Main content area

Glycerol valorization to lactic acid catalyzed by hydroxyapatite‐supported palladium particles

Shen, Lingqin, Yu, Zhongyong, Zhang, Di, Yin, Hengbo, Wang, Chengtao, Wang, Aili
Journal of chemical technology and biotechnology 2019 v.94 no.1 pp. 204-215
acetaldehyde, biomass, catalysts, fermentation, glycerol, hydrogen cyanide, hydroxyapatite, lactic acid, nanoparticles, oxidation, palladium, sodium hydroxide
BACKGROUND: Catalytic formation of lactic acid from biomass glycerol is a sustainable alternative to the conventional fermentation process starting from carbohydrate and the chemical route using HCN and acetaldehyde. Highly concentrated glycerol can be effectively converted to lactic acid using hydroxyapatite‐supported palladium particles in the presence of NaOH. RESULTS: The 3% hydroxyapatite‐supported palladium catalyst (Pd₃/HAP) demonstrates excellent activity (TOF = 1274 h⁻¹ for a batch time of 90 min) with a high selectivity (95%) towards lactic acid at 99% glycerol conversion (230 °C, NaOH:glycerol molar ratio = 1.1, and glycerol/total Pd intake = 1926). Under the same reaction conditions, the selectivities of lactic acid were 82% and 90% on Pd₀.₇₅/HAP and Pd₁.₅/HAP catalysts, respectively. The Pd₃/HAP catalyst was recycled five times in a batch set‐up without a significant drop in activity and lactic acid selectivity, which is indicative of good catalyst stability. CONCLUSIONS: Pd‐based catalysts on available hydroxyapatite supports are efficient catalysts for glycerol selective oxidation. The catalysts possess active PdO and Pd⁰ species well dispersed on the functionalized hydroxyapatite support. Pd⁰ nanoparticles and NaOH synergistically catalyze the reaction process. © 2018 Society of Chemical Industry