Hydroxymethylfurfural (HMF) is considered a high potential biogenic platform chemical that can be produced from carbohydrates by hydrothermal or acid-catalyzed dehydration processes. Its separation ...from polar liquid phase reaction mixtures still remains a challenge on the way to commercialization. Recently, liquid phase adsorption of HMF has been considered a viable and energy efficient method. While conventional adsorbents show competitive adsorption in the reaction mixture, we herein report for the first time the highly selective adsorption of HMF from aqueous solutions on nanoporous hyper-cross-linked polymers (HCP). Excess adsorption isotherms of fructose (F), HMF, and its follow-up products levulinic acid and formic acid were measured under equilibrium conditions, and the data were modeled accordingly. Additionally, the desorption behavior was investigated. Overall, the evaluated HCP as well as similar nonpolar adsorbents exhibit great potential for future process development regarding efficient adsorptive separation technologies for the utilization of renewable feedstock.
A series of Ca/Al-mixed oxides derived from hydrocalumite (HC) with Ca/Al atomic ratio of 2 was prepared by calcination at different temperatures and they were evaluated in transesterification of ...glycerol with diethyl carbonate (DEC) to produce glycerol carbonate (GC). HC was tested as non-calcined and calcined at different temperatures (600, 700, 800, and 900 °C). The catalysts presented a well-crystallized structure with low specific surface area. Non-calcined hydrocalumite presented higher density of basic sites (571 μmol g
−1
) with major proportion of strong basic sites; after calcination, catalyst basicity dropped dramatically. Reactions were performed with different temperatures (from 90 to 130 °C), catalyst amounts (5, 10, and 15 wt%), and solvents (dimethyl sulfoxide and dimethylformamide). Promising results were found using HC calcined at 700 °C, reaching 90% of glycerol conversion and 91% of GC selectivity at 130 °C.
Glycerol oxidation was investigated using as catalyst an acid zeolite (H-ZSM-5) impregnated with different contents of Pt (1 and 3 wt%), and H
2
O
2
and air as oxidants. Catalysts were characterized ...by XRD, XRF, FT-IR,
27
Al MAS NMR, N
2
adsorption, NH
3
-TPD, XPS and TEM. After calcination, catalysts were reduced at 1000 °C under H
2
and this treatment lead to some dealumination that influenced catalyst acidity. The influence of acidity was evaluated in glycerol oxidation. All tested catalysts were able to oxidize glycerol, and the main products were 1,3-dihydroxyacetone, glyceric acid and glyceraldehyde.
The use of mononuclear Cu(II) 2,2'-bipyridine and 1,10-phenantroline complexes as catalysts in the oxidation of benzene, using hydrogen peroxide and tert-butyl hydroperoxide as oxidant in CH₃CN/H₂O ...solution is presented. The reactions were carried out at 25 and at 50 °C. The complexes Cu(bipy)₃Cl₂ · 6H₂O (1), Cu(bipy)₂ClCl · 5H₂O (2), Cu(bipy)Cl₂ (3), Cu(phen)₃Cl₂ · 7H₂O (4), Cu(phen)₂ClCl · 5H₂O (5), Cu(phen)Cl₂ (6) were able to oxidize benzene into phenol, hydroquinone and p-benzoquinone. Highest conversion (22%) was obtained using Cu(Phen)Cl₂ (6) as catalyst.
In biorefinery processes often the downstream processing is the technological bottleneck for an overall high efficiency. On the basis of recent developments, the selective liquid phase adsorption ...applying highly hydrophobic porous materials opened up new opportunities for process development. In this contribution, the efficiency of selective liquid phase adsorption is demonstrated for the separation and purification of itaconic acid from aqueous solutions for the first time. A wide range of different adsorbents was screened, revealing the surface polarity as well as textural properties as critical parameters for their performance. Adsorption from mixed solutions of itaconic acid and glucose exhibited extraordinary high selectivities for adsorbents with highly hydrophobic surfaces, especially certain activated carbons and hyper-cross-linked polymers. Evaluation of the pH dependence showed that the respective molecular species of itaconic acid/itaconate has a major impact on the adsorption performance. Additionally, experiments on a continuously operated fixed-bed adsorber were carried out, and the desorption behavior was evaluated. Overall, the technical feasibility of the selective adsorptive removal of itaconic acid from aqueous solutions with hydrophobic adsorbents is demonstrated as a model system for an alternative technology to conventional separation strategies in biorefinery concepts.
