Enhancing the activity of MoS2/SiO2-Al2O3 bifunctional catalysts for suspended-bed hydrocracking of heavy oils by doping with Zr atoms

[Display omitted] •Zr-doped SiO2-Al2O3 mixed oxides were synthesized by a sol-gel-hydrothermal way.•Doping SiO2-Al2O3 with Zr atoms significantly increases the acidic site numbers.•Zr-doped mixed oxides were combined with MoS2 to produce bifunctional catalysts.•The catalysts show higher activity for suspended-bed hydrocracking of heavy oils. Developing catalysts with not only hydrogenation activity but also cracking activity is very important for the advancement of suspended-bed hydrocracking technology. Within this respect, MoS2/SiO2-Al2O3 bifunctional catalyst is a kind of typical catalysts with both hydrogenation and cracking activity. Herein, a series of Zr-doped SiO2-Al2O3 mixed oxides were synthesized by a sol-gel coupled with hydrothermal method. The synthesized mixed oxides were characterized for chemical structures and acidic properties. It is found that doping SiO2-Al2O3 with Zr atoms significantly increases the numbers of acidic sites. The Zr-doped SiO2-Al2O3mixed oxides were then combined with dispersed MoS2, which was in-situ produced from oil-soluble Mo precursors, to fabricate a novel kind of bifunctional catalysts for suspended-bed hydrocracking of heavy oils. Owing to the significantly increased numbers of acidic sites in Zr-doped SiO2-Al2O3 mixed oxides, corresponding bifunctional catalysts demonstrate much enhanced activity for suspended-bed hydrocracking of heavy oils in relative to MoS2/SiO2-Al2O3 bifunctional catalysts.