The oligomerization of 1-butene using NaY zeolite ion-exchanged with different nickel precursor salts Original Research Article

A number of catalysts were prepared by ion exchanging NaY extrudates with different nickel precursor salts. These nickel exchanged NaY catalysts (NiNaY) were used to oligomerize butenes in the liquid phase using a batch reactor. The acidity of catalysts, determined by temperature programmed desorption, was found to be dependent on the type of nickel precursor salt. The catalyst derived from nickel acetate was found to have the highest acid strength, whereas the one derived from nickel chloride had the weakest acid strength. The nickel chloride catalyst apparently had the highest activity of all those tested; this is attributed to the low deactivation rate of this catalyst. The addition of ammonium fluoride and ammonium chloride to NiNaY derived from a nickel nitrate precursor salt resulted in an enhancement of oligomerization activity. Temperature programmed desorption (TPD) studies indicate that the addition of halide anions lead to a modification of acid sites in the original NiNaY. The catalyst formed from the ammonium fluoride promotion showed the highest activity, best dimer selectivity and lowest deactivation rate of all the halide promoted catalysts tested under the reaction conditions used in this study.A study of the effect of temperature on the oligomerization reaction revealed that the reaction is diffusion-rate limited under the conditions used in this study. Solvent was found to play an important role on activity and deactivation of the NiNaY catalysts.