Sulzer GTC technology licensing

A global licensor for your process technologies and mass transfer solutions

Offering innovative, custom solutions for the refining, chemical, petrochemical and gas processing industries. Refining, petrochemical and chemical companies around the world rely on Sulzer GTC’s advanced technology to optimize production capacity and efficiency, reduce operating cost and minimize environmental impact.

gtc technology licensing
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GTC’s innovations center around:

  • Technology licensing
  • Engineering services
  • Technical services
  • Process equipment technology (PET)
  • Energy saving services
  • Chemicals and catalysts
  • Research and development

Our patented suite of technologies fall broadly into the Petrochemical, Refinery, Gas Processing and Polyester Intermediates market segments. GTC’s petrochemical technologies available for license focus on value-added products from the steam cracker including BTX, styrene, naphthalene and various C5s. It is important for crackers using liquid feedstocks to upgrade all of the by-products in order to maintain competitiveness with the crackers using low-cost ethane feedstock. Our refining technologies upgrade fuel streams or convert fuel to higher value petrochemicals. These include CCR naphtha reforming, light naphtha isomerization and direct recovery of BTX from FCC gasoline.

GTC’s portfolio also includes a range of processes for meeting the clean fuels mandate for benzene reduction and low-sulfur products. In the polyester value chain, GTC’s licensees can benefit from breakthrough technology to reduce bromine and burning losses in the PTA oxidation system and avoid the high-pressure hydrogenation system to purify the TA. We offer a hybrid adsorption/crystallization scheme for PX recovery, and conversion of all aromatics in the raw material in xylenes, with the option for zero benzene co-production using our toluene alkylation process.

Our portfolio comrpises, among others:

Figure 1. Integrated BioFlux® Unit

BioFlux Renewable Diesel

Versatile Hydrotreating Process

BioFlux® is a novel hydrotreating technology that addresses key issues challenging renewable diesel operators.

The BioFlux® Hydrotreating Unit has been designed to overcome the deficiencies of a trickle-bed design by completely dissolving hydrogen into the liquid.  High liquid mass flux is maximized in the reactor, and the proprietary reactor internals ensure complete mixing of feed and hydrogen for even distribution across the catalyst. In the first stage, triglycerides and lipid-based feeds are reacted with hydrogen to remove oxygen and saturate olefins, which generates a diesel-range hydrocarbon product.  Water, CO2, and other by-products are also generated. After by-product removal, a portion of the first reactor product is recycled and mixed with fresh feed. This recycled effluent provides three benefits: pre-heat to the fresh feed, which reduces the requirement for supplementary preheat; supply of additional hydrogen; and elimination of large gas recycle.  Combined, these changes lead to a 25% reduction in CAPEX and a 25 – 50% reduction in OPEX. 

Yield of diesel from BioFlux® is approximately 95-99wt%. On a volume basis, it is nearly an even ratio, i.e., one barrel of renewable diesel can be produced from each barrel of feed, which meets or exceeds relevant standards, such as ASTM D975 (US), EN590 and EN15940 (Euro). Renewable naphtha, sustainable aviation fuel, or bio-propane can also be collected as saleable product from a BioFlux® unit.

Figure 2. BioFlux Reaction Zone Configuration. A liquid recycle is used to deliver hydrogen and pre-heat the hydrocarbon feed.

Process Advantages

  • Low-CAPEX, low-OPEX
  • Higher throughput and increased yield
  • Lowered hydrogen consumption
  • Superior operational stability
  • Extended catalyst life
  • Suitable for grassroots or revamp units

BioFlux is offered by Sulzer GTC in cooperation with Duke Technologies.


GT-BTX®: Aromatics Recovery

Using Extractive Distillation GT-BTX® removes benzene, toluene and xylenes (BTX) from refinery, petrochemical or coke oven aromatics streams such as catalytic reformate, pyrolysis gasoline or coke oven light oil (COLO).

GT-BTX® is an aromatics recovery technology that uses extractive distillation to remove benzene, toluene and xylene (BTX) from refinery, petrochemical or coke oven aromatics streams such as catalytic reformate, pyrolysis gasoline or coke oven light oil (COLO). With lower capital and operating costs, simplicity of operation, a wider range of feedstock and solvent performance, extractive distillation is superior to conventional liquid-liquid extraction processes. Flexibility of design allows use for grassroots aromatics recovery units, debottlenecking, or expansion of conventional extraction systems.

