DUAL MECHANISM OF PYRIDINE HYDRODENITROGENATION ON MOSX-BASED CATALYSTS - EXPERIMENTAL-EVIDENCE

Hydrodenitrogenation (HDN) of pyridine has been performed on Mo and NiMo-based catalysts first sulfided and then treated under H2 at various temperatures TR in order to progressively create anionic vacancies at the active phase. No H2S has been admitted in the feed during the test performed at 3 MPa. The changes in the products and the effect of the H2 partial pressure have been interpreted by a dual mechanism of HDN. The classical consecutive scheme to pentane as product with detection in the gas phase of piperidine as an intermediate product has been found dominent at low TR. At higher TR, with a more sulfur-deficient catalyst, another route without any detection of the intermediate piperidine has been observed. © 1991.