Effect of heating rate on pyrolysis characteristics and char structure of Zhundong lignite coal

It is necessary to research thoroughly on the pyrolysis process of Zhundong lignite coal,in order to simplify the preparation process of activated coke,cut the production cost and improve the utilization of the lignite coal. The py- rolysis characteristics of Zhundong lignite coal were investigated by thermos-gravimetric analysis ( TGA) at different heating rates of 10,20,30,40 and 50 ℃ / min. Meanwhile,two kinds of activated carbons (SC1 and SC2) were respec- tively prepared at 800 ℃ by rapid-pyrolysis and temperature-programmed pyrolysis. To obtain the information of char on pore structure parameters,organic functional groups and carbon skeleton structures,the chars were characterized by BET,FT-IR and Raman. Results showed that the variation range of activation energy and pre-exponential factor were 38. 89-229. 13 kJ / mol and 108. 26-1. 18×109 s-1 ,which were analyzed by TGA data for the pyrolysis of Zhundong lignite coal. The efficiency energy was transmitted to promote the decomposition of organic molecules and produce a large amount of volatile during the pyrolysis process with a heating rate of 30 ℃ / min. Simultaneously,a reasonable temperature gradient inside the coal char prevented the pore structure blocking caused by thermal condensation reac- tion. Also,the smooth release of volatiles promoted the formation of pore structure. The char produced by temperature programmed pyrolysis had the specific surface area of 312. 91 m2 / g,average pore volume of 0. 178 cm3 / g and average pore size of 2. 271 nm at a burning-off rate of 46. 5% . The char produced by rapid-pyrolysis had the specific surface area of 424. 25 m2 / g,average pore volume of 0. 189 cm3 / g and average pore size of 2. 342 nm at a burning-off rate of 37. 3% . A large number of amorphous structures and defect structures were generated in precursor char during the rap- id-pyrolysis process,which were conducive to the construction of microporous pore structure at activation stage.