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Residue Hydroconversion & Hydroprocessing

Tightening environmental regulations, including IMO fuel specifications, and increasing pressure to maximize bottom-of-the-barrel value have made residue hydroprocessing and hydroconversion essential technologies for vacuum residue (VR) upgrading.

Axens offers two proven hydrogen-addition pathways: fixed-bed residue hydrotreating with Hyvahl™ and ebullated-bed hydrocracking with H-Oil®, enabling refiners to improve residue conversion, product quality and profitability.

Turning Feedstock Challenges into Opportunities

As market dynamics continue to evolve, future-ready refineries need the flexibility to process diverse crude oil feedstocks without compromising product quality. Advanced residue conversion technologies, including fixed-bed Residue Hydrotreating (Hyvahl™) and ebullated-bed hydrocracking (H-Oil®), enable refiners to unlock greater value from challenging feedstocks right from the start of the refining process.

200+

Successful reactor permutations completed with zero safety incidents, enabled by Axens' Permutable Reactor System (PRS™) for catalyst replacement without unit shutdown.

93%

Of net residue conversion has been achieved and sustained in commercial operation. This demonstrates the value of vacuum bottoms recycle in maximizing residue upgrading and expanding the limits of conversion.

60Y

H-Oil® technology is a proven solution backed by more than 60 years of operating experience. Continuous feedback from operating units and ongoing design enhancements have delivered significant benefits to both new and existing units.

Select an application

Atmospheric and vacuum residue (AR/VR) hydrotreating—also known as residue desulfurization (RDS)—is designed to upgrade heavy residues into higher‑value products. Depending on refinery objectives, an RDS unit can either produce low‑ to ultra‑low‑sulfur fuel oil (LSFO/VLSFO/ULSFO) for bunker applications, or pretreat residue to supply a cleaner feed to Residue Fluid Catalytic Cracking (RFCC) units, boosting yields of high‑value gasoline, diesel and chemicals while limiting RFCC operating costs. 

The same fixed‑bed hydrotreating technology is also applied to specialty streams such as slurry oil or pyrolysis oil to produce premium carbon‑materials feedstocks (e.g., carbon black, anode‑grade or needle‑coke precursors). 
Axens’ portfolio combines the Hyvahl™ process and advanced resid hydrotreating catalysts.

Process Technologies

Hyvahl™

Hyvahl™ is Axens’ fixed‑bed RDS technology built around staged catalyst sections and a Permutable Reactor System (PRS™) for demanding residue services. The reaction section typically starts with PRS™ guard reactors performing HDM (demetallization), where a significant share of metals, sediment and asphaltenes is removed to protect downstream catalysts, then proceeds through a transition zone and a final refining section for deep hydrotreating: HDS/HDN and CCR reduction (HDCCR). 

PRS™ relies on a proven lead/lag guard‑bed arrangement and dedicated valving so a guard reactor can be taken offline for catalyst replacement while the main reactor section remains in operation—supporting longer cycles and stable effluent quality on high‑contaminant feeds, including up to 100% VR.

Commercial track record: 8 Hyvahl™ units processing AR, VR and slurry feeds are in operation, representing 35+ years of cumulative operating experience. 

Commercial Bulletin
Scheme Hyvahl Axens

Catalysts & Grading Materials

Catalysts

Residue Hydrotreating Catalysts

RDS units include a number of reactors in series, each with a dedicated function. These units require a tailored catalyst system characterized by three reaction zones where the types and quantities of each catalyst are determined as a function of the feedstock difficulty and the objectives of the unit.

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Gradings

Arsenic Management

Arsenic is by far the most severe poison for Catalysts. Arsenic maximum allowable content on hydroprocessing catalysts during operation, depending upon the service, is in the range of hundreds of wppm.

