A5068454158- Catalysis for Biomass Conversion
- Biofuel production and bioconversion
- Enzyme Catalysis and Immobilization
- Zeolite Catalysis and Synthesis
- Mesoporous Materials and Catalysis
- Carbohydrate Chemistry and Synthesis
- Extraction and Separation Processes
- Chemical Synthesis and Characterization
- Catalysis and Hydrodesulfurization Studies
- Supercapacitor Materials and Fabrication
- Catalysts for Methane Reforming
- Adsorption and biosorption for pollutant removal
- Catalytic Processes in Materials Science
- Diet, Metabolism, and Disease
Veer Kunwar Singh University
2025
University of Delaware
2011-2013
Center for Innovation
2011-2013
5-(Hydroxymethyl)furfural (HMF) and levulinic acid production from glucose in a cascade of reactions using Lewis (CrCl3) catalyst together with Brønsted (HCl) aqueous media is investigated. It shown that CrCl3 an active isomerization to fructose, the combined catalysts perform dehydration/rehydration reactions. A speciation model conjunction kinetics results indicates hydrolyzed Cr(III) complex [Cr(H2O)5OH](2+) most Cr species probably acts as acid-Brønsted base bifunctional site. Extended...
The role of molecular structure on pentose dehydration to furfural has been examined using HCl as a Brønsted acid catalyst in single phase aqueous media. It is shown that xylulose results much higher yield than xylose under similar reaction conditions. Furthermore, cascade reactions for the efficient conversion pot reactor presented whereby Lewis acid, CrCl3, used isomerize xylulose, and HCl, employed dehydrate furfural. Using combination acids, ∼39% achieved compared ∼29% alone, at moderate...
A nonenzymatic route for xylose isomerization in an aqueous medium using zeolite Sn-beta as a catalyst is demonstrated. Xylulose and lyxose are the primary secondary products. The maximum yield to xylulose 27%, with 11% at ∼60% conversion 100 °C. When combined Brønsted acid catalyst, furfural forms single pot from much lower temperatures than typically employed this reaction.
Herein, the first comparison of mechanisms glucose-to-fructose isomerization in aqueous media enabled by homogeneous (CrCl3 and AlCl3 ) heterogeneous catalysts (Sn-beta) using isotopic-labeling studies is reported. A pronounced kinetic isotope effect (KIE) was observed if deuterium label at C2 position, thus suggesting that a hydrogen shift from to C1 positions rate-limiting step with three catalysts. (13) C (1) H NMR spectroscopic investigations confirmed an intra-hydride-transfer reaction...
We perform the first extensive experimental kinetic studies of fructose dehydration and 5-hydroxymethyl furfural (HMF) rehydration at low temperatures over a wide range conditions (T ∼ 70–150 °C; pH values 0.7–1.6 initial concentrations (5–20%w/v) HMF (2.5–10%w/v)). Guided from insights our first-principles calculations, we isotope effect (KIE) experiments labeled to validate rate-limiting step. Subsequently, develop skeleton model for that integrates fundamental accounts KIE, as well...
The main paths by which zeolites carry out the dehydration of fructose to HMF and rehydration levulinic acid in aqueous solutions are elucidated using an H-BEA zeolite with SiO2/Al2O3 = 18 (H-BEA-18) as a representative solid catalyst. Specifically, relative role homogeneous chemistry (both solvent- zeolite-induced), effect external surface sites, adsorption products reactants on catalyst for these reactions is delineated. We found that H-BEA-18 increases conversion part catalyzing...
Background: Water is essential for all life, but pollution, including heavy metals, poses severe health risks. The adsorption technology, known being safe, cost-effective, and eco-friendly, uses silica to remove zinc ions from water. This paper detailed the kinetics, isotherms, thermodynamics of this process. Methods: A stock solution sulfate in distilled water was prepared. Silica oxide, with its high surface area, used solutions 5, 10, 15, 20 mg/L concentrations. double beam atomic...
The G4 ab initio method was used in combination with the COSMO-SAC solvation model to predict reaction free energies (ΔG) of glucose dehydration reactions mixtures water and dimethyl sulfoxide (DMSO). Experiments were also conducted estimate ΔG values for anhydroglucofuranose levoglucosan. predicted found be quantitative agreement experimental values. calculations show that hexose 5-(hydroxymethyl)furfural (HMF) is an irreversible reaction, whereas anhydroglucose could reversible depending...
ADVERTISEMENT RETURN TO ISSUEPREVCorrectionNEXTORIGINAL ARTICLEThis notice is a correctionCorrection to Kinetics of Homogeneous Brønsted Acid Catalyzed Fructose Dehydration and 5-Hydroxymethyl Furfural Rehydration: A Combined Experimental Computational StudyT. Dallas Swift, Christina Bagia, Vinit Choudhary, George Peklaris, Vladimiros Nikolakis*, Dionisios G. Vlachos*Cite this: ACS Catal. 2014, 4, 5, 1320Publication Date (Web):April 1, 2014Publication History Published online1 April...