Development of Ga-ZSM-11 zeolites for the synthesis of lactic acid

Abstract

In the present work, we analyzed the influence of the reaction temperature and the gallium content in zeolite ZSM-11 (MEL structure) in the production of lactic acid from dihydroxyacetone (DHA). The metal cation was incorporated by wet impregnation in different concentrations (~2-10% w/w). The ZSM-11 structure was confirmed by XRD for all samples, whereas in the impregnated materials the crystallinity decreased as the amount of the cation incorporated in the catalyst increased. The surface area was analyzed by BET method and it was found that it decreases when the incorporated Ga content increases. By means of FTIR with pyridine adsorption, the amount, strength and ratio of acidic sites were determined. The study by TPR indicated the reduction of the superficial species neighboring the Ga-O bonds and the reduction of Ga+3 to Ga+. The UV-visible diffuse reflectance analysis indicated the dispersion of the possible agglomerates of gallium oxides. These materials exhibited a good catalytic performance in the conversion of dihydroxyacetone (DHA) to lactic acid, a platform molecule of great current interest.