Pyrolysis characteristics and kinetic study of coal in a novel concentrating photothermal thermogravimetric analyzer: Effect of heating rate

•A concentrating photothermal TGA with wide range heating rate was developed.•The maximum mass loss rate of coal pyrolysis increased linearly with heating rate.•The mean activation energy decreased exponentially with the increase of heating rate.•The transformation rates of functional groups were accelerated with the heating rate.•The activation energy was binomially correlated with the I(Gr+Vl+Vr)/ID.