Characteristics and catalytic behavior of NiAlCe catalysts in the hydrogenation of canola oil: the effect of cerium on cis/trans selectivity

Abstract

A series of co-precipitated cerium-promoted nickel-aluminum catalysts was prepared. The physicochemical properties of the precursors were analyzed by means of various methods including XRF, HT-XRD, TPR, surface area and thermal decomposition as well as porosity measurements. The activity and selectivity of the NiAlCe catalysts in the hydrogenation reaction of canola oil were investigated and the results compared to those for the cerium-free catalyst. Besides improving some physicochemical properties of the precursors, the addition of cerium significantly improved the cis/trans selectivity, yet at the expense of some loss of the activity in case of larger cerium loadings. Upon addition of a relatively low amount of cerium (0.67 wt%) the content of the C18:1 trans fraction decreased by ca. 35 %. Together with the synergistic effect of the hydrogen pressure a significant decrease of the C18:1 trans fraction by ca. 48 % could be achieved. Furthermore, compared to the cerium-free catalyst, the addition of cerium resulted in a slower drop of the C18:1 cis fraction and a slower increase of the C18:0 fraction in time during the hydrogenation process.

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

“…Overall, Ni/Al 2 O 3 and 3_Ni/ZnO/Al 2 O 3 have yielded lower trans- fat and higher saturated fat as compared to Pt/Al 2 O 3 , Pd/Al 2 O 3 which was performed using sunflower oil. Comparing with other hydrogenation processes using Ni-based catalysts, such as Ni–Mg–Ag/D, Ni–Ce, and Ni–B, this work has demonstrated comparable if not lower trans- fat formation, though it should be noted that the reaction conditions and type of oil vary slightly from one another, which may have subsequently affected the overall trans -fat and saturated fat contents. Therefore, this work has managed to show the potential of incorporating ZnO onto Ni/Al 2 O 3 catalysts; seeing the positive results may provide in enhancing the hydrogenation activity and balancing between the formation of both trans -fat and saturated fats, depending on individual applications and requirements.…”

“…Modification of catalyst formulation by addition of another element to form a bimetallic catalyst was also found to alter the electronic structure of the active phases which helped to enhance the selectivity, activity, and stability of the catalysts. , For nickel catalyst, addition of cerium, silver, and boron were reported to reduce trans -fats formation but with some loss of activity compared to a single-metallic Ni catalyst. The effect of an additional element on selectivity of a Ni catalyst was also demonstrated by incorporation of sulfur as a promoter to increase trans -selectivity, which enabled the partially hydrogenated soybean oil to have a steeper melting profile similar to that of cocoa butter in order to act as a low-cost cocoa butter replacer albeit being deleterious to health.…”

“…16 Concurrently, certain changes in catalyst formulation and composition would also modify the pore characteristics. For example, varying amounts of cerium added into nickel catalyst 17 as well as addition of silver into nickel catalyst 18 were reported to slightly change the pore characteristics. Incorporation of Zn in Ni catalyst was also observed to substantially change the specific surface area of the catalyst.…”

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

“… 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 …”

“…support type, active metal content, reduction temperature, presence of doping agents, synthesis methods, etc. [2] , [3] , [4] , [5] . To illustrate, some of these properties such as the pore volume, pore length, particle size, total surface area and Ni crystallite size play a crucial role in determining the activity and selectivity of the catalysts [6] , [7] .…”