(111c) Novel Ni-Siral Catalysts for the Production of Alkenes and Cyclo-Alkanes Via Ethylene Oligomerization

The adverse environmental impact of fossil fuels has expedited the development of alternative energies specifically biofuels to gain traction. Constituents of jet fuel such as linear and cyclic hydrocarbons can be produced from sustainable sources which have the ability to reduce soot generation, prevent leaks in fuel systems and increase energy content. Research has shown that solid heterogenous catalysts play a pivotal role in reactions that promote yield and selectivity of linear and cyclic hydrocarbon compounds which are constituents of jet fuel. The oligomerization of ethylene is one of the main routes considered for the conversion of ethylene into these hydrocarbon mixtures. Commercial ethylene oligomerization process uses organometallic based homogeneous catalyst, in which case it is difficult and expensive to separate catalyst from products. Conversely, the development of heterogeneous catalyst with the ability to promote coke dissolution preventing pore plugging and consequent catalyst deactivation is a paramount factor in this reaction. Previous studies have reported production of 43% yield of liquid products with supercritical ethylene at 65 bar and 200 with 2.8wt % nickel loading of a novel Ni-SIRAL 40 HPV catalyst, consequent of its large pore volume and hence its ability to minimize coking.

Therefore, this study explores the production of liquid alkanes and cyclo-alkanes via the oligomerization of ethylene by loading 2.8wt % nickel on different SIRAL supports (SIRAL 10, SIRAL 20, SIRAL 30, SIRAL 40, SIRAL 40 HPV which have pore volumes of 0.75, 0.8, 0.9, 1.0 and 1.5 ml/g respectively) as SIRALs have a comparatively high level of surface acidity, large pore volume which minimizes coking making them useful as support materials. Testing the five catalysts synthesized (Ni-SIRAL 10, Ni-SIRAL-20, Ni-SIRAL 30, Ni-SIRAL 40, Ni-SIRAL 40 HPV) in the ethylene oligomerization reaction, this study will report the following (i) the activity of the different catalysts in the fixed-bed reactor used to carry out the oligomerization reaction. (ii) the most promising SIRAL support for increased liquid yield and product selectivity (iii) investigation of the effect of physiochemical properties obtained via characterization of the catalysts on the oligomerization reaction (iv) tested performance results of the Ni-SIRAL catalysts under different reactor conditions of varying temperature and pressure. Furthermore, the active metal (Ni) in the catalyst which produces the most promising results will be replaced with another active metal, chromium for further investigation.