Abstract:-The liquid phase oxidation of glycerol was performed producing fine organic acids. Catalysts based on Pt, Pd and Bi supported on activated carbon were employed to perform the conversion of glycerol into organic acids at 313 K, 323 K and 333 K, under atmospheric pressure (1.0 bar), in a mechanically agitated slurry reactor (MASR). The experimental results indicated glycerol conversions of 98% with production of glyceric, tartronic and glycolic acids, and dihydroxyacetone. A yield of glyceric acid of 69.8%, and… Show more
“…The kJ/mol, respectively, the value ranges of which are well consistent with previous reports on the same reaction. [28,54,55] Importantly, we find that the presence of Fe lowers the activation energies for primary and secondary oxidation on Pt catalyst. The activation barrier for lactic acid formation is almost unchanged but that for C−C cleavage is much lower on bimetallic PtFe(1) catalyst.…”
Section: Pt and Fe Element Dispersion Within Bimetallic Clustersmentioning
By exploiting the large difference in lattice constants between Pt and Fe metals, anisotropic growth of bimetallic PtFe clusters with high index numbers have been prepared to investigate their catalytic performance in oxidation of biopolyols. Surface characterization using transmission electron microscopy shows that etching effects caused by Fe 3+ and anisotropic growth induced by lattice mismatch contributed to the final nanocrystal geometry. The bimetallic PtFe heterocluster is shown to exhibit an unprecedented six-fold enhanced catalytic activity and threefold higher selectivity compared to monometallic Pt and Fe catalysts, in oxidation of biomass-derived polyols to dicarboxylic acids. A detailed study on structure-dependent kinetics of oxidation of glycerol, based on concentration-time profiles on Pt and PtFe catalysts, reveals that the presence of Fe in Pt catalysts significantly enhances the rate of oxidation and decreases the activation barriers for primary and secondary oxidation steps leading to enhanced catalytic activity and selectivity. The lattice mismatch methodology employed in this work provides a unique tool for designing high index catalytically active materials for various other industrial applications.
“…The kJ/mol, respectively, the value ranges of which are well consistent with previous reports on the same reaction. [28,54,55] Importantly, we find that the presence of Fe lowers the activation energies for primary and secondary oxidation on Pt catalyst. The activation barrier for lactic acid formation is almost unchanged but that for C−C cleavage is much lower on bimetallic PtFe(1) catalyst.…”
Section: Pt and Fe Element Dispersion Within Bimetallic Clustersmentioning
By exploiting the large difference in lattice constants between Pt and Fe metals, anisotropic growth of bimetallic PtFe clusters with high index numbers have been prepared to investigate their catalytic performance in oxidation of biopolyols. Surface characterization using transmission electron microscopy shows that etching effects caused by Fe 3+ and anisotropic growth induced by lattice mismatch contributed to the final nanocrystal geometry. The bimetallic PtFe heterocluster is shown to exhibit an unprecedented six-fold enhanced catalytic activity and threefold higher selectivity compared to monometallic Pt and Fe catalysts, in oxidation of biomass-derived polyols to dicarboxylic acids. A detailed study on structure-dependent kinetics of oxidation of glycerol, based on concentration-time profiles on Pt and PtFe catalysts, reveals that the presence of Fe in Pt catalysts significantly enhances the rate of oxidation and decreases the activation barriers for primary and secondary oxidation steps leading to enhanced catalytic activity and selectivity. The lattice mismatch methodology employed in this work provides a unique tool for designing high index catalytically active materials for various other industrial applications.
“…These models are commonly used realistic approach to derive the rate expression for heterogeneous reactions. The selection of models was based on the analysis of literature data on the kinetic modeling of the conversion of glycerol into PG [37], LA [38,39] and other carboxylic acids [40] in an alkaline media.…”
Mechanism analysis and kinetic modeling of glycerol conversion into lactic acid in the alkaline media with and without heterogeneous catalyst Cu NPs are reported. The reaction pathways were determined in agreement with the experimental results and comprise several types of reactions, namely dehydrogenation, hydrogenolysis, dehydration and C–C cleavage. Experimental concentration-time profiles were obtained in a slurry batch reactor at different glycerol, NaOH and Cu NPs concentrations in a temperature range of 483–518 K. Power law, Langmuir–Hinshelwood (LH) and Eley–Rideal (ER) models were chosen to fit the experimental data. The proposed reaction pathways and obtained kinetic model adequately describe the experimental data. The reaction over Cu NPs catalyst in the presence of NaOH proceeds with a significantly lower activation barrier (Ea = 81.4 kJ∙mol−1) compared with the only homogeneous catalytic conversion (Ea = 104.0 kJ∙mol−1). The activation energy for glycerol hydrogenolysis into 1,2-propanediol on the catalyst surface without adding hydrogen is estimated of 102.0 kJ∙mol−1. The model parameters obtained in this study would be used to scale an industrial unit in a reactor modeling.
“…Varma's group investigated reaction network for glycerol conversion to various carboxylic acids on PtBi/C catalysts . Due to complex reaction network for the formation of a variety of C 1 to C 3 acids, a progressive modeling methodology was employed for each sub‐network with oxalic acid, glycoxalic acid, dihydroxyacetone, glyceric acid and glycerol as initial reactants.…”
Section: Figurementioning
confidence: 99%
“…Brainer and colleagues studied oxidation kinetics on PdPtBi/C trimetallic catalysts. A mechanism involving adsorption of glycerol and acids on one type of site with O 2 on another site is proposed and validated with experimental data . Zaera and coworkers studied glycerol oxidation on Pt/SiO 2 catalyst and found that the observed changes are mainly due to a reversible poisoning of the catalyst by dihydroxyacetone (and possibly other primary products) …”
Conversion of biomass to chemicals provides essential products to human society from renewable resources. In this context, achieving atom‐economical and energy‐efficient conversion with high selectivity towards target products remains a key challenge. Recent developments in nanostructured catalysts address this challenge reporting remarkable performances in shape and morphology dependent catalysis by metals on nano scale in energy and environmental applications. In this review, most recent advances in synthesis of heterogeneous nanomaterials, surface characterization and catalytic performances for hydrogenation and oxidation for biorenewables with plausible mechanism have been discussed. The perspectives obtained from this review paper will provide insights into rational design of active, selective and stable catalytic materials for sustainable production of value‐added chemicals from biomass resources.
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