ExxonMobil chemical celestia waves

Specialty hydroprocessing (Celestia™ catalyst)

Through unprecedented hydrodesulferization (HDS), hydrodenitrogenation (HDN) and aromatic saturation activity, Celestia™ ultra-high activity, bulk-metal hydroprocessing catalyst can provide you with step-out performance and operational flexibility.

Key benefits

Celestia catalyst application

Celestia catalyst is jointly developed by industry leaders ExxonMobil and Albemarle. Often deployed with its predecessor, Nebula®, the new Celestia catalyst provides operational flexibility, exceptional earnings and refinery optimization to add value beyond the hydrotreating battery limits. Commercial applications of these technologies are available in distillate hydrotreaters, as well as in light cycle oil (LCO) and vacuum gas oil (VGO) hydrocracker pretreaters.

celestia catalyst application chart

Hydroprocessing value

The Celestia™ catalyst activity, when used well, can help improve margins by delivering value beyond the hydrotreating unit battery limits in many ways, including:

Processing challenged/opportunity crudes

Enabling feed scale-up

high-value products in the refinery


Proven performance

Based on the expertise gained through more than a decade of commercial experience with Nebula, Celestia was developed by ExxonMobil and Albemarle as the next step in advancing catalyst technology. Since 2015, Celestia has demonstrated step-out performance and created new opportunities for growth at ExxonMobil facilities. Now it is available to refiners in fuels application.

value captured in the refinery graph

Case study

A stacked load of Celestia and Nebula catalysts was loaded into the pretreat section of a once-through heavy feed hydrocracker, processing a challenging blend of high endpoint virgin and coker vacuum gas oils (VGOs) to produce fuels and steam cracker feed. The unit pretreat reactor was loaded with approximately 30% Celestia/Nebula. The Celestia deployment was a first application; Nebula had been part of prior reactor loads.

The addition of the Celestia catalyst produced significant value to the VGO hydrocracker operation:

  • The feed rate of a highly challenging coker VGO was maximized
  • Significantly reduced Nitrogen slip
  • Increased aromatic saturation and unit conversion with higher diesel and jet yields
  • Improved product quality, including diesel cetane and jet smoke point
  • Hydrocrackate export quality improved, leading to higher profitability in an affiliate steam cracker Higher heat recovery leading to a reduction in furnace firing and significant energy savings

pretreating with celestia in single stage hydrocrackling

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