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• In building the petrochemical value chain, how much further can we see the FCC unit being used to increase olefins production with the wide range of feedstocks currently available, including waste plastics-derived pyrolysis oil?

  Mar-2023

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Answers

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• Sanjay Bhargava, KBC (A Yokogawa Company), Sanjay.bhargava@kbc.global

  FCC gasoline is a major component of refinery-produced gasoline. Therefore, minimising FCC gasoline production can be an important step for oil refineries to reduce Scope 3 emissions. One way to reduce FCC gasoline is to convert it to propylene, as the demand for propylene is expected to increase significantly. Therefore, FCCs could become an additional source of propylene to meet the demand.

  Currently, FCCs produce about 4-8 wt% propylene on feed and have the potential to produce over 15 wt%. As a result, FCCs present the industry with a significant potential to produce more propylene while, again, reducing Scope 3 emissions. Olefin production in FCCs can be increased by several methods.

  Some of these include:
  • Operational changes with higher severities (higher riser outlet temperatures)
  • Naphtha injection or FCC naphtha recycle
  • Catalyst modifications to more olefin selective catalysts (such as smaller cell size with lower Al2O3)
  •· Catalyst additives (C3= selective ZSM-5)
  • Mechanical changes with available licensor technologies to accommodate higher severities.

  Waste-derived pyrolysis oil can also serve as a feedstock to FCCs. These include olefinic and aromatic-free feedstocks for FCCs and will produce naphtha and olefins in FCCs. However, the contaminants in pyrolysis oil, such as nitrogen, oxygen, chlorides, iron, and calcium, are significantly higher in pyrolysis oil than typical FCC feedstocks and, therefore, need pretreatment for contaminants before consideration as an FCC feedstock. If left untreated, the contaminants will cause increased corrosion and fouling in the downstream equipment and a significant increase in catalyst consumption due to catalyst poisoning.

  More environmentally friendly pathways that produce lower CO2 emissions are available for olefin production, such as waste plastics-derived pyrolysis oil facilities. However, each alternative has its pros and cons. For example, pyrolysis oil conversion to olefins requires significant electrical energy that may not be all green and has its own pollution problems from ash and other materials. Further, these facilities are expensive to set up, operate, and maintain. KBC believes the energy transition will take time. Thus, FCCs will play a significant role in the C3= olefin production market while co-existing with alternative pathways.

   

  Mar-2023