Isobutane/butene alkylation on a LaNaY zeolite. Characterization of carbonaceous deposits by CP/MAS13C n.m.r. spectroscopy

A LaY zeolite catalyst was used for the alkylation of isobutane with 1-butene. The zeolite is highly active and selective initially, but it rapidly deteriorates due to the formation of carbonaceous deposits. These deposits were characterized by elemental analysis and CP/MAS13C n.m.r. spectroscopy. In the deposits formed at 80°C, i.e., a typical alkylation temperature, only paraffinic carbon is detected. With increasing reaction temperature, the nature of the coke changes in a pronounced manner: more and more aromatics and olefins are found.