INFLUENCE OF NH3 PARTIAL-PRESSURE ON THE ACTIVITY OF AN INDUSTRIAL HYDROCRACKING CATALYST FOR THE HYDROCONVERSION OF N-HEPTANE

The hydroconversion of n-heptane has been studied either in the presen ce or absence of NH3 on a hydrocracking catalyst prealably deactivated by coke in an industrial unit. When NH3 is added, a loss of activity is observed (deactivation) but is totally reversible (inhibition). Thi s loss is all the more important as long as the NH3 partial pressure i ncreases. An equation linking the hydroconversion rate of n-heptane an d the pressure of ammonia has been elaborated It is based on a classic al bifunctional mechanism assuming that the limiting step is the isome risation of intermediate n-heptanic carbenium ions. In industrial unit s, this equation could be used to ajust the operating conditions each time the feed is changed.