Effect of synthesis technique on the activity of CoNiMo tri-metallic catalyst for hydrotreating of heavy gas oil

•Influence of synthesis procedure on HDS activity of CoNiMo catalyst is explained.•Ni impregnation prior to Co in CoNiMo catalyst leads to higher MoOX dispersion.•Co and Ni showed dual promotion effect in CoNiMo trimetallic catalysts.•Co-NiMo/γ-Al2O3 catalyst shows 8% and 38% higher HDS and HDN activity.•Co-NiMo/γ-Al2O3 is a potential catalyst to hydrotreat bitumen derived HGO.