Pyrolysis and catalytic pyrolysis behaviors of two kinds of coals with different ranks were determined by thermogravimetric analyzer-mass spectrometry (TG-MS) and a high-frequency furnace. A quantitative method of on-line gas analysis was proposed using quadrupole mass spectrometry. The effects of pyrolysis temperature (650-800 degrees C) and Na2CO3 loading amount (0-15 wt.%) on the gaseous compounds evolution were investigated. The results show that loading Na2CO3 on coal was favorable for gas production in pyrolysis process. The yields of light gas species in the high-frequency furnace were lower than those in TG-MS. By comparing the pyrolysis yields of gas and solid in the high-frequency furnace and TG-MS, it was concluded that heating methods had great effects on the reaction mechanism and product distribution of pyrolysis and catalytic pyrolysis of coals. Moreover, the evolution processes of gaseous compounds were related to the presence of different functional groups in the solid samples. (C) 2015 Elsevier Ltd. All rights reserved.