Browsing by Subject "Oligomerization"

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    FTIR spectroscopic study on nickel(II)-exchanged sulfated alumina: nature of the active sites in the catalytic oligomerization of ethene
    (Springer, 2002) Davydov, A. A.; Kantcheva, M.; Chepotko, M. L.
    The nature of the active sites in nickel(II)-exchanged sulfated alumina in the reaction of ethene oligomerization has been studied by means of FTIR spectroscopy of adsorbed CO. It has been established that isolated nickel(I) species are the active sites in this process. These sites are formed by a reduction process, in which protonic centers are involved. The latter are due to the presence of covalently-bonded sulfate ions on the catalyst surface.
  • Thumbnail Image
    ItemOpen Access
    Oligomerization of ethylene in a slurry reactor using a nickel/sulfated alumina catalyst
    (American Chemical Society, 1997) Zhang, Q.; Kantcheva, M.; Dalla Lana, I. G.
    During the oligomerization of ethylene over heterogeneous catalysts, the production of α-olefins may be lowered because of an accompanying deactivation of catalyst resulting from strong adsorption of products, by isomerization or by a tendency to copolymerize into branched products. The oligomerization of ethylene was studied using Ni(II)/sulfated alumina catalysts prepared with a nonporous fumed alumina (ALON) support. The influences of methods of catalyst preparation and activation upon oligomerization activity were screened using a gas - solid microreactor. On the basis of the test results obtained in the microreactor, a modified form of the superior catalyst was prepared and its performance was examined in more detail using a well-agitated gas - liquid - solid slurry reactor. This catalyst exhibited very good oligomerization activity with no apparent deactivation in the slurry reactor at temperatures at or below 298 K and at near-atmospheric pressure. Complete conversion of the ethylene with the production of mainly two oligomers, 1-butene and 1-hexene, was attained. After 34 h in the slurry, formation of a significant amount of two branched C6 isomers was observed.