Influence of Nitrogen Feed Content On The Performances of A Zeolite Hydrocracking Catalyst

Abstract Hydrocracker feeds are usually rich in nitrogen compounds. These are partially transformed by the first-step hydrotreatment catalysts, creating an ammonia pressure in the reactors. This paper shows the effects of ammonia pressure on the performances of a zeolite hydrocracking catalyst. Ammonia has a strong negative effect on the activity for n-heptane conversion, especially at low ammonia pressures. Adsorption of ammonia on the acidic sites of the zeolite is quickly reversible for a wide range of pressure. However, at zero pressure, ammonia desorption is slow, meaning that the molecule remains strongly adsorbed on the most acidic sites of the zeolite. Ammonia also modifies strongly the products selectivity. Iso-heptane yield is increased to the expense of cracked products yield.