Loblolly pine residue prepared with and without zeolite ZSM-5 was pyrolyzed at 600℃ and the pyrolysis oil was hydrogenated using formic acid as a hydrogen source,in the presence of a Ru/activated carbon catalyst.As indicated by the pyrolysis yield,addition of the zeolite ZSM-5 increased the yield of light oil but decreased the yield of heavy oil.The pyrolysis oils were analyzed by 13C-,31p-,19F-nuclear magnetic resonance (NMR),and heteronuclear single quantum coherence or heteronuclear single quantum correlation nuclear magnetic resonance (HSQC-NMR),demonstrating that the zeolite ZSM-5 can efficiently induce decarboxylation reactions and decrease the content of aliphatic hydroxyl groups in the heavy oil by 57％.After hydrogenation of the pyrolysis oil,the aromatic carbon content decreased by 78％,with a significant increase in the aliphatic carbon content.