Gas evolution characteristics of lignite during low-temperature pyrolysis

• Lignite quality improving.
• Low-temperature pyrolysis.
• Gaseous products evolution characteristics.
• Morphological characteristics.

The results of low-temperature pyrolysis of lignite are presented in this paper. The investigation focused on the effect of pyrolysis temperature on the gaseous product distribution, as well as morphological and structural variation. The gases evolved were analyzed by gas chromatography. Graphs of evolved gaseous components versus temperature were constructed to study their evolution characteristics. Morphological characteristics were observed at different pyrolysis temperatures. The semi-char surface had numerous bumps and hollows with deep cracks after low-temperature pyrolysis. The structural variation between the raw lignite and semi-char product was determined by Brunauer–Emmett–Teller techniques. The semi-char had well-developed flow structures with irregular shapes and appeared fairly molten, which indicated structural change during the evolution of the gaseous products.