Effect of the Composition and Synthesis Procedure of the Catalysts Based on the CoAl-Hydroxides on their Properties in Furfural Hydrogenation

Abstract

CoAl-hydroxides with Co/Al = 2 and 4 were synthesized by traditional coprecipitation method and mechanochemical route. Structure properties of the samples on the all preparation stages of the catalysts, the transformations occurred during cobalt reduction from corresponding oxides, textural characteristics of calcined and reduced samples, as well as size, morphology and composition of the particles that formed after high temperature treatments were studied in detailed. It was established, that synthesis procedure of CoAl-hydroxides has a significant impact on phase composition and properties of obtained systems. The phase of layered double hydroxide formed only when using coprecipitation method. The mechanochemical approach allowed to obtained the materials with higher specific surface area. According to TEM data, the samples prepared by coprecipitation (after oxidative and reductive treatments) had a “core-shell” structure where metallic atoms of Co were in core and shell consisted of CoAl-spinel. The samples synthesized by mechanochemical route had Co nanoparticles with high dispersion on the surface. The catalysts based on CoAl-systems prepared by mechanochemical method were more active in the furfural hydrogenation. Conversion of furfural achieved 97% for the sample with Co/Al = 4. Herewith, selectivity of furfural formation for all studied catalysts was almost 100% irrespective of synthesis procedure and Co/Al ratio.