Specialty Hydroprocessing

Specialty hydroprocessing (RHT/RHC)

ExxonMobil’s Raffinate Hydrotreating (RHT) and Raffinate Hydroconversion (RHC) technologies are commercially proven processes that can transform a Group I solvent lube plant into a Group II/II+/III advanced and flexible manufacturing facility in a cost-effective way.

Key benefits


RHT is ideally suited to provide a cost-effective solution for operators that want to convert a solvent plant from Group I to Group II/II+/III base stock production while retaining the existing solvent extraction plant. The RHT products are of the proper quality to be further processed with advanced Catalytic Dewaxing, such as ExxonMobil’s MSDW™ process. The flexibility of the RHT process allows the operator to vary the product Viscosity Index, thus effectively choosing which base stock Group to produce. RHT/MSDW can be applied to the full base stock slate, thus eliminating the need for the solvent dewaxer, or to selected grades only. In this second case, where some Group I base stocks continue to be produced via the conventional solvent-based route, overall lube production may even be increased through judicious optimization of the entire lube complex.


Manufacturers who want to upgrade their existing Group I plant to produce Group II/II+ base stocks for selected grades, while maintaining Group I production for others, should also consider the RHC technology. RHC processes raffinates from the existing solvent extraction into Group II+ oils that are then solvent dewaxed in the existing dewaxer. Group I lubes are processed only on the solvent extraction unit. The 1999 streaming of the Baytown RHC unit proved that an existing solvent plant can be transformed into a flexible facility to produce Group I products and Group II/II+ base stocks as well, at moderate cost. The RHC feeds can be under-extracted, thus expanding the solvent extraction unit capacity and providing maximum lube recovery from the combined extraction/RHC steps.
RHT and RHC thus offer a high-value process solution to expanding both the product range and the operating flexibility of an existing solvent-based lube plant. This raises the production value of the existing facilities while expanding the product quality capabilities and maximizing existing equipment use.


  • Leverage existing refinery infrastructure and process capacity
  • May result in significantly lower CAPEX investment than a new grass roots all-catalytic plant
  • Existing vacuum distillation equipment is retained
  • Existing solvent extraction is retained for feed preparation
  • Optimizing severity between solvent extraction and RHC maximizes total lube production
  • Existing solvent dewaxing can be retained, thus preserving wax byproduct
  • Low-risk application
  • Well-understood and widely deployed catalytic hydroprocessing technology
  • Commercially available catalyst choices
  • Robust design accommodates a wide range of crudes, VDU and extraction operations
  • Stable operation with long cycle life
  • Flexible operation
  • Adjust to saturates and VI needs by modifying solvent extraction and/or RHC severity
  • Adjust to NOACK needs with processing and back-end fractionation
  • Process full range of viscosity grades, or only selected ones to maximize value to refinery

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