COMPARISON OF THE EFFECTS OF NITROGEN POISONING ON MOLYBDENUM OXYCARBIDE AND PT BETA-ZEOLITE CATALYSTS IN THE ISOMERIZATION OF N-HEPTANE/

The effect of nitrogen-containing compounds was studied over MoO3-carb on-modified and Pt-(1,5 wt %)/beta-zeolite catalysts using n-heptane i somerization as the test reaction and piperidine and pyridine as the p oisoning molecules, n-Heptane isomerization performed over both cataly sts under pure feed showed no deactivation as a function of time on st ream. At a pressure of 6 bar the MoO3-carbon-modified catalyst exhibit ed a high resistance to deactivation up to 10 ppm of nitrogen, while t he Pt-based catalyst was strongly deactivated down to 30% of its initi al activity after 20 h. At higher concentrations of nitrogen (greater than or equal to 40 wt ppm) deactivation occurred over both catalysts as a function of time. Results obtained after different regeneration r egimes on the MoO3-carbon-modified deactivated catalyst led to the con clusion that the deactivation observed was essentially due to coke for mation. Finally, increasing the total pressure allowed a better resist ance to deactivation by hydrogenating the coke residues over the MoO3- carbon-modified catalyst.