Sulzer GTC’s GT-BTX process is a result of extensive testing of extractive distillation solvents and blends. Our experience indicates that certain combinations of solvent components enhance extraction performance. Co-solvents also provide an additional parameter for the optimization of unit performance (e.g., stability, mass transfer efficiency). GT-BTX utilizes the Techtiv-100® extractive distillation solvent which provides optimum extractive distillation performance. GT-BTX has no special feed preparation requirements and is capable of handling a wide-range (BTX) feedstock while producing very high aromatics purities (99.99 wt.% plus) at high recoveries (99.9 % plus).

Process Overview

The flow scheme of the GT-BTX process consists of two columns: an extractive distillation column (EDC) and a solvent recovery column (SRC).

Since the basic separation in the GT-BTX process is achieved by distillation, the operation of the unit is very simple and intuitive. Control of the main process parameters are achieved in a manner similar to that of a regular distillation column.

Hydrocarbon feed is preheated with hot circulating solvent and fed at a mid-point into the EDC. Lean solvent is fed at an upper point and selectively extracts the aromatics into the tower bottoms in a vapor/liquid distillation operation. The non-aromatics hydrocarbons exit from the top of the column. A portion of the overhead stream is returned to the top of the column as reflux, which washes back any entrained solvent.

Rich solvent from the bottom of the EDC is routed to the SRC, where the aromatics are stripped overhead. The SRC is operated under a vacuum to reduce the boiling point at the bottom of the column.

Lean solvent from the bottom of the SRC is passed through a heat exchanger before returning to the EDC. A small portion of the lean circulating solvent is processed in a solvent regeneration step to remove heavy decomposition products.

The SRC overhead mixed aromatics product is routed to the purification section, where it is fractionated to produce chemical-grade benzene, toluene and xylenes.



The benefits of extractive distillation, particularly those highlighted by GT-BTX technology, may be summarized as follows:

  • Simple two-column ED system which requires 30-40 percent lower capital cost than conventional liquid-liquid extraction systems
  • Carbon steel construction throughout
  • Smaller plot requirement than other systems
  • Lower solvent inventory that further reduces investment requirement
  • Solvent blend exhibits highest selectivity among all others in commercial use. Solvent properties allow wide boiling range materials (C5- C9) to be fed into unit, with varying aromatics content
  • A short time is required to stabilize unit (few hours vs. few days with liquid-liquid extraction systems)
  • Lowest speci­fic energy consumption (20-30 percent less than others)
  • Very low solvent consumption and circulation rates
  • Higher product purity and aromatic recovery
  • Insignificant fouling compared to liquid-liquid contactors
  • The benzene product from GT-BTX is nitrogen free. Unlike some competing solvents, GTC’s solvent is free of basic nitrogen containing components, which permanently poison the catalyst in many benzene consuming units




FCC Gasoline Desulfurization Technology

Meeting the World’s Clean Gasoline Needs

GT-BTX PluS is a variation of GT-BTX that uses extractive distillation technology for simultaneous recovery of BTX and thiophenic sulfur species from refinery or petrochemical aromatic-containing streams. The technology helps produce low sulfur gasoline meeting the 10 ppm limit of sulfur without change in octane value.  An alternative use of GT-BTX PluS is to generate a large volume of aromatics to produce paraxylene without the requirement of a typical naphtha reformer unit.  The aromatics recovery is especially attractive for use with feedstocks produced from high severity FCC operations.

The process is optimally installed on the FCC mid-cut naphtha stream. GT-BTX PluS removes all thiophenes and some of the mercaptan species from the FCC gasoline feed.  The olefin-rich raffinate can be sent directly to the gasoline pool for blending, or to a caustic treating unit to remove the mercaptan-type sulfur compounds before being sent to the gasoline. The desulfurized aromatics extract stream can be directly fed into petrochemical production units instead of recycling to the naphtha reformer. GT-BTX PluS provides an effective solution for meeting today’s clean gasoline requirements and gives refiners the ability to convert lower-value gasoline components into higher-value petrochemicals.

Process Description

The optimum feed is the mid fraction of FCC gasoline from 70°C to 150°C.  This material is fed to the GT-BTX PluS unit, which extracts the sulfur and aromatics from the hydrocarbon stream.  The sulfur-containing aromatic components are processed in a conventional hydrotreater to convert the sulfur into hydrogen sulfide (H2S).  Because the portion of gasoline being hydrotreated is reduced in volume and free of olefins, hydrogen consumption and operating costs are greatly reduced.  In contrast, conventional desulfurization schemes must process the majority of the gasoline through hydrotreating units to remove sulfur, which inevitably results in olefin saturation, octane downgrade and yield loss.

