Pyrolysis is an efficient approach for coal clean utilization.To improve the tar yield in coal pyrolysis

several processes to integrate catalytic and/or low-temperature plasma activation of methane (including partial oxidation

CO2 reforming

steam reforming

methane aromatization and cold plasmas) with coal pyrolysis were reviewed.The results showed that all integrated processes can obviously improve the tar yield compared with the pyrolysis under N2 or H2

and are adaptable to different coals.These methods provide new approaches for enhancing the tar yield.The mechanism for high tar yield was analyzed by the isotopic trace techniques.The analysis of main components in the tar from the integrated process by GC-MS indicates that some free radicals (like· CHx

·H) are formed by the catalytic activation of methane on Ni-based catalysts or the excitation by electrons with higher energy in low-temperature plasma.These active species participate in the formation of coal tar by the interaction with the free radicals cracked from coal

leading to the remarkable enhancement.The reactor designing of the integrated process and the catalyst development with good catalytic performances for methane activation are the key to the industrial utilization in the future.