Mar-2025

Catalyst rejuvenation for greener hydroprocessing

The chemical industry enables so much of modern life, reaching 96% of all manufactured goods. However, its contribution to emissions cannot be denied, making sustainability an increasingly important part of a business’s strategy.

Jignesh Fifadara and Madeline Green
Evonik Catalysts

Article Summary

Refiners face a balancing act to produce marketable products and maintain competitiveness in the face of increasingly stringent environmental regulations, external pressures, and surging energy costs. The challenge is to find economically efficient and sustainable operation methods without compromising performance or safety. Here, catalyst rejuvenation presents a solution. Marrying performance and cost savings, this technology can help businesses minimise environmental impact and reduce waste.

Rejuvenation technology
Evonik’s proprietary Excel rejuvenation technology focuses on reusing a catalyst after its lifecycle. A type of sustainable catalyst process, it recovers the full activity of spent hydrotreating catalysts, including the highly active Type II, to ensure their reuse in refining hydrotreating applications, with no loss to unit performance. The process involves the following steps:
• Verification: Only the highest quality catalysts are eligible for Excel rejuvenation in reuse applications. They must be free from contaminants, meeting strict chemical and physical specifications.
• Regeneration: A simple oxidation reaction that removes carbon and sulphur. Evonik’s technology utilises a moving belt, minimising attrition, maximising yields, and maintaining physical properties to restore 65-85% of original activity (depending on the original catalyst type).
• Rejuvenation: The catalyst undergoes a treatment process to redisperse the active metals across the catalyst substrate, restoring active sites to the catalyst’s original fresh activity.

The technology is relevant to both refining and re- refining and applicable to all manufacturers of both CoMo and NiMo catalysts. Potential applications include, but are not limited to, naphtha, kerosene, gasoline, ultra-low sulphur diesel (ULSD), gasoil, and hydrocracker pretreaters. Excel rejuvenation technology has been in commercial service since 2015 at numerous refineries internationally, consistently meeting or surpassing expectations.

Case study: High-pressure diesel hydrotreater
It can be seen in Figure 1 how Excel rejuvenated catalysts brought significant sustainability, performance and, cost benefits when used in an ULSD unit in Europe. The unit processes a blend of light gas oil (LGO), vacuum gas oil (VGO), and coker distillate at high pressure (72 barg) and severe liquid hourly space velocity (LHSV). Originally loaded with fresh catalysts, the business considered switching to rejuvenated catalysts for reduced lead times and lower fill costs.

Evonik supplied an Excel rejuvenated high-activity NiMo catalyst from its inventory, accompanied by the proprietary CatGuard top bed grading and Durocel bed supports, providing a full reactor solution. The rejuvenated catalyst performed equivalently to the previous cycle and at reduced expense. Scope 3 emissions were reduced due to using these catalysts, proving that performance does not need to be compromised in the journey to reduce emissions.

Environmental impact and waste were further minimised by the fact that using rejuvenated catalysts, as opposed to fresh ones, reduces the number of catalysts that would typically end up in landfills.

Case study: Low-pressure distillate hydrotreater
Similar benefits were recorded at a low-pressure distillate hydrotreater in North America, spanning performance, cost, and environmental impact.

The hydrotreating unit processes a blend of distillate cuts at low pressure (35 barg) and high LHSV to produce ULSD and jet fuel. Sourced from Evonik’s inventory, an Excel rejuvenated CoMo catalyst (KF-757) was used, with technical projections in line with the refinery’s performance objectives. A full reactor solution was provided.

As Figure 2 shows, Excel rejuvenated catalysts provided excellent stability and a low deactivation rate over the course of the cycle, meeting expectations with equivalent performance to the previous cycle. The refinery also benefited from lower Scope 3 emissions and reduced waste.

Conclusion
Performance does not have to be sacrificed in the pursuit of reduced emissions. Catalyst rejuvenation technology can support businesses in minimising waste and reducing emissions while maintaining stable and equivalent performance to fresh catalysts.

Additionally, externally certified Life Cycle Assessments provide avoided emissions calculations. In the instance of Excel rejuvenated catalysts, it has been found that their use results in a 60% reduction in CO₂eq/per kg of catalyst Global Warming Potential (GWP) emissions compared to fresh catalysts.

It is also crucial to note the cost savings Excel rejuvenation technology presents: between 30-50% savings when purchased directly from Evonik’s inventory and up to 50-70% savings when refining organisations reuse catalysts within their own systems.

A comprehensive solution for companies aiming to optimise performance, Excel rejuvenation technology allows for a greener, more circular approach to catalyst management.
Excel, CatGuard, and Durocel are marks of Evonik.