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Gradings

Gums & Polymer formation control

Pressure drop induced by gum formation is frequently encountered in unit processing some cracked feedstock derived from various conversion processes. The olefins and mainly the diolefins contained in these streams tend to polymerize and get oxidized forming a crust which deposit in the upper layers of the reactor.

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Gradings

Nickel & Vanadium Management

Nickel and vanadium are naturally present in Crude Oil and usually in fractions boiling over 500°C. Nickel and vanadium poisoning affect only VGO and resid hydrotreaters and hydrocrackers.

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Gradings

Silica Management

Silicon is a well-known widespread poison for hydroprocessing catalysts. The main contributor to silicon is the Delayed Coker. In addition, there is a general tendency in the oil production industry to use more silicon-based flow improvers.

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Gradings

Speciality Bed Topping

In Hydroprocessing reactors, pressure drop is mainly induced by particulates build-up and gum formations. Pressure drop not only affect the capacity of the unit but can also have detrimental impact on the distribution.

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Furnaces & Heat Recovery

Furnaces for Benzene Production

Heurtey Petrochem Solutions offer furnaces for various services with high fuel efficiency, lowest emissions and maximum modularization. Additionally, Heurtey Petrochem Solutions offer emission reduction technology / system design for various pollutants which are integrated with furnaces and waste heat recovery units.

Find out more
Aromatics

Consulting, Supply & Support

Consulting, Studies & Audits

Axens offers a customized approach, including tailored studies, audits and consulting services, covering technical and operational challenges.

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Unit Revamps & Retrofits

You face many challenges, which include operating in a safe, reliable and environmentally sound manner while responding to changing markets dynamics.

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Training Solutions & Knowledge Management

Designed for all Axens technologies, dedicated to operators & engineers, Axens offers customized training solutions to all our licensees, covering the whole range of Axens technologies.

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Technical Support & Performance Management

Axens is fully committed to be your partner and provide assistance and support during your project lifecycle, from conception to start-up & running operations.

Read more

Digital Services & Applications

Axens' digital platform combines real-time data and digital solutions to optimize operations, reduce environmental impact, and lower costs while maximizing profitability. By delivering actionable insights and detailed performance reports, it enhances asset operation and performance for smarter, more efficient outcomes.

Read more

Catalyst Protection Systems

Impurities, fines, gums, scales and inorganic matter can be carried over with the feed. While catalyst performance is steadily increasing due to constant innovation, they are often more sensitive to poisoning.

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Reactor Internals

In today’s complex environment, refineries and petrochemical plants around the world need advanced solutions to reach operational excellence. In units featuring fixed-bed reactors, the use of high-efficiency reactor internals are essential to help achieve this goal.

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With industry-leading feed flexibility, H-Oil® enables refiners to capitalize on lower-cost opportunity crudes and residue streams. Suitable feeds range from atmospheric and vacuum residues (ARs and VRs) to refractory oils such as DAOs, VGOs, HCGOs, coal liquefaction slurries (DCL), and steam cracker PyOil.

Process Technologies

H-Oil®

Axens is the global leader in ebullated-bed hydrocracking, with more than 25 commercial references worldwide, making H-Oil® one of the most proven residue conversion technologies for vacuum residue upgrading and heavy oil upgrading. Backed by decades of operating experience, H-Oil® converts heavy feedstocks and vacuum residues into high-value products, achieving vacuum residue conversion levels from 70 to 93 wt%.

Its unique ebullated-bed reactor design, with continuous catalyst addition and withdrawal, delivers high-performance residue hydrocracking, residue hydroconversion, and hydrodesulfurization while eliminating shutdowns for catalyst replacement and achieving stream factors above 96%. H-Oil® has successfully processed a broad range of heavy feedstocks, from Russian Urals vacuum residue and Canadian bitumen to PyOil, either in standalone configurations or as part of Crude-to-Chemicals schemes.

