Abstract: The Ni/olivine catalyst with olivine as a carrier was used to improve the tar quality of Hamin Naomaohu coal during catalytic pyrolysis. The effects of pyrolysis temperature and nickel loading on the yield and composition of tar were studied in a fixed-bed reactor. The tar quality was evaluated by simulated distillation, the specific composition of tar was determined by GC-MS, and the mechanism of quality improvement was analyzed. The results showed that the highest yield of tar was 16.20% at 500 ℃. After the adding Ni/olivine catalyst, when the Ni content was 5%, the tar yield decreased significantly and reached the lowest 14.36%, the mass fraction of heavy tar component decreased from 35% to 30%, and the light tar yield increased by 15.59%. The gas yield decreased significantly, but the H₂ content increased significantly. The relative content of short-chain aliphatic hydrocarbons, benzenes, phenols and naphthalenes in the tar components increased, which showed that Ni/olivine catalyst could improved the quality of tar by catalytic cracking of long-chain alkanes and polycyclic compounds in tar, and the best quality improvement effect was achieved when the Ni mass fraction was 5%.

Key words: low-rank coal, in-situ, catalytic pyrolysis, Ni/Olivine catalyst, tar upgrading