts (MnO x -100, 164 Mn4Ce0.05O x , 166 and Mo-MnO x 167 ) to selective convert monosaccharide into formic acid. Among them, a manganese oxide (MnO x -100) catalyst prepared from hydrothermal treatment gave the highest formic acid yield of 81%, whereas Mo-modified Mo-MnO x showed high tolerance to the high concentration of glucose (110 g/L, 54% yield of formic acid).…”

“…For Mn 4 Ce 0.05 O x , the adsorption energy of xylose on the Ce site was much lower than that on the Mn site, which favored the binding of xylose on the catalyst. 166 The reaction pathway was analyzed by monitoring the intermediates through ultraperformance liquid chromatography over a time course, where arabinose and glyoxylic acid were found to be the dominant intermediates during glucose conversion. 164 However, the stability of the developed Mnbased catalysts was not evaluated.…”

Oxidative Cleavage of C−C Bonds in Non‐aromatic Oxygenates with Molecular Oxygen for Synthesis of Carboxylic Acids

“…Further studies are necessary to elucidate the Recently, oxidation systems of sugars to formic acid with non-vanadium catalysts have been reported. Feng Shen et al reported CeO 2 -and MoO x -modified MnO x catalysts for sugar oxidation to formic acid, and the obtained yields were 65.1 %-C from xylose [53] and 54 %-C from glucose, [54] respectively. Relatively severe conditions are necessary (433 K, 3 MPa O 2 ).…”

“…Feng Shen et al. reported CeO 2 ‐ and MoO x ‐modified MnO x catalysts for sugar oxidation to formic acid, and the obtained yields were 65.1 %‐C from xylose [53] and 54 %‐C from glucose, [54] respectively. Relatively severe conditions are necessary (433 K, 3 MPa O 2 ).…”