Effects of ZnO on Characteristics and Selectivity of Coprecipitated Ni/ZnO/Al2O3 Catalysts for Partial Hydrogenation of Sunflower Oil

Ni/ZnO/Al2O3 catalysts at different molar ratios were synthesized and characterized, and the catalytic performances were assessed by partial hydrogenation of sunflower oil. Ni:Zn at various molar ratios have resulted in varying degrees of Ni and Zn migration from the bulk to the catalyst surface, which led to different pore characteristics. Catalysts with equimolar Ni:Zn have shown wider pores and higher pore volumes and achieved 23% higher hydrogenation activity than Ni/Al2O3. The presence of ZnO also led to higher Ni surface area and dispersion, and TEM images have indicated that this could be attributed to ZnO that acts as a spacer for the Ni crystallites. However, the Ni surface area diminishes as the ZnO content becomes higher. The presence of ZnO in Ni/ZnO/Al2O3 catalysts is also shown to lower trans-fats formation when wide pores are available.