Synthesis of calcium lactate starting from glycerol and calcium hydroxide catalyzed by copper-based catalysts in aqueous solution

Abstract

The direct synthesis of calcium lactate starting from glycerol and calcium hydroxide in an aqueous solution catalyzed by hydroxyapatite nanorod (HA)-, titanate nanowhisker-, and activated carbon (C)-supported metallic copper catalysts was investigated. The selectivity of calcium lactate was above 91% at the glycerol conversions of 92–––95% when the reaction was catalyzed by Cu(16)/HA catalyst in an aqueous solution with a Ca(OH)2/glycerol molar ratio of 0.6:1.0 at 230 °C for 2–––4 h. The Cu/HA catalyst with a higher alkalinity and a smaller copper particle size exhibited higher catalytic activity in the synthesis of calcium lactate starting from glycerol and Ca(OH)2 than the Cu/titanate and Cu/C catalysts. The reaction kinetics simulation shows that the activation energy on the Cu(16)/HA catalyst is 43.85 kJ·mol−1. When calcium lactate was separated from reaction mixture by the concentrated crystallization method, the yield of calcium lactate was up to 87.9% with the purity of 95.5%.