Supercritical Carbon Dioxide as a Reaction Medium for the Zeolite-Catalyzed Alkylation of Naphthalene

Abstract

The alkylation of naphthalene with methanol and 2-propanol over the zeolite catalyst LaNaY-73 has been conducted in supercritical carbon dioxide as the reaction medium at 250 °C. Catalytic experiments under flow conditions have been performed at high dilution of the reactants (mole fractions < 0.05) and in the pressure range from 1 to 400 bar. Catalyst deactivation is strongly reduced at supercritical conditions as compared to the one in the gas phase. A pressure increase at supercritical conditions results in a higher catalyst activity. The yield ratio of the major reaction products, i.e., mono- and dialkylnaphthalenes, mainly depends on the alcohol/naphthalene ratio in the feed and is independent of the reaction pressure and the degree of catalyst deactivation. The distribution of isomers within the mono- and dialkylated products changes with time on stream, according to a shift from thermodynamically to kinetically controlled product formation, the extent being dependent on the reaction pressure and th...