Impact of the chemical constituents of hydrotreater feed on catalyst activity. [Shell 324 M with 12. 4 wt % Mo and 2. 8 wt % Ni on alumina support]

In this paper the impacts on catalyst activity of four different chemical classes of compounds found in hydrotreater feeds are presented. These chemical classes included the aliphatic hydrocarbons, neutral polycyclic aromatic compounds (PAC), nitrogen polycyclic aromatic compounds (N-PAC) and hydroxy polycyclic aromatic hydrocarbons (HPAH). Separation of a light hydrotreater process stream into four chemical classes has shown that about half of the stream is composed of aliphatic hydrocarbons. There are also small amounts of N-PAC and HPAH fractions. Hydrotreating each of these four fractions and the whole process stream with catalyst has shown that all four fractions cause deactivation. The greatest deactivation is due to the N-PAC fraction, although the HPAH fraction also yields greater deactivation than the whole process stream. The deactivation is caused primarily by active site poisoning, with a lesser amount due to a decrease in effective diffusivity. 9 refs., 1 fig., 3 tabs.