Influence of pyrolysis conditions on the mercury removal characteristics and physicochemical properties of biomass coke

•The pyrolysis temperature and atmosphere have great influence on Hg0 removal of BC.•N2 + 7% O2, higher pyrolysis temperature and heating rate develop the pore structure.•BC-N2 + 7% O2-800-10 has the best Hg0 removal rate of 34.89% under all the pyrolysis conditions.•Hg0 removal of BC mainly by chemical adsorption with main content of HgO.