Catalytic hydrogenolysis of lignin and model compounds over highly dispersed Ni-Ru/Al2O3 without additional H2

•A highly dispersed Ni-Ru/Al2O3 based on layered double hydroxide was prepared.•Model compounds can be completely transformed into monomers below 150 °C without H2.•The transfer of electrons from Ni to Ru is beneficial to form active hydrogen on the catalyst.•Isopropanol as hydrogen source exhibits much better performance than other solvents.•Apparent activation energies increase in the order: α-O-4 (90.6 kJ/mol) < β-O-4 (126.7 kJ/mol) < 4-O-5 (172.2 kJ/mol).