Combined with proven residue hydrotreating catalysts and extensive commercial expertise, H-Oil® enables refiners to maximize bottom-of-the-barrel conversion, enhance residue valorization, and produce cleaner fuels, including Very Low Sulfur Fuel Oil (VLSFO) and Ultra Low Sulfur Fuel Oil (ULSFO).

Advanced Options to Maximize H-Oil® Performance

Several configuration options enable refiners to further increase conversion, improve product stability, and maximize value from heavy residue processing.

  • Low Space Velocity Operation 
    Achieve over 90% vacuum residue conversion while maintaining excellent product quality and stability.
  • HCAT® Technology from HTI 
    HCAT® liquid catalyst precursor technology enhances catalytic hydrogen transfer, expands the conversion envelope, and further improves product stability.
  • Integrated Residue Upgrading Schemes 
    H-Oil® can be integrated with SDA, Delayed Coking, or Flexicoking® units to maximize residue valorization, reduce carbon rejection, and increase the recovery of valuable products from heavy feedstocks.

These flexible configurations allow refiners to tailor H-Oil® performance to specific feedstock challenges and business objectives. 

Commercial Bulletin
Scheme Axens H-Oil

Furnaces & Heat Recovery

Furnaces for Benzene Production

Heurtey Petrochem Solutions offer furnaces for various services with high fuel efficiency, lowest emissions and maximum modularization. Additionally, Heurtey Petrochem Solutions offer emission reduction technology / system design for various pollutants which are integrated with furnaces and waste heat recovery units.

Find out more
Aromatics

Consulting, Supply & Support

Consulting, Studies & Audits

Axens offers a customized approach, including tailored studies, audits and consulting services, covering technical and operational challenges.

Read more

Unit Revamps & Retrofits

You face many challenges, which include operating in a safe, reliable and environmentally sound manner while responding to changing markets dynamics.

Read more

Training Solutions & Knowledge Management

Designed for all Axens technologies, dedicated to operators & engineers, Axens offers customized training solutions to all our licensees, covering the whole range of Axens technologies.

Read more

Technical Support & Performance Management

Axens is fully committed to be your partner and provide assistance and support during your project lifecycle, from conception to start-up & running operations.

Read more

Digital Services & Applications

Axens' digital platform combines real-time data and digital solutions to optimize operations, reduce environmental impact, and lower costs while maximizing profitability. By delivering actionable insights and detailed performance reports, it enhances asset operation and performance for smarter, more efficient outcomes.

Read more

Catalyst Protection Systems

Impurities, fines, gums, scales and inorganic matter can be carried over with the feed. While catalyst performance is steadily increasing due to constant innovation, they are often more sensitive to poisoning.

Read more

Reactor Internals

In today’s complex environment, refineries and petrochemical plants around the world need advanced solutions to reach operational excellence. In units featuring fixed-bed reactors, the use of high-efficiency reactor internals are essential to help achieve this goal.

Read more

Maximize the Conversion in Residue Hydroconversion & Hydroprocessing

Mature & Proven

Decades of commercial success, with more than 60 years of operating experience worldwide.

Market Adaptation

Designed to process a broad range of crudes, with performance supported by IFPEN pilot testing.

High Availability

Replace guard catalyst via PRS lead/lag operation, without shutting down the main reaction section—maximizing on‑stream factor.

Enhanced Flexibility

HCAT® catalyst precursor technology from HTI can be applied to operating and grassroots units, expanding conversion envelope and improving product stability.

Seamless Integration

Easy integration with downstream conversion technologies enables maximum residue upgrading and on-spec product production.

Safe & Reliable

Proven, dependable operation with PRS isolation/valving features designed for safe switching and stable performance over time.

