Hydrogenolysis of birch ethanol-lignin in supercritical ethanol over Ru and Ni catalysts bifunctional supported on oxidized carbon
Abstract
Here we studied the process of catalytic hydrogenolysis of organosolvent birch wood lignin (Betula alba) in supercritical ethanol under soft conditions - 260 ºC, 4-8 МPa. We use the nanoscale Ru and Ni metallic particles supported on oxidized carbon material Sibunit like bifunctional catalysts. We characterized the catalysts by TEM, N2 adsorption (BET), suspension pH. We analyze the liquid and gaseous reaction products by gas chromatography (GC) and gas chromatography with mass spectrometry (GC-MS). We found that Ru- and Ni-contained catalysts increase the liquid products yields (significant increasing of yields of monomeric components) and prevent formation of gas and char. The maximal yield of products (81 wt. %) was obtained in presence of catalyst contained 3 wt. % of Ru, moreover the monomer yield was 36 %. The use of carbon support with high concentration of acid sites allows us to enhance the process of lignin ethanolysis. The same time we found that use of Ni catalysts leads to formation of C-C bond cracking products. The use of Ru catalysts result in formation of hydrogenation products.