Oxidation of elemental mercury vapor over γ-Al2O3 supported CuCl2 catalyst for mercury emissions control

•CuCl2 forms multiple copper species on γ-Al2O3 surface.•At low loadings, CuCl2 and γ-Al2O3 form inactive copper aluminate.•At high loadings, additional CuCl2 exists in highly dispersed amorphous form.•CuCl2/γ-Al2O3 works as a redox catalyst in O2 and HCl gases for Hg(0) oxidation.