Conversion of Lignocellulosic Waste Into Cyclohexanol and 1-methyl-1,2- Cyclohexanediol Using New Hydrotalcite-based Catalysts

Abstract

Cyclohexanol and 1-methyl-1,2-cyclohexanediol were produced via the hydrotreating of guaiacol, using new hydrotalcite-based nickel (HT-Ni-R) and cobalt (HT-Co-R) catalysts.. Guaiacol is the most representative model compound for lignin-derived bio-oils. Catalysts were prepared by co-precipitation of the metals (Mg-Al, Ni or Co) followed by direct reduction with H2 at high temperature (550°C). Active species are highly dispersed Ni0 and Co0 particles formed upon reduction of part of the Ni2+ and Co2+. The main effect of the new synthesis procedure is to remarkably increase the dispersion of these metal particles, compared to those on the supported catalysts. Cobalt catalyst is more efficient for oxygen removal than the nickel catalyst, but this latter is more efficient for aromatic´s hydrogenation. HT-Ni-R produced 1-methyl-1,2-cyclohexanediol as the main product (70%). The main reaction pathway with HT-Co-R was the formation of cyclohexanol (41%). The high metal dispersion induced by the proposed synthesis procedure is the most important advantage of the new catalysts allowing the obtention of products with added value from potential renewable resources as lignin.