Xilinguole lignite pyrolysis under methane with or without Ni/Al2O3 as catalyst

•Lignite (XL) pyrolysis in methane was investigated by TG-MS and in fixed-bed reactor.•Methane activated by Ni/Al2O3 enhances gas evolution in XL pyrolysis.•XL pyrolysis in methane with catalyst achieves the highest tar and char yields.•Free radical induced effect facilitates both XL pyrolysis and methane activation.

The effect of methane on Xilinguole lignite (XL) pyrolysis with or without Ni/Al2O3 as catalyst was investigated with thermogravimetry coupled with mass spectrometer and in a fixed-bed reactor. The results show that methane activated by catalyst can promote XL pyrolysis, increasing tar yield and gas releasing. Methane without catalyst can also enhance gas evolution of XL pyrolysis, but has little effect on tar yield. The increase of char yield in XL pyrolysis under methane is attributed to carbon deposited from methane decomposition. There exists induce effect between coal radicals and methane which facilitates methane activation at low temperature and increases gas evolution during XL pyrolysis even without catalyst.