Title
Experimental and theoretical study of birch ethanol lignin hydrogenation products on Ru/C catalyst
Authors
ALEKSANDR S. KAZACHENKO, FERIDE AKMAN, ANGELINA MIROSHNIKOVA, ANDREY SKRIPNIKOV, XIAOMIN LI, VALENTIN V. SYCHEV, O. S. SELEZNEVA, UTKIRJON HOLIKULOV, NOUREDDINE ISSAOUI and OMAR M. AL-DOSSARY

Received April 3, 2024
Published Volume 58 Issue 9-10 September-December
Keywords lignin, hydrogenation, ethanol, DFT, biomass

Abstract
Plant biomass is a valuable raw material for the production of important chemicals. Lignin depolymerization processes make it possible to obtain valuable aromatic substances. In this work, the aromatic products of birch ethanol lignin hydrogenation were studied. The lignin depolymerization process was carried out on a ruthenium catalyst, varying the oxidation temperature of the carbon carrier. The hydrogenation products were analyzed by GC, GC-MS and DFT. It was shown that the highest yield of monomeric methoxyphenols (about 11 wt%) was achieved using the 3% Ru/C(400) catalyst. Catalysts have a significant effect on the yield and composition of solid, liquid and gaseous products. Thus, the use of the most effective 3% Ru/C(400) catalyst increased the yield of monomeric methoxyphenols from 2.2 to 11.1 wt% compared to the non-catalytic experiment. The liquid products of birch ethanol lignin hydrogenation mainly consist of syringol derivatives, which were studied using density functional theory methods. Spectroscopic (FTIR and NMR) characteristics, HOMO-LUMO, Mulliken atomic charges, electronic parameters, MEP and ALIE were calculated. Optical softness, softness and maximum charge transfer index values increased with increasing chain length of the alkyl radical and the appearance of a double bond.