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• Maximising cycle duration of hydroprocessing units has always been important to refiners, but what other step-out gains can we see from catalyst developments in terms of volume swell, PNA saturation, and HDN activity while achieving high HDS performance?

  Mar-2023

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Answers

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• Andrew Layton, KBC (A Yokogawa Company), andrew.layton@kbc.global

  CoMo catalyst was the typical distillate catalyst with high HDS but has improved in terms of available active sites and better surface areas contacting through Type II and equivalent catalyst active area changes. In many cases, these catalyst types also minimise H2 consumption. To process feeds high in N2 and boost cetane and cloud point, different catalysts became more important.

  NiMo catalysts improve Arosat (aromatics saturation) and HDN (most important in high N2), cracked and heavier feeds with additional Type II metals/base interaction. NiMo HDS/HDN reactions occur more through ring saturation than CoMo catalysts. Sometimes NiCoMo catalysts are a better fit.

  Improvements in catalyst ex-situ regeneration have enabled better catalyst re-use without sacrificing activity, even for Type II catalysts.

  While massive metal catalysts for high Arosat and HDS have a higher cost and higher H2 consumption, these catalysts deliver a large increase in potential activity and aromatic saturation capability. This type of catalyst can be considered when a sufficiently high partial pressure of hydrogen is available and for some lubes operations.

  Providing the reactor design is flexible enough to control bed temperatures adequately, isomerisation catalysts are now used in the bottoms beds to improve cold flow properties. The cloud reduction/isomerisation catalysts are also improving to reduce yield loss resulting from cracking reactions.
  Most vendors offer tailored solutions, though massive metal catalysts currently have limited suppliers.

  Each round of development affects the relative catalyst ranking. Thus, the catalyst selection should not be based on one vendor for too long without comparing catalysts from multiple vendors.

  Note that maximising cycle length may now conflict with minimising energy use and carbon emissions as longer run length can mean more fouling, require high-pressure operations, and increase compression costs. Thus, optimum cycle length should be re-evaluated for both new and existing units.

   

  Mar-2023