Optimising hydrotreating catalyst reuse with Excel rejuvenation technology (ERTC)

The refining industry is currently under pressure to optimise profit margins in challenging financial conditions while adapting to a changing global climate and resultant stricter environmental regulations. In this scenario, the industry needs to optimise its operating procedures and costs, and maximise profitability.

Guillaume Vincent
Evonik Catalysts

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Article Summary

Over many decades, our economy has taken a linear “take-make-dispose” approach, meaning raw materials are collected, transformed into products (e.g. hydrotreating catalysts) and used until they are finally disposed as a waste (e.g. in landfill). This has meant replacing hydrotreating catalysts at the end of their cycle, which can represent a significant expenditure for a refinery. However, depending on the severity of the hydrotreating application, the catalyst may be reusable after its cycle life, if it is clean enough, leading to a more “circular economy” approach, which aims to minimise the use of our resources.

Switching to a circular economy will allow us to optimise raw material usage, preventing waste, maximising reuse and saving money while also reducing total annual greenhouse gas (GHG) emissions. This approach can provide many benefits, such as reducing environmental impact, improving the security of the supply of raw materials, increasing competitiveness, and boosting economic growth.

Evonik offers a diverse set of hydroprocessing products and services, which can help refiners to reduce operating costs and maximise profitability while remaining environmentally conscious with their hydroprocessing applications. These solutions allow refiners to achieve the following benefits with catalysts:

1: Reduction of the catalyst refill cost compared to fresh catalyst

2: Faster catalyst supply compared to long lead time for fresh catalysts

3: Better environmental footprint: reduction of GHG emissions, avoidance of catalyst waste to landfill and optimal catalyst reuse.

4: Similar performance compared to fresh catalyst: hydrodesulphurisation/hydrodenitrogenation (HDS/HDN) activities, stability, and volume swell.

Evonik’s circular economy model
In hydrotreating reactors, catalysts are typically replaced after an interval of six months to four years, depending on the severity of the application. Hydrotreating catalysts are mainly deactivated by coke deposition over their lifetime. In order to recover the catalyst activity, the coke is burned off under mild oxidative conditions (e.g. ex-situ regeneration). During this heating treatment, active sites can agglomerate and inhibit the catalyst activity. Excel® rejuvenation, a step beyond regeneration, restores activity to near fresh levels. Excel rejuvenation enables these agglomerates to be dissolved while re-dispersing the active sites by utilising a proprietary chemical treatment (see Figure 1).

By using Excel rejuvenated catalysts, GHG emissions will be reduced, in comparison with fresh catalyst production, by approximately 6000 kg CO2eq/ton of  fresh catalyst replaced and thus contribute significantly to the circular economy. To put this into perspective, each ton of rejuvenated Excel catalyst saves as much CO2 as a business class flight for one person from Frankfurt to New York and back.

Over the past five years, Evonik has supplied more than 7500 tons of Excel rejuvenated catalysts refineries worldwide, resulting in reduced emissions of 45,000 tons of CO2eq. Excel rejuvenation technology allows the reduction of GHG emissions by about 67% compared to fresh production by limiting the raw materials usage compared to fresh production (see Figure 2).

Cost savings
Excel rejuvenation can also help refineries reduce their reactor refill cost with respect to full fresh load. Indeed, the refill cost is highly dependent on the molybdenum pricing, which represents a significant part of the fresh catalyst. An example is given below for 100 mt of hydrotreating catalyst (Mo = 15 wt%) including three different loading configurations, either as stacked beds with fresh/Excel rejuvenated catalysts or full load of Excel rejuvenated catalysts:

1: 25% Excel along with fresh
2: 50% Excel along with fresh
3: A full load of Excel (see Figure 3)

Hydrotreating catalyst performance
Excel rejuvenated catalysts demonstrated similar activity and stability performance as fresh catalysts. They are an excellent alternative to fresh catalysts for most hydrotreating applications: naphtha, kerosene, diesel, ultra-low sulphur diesel (ulsd) and vacuum gasoil (vgo) pretreat. As of today, Evonik has supplied more than 7500 mt of various type 2 catalysts, leading to more than 120 commercial loads of Excel rejuvenated catalysts. Excel rejuvenation has been in commercial service since 2015 at a number of refineries around the world and has met or exceeded expectations in every case.

For more information contact: guillaume.vincent@evonik.com


This short article originally appeared in the 2021 ERTC Newspapers, produced by PTQ / DigitalRefining.

You can view the Day 1 Newspaper HERE
You can view the Day 2 Newspaper HERE

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