Efficient Generation of Lactic Acid from Glycerol over a Ru-Zn-CuI/Hydroxyapatite Catalyst

Graphical Adding value : A Ru-Zn-Cu I catalyst supported on hydroxyapatite (HAP) was applied for the conversion of glycerol, a biodiesel byproduct, to lactic acid (see scheme). Cu I inhibits C−C bond cleavage and thus improved the yield of lactic acid in this system. The biodiesel production process generates a significant amount of glycerol as a byproduct. A drive to add value has attracted worldwide attention, with the aim of improving the overall effectiveness and profitability of biodiesel production. Herein, we report hydroxyapatite (HAP)-supported Ru-Zn-Cu I (Ru-Zn-Cu I /HAP) as effective catalysts for the transformation of glycerol to lactic acid (LA).The catalysts were characterized by using different techniques. The effects of catalyst composition, reaction time, and temperature on the conversion and product distribution were investigated. It was revealed that Ru nanoparticles of less than 2 nm were dispersed uniformly on HAP. Cu I could effectively inhibit the cleavage of C−C bonds, which led to improved yields of LA. Under optimized conditions, the yield of LA could reach 70.9 % over Ru-Zn-Cu I /HAP. Furthermore, the catalyst could be reused at least four times without an obvious loss of activity or selectivity.