- The selective oxidation of glycerol over metal-free photocatalysts: insights into the solvent effect on catalytic efficiency and product distribution
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Selective oxidation of glycerol to high value-added derivatives is a promising biomass conversion pathway, but the related reaction mechanism, in particular the solvent effect, is rarely studied. In this work, O-doped g-C3N4was used as a metal-free catalyst to catalyze the selective oxidation of glycerol in different solvents. It was found that solvents can affect both catalytic efficiency and product distribution. A series of controlled experiments and theoretical calculation were applied to attest that the difference in interaction between glycerol and catalysts in different solvents is the main factor: competitive adsorption and hydrogen bond network from water inhibit the adsorption and activation of glycerol on the catalyst surface and reduce the conversion efficiency, while in acetonitrile, the stronger adsorption makes the oxidation reaction continue to yield esters. Two reaction routes in different solvents over O-doped g-C3N4are proposed for the first time, which is helpful for people to better understand the related reaction mechanism.
- Fan, Mingming,Haryonob, Agus,Jiang, Pingping,Leng, Yan,Yue, Chengguang,Zhang, Pingbo
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p. 3385 - 3392
(2021/06/06)
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- Study on the one-pot oxidative esterification of glycerol with MOF supported polyoxometalates as catalyst
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In this work, glycerol was treated under green and mild conditions (water solvent, H2O2 oxidant, 40°C) in an attempt to utilise its additional value. With a metal organic framework (MOF) supported polyoxometallate (POM) as a catalyst, esters were generated as one of the major products which could be useful for various industrial applications. The selectivity of esters formation reached 34.5% in this one-pot oxidative esterification process. Benefiting from the pore limitation effect of the MOF, diffusion was restricted and the original products could be further transformed into esters with the existence of the POM. No other reagents were needed during this process, and all of the intermediates were produced from glycerol itself. The oxidative esterification reaction was studied in detail including the role of the MOF, the influence of pH and the POM type, the mechanism and so on. It was concluded that the POM served as the active site for this oxidative esterification process and H2O2 provided weak acidity in addition to the source of oxygen. Too stronger acidity and oxidizability were unfavourable to the generation of esters. Also, the catalysts could be recovered after reaction, exhibiting good stability and reusability.
- Zhu, Jie,Wang, Peng-Cheng,Lu, Ming
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p. 3383 - 3393
(2015/06/08)
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- Identification and determination of α-dicarbonyl compounds formed in the degradation of sugars
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The α-dicarbonyl compounds formed in the degradation of glucose and fructose were analyzed by HPLC using 2,3-diaminonaphthalene as derivatizing reagent, and identified as glucosone (GLUCO), 3-deoxyglucosone (3DG), 3-deoxyxylosone (3DX), tetrosone (TSO), triosone (TRIO), 3-deoxytetrosone (3DT), glyoxal (GO), and methylglyoxal (MGO). The results suggest that α-dicarbonyl compounds were formed from glucose via non-oxidative 3-deoxyglucosone formation and oxidative glucosone formation in glucose degradation. In addition, TRIO, GO, and MGO were also formed from glyceraldehyde as intermediate. The α-dicarbonyl compounds might be formed from glucose via these pathways in diabetes.
- Usui, Teruyuki,Yanagisawa, Satoshi,Ohguchi, Mio,Yoshino, Miku,Kawabata, Risa,Kishimoto, Junko,Arai, Yumi,Aida, Kaoru,Watanabe, Hirohito,Hayase, Fumitaka
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p. 2465 - 2472
(2008/03/27)
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- TREATMENT OF SUGAR SOLUTIONS
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A process for treating a solution containing sugar and α-oxoaldehydes, comprising the step of adding a catalyst which comprises an optionally substituted histidine amino acid, such that the α-oxoaldehydes are catalytically converted to aldonic acids.
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Page/Page column 12; 13; Sheets 5-8
(2008/06/13)
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