Comparative Study on Microwave Co-pyrolysis Products of Low-Rank Coal under CH4 and N2 Atmosphere

Microwave pyrolysis is a new research method for deeply processing of low-rank coal. This paper conducted comparative study on microwave co-pyrolysis products of low-rank coal under CH4 and N-2 atmosphere, respectively. The composition and content of tar and bluecoke were analyzed by gas chromatography-mass spectrometry and fourier transform infrared spectrometer. The results indicated that compared with N-2 atmosphere, the yield of liquid products (tar and pyrolysis water) obtained under CH4 atmosphere increased by 5.4 wt.%, whereas the bluecoke yield decreased by 3.0 wt.%; The content of S element in the bluecoke obtained under CH4 atmosphere was less than 0.30 wt.% to meet Bluecoke Standard S-1 Grade, and the ash content was just 6.72 wt.% to meet Bluecoke Standard A-3 Grade. Furthermore, the content of -OH. C=C and -C=O functional groups in the bluecoke were higher; The alkanes and olefins compound content in tar obtained under CH4 atmosphere were 9.1 wt.% and 7.9 wt.% higher than that under N-2 atmosphere, meanwhile, the aromatic hydrocarbons compound content was 35.5 wt.% lower than that under N-2 atmosphere.