III International Conference

PP-II-120PECULIARITIES OF LACTIC ACID AND METHYL LACTATEHYDROGENATION OVER SILICA-SUPPORTED COPPERSimonov M.N., Simakova I.L., Demeshkina M.P., Minyukova T.P., Khassin A.A.Boreskov Institute of Catalysis, SB RAS, Novosibirsk, RussiaE-mail: smike@catalysis.ru, simakova@catalysis.ruIn the present work general peculiarities of lactic acid and methyl lactate hydrogenationto propylene glycol over silica-supported copper were studied. Gas-phase catalyticexperiments were conducted in fixed-bed reactor at atmospheric pressure. It was found, thatunder equal conditions methyl lactate conversion and selectivity of propylene glycolformation are higher than that for lactic acid. It was revealed, that the nature of solvent has agreat effect on distribution of by-products. Pure methyl lactate hydrogenation gives lessamount of by-products than that for aqueous and methanol methyl lactate solutions. It wasshown, that selectivity of propylene glycol formation starting from methyl lactate increasesfrom 78% to 98% as temperature decreases from 200 o C to 140 o C.A catalytic method of synthesis of commercially valuable propylene glycol over thecopper-containing catalysts is in progress [1] instead of currently petroleum-based one wherepromising starting material is a refined lactic acid obtained by fermentation of crude biomass.The aim of this work is to study lactic acid and methyl lactate hydrogenation to propyleneglycol over silica-supported copper.For hydrogenation experiments the 17 wt.% water solution of lactic acid was used.According to gas-liquid chromatography analysis and chromatography-mass spectrometrypropylene glycol and propionic acid are the main products of lactic acid conversion. It wasfound that 45,5 wt.% Cu/SiO 2 catalyst sample prepared by homogenous depositionprecipitationmethod exhibits the maximum selectivity of 1,2-propandiol formation [2]. Highcatalytic activity seems to be caused by great specific surface area of metallic copper [3].It is well-known that derivatives of carboxylic acids, e.g. esters, are more reactive incomparison with carboxylic acids in reactions of hydrogenation [4]. It was revealed, thathydrogenation of methyl lactate in a water solution at temperature 200 o С, results in methyllactate conversion to 99 % and selectivity of propylene glycol formation to 78 %. It wasestablished, that the conversion and selectivity of propylene glycol formation decrease withincrease of reagent supply. The basic by-products were propionic and lactic acids and methyl-2-methoxypropanoate.384