Article

Acid-Catalysed Conversion of Saccharides into Furanic Aldehydes in the Presence of Three-Dimensional Mesoporous Al-TUD-1

Department of Chemistry, CICECO, University of Aveiro, 3810-193 Aveiro, Portugal.
Molecules (Impact Factor: 2.42). 06/2010; 15(6):3863-77. DOI: 10.3390/molecules15063863
Source: PubMed

ABSTRACT

The one-pot acid-catalysed conversion of mono/di/polysaccharides (inulin, xylan, cellobiose, sucrose, glucose, fructose, xylose) into 2-furfuraldehyde (FUR) or 5-hydroxymethylfurfural (HMF) in the presence of aluminium-containing mesoporous TUD-1 (denoted as Al-TUD-1, Si/Al = 21), at 170 degrees C was investigated. Xylose gave 60% FUR yield after 6 h reaction; hexose-based mono/disaccharides gave less than 20% HMF yield; polysaccharides gave less than 20 wt % FUR or HMF yields after 6 h. For four consecutive 6 h batches of the xylose reaction in the presence of Al-TUD-1, the FUR yields achieved were similar, without significant changes in Si/Al ratio.

Download full-text

Full-text

Available from: Anabela Valente
  • Source
    • "The sample was analyzed using a UV spectrophotometer Perkin Elmer Lambda 35. In analyzing the sugar concentration, this method relies on the dehydration of the hydrolyzed sugar into furfural derivatives when it reacts with the concentrated sulfuric acid (Lima et al., 2010). For reference solutions, monosaccharide stocks were dissolved in DDI water to make aliquot. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Sterilization and digestion are two important steps in the palm oil milling process prior to oil extraction. After sterilization, palm fruitlets are stripped and then fed into a digester where the fruitlets are heated with atmospheric pressure steam to soften and loosen the mesocarp fiber. The effect of different pressures of sterilization on digestion operation needs to be investigated. To convey better understanding of the process, several tests were performed on the fruitlets sterilized under different sterilization conditions, i.e., 40 and 70 psi. Oil released, sludge formation and water absorption during the digestion process were analyzed. It was found that fruitlets sterilized at 70 psi contained more sugar content in the condensate due to more hydrolyzed sterilized fruit. It was also found that fruit sterilized at higher pressure released more oil into the condensate and absorbed more water.
    Full-text · Article · Jan 2016
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this Critical Review, we discuss how carbohydrates can be transformed into a variety of chemicals through heterogeneous catalysis. We focus particularly on oxidation, reduction and dehydration of hexoses, as well as one-pot reactions of di- and polysaccharides. Most of the reactions involve heterogeneous catalysts, although some interesting homogeneously catalyzed processes are also included.
    No preview · Article · Mar 2011 · Green Chemistry
  • [Show abstract] [Hide abstract]
    ABSTRACT: We have prepared a series of well-characterized acid catalysts, including Zr–P, SiO2–Al2O3, WOX/ZrO2, γ-Al2O3, and HY zeolite and tested them for aqueous-phase dehydration of xylose. We have characterized the concentration of both Brønsted and Lewis acid sites in these catalysts with TPD and FT-IR spectroscopy using gas-phase NH3 and compared the catalytic activity and selectivity with that of homogeneous catalysts for the dehydration of aqueous solutions of xylose. The catalyst selectivity is a function of the Brønsted to Lewis acid site ratio for both the heterogeneous and homogeneous reactions. Lewis acid sites decrease furfural selectivity by catalyzing a side reaction between xylose and furfural to form humins (insoluble degradation products). At 20% xylose conversion, catalysts with high Brønsted to Lewis acid ratios, such as Zr–P, exhibit furfural selectivities as much as 30 times higher than catalysts with higher Lewis acid site concentrations. Dehydration reactions using ion-exchange polymer resins with high Brønsted acid site concentrations showed similar selectivities to Zr–P and HCl. Using HY zeolite revealed a low furfural selectivity due to strong irreversible adsorption of the furfural in the pores, causing an increase in the rate of humin formation. Thus, to design more efficient aqueous-phase dehydration catalysts, it is desirable to have a high ratio of Brønsted to Lewis acid sites. Furthermore, gas-phase characterization of acid sites can be used to predict catalytic activity in the aqueous phase.
    No preview · Article · Apr 2011 · Journal of Catalysis
Show more