What our Clients Say

Residue Hydroconversion & Hydroprocessing

Continuous Technical Guidance for Sustainable Performance

Over nearly seven years of operation, the H-Oil® unit has demonstrated strong flexibility in processing a wide range of vacuum residues. While clients may expect challenges when processing low-sulfur residues or feedstocks with high CCR, metals, and asphaltene contents, these can be successfully managed through careful operation and feedstock control...
Residue Hydroconversion & Hydroprocessing

A Flexible Solution for Changing Crude Markets

Since its start-up in 1997, the H-Oil® unit has demonstrated exceptional flexibility, operating successfully for nearly 30 years on a wide range of feedstocks. While the unit primarily processes vacuum residues from low-metal crudes, it can effectively adapt to feedstocks with higher metals and asphaltene contents...

    Frequently Asked Questions

    Why do refiners choose Ebullated Bed technology?

    Refiners choose H-Oil® because it helps maximize conversion of heavy residues, improve crude flexibility, increase production of valuable clean fuels, and enhance refinery profitability.

    How long does the catalyst cycle last?

    One of the key benefits of H-Oil® is the ability to continuously add fresh catalyst and withdraw spent catalyst while the unit remains online. Therefore, the Ebullated Bed technology cycle does not depend on the catalyst activity.

    How does Hyvahl™ and H-Oil® support sustainability and regulatory compliance?

    Together, these Axens technologies enable cleaner fuel production, reduced environmental impact, and enhanced refinery sustainability. Hyvahl™ produces low-sulfur and ultra-low-sulfur fuel oils compliant with regulations such as the IMO marine fuel sulfur limits, while H-Oil® upgrades heavy residues into cleaner, higher-value fuels and improves the overall utilization of crude oil resources.

    How does Permutable Reactor System PRS™ improve unit availability?

    PRS™ uses a lead/lag guard reactor configuration that lets operators isolate one guard reactor and perform all required operations for its catalyst replacement while the rest of the unit remains in service, helping maximize on‑stream factor and avoid shutdowns driven by guard bed pressure‑drop or premature deactivation.
      Explore some

      Resources

      FAQ

      How does Permutable Reactor System PRS™ improve unit availability?

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      FAQ

      How does Hyvahl™ and H-Oil® support sustainability and regulatory compliance?

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      FAQ

      Why do refiners choose Ebullated Bed technology?

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      FAQ

      How long does the catalyst cycle last?

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      More resources
      Insight

      Maximizing the Production and the Transformation of Aromatics

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      Insight

      Targeting the Highly Coveted Olefins

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      Insight

      Recommended Process Routes for Maximized Oil Conversion to Aromatics and Olefins

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      Insight

      From Refining to Chemicals, a Switch of the Yield in 4 Stages

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      See all Insights
      Petrochemicals
      Case Study

      Case Study - Refining to olefins production

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      Oil Refining
      Case Study

      Case Study - Refining petrochemicals integration

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      See all Case studies
      Whitepaper

      White Paper - Crude-to-Chemicals

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      Technical article

      Technical Article - Guiding the crude-to-chemicals complex towards a net-zero future

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      Technical article

      Technical Article - Implementing Advanced Technologies for Crude to Chemicals Projects

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      Technical article

      Technical Article - Flexible Upgrading of Heavy Feedstocks

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      Technical article

      Technical Article - First Residue Hydrocracker Starts-Up In Asia/Pacific

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      See all Technical articles
      FAQ

      Why do refiners choose Ebullated Bed technology?

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      FAQ

      How long does the catalyst cycle last?

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      FAQ

      How does Hyvahl™ and H-Oil® support sustainability and regulatory compliance?

      Read more
      FAQ

      How does Permutable Reactor System PRS™ improve unit availability?

      Read more
      See all FAQ
      Press release

      Axens and Sinopec Zhenhai Refinery & Chemicals Company announce the completion of the Performance Guarantee Test Run of H-Oil® unit

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      Press release

      Axens Signs an Agreement with Hengyi Industries to Provide FLEXICOKING™ Technology

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      Press release

      Axens and ExxonMobil Sign Alliance Agreement

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      Press release

      Axens and ExxonMobil Catalysts and Licensing LLC Sign Alliance Agreement

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