AM-10-152 ULSD Catalyst Stability: Making the Cycle Length

Description:

Since moving to ultra-low sulfur diesel specifications, catalyst stability in distillate hydrotreaters has become a more important issue than ever before. Planning a cycle length can be difficult, as the margin for error in ULSD is already extremely narrow, and small unit upsets or overtreatment can cause catalyst deactivation that shortens catalyst life by months. Short cycles are costly to the refiner, and an increased catalyst change-out rate introduces significant safety concerns. There is big incentive to find stable catalysts: those that can not only produce ULSD but that will go the distance and make or exceed the cycle length even if it hits bumps in the road. The first step is a reliable test program to screen and evaluate catalyst stability. The next step is not only to understand the results, but to interpret them to make technical and commercial decisions about catalysts. This paper will focus on the importance, relevance and limitations of testing catalyst stability in the pilot plant. First, we will describe BP’s testing protocol and method. Second, we will present the results of a BP-Axens replicate study focusing on test repeatability and reproducibility.