Canadian Journal of Chemical Engineering, Vol.94, No.8, 1524-1532, 2016
HYDROPROCESSING OF 4-METHYLANISOLE AS A REPRESENTATIVE OF LIGNIN-DERIVED BIO-OILS CATALYZED BY SULPHIDED CoMo/gamma-Al2O3: A SEMI-QUANTITATIVE REACTION NETWORK
Catalytic hydroprocessing of 4-methylanisole as a representative of lignin-derived bio-oils was catalyzed by a commercial sulphided CoMo/gamma-Al2O3 catalyst in a fixed-bed flow reactor at various space velocities, temperatures, pressures, and feed compositions. An approximate reaction network is presented that accounts for the major products, and approximate kinetics are also presented. The kinetically significant reactions are 4-methylanisole conversion to (a) 4-methylphenol via hydrogenolysis, (b) toluene and benzene via hydrodeoxygenation, (c) cyclohexanone and methylcyclohexanone via hydrogenation, and (d) methylphenol derivatives via alkylation and transalkylation. The formation of toluene and benzene along with water and methanol from 4-methylanisole is inferred to result from direct scission of the C-aromatic-O bond. Cleavage of the C-methyl-O bond is faster than cleavage of the C-aromatic-O bond. The main pathway to toluene formation is the hydrogenolysis of the C-aromatic-O bond of the intermediate 4-methylphenol.