The adsorption of biogenic hydroxymethylfurfural and fructose from aqueous phase reaction mixtures on polymer‐based spherical activated carbons was studied. The adsorbents show a high capacity in ...combination with an outstanding selectivity due to their hydrophobic surface. Equilibrium isotherms and breakthrough curves of single and multicomponent solutions as well as the desorption behavior were measured and modelled accordingly. Overall, the results obtained enable further process development for adsorptive liquid phase separation in future biorefinery processes.
Biogenic hydroxymethylfurfural is selectively adsorbed from aqueous solutions using highly hydrophobic polymer‐based spherical activated carbons. Investigation of equilibrium adsorption and breakthrough curves revealed the potential for further process development to tackle the issue of aqueous phase separation in biorefinery processes.
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•Phosphotungstic acid supported on activated carbon for fructose dehydration to HMF.•Accessible acid sites and high acid density are important for fructose dehydration.•DMSO provided ...efficient fructose dehydration, resulting in high HMF yield.•Temperature has major effect into fructose dehydration and HMF yield.•Kinetic and the activation energy of fructose conversion to HMF were determined.
Phophotungstic acid (HPW) supported on activated carbon (AC) was prepared and used for dehydration of fructose to 5-hydroxymethylfurfural (HMF), a biomass-derived precursor for chemicals and fuels. Different characterization techniques showed that Keggin structure of HPW was maintained after impregnation process by incipient wetness method with ethanol as solvent. The high mass content of the active phase (50 wt%) on the support resulted in accessible acid sites and high acid density, important for the dehydration reaction. The effects of reaction time, catalyst amount, and temperature were investigated. The catalytic system with dimethyl sulfoxide (DMSO) as solvent provided an efficient transformation of fructose to HMF, resulting in high HMF yields (99.3 %) and total fructose conversion after 30 min of reaction at 140 °C. Fructose conversion was not significantly affected by the catalyst amount. On the other hand, the increase in temperature resulted in greater and faster conversion. HMF yield was deeply affected by all reaction variables. Moreover, HPW/AC was reused five times without significant loss of activity. Additionally, a kinetic evaluation was performed and the activation energy of fructose conversion to HMF was 109.4 kJmol−1.
This work aims at the soybean free fatty acid deoxygenation using palladium supported (1wt.%) on different clays as catalysts. The results presented a promising technology for the single-stage ...production of hydrocarbons in the diesel fuel range. Clays used as palladium support were a natural Brazilian Montmorillonite (BM), this same clay in its pillared form (PILCBM) and two commercial clays (K10 and KSF). Catalysts were characterized by N2 adsorption, X-ray diffraction (XRD), FTIR spectra of adsorbed pyridine, CO chemisorption and scanning electron microscopy (SEM). Reactions were carried out in batch mode, under different H2 pressures (10, 20, 30 and 40bar) at 300°C. Reactions performed using Pd/K10 as catalyst at 30bar of H2 presented interesting results: 74.5% conversion after 6h and selectivities to n- and i-alkanes equal to 69% and 29%, respectively.
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•Pd/clays were used as catalysts to transform free fatty acids in hydrocarbons.•n- and i-alkanes were obtained as main products when Pd/K10 was used as catalyst.•Efficient method to obtain high quality fuel from renewable raw material•Pd/K10 shows high activity–selectivity to produce hydrocarbons in the diesel range.
Mononuclear 1,10-phenantroline Cu(II) complexes: Cu(phen)
3Cl
2·7H
2O (
1), Cu(phen)
2ClCl·5H
2O (
2), Cu(phen)Cl
2 (
3) were used to oxidize cyclohexane, using hydrogen peroxide as oxidant. All ...complexes were able to produce cyclohexanol and cyclohexanone with low to moderate yields. Adipic acid was also formed in the reaction. The highest conversion was obtained with the system Cu(phen)
2ClCl at 70
°C, with 67% of total yield. It was also possible to relate the catalytic activity in cyclohexane oxidation, as well as toluene oxidation, with the redox properties of the complexes:
the most easily reducible, being also the most active.
In this work, we present the cyclohexane oxidation catalyzed by the mononuclear 1,10-phenantroline Cu(II) complexes: Cu(phen)
3Cl
2·7H
2O (
1), Cu(phen)
2ClCl·5H
2O (
2), Cu(phen)Cl
2 (
3), using hydrogen peroxide as oxidant, in acetonitrile:water (3.5:1) solution. The reactions were carried out at temperatures ranging from 25
°C to 70
°C. All complexes were able to oxidize cyclohexane into cyclohexanol and cyclohexanone with low to moderate yields. Adipic acid was also formed in the reaction. The highest conversion was obtained with the system Cu(phen)
2ClCl/H
2O
2/70
°C, with 67% total yield. Furthermore, these complexes were also able to oxidize toluene at room temperature.
