Effects of different temperature chars on distribution of pyrolysates for Naomaohu coal

Intrinsic characteristics of Naomaohu coal pyrolysis in a two-stage fixed-bed reactor have been investigated in this study. The pyrolysates were detected by the simulated distillation, ultimate analysis and GC–MS to analyze the effect of different temperature chars on pyrolysis volatiles. The results showed that the slight secondary reactions occurred when the volatiles flowed through the 100–400 °C char layer, the yield of pyrolysis gas increased slightly, the tar yield had a little decrease, the atomic H/C ratio was higher than that of blank contrast experiment, and the quality of oil increased. Under the action of 500–900 °C char layer, the drastic secondary reactions of the volatiles occurred, the yield of pyrolysis gas increased obviously, and the yield and quality of oil decreased. The results of two-stage experiments with and without char effect were similar to the temperature change, indicating that temperature played a major role in affecting the distribution of pyrolysates. Whereas char was beneficial for the content and quality of light oil in the low-temperature range, the process of volatiles through the semi-coke layer enhanced H2 and CH4 yield during the total temperature range. Char also had an adsorption action, which gradually weakened with the temperature increased.