Publication Search

The quality requirements for motor fuels are still tighter; the sulfur content has been reduced to 10 mg.kg-1 since 2009. A significant parameter in the ULSD production process is a hydrotreating catalyst and its long term activity. The determination of the long-term activity of HDS catalysts is not often applied to incorporate time constraints and economic factors. Usually, the initial catalytic activity is determined, but the rate of activity decrease is a very important parameter. In the practice, the decrease of activity is compensated by the increasing of the reaction temperature. Operating equipment has an upper temperature limit above which the unit cannot be effectively operated.Our research was focused on the verification and implementation of the testing method for the long-term catalytic activity. The verification was carried out with two commercial HDS catalysts. It included (i) testing of the initial activity and (ii) the determination of the rate of activity decrease. Deactivation step of a HDS catalyst was realized by injection of highly aromatic raw materials with a tendency to coking. During 2 hours the non-standard reaction conditions were set (atmospheric pressure, without hydrogen flow). After the deactivation period the typical conditions were set (pressure 4.5 MPa, hydrogen flow 300 Nm3/m3, and WHSV 1.0 kg/dm3cat). Subsequently, the reaction temperature for sulfur level 10 mg.kg-1 (ppm) was determined. The catalysts were also placed into the industrial reactor and allowed to run for approximately 16 month in industrial conditions (deactivation). The residual activity of the catalysts was determined. The results from the accelerated and the industrial deactivation run were compared. The accelerated deactivation procedure corresponds with the results of the residual activity of operational catalysts deactivation.