Catalytic hydrodechlorination of chloroaromatic gas streams promoted by Pd and Ni: The role of hydrogen spillover

► Effective application of catalytic hydrodechlorination in the treatment of toxic chloroaromatic gas streams. ► Demonstration of spillover hydrogen associated with Pd/Al2O3, Ni/Al2O3, Pd + Al2O3 and Ni + Al2O3. ► Combination of Al2O3 with Pd, Ni, Pd/Al2O3 and Ni/Al2O3 enhances spillover content. ► Spillover hydrogen contributes to enhanced hydrodechlorination performance.