THE OLIGOMERIZATION OF 1-BUTENE USING NAY ZEOLITE ION-EXCHANGED WITH DIFFERENT NICKEL PRECURSOR SALTS

A number of catalysts were prepared by ion exchanging NaY extrudates w ith different nickel precursor salts. These nickel exchanged NaY catal ysts (NiNaY) were used to oligomerize butenes in the liquid phase usin g a batch reactor. The acidity of catalysts, determined by temperature programmed desorption, was found to be dependent on the type of nicke l precursor salt. The catalyst derived from nickel acetate was found t o have the highest acid strength, whereas the one derived from nickel chloride had the weakest acid strength. The nickel chloride catalyst a pparently had the highest activity of all those tested; this is attrib uted to the low deactivation rate of this catalyst. The addition of am monium fluoride and ammonium chloride to NiNaY derived from a nickel n itrate precursor salt resulted in an enhancement of oligomerization ac tivity. 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 pro motion showed the highest activity, best dimer selectivity and lowest deactivation rate of all the halide promoted catalysts tested under th e reaction conditions used in this study. A study of the effect of tem perature on the oligomerization reaction revealed that the reaction is diffusion-rate limited under the conditions used in this study. Solve nt was found to play an important role on activity and deactivation of the NiNaY catalysts. (C) 1997 Elsevier Science B.V.