Catalysis 2024 Issue



25% Excel/75% Fresh 50% Excel/50% Fresh 100% Excel
















Moly pricing ($/lb)

Figure 4 Excel technology can deliver substantial cost savings to the refiner

within their systems, they can achieve even higher cost sav- ings, ranging between 50% and 70% compared to the use of fresh catalysts. This option can also directly contribute to a refinery’s sustainability goals through reduced waste and GHG emissions. For additional flexibility, the regenerated catalysts can be easily cascaded between different units of varying severities or across refining sites. One of the key cost savings drivers over the last few years has been the fluctuating price of molybdenum (Mo), as this metal makes up a significant part of fresh catalyst (see Figure 4 ). An example is provided for 100 mt of hydrotreat - ing catalyst (Mo = 15 wt%), including three different loading configurations, either as stacked beds with fresh/ Excel reju - venated catalysts or a full load of rejuvenated catalysts:  25% of Excel rejuvenated catalysts, along with fresh catalysts.  50% of Excel rejuvenated catalysts, along with fresh catalysts.  A full load of Excel rejuvenated catalysts. Figure 4 highlights the recent variability in molybdenum pricing and the impact on cost savings to the refiner. Rejuvenation technology: Case studies in context Examining the case of a high-pressure diesel hydrotreater in Europe – specifically, a commercial ULSD unit – it can be seen

how Excel rejuvenated catalysts contributed to enhanced performance, cost savings, and sustainability benefits within the business. The hydrotreating unit processes a blend of light gasoil (LGO), vacuum gasoil (VGO), and coker distillate at high pressure (72 barg) and severe liquid hourly space velocity (LHSV). Originally, it was loaded with fresh catalysts, but the refiner considered a transition to rejuvenated catalysts due to the advantages of reduced lead times and lower fill costs. Once Evonik’s technical projections aligned with their per - formance objectives, the unit opted for an Excel rejuvenated high-activity NiMo catalyst (DN-3636), sourced from the Evonik inventory, accompanied by the proprietary CatGuard top bed grading and Durocel bed supports to provide a full reactor solution. As demonstrated in Figure 5 , the Excel rejuvenated cat - alyst’s performance was equivalent to the fresh catalyst in the previous cycle and at a reduced expense to the refiner. In addition, Excel rejuvenated catalysts contributed to a reduction in the refinery’s Scope 3 emissions, proving that emissions can be mitigated without sacrificing performance. Meanwhile, another supporting factor for using Excel reju - venated catalysts as opposed to fresh is that it reduces the number of catalysts that would typically go to landfill, min - imising environmental impact and waste and reducing the costs associated with disposal. A second case study demonstrating the commercial appli - cation of Excel rejuvenated catalysts involves a low-pressure distillate hydrotreater in North America. Once again, the cat - alysts brought performance, cost savings, and sustainability benefits to the refinery’s operation. The hydrotreating unit in question processes a blend of distillate cuts at low pressure (35 barg) and high LHSV to produce ULSD and jet fuel. Evonik worked closely with the refiner to explore catalyst options for the next cycle, using its kinetic model to project performance based on expected feed characteristics and operating conditions. Despite the refinery’s intention to handle more challenging feeds compared to the previous cycle, the technical projec - tions for an Excel rejuvenated CoMo catalyst (KF-757) from the inventory were in line with the performance objectives. A full reactor solution was provided, including Evonik’s CatGuard top bed grading and Durocel bed supports.






NiMo Excel

Alternative fresh catalyst


Days on stream

Figure 5 The Excel rejuvenated catalyst performed equivalently to the fresh catalyst in the previous cycle


Catalysis 2024

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