Excel® Rejuvenation: DHT Unit Case Study with Asian Refiner
Michael Martinez
Global HPC Technical Manager
Porocel Industries, LLC

Guillaume Vincent
HPC Business Segment
Manager Catalyst Recovery
Europe S.A.

Recent developments in rejuvenation technology enable activity recovery near fresh levels. By combining high activity rejuvenated catalyst with comprehensive top bed grading packages refineries are meeting stringent low sulfur diesel targets and achieving substantial cost savings. Through careful analysis of the feed and operating conditions, high activity rejuvenated catalysts can be installed with no impact on performance in a wide range of hydroprocessing applications. This article focuses on the commercial application of Excel® rejuvenated Type 2 CoMo catalyst in an Asian refiner that has observed equal performance to fresh catalyst while benefitting from reduced fill cost.

Conventional regeneration is a wellaccepted industrial process used to restore catalyst activity to 60 - 85% of fresh. The temperatures applied during the regeneration process effectively convert the active sites back to metal-oxides while removing carbon and sulfur. However, the exposure to high temperatures can cause sintering of the active metal sites and formation of agglomerates in the crystal structure such as CoMoO4 and NiMoO4, which inhibit full sulfiding of the metal oxides.

Traditional rejuvenation is a proven method to redisperse the active metal sites and increase the HDS and HDN activity beyond conventional regeneration. However, the rejuvenation technologies available to date have limited their application to select catalyst grades. Excel® rejuvenation technology expands the range of hydrotreating catalysts across all major manufacturers and consistently restores relative volumetric activity (RVA) to about 95% for Type 2 and about 100% for Type 1 catalysts of their initial activity. This patented process gives refiners an excellent alternative to fresh catalyst in a wide range of hydrotreating applications from naphtha through heavy gas oil. Excel® rejuvenation can be performed on the refiner's catalyst as a post-regeneration process. First, Porocel evaluates the spent catalyst to ensure only high quality uncontaminated catalysts are selected for rejuvenation. Catalyst chemical and physical properties are evaluated after regeneration and again after rejuvenation to confirm adequate activity.

The two-step process consists of an initial thermal regeneration to remove carbon and sulfur followed by a proprietary chemical treatment, which re-disperses metals and restores/stabilizes active sites for maximum activity. The process is applicable to Porocel regenerated catalysts or other brands, and can be performed at all of Porocel's facilities in North America, Europe and Asia. Up to date, Excel® rejuvenated catalysts have been loaded in many hydrotreating applications, worldwide, as Full Reactor Load (FRL) or as stacked beds, namely:
  • Diesel Hydrotreating Units (DHT)
  • Naphtha Hydrotreating Units (NHT)
  • Ultra-Low Sulfur Diesel (ULSD)
  • Cat Feed Hydrotreating (CFH)
  • Re-refining for lube oil production
Commercial Experience

Figure 1: Loading profi le and process conditions of DHT Unit loaded with Excel® Type 2 CoMo catalyst in Asia.

Porocel® has developed its own HPC kinetic model based on extensive in-house pilot tests in order to simulate hydrotreating unit's performance. Extensive technical support from startup through the end of cycle is included with all catalysts sold to ensure refiners achieve maximum performance including:
  • Complete design of reactor catalyst loading
  • Catalyst performance projections based on refinery process conditions
  • Review of start-up procedures with the refiner
  • On-site technical support during loading and activation
  • Troubleshooting
  • Unit monitoring during the cycle
  • Performance warranty

Table 1: Asian refi ner DHT performance with Excel® Type 2 CoMo catalyst

Full Reactor Loads (FRL) of high activity regenerated and/or Excel® rejuvenated catalysts drawn from Porocel's inventory combined with CatGuard® grading materials and ceramic bed supports (Durocel-222) are well suited for use in most units to meet your expected cycle length and product specifications. Up to date, Porocel® can supply the following top bed grading to maximize the cycle length of the hydrotreating unit:
  • Durocel-M1: Inert ceramic medallion offering better flow distribution
  • CatGuard® PMT-20: NiMo catalyst offering mild HDS/HDN activity to control hydrogenation of reactive components and mitigate pressure drop issues
  • CatGuard® PMT-21: NiMo catalyst specially designed to trap silicon while offering mild hydrogenation
  • CatGuard® PMT-30: NiMo catalyst specially designed to trap Nickel/ Vanadium from heavier feedstocks
  • CatGuard® PMT-40: NiMo catalyst specially designed to trap Arsenic
Porocel's FRL approach allows refiners to realize significant catalyst cost saving and decrease the quantity of hazardous waste generated, versus installing 100% fresh catalyst. Porocel's Excel® rejuvenation technology has been installed commercially and demonstrated high activity and robust stability. A full load of Type 2 CoMo catalyst was rejuvenated with Porocel’s Excel® technology and combined with CatGuard® top bed grading catalysts in a Diesel Hydrotreating (DHT) unit in Asia (Fig. 1).

The unit processes a blend of 30% light vacuum gas oil (LVGO) with straight run diesel (SRGO) in a challenging service with high throughput (LHSV =1.5 hr-1) and low inlet pressure 20 barg (290 psig). The primary objective of the hydrotreater is to produce low sulfur diesel, targeting a product sulfur of 450 ppmw. Porocel worked closely with the refiner to design a catalyst load incorporating high activity Excel® rejuvenated catalyst to meet all unit objectives. The Excel® rejuvenated catalyst is outperforming the fresh Type 2 CoMo catalyst loaded in the previous cycle and the actual performance of the DHT unit loaded with Excel® rejuvenated Type 2 CoMo is summarized in Table 1.

After 6 months on stream, the Excel® rejuvenated catalyst is exhibiting excellent stability despite the low unit pressure and heavy feed blend. A plot of normalized WABT vs Days on stream is presented in

Excel® rejuvenated catalyst is giving the refiner the expected performance, while enabling substantial cost savings versus loading fresh catalyst. The Asian refiner by using Porocel's FRL has saved approximately 450,000 USD (or400,000 EUR) for its DHT unit compared to an entire fresh load while achieving the same performance.


With the continuous refining-industry focus on value, Porocel's latest development, Excel® rejuvenation technology, provides the highest hydroprocessing catalyst activity at an unmatched economic value. Refiners seeking high activity hydroprocessing catalyst while keeping a close eye on catalysts costs are very well served by this method of rejuvenation, which can be applied to catalyst from the refiner's own units (as a service) or to regenerated catalyst from Porocel's own extensive catalyst inventory.

By combining Excel® rejuvenated main bed catalysts with other HPC products, such as Durocel-222 (ceramic bed support) and CatGuard® metal traps, for a Full Reactor Load (FRL), Porocel's HPC solutions enable refiners to achieve all unit objectives while saving 30 – 70% versus the cost of fresh catalyst loads. In addition, catalyst reuse helps refiners to significantly reduce the cost and the environmental impact of catalyst disposal. Porocel maintains a global inventory of rejuvenated catalyst available for use in combination with fresh catalyst or on its own. All Porocel rejuvenated catalysts are analyzed to ensure they meet stringent physical and chemical standards and come with a complete certificate of analysis to ensure high performance..