Effects of ZnO on Characteristics and Selectivity of Coprecipitated Ni/ZnO/Al₂O₃Catalysts for Partial Hydrogenation of Sunflower Oil

Abstract

Ni/ZnO/Al 2 O 3 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/Al 2 O 3 . 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/Al 2 O 3 catalysts is also shown to lower trans-fats formation when wide pores are available.

Enhanced Anticorrosion Performance and Mass Preparation of Magnetic Metal-Doped Zinc Oxide Nano Solid Solutions

“…43,44 The Ni 2p 3/2 and Ni 2p 1/2 core levels were observed at 852.8 and 870.1 eV (Figure 2c 2 ), respectively, with a spin−orbital splitting of 17.3 eV, indicating that Ni ions in Ni-doped ZnO NSSs may have a valence of +2. 45 In the XPS spectra of O 1s (Figure 2a 3 , b 3 , and c 3 ), the first peak with a low binding energy around 529.6 eV can be attributed to the interaction between the O 2− ion and Zn 2+ ion in the wurtzite structure. 46 The peaks at high binding energy around 532.3 eV arose from the O−H group of H 2 O which was adsorbed on the nanoparticles surface.…”

Ultrasound-assisted sequentially precipitated nickel-silica catalysts and its application in the partial hydrogenation of edible oil

“…In this case, the enhanced removal of the chemisorbed half-hydrogenated intermediate from the active sites could prevent the further isomerisation to TFAs. This alteration in electronic properties may be used to explain the decrease in TFA formation for the sonicated catalysts, relative to the unsonicated counterpart [2] , [94] . Hence, one of the functions of ultrasound in this case of catalyst synthesis might be as a selectivity modifier for the Ni catalyst.…”

“…Hence, one of the functions of ultrasound in this case of catalyst synthesis might be as a selectivity modifier for the Ni catalyst. Through sonication, the bonding strength of the adsorbates on the active sites were altered, which resulted in the increase of the energy barrier required for fatty acid isomerisation or the decrease of the energy barrier for hydrogenation that hastens cis -C18:1 to C18:0 conversion [94] . In particular, the shift from a higher to lower binding energy in the sonicated catalysts as observed in the XPS results ( Table 5 ) complemented this finding.…”

“… Sample Temperature and pressure Initial IV Final IV Reaction time (min) Trans -fats (%) Saturated fats (%) Oil feed employed Ref. Ni/ZnO/Al 2 O 3 180 °C 5 bar 162 70 130 22.8 33.5 Sunflower [94] Ni/SiO 2 180 °C 4.5 bar 138 70 44 26.1 33.6 Sunflower [62] Ni-Mg-Ag/D 160 °C 1.6 bar 130 90 255 26.3 5.8 Soybean [100] Ni-Ce/Al 2 O 3 180 °C 6 bar 115 70 33 26.4 16.6 Canola [4] Pd-Ru/SBA-15 110 °C 5 bar 130 70 60 24.5 16.5 Sunflower [101] Pd/γ- Al 2 O 3 100 °C 4.2 bar 125 90 20 19.9 5.6 Sunflower [102] Pd/SBA-15 110 °C 5 bar 130 80 60 34 10 Sunflower [103] Pt-Ni/SiO 2 170 °C 3 bar 130 70 180 …”

Investigation on the Catalytic Hydrogenolysis of Lignin over NbOx–Ni/ZnO–Al2O3

“…The peak centered at about 852 eV could be corresponding to Ni 0 . The peak located at about 856 eV could correspond to nickel aluminate . The peaks at 855.8 eV, 861.5 eV were attributed to NiO. − In addition, by calculating the peak area of various chemical states of Ni element in the XPS spectra, it was found that Ni 0 content increased from 12.3% to 20.2% with the increase of Nb/Ni ratio (Table S1).…”