Abstract: The lignite and FCC slurry （FCCS） were co-processed in an autoclave using molybdenum naphthenate oil soluble catalyst in H2 atmosphare. Solid residues derived from the reaction at different time were obtained and analyzed by Fourier transform infrared spectroscopy（FT-IR）. The reaction process was speculated by combination of peaks fitting of the specific bands of different functional groups in FT-IR spectra using Peakfit software and the conversions and product distribution of different functional groups. Results showed there are five different types of hydrogen bonds in the solid residues, among which the hydrogen bond from hydroxyl association is at most, while the hydrogen bond formed through the association of the phenolic hydroxyl group and ether group in oxygen-containing functional groups account the maximum. The reaction process can be divided into three stages：in the first stage, the coal conversion raises rapidly, all kinds of the functional groups decreases and the fat chain breaks down a lot; the second stage is the stable phase of coal conversion, in which the amounts of phenolic hydroxyl groups and ether groups reduce, and the other oxygen-containing groups change little; in the third stage, the coal conversion reaches much deeper, the content of oxygen-containing compounds and aliphatics in solid residues further decreases, resulting in minimized association of hydrogen bonds.

Key words: co-processing of coal and heavy oil, solid residue, infrared spectrum