Lactic acid (LA) is an important intermediate in the fine chemical industry because it is utilized as a building block for the production of biodegradable plastics. In this study, a series of tin phosphate phase transfer catalysts modified with several surfactants have been prepared by a facile one-pot synthesis method and tested for the direct conversion of trioses to LA under hydrothermal conditions. Poly(ethylene glycol) (PEG) was identified as the most promising surfactant, and the product distribution closely depended on the reaction temperature, catalyst loading and substrate concentration. Complete DHA conversion and a good yield of up to 96.1% of LA were obtained at 140°C after 4 h of reaction time. Pyridine FTIR demonstrated the presence of Brønsted and Lewis acid sites, which play crucial roles in the dehydration of DHA to pyruvaldehyde (PA) and the following isomerization of generated PA to LA. Furthermore, the isomerization of PA to LA was found to be the rate-determining step. A possible reaction mechanism was proposed: 1) the coordination between PEG and the metal ions caused a greater separation of the tin ions from the phosphate anions, making them more potent Lewis acid sites, and 2) the PEG behaved as a phase transfer catalyst during the reaction. This study paves the way for the further design of improved solid acid catalysts for aqueous phase production of LA from carbohydrates.Catal. Sci. Technol. This journal is † Electronic supplementary information (ESI) available: Catalytic conversion of GLA to LA by SnP with various surfactants, the results of DHA after a prolonged reaction time of 6 h and the postulated roles of SnP-PEG2000. See

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Polymerizates of imidazole and epichlorohydrin ([IMEP]Cl) were used to convert simple sugars to lactic acid in water at low temperatures.

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A new lignin-based resin (LBR) was prepared by condensation polymerization of sodium lignosulfonate with glucose under acidic conditions. The physical and chemical properties of LBR were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and 13 C cross-polarization magic angle spinning nuclear magnetic resonance ( 13 C CP MAS NMR). Structure analyses revealed that the resulting spherical particles are composed of amorphous cross-linked phenylpropane-based polymers that have a high density of acidic groups and high thermal stability. The adsorption performance of heavy metals (Cr(III), Cu(II), Ni(II), Pb(II), and Cd(II)) onto LBR were investigated. Langmuir, Freundlich, and Dubinin− Radushkevich (D-R) models were applied to analyze the experimental data. The maximum adsorption capacity of LBR for the five metals was in the following order: Pb(II) ≫ Cu(II) > Cd(II) > Ni(II) ≈ Cr(III). The experimental data were also tested by pseudo-first-order, pseudo-second-order, and intraparticle diffusion kinetic models. The adsorption process of all metal ions on LBR is well-described by the pseudo-second-order model. Moreover, the regeneration method of LBR was also studied.

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Siliceous tin phosphates were demonstrated to be efficient Brønsted–Lewis acid bifunctional catalysts during the conversion of triose sugars to LA under hydrothermal conditions.