Catalysis 2024 Issue




Active sites

Metal redispersion

Active sites

Coke, sulphur


Fresh catalyst

Spent catalyst

Regenerated catalyst



Excel rejuvenated



Hydrotreating reactions

Mild regeneration

Catalyst activity 65 –85%

Proprietary organic molecules

Active sites restored

Catalyst activity Fresh performance

Figure 2 The rejuvenation technology redisperses active metals to restore catalyst activity back to its original state

and rejuvenation processes, which can restore activity nearly equal to that of fresh catalysts. The third method of deactiva- tion involves contamination by metals in the feed, which can poison the catalyst and lead to an irreversible loss of activity. A key point to note about catalyst regeneration and reju- venation technology is that only the highest quality catalysts are eligible for reuse applications. They must meet strict chemical and physical specifications. As mentioned, metal contaminants such as silicon, vanadium, and sodium (among many others) lead to irreversible deactivation. Poisoned cat- alysts are not well suited for reuse in refining applications. The chemical make-up is closely analysed on discrete por- tions of each batch of catalyst to ensure only ’clean’, uncon- taminated catalysts are approved to be regenerated and rejuvenated for reuse. The physical specifications are also analysed to ensure the catalyst has not been damaged dur- ing the hydrotreating cycle by evaluating parameters such as surface area, pore volume, and crush strength. Since the catalyst also goes through multiple additional handling steps, length and attrition are closely monitored to eliminate pressure drop concerns when reusing the catalyst in hydrotreating applications. Once the catalyst is verified to be free from contaminants and meets the bespoke physical property specifications, it is ready to undergo the first step of regeneration. The process The regeneration process is a combustion reaction that removes carbon and sulphur to restore some catalyst activity. Evonik’s technology utilises a moving belt (see Figure 2 ), a gentle process that minimises attrition, maximises yield, and maintains the physical properties of the catalyst. Additionally, the process integrates precise temperature control to ensure a uniform regeneration without hot spots or overheating of the catalyst. With this process alone, around 65-85% of the original activity can be restored, depending on the original catalyst type. If further activity recovery is required, the catalyst pro- ceeds to a second step, where Excel rejuvenation is intro- duced. In this phase, the catalyst undergoes a proprietary chemical treatment process to redisperse the active metals that have agglomerated across the catalyst substrate. This efficient redispersion of metals restores catalyst activity to its original fresh state. The technology is unique because it applies to all manu- facturers of both CoMo and NiMo catalysts, as demonstrated in the following case studies. It is also compatible with most

hydrotreating applications, spanning both low- and high- severity operating conditions or challenging feed charac- teristics. Excel rejuvenation has been in commercial service since 2015 at numerous refineries worldwide, consistently meeting or surpassing expectations (see Figure 3 ). Demonstrable benefits Given the refining industry’s unwavering focus on value and the demand for high-activity hydroprocessing catalysts, this technology serves as a highly advantageous solution for those looking to optimise costs and boost profitability and competitiveness. It delivers the same performance benefits and technical support that is to be expected from fresh cata- lysts but at 30-70% of the cost. It can also be applied to both Type I and Type II NiMo and CoMo catalysts in a range of hydrotreating applications, from naphtha through to heavy gasoil. Typically, the refiner has two options for implement - ing this technology into operations:  Supplied as a product from Evonik’s global inventory pool of high-quality catalysts Acquiring the catalyst this way can result in 30-50% cost savings in comparison to the base case of purchasing fresh catalysts. Due to this global presence, many high-quality and diverse spent catalysts can be accessed and rejuvenated quickly. Another key advantage this route offers is faster catalyst supply, with a substantially reduced lead time compared to fresh catalyst procurement.  As a service, applied to the refiner’s own catalyst Most significantly, when refining organisations reuse catalysts


Over 30 dierent catalyst types

>125 CoMo loads




>35 NiMo loads





2017 2018

2019 2020 2021 2022 2023

Figure 3 Significant growth of Excel rejuvenation globally across many catalyst types


Catalysis 2024

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