FCC gasoline is fed to the extractive distillation column (EDC).  In a vapor-liquid operation, the solvent extracts the sulfur compounds into the bottoms of the column along with the aromatic components while rejecting the olefins and non-aromatics into the overhead as raffinate.  Nearly all of the non-aromatics, including olefins, are effectively separated into the raffinate stream.  The raffinate stream can be optionally caustic washed before routing to the gasoline pool or to an aromatization unit to further increase benzene, toluene and xylene (BTX) production.

Rich solvent, containing aromatics and sulfur compounds, is routed to the solvent recovery column (SRC), where the hydrocarbons and sulfur species are separated, and lean solvent is recovered in columns bottoms.  The SRC overhead is hydrotreated by conventional means and either used as desulfurized gasoline or directed to an aromatics plant.  Lean solvent from the SRC bottoms is recycled back to the EDC.


Process Advantages

  • Reduced OPEX and CAPEX in desulfurization from treating full-range naphtha.
  • Less hydrogen consumed than if the full-range material were hydrotreated.
  • HDS function required only for sulfur removal.
  • Octane value fully retained due to the diversion of feed olefins from hydrotreater.
  • Gasoline yield completely maintained.
  • High-quality aromatics produced from FCC gasoline.
  • Sulfur content of the FCC gasoline fraction being sent to the gasoline pool reduced to less than 20 ppm.
  • Segregated olefin-rich stream may be converted into propylene or additional aromatics.
  • Greater utilization of the naphtha reformer, compared to units that recycle the cracked gasoline.
  • Opportunity to feed more fresh naphtha and generate more hydrogen.
dividing wall

GT-DWC® - Dividing Wall Column Design Saves Costs and Energy

Dividing Wall Column Design Saves Costs and Energy

Sulzer GTC Technology’s process equipment technology offerings can include the dividing wall column (DWC), which separates a multi-component feed into three or more purified streams within a single tower, thereby eliminating the need for a second column. This design saves capital and energy costs normally invested in a separation unit.

The DWC design uses a vertical wall to divide the middle of the column into two sections. The feed is sent to one side of the column called the pre-fractionation section. There the light components travel up the column where they are purified while the heavy components travel down the column. The liquid flow from the column’s top and the vapor flow from the bottom are routed to their respective sides of the dividing wall.

From the opposite side of the wall, the side product is removed from the area where the middle boiling components are most concentrated. This arrangement is capable of producing a much purer middle product than a conventional side draw column of the same duty, and at a higher flow rate. And for the same product specifications, GTC-DWC requires substantially lower capital and operating cost than a conventional two-column system.

The technology is especially suited for removing a heartcut from a multi-component mixture, where the alternative is a series of fractionating Towers

Benefits of GT-DWC

Process Design and Control Scheme

  • Conceptual design to basic engineering package of the dividing wall column, coupled with dynamic simulation modeling, ensures reliable process design and a solution that is optimized for your specific application.
  • DWC Internals
  • Sulzer GTC is a leading supplier for column internals of all types.
  • Our integration of process and application knowledge results in innovative designs of DWC internals.
  • Sulzer GTC internals ensure correct pressure balance and arrangement along with internal distribution. This is the key to reliable, trouble-free operation of dividing wall columns.

Engineering Services

  • Sulzer GTC provides detailed engineering, procurement and construction management for all DWC applications.


Maximizing LPG Recovery from Fuel Gas Using a Dividing Wall Column

Refinery off gas is a mixture of hydrogen and hydrocarbons from various units within the refinery, pooled together to be used as a fuel for heating purposes. The fuel gas contains valuable components such as propane, which can provide additional revenue to the refinery. The economics of LPG recovery fluctuates with LPG pricing and energy cost. GT-LPG Max provides a cost-effective solution for recovering LPG product using a novel process concept of absorption plus distillation within the same fractionating vessel. The technology is well suited for low-pressure refinery off gas as well as associated natural gas streams. The process is based on avoiding thermodynamic inefficiencies in conventional absorption and distillation columns by incorporating the unit operations in a single top dividing wall column (DWC). The feed side of the top DWC recovers the C3+ components from the fuel gas through absorption. The other side of the DWC uses distillation to split between C3 and C4 components to produce LPG product.


GT-LPG Max offers the following benefits:

  • 99% propane recovery without the use of external refrigeration
  • Lower operating pressure (200 – 250 psig)
  • Lower CAPEX and OPEX

Process Advantages

  • PX in xylenes reaches thermodynamic equilibrium after reaction
  • EB dealkylation to benzene or isomerization to xylenes. With the EB-dealkylation catalyst, the by-product benzene is produced at high purity by simple distillation
  • Low H2/HC, high WHSV, low xylenes loss
  • Long cycle length
  • Efficient heat integration scheme reduces energy consumption
  • Turnkey package for high purity benzene, toluene, and paraxylene production available


Styrene recovery from raw pyrolysis gasoline (pygas) derived from the steam cracking of naphtha, gas oils, and natural gas liquids (NGL)

GT-Styrene is Sulzer GTC’s extractive distillation process that directly recovers styrene from the raw pyrolysis gasoline derived from the steam cracking of naphtha, gas oils, and natural gas liquids (NGL).  The styrene, produced at high purities and suitable for polymerization,  is a less costly alternative to conventional styrene production routes.  If desired, the mixed xylenes can also be extracted from the pygas, raising their value as a chemical feedstock.  Our GT-Styrene process is economically attractive to steam cracker operators which produce greater than 500 KMTA ethylene from liquids feedstock.

Process Description

Raw pyrolysis gasoline is prefractionated into a heartcut C8 stream.  The resulting styrene concentrate is fed to an ED column and mixed with a selective solvent, which extracts the styrene to the tower bottoms.  The rich solvent mixture is routed to a solvent recovery column (SRC), which recycles the lean solvent back to the ED column and recovers the styrene overhead.  A final purification step produces a 99.9% styrene product containing less than 50-ppm phenyl acetylene.  The ED column overhead can be further processed to recover a high-quality mixed-xylene stream.  A typical world-scale cracker can produce approximately 25,000 tpy styrene and 75,000 tpy mixed xylenes from pyrolysis gasoline.

Process Advantages

  • Produces polymer-grade styrene at 99.9% purity
  • Allows the recovery of isomer-quality mixed xylenes for paraxylene production
  • Debottlenecks pygas hydrotreater and extends cycle length
  • Reduces hydrogen consumed in hydrotreating
  • Optimized solvent system and design provide economical operating costs


Low-cost material for PX manufacture production

Toluene methylation is an effective and economical solution to maximize PX yields by adding the methyl group from low-cost methanol to the aromatic ring. Sulzer GTC’s GT-TolAlk is an effective way to derive PX while eliminating benzene production.

Process Overview

The feedstock, consisting of methanol and toluene, is processed in the toluene methylation reaction section where the toluene is alkylated into xylenes. The reactor effluent is processed in the fractionation section to produce the mixed xylene product. Unconverted toluene is separated and recycled back to the reaction section. C9+ aromatics fraction is also produced and separated, and is available as feedstock to the transalkylation unit, as the C9+ cut is rich in tri-methyl benzene.

Process Advantages

  • Simple fixed-bed, low-pressure process
  • No hydrogen needed
  • High production capacity
  • Effective addition of methyl group to aromatic ring
  • Very low EB in C8 aromatics; higher PX content compared to reformate xylenes
  • Potential for zero benzene by-product

Concept of Toluene Methylation

Traditional toluene-based PX technologies involve re-arrangement of the alkyl groups though various methods. Benzene is the typical by-product due to insufficient methyl groups compared to phenyl groups. By adding methyl groups to the aromatic ring, GT-TolAlk replenishes the methyl group shortage to yield more xylene over benzene.



Low-cost material for PX manufacture production

GT-TransAlk process technology produces benzene and xylenes through transalkylation of the methyl groups from toluene and/or heavy aromatics streams. The technology features a proprietary zeolite catalyst and can accommodate varying ratios of feedstock, while maintaining high activity and selectivity. GT-TransAlk is especially well-suited for processing heavy aromatics (C9-C10+) with a long run length, in order to maximize the production of xylenes from the aromatic feedstock. High purity benzene is produced by simple distillation.

Process Description

The technology encompasses three main processing areas: splitter, reactor, and stabilizer sections. The heavy-aromatics stream (C9+ feed) is fed to the splitter. The overhead C9/C10 aromatic product is the feed to the transalkylation reactor section. The splitter bottoms are exchanged with other streams for heat recovery before leaving the system. The aromatic product is mixed with toluene and hydrogen, vaporized, and fed to the reactor. The reactor gaseous product is primarily unreacted hydrogen, which is recycled to the reactor. The liquid product stream is subsequently stabilized to remove light components. The resulting aromatics are routed to product fractionation to produce the final benzene and xylene products. The reactor is charged with zeolite catalyst, which exhibits both long life and good flexibility to feed stream variations including substantial C10 aromatics. Depending on feed compositions and light components present, the xylene yield can vary from 25% to 32% and C9 conversion from 53% to 67%.

Process Advantages

  • Simple, low cost fixed-bed reactor design; drop in replacement for other catalysts
  • Very high selectivity; benzene purity is 99.9% without extraction
  • Physically stable catalyst
  • Flexible to handle up to 90+% C9+ components in feed with high conversion
  • Catalyst is resistant to impurities common to this service
  • Moderate operating parameters; catalyst can be used as replacement for other transalkylation units or in grass roots designs
  • Decreased hydrogen consumption due to low cracking rates
  • Significant decrease in energy consumption due to efficient heat integration scheme



High conversions to the key iso-components while maintaining prolonged catalyst service lifetimes, simple operation and resistance to process impurities

The Isomalk℠ family of technologies are based on the use of mixed metal oxide (nonchlorinated) catalysts that operate at low temperatures, thus allowing refiners to enjoy high conversions to the key iso-components while maintaining prolonged catalyst service lifetimes, simple operation and resistance to process impurities. These processes include Isomalk-2 for C5-C6 isomerization, Isomalk-3 for C4 isomerization and Isomalk-4 for C7 paraffins isomerization.  The Isomalk technologies are licensed in partnership by Sulzer GTC and NPP Neftehim.


Isomalk-2 is a low-temperature isomerization technology that has been commercially proven in grassroots applications, revamps of semi regenerative reforming units and replacement of other isomerization technologies. This flexible process utilizes a robust platinum-containing mixed-metal oxide SI-2™ catalyst that works effectively at the low temperatures of 120-140°C (250-285°F) while delivering great stability against the influence of catalytic poisons. Isomalk-2 is a competitive alternative to the three most commonly used light-gasoline isomerization processes: zeolite, chlorinated aluminum oxide and sulfated zirconium oxide catalysts. This technology has been commercialized in all possible modes of configuration. By applying the full recycle configuration, an isomerate with a 92.5 RON value has been achieved in a world-scale reference unit.

Process Overview

Isomalk-2 offers refiners a cost-effective isomerization option that consistently demonstrates reliable performance with all standard process configurations, including:

  • Once-through isomerization
  • Once-through with prefeed deisopentanizer
  • Recycle of low-octane pentanes and hexanes
  • Full recycle of all nonbranched paraffins and prefeed deisopentanizer
  • Each scheme generates different yield and octane results. The following examples are for an LSR (Light Straight Run) process stream but may also be applied to a condensate stream or some LSR/condensate combinations.

Each scheme generates different yield and octane results. The following examples are for a LSR (Light Straight Run) process stream, but may also be applied to a condensate stream or some LSR/condensate combinations.

Once-Through Isomerization

In a once-through isomerization process scheme, the LSR is mixed with hydrogen make-up gas. The mixture is then heated and enters a first reactor where benzene saturation and partial isomerization take place.

The gas-product mixture exits the first reactor, is cooled and then fed to a second reactor to complete the isomerization reaction at chemical equilibrium. The product mixture from the second reactor is cooled and fed to a gas separator, where the mixture is separated from the excess hydrogen gas. Excess hydrogen is combined with make-up hydrogen and fed through the recycle dryers for blending with feed. No hydrocarbon feed drying is required. Saturated isomerate from the separator is heated and fed to the stabilizer. The stabilizer’s overhead vapors are cooled and fed to a reflux drum. Liquid hydrocarbons from the reflux are returned to the stabilizer as reflux, while uncondensed light hydrocarbons are separated and sent to the off-gas system. The bottom product or isomerate is cooled and sent to gasoline blending.

Recycle of Low-Octane Pentanes and Hexanes

In an isomerization process scheme with recycle of low-octane pentanes and/or hexanes, the isomerate is produced and then fed to a fractionation column(s). Overhead and bottoms isomerate streams are cooