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• How can we minimise the time for catalyst to be fully sulphided?

  Mar-2021

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Answers

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• Guillaume Vincent, Porocel, gvincent@porocel.com

  Hydrotreating catalysts with metals in the oxide state are inactive for removing sulphur or nitrogen from hydrocarbon feedstocks. These metal oxides must be converted to metal sulphides to maximise activity according to one of the following options:

  -    In situ sulphiding, which requires sulphiding agents (for instance DMDS), heat, and hydrogen during the activation
  -    Ex situ preactivation (UltraCAT technology) which is fully preactivated and ‘ready-to-use’
  Legacy Porocel, which is now part of Evonik, specifically developed UltraCAT preactivation to provide a solution to convert oxidic catalysts in their sulphide state while offering the following benefits:
  -    Provide full activity for temperature limited units (<600°F/<315°C)
  -    Avoid temperature excursions and metal reduction during start-up
  -    Minimise H₂S generation for downstream units sensitive to sulphur (noble metal catalysts)
  -    Avoid the use of sulphiding agents, long dry-out steps, and complicated in situ activation
  -    Provide cracked feed protection, which allows the introduction of cracked feed immediately after start-up

  For in situ sulphiding, the typical dry-out step under hydrogen may last 24 hours and even up to 72 hours. This time is necessary to efficiently dry out the oxidic catalyst prior to ramping up the unit temperature and starting the DMDS injection, which typically lasts for an additional 24 hours.

  By using UltraCAT technology, your catalyst is delivered to your site fully preactivated and ready to use once the unit reaches the start of cycle temperature. With UltraCAT technology, there are no temperature holds and no DMDS injection, which results in faster start-ups with maintained optimal catalyst performances. The technology offers a cracked feed protection which allows refiners to gradually introduce the cracked feedstocks immediately after start-up, whereas a three-day break-in period is typically required for in situ sulphiding. A typical time savings comparison between in situ sulphiding and UltraCAT preactivation is shown in Figure 1.

  Mar-2021