To evaluate the effects of temperature on coal pyrolysis products

Baiyinhua lignite was pyrolyzed at different temperatures (400~600 ℃) in tube furnace via temperature programming method.The chemical and physical structures of the obtained char were investigated using the Fourier infrared spectrometer (FTIR) and nitrogen isothermal adsorption method.Meanwhile

the GC-MS and gas chromatography combined with online electronic balance were adopted to analyze the composition of pyrolysis tar and gas yields to explore the lignite pyrolysis characteristics.The results show that

in the pyrolysis

as the pyrolysis temperature raised

the char yield reduced gradually while the pyrolysis gas and tar yields increased.As for the gas

the CO_2 yield was the highest and reached a stable level of 74.4 mL/g at temperatures higher than 450 ℃ Besides

fatty hydrocarbon and oxygencontaining compounds occupied the main part of tar composition while nitrogen-containing compounds mainly exists in the form of pyridine and quinoline rings with stable structure.Pyrolysis can effectively improve the coal rank and increase the aromatic carbon rate and ring condensation degree.Furthermore

as a result of volatile evolution

functional group decompositions and tar formation

the average pore diameter first increased and then decreased with the rising pyrolysis temperature

while the specific surface area and pore volume exhibited the opposite trend.