Changes in char structure during the low-temperature pyrolysis in N2 and subsequent gasification in air of Loy Yang brown coal char

•This study traces the char structural changes in N2/air at low temperature.•The loss of O-containing species led to reduced intensity from large rings in N2.•The less gasified char obtained at 850 °C was more accessible to oxygen at 420 °C.•The original char structure determines the reaction pathway for small/large rings.