Mg(OH)2 -Facilitated Liquid-Phase Conversion of Lactic Acid into 1,2-Propanediol over Cu: An Experimental and Theoretical Study

Abstract

Mg(OH)₂ is found to exhibit superior performance in the liquid-phase conversion of lactic acid (LA) into 1,2-propanediol over Cu. A conversion of 90 % with a selectivity of 98 % is achieved at 513 K and 5 MPa H₂ . Mg(LA)₂ could be identified as a crucial intermediate in this reaction, as it undergoes faster conversion than the combination of LA and Mg(OH₂ ) and regeneration of Mg(OH)₂ through the conversion of Mg(LA)₂ as a substrate. DFT calculations reveal that the energetic span of the reaction decreases from 46.6 kcal mol^-1 catalyzed with no cation to 43.6 kcal mol^-1 with [Mg(OH)]⁺ , confirming the facilitating effect of Mg(OH)₂ .

Keywords: alcohols; carboxylic acids; copper; hydrogenolysis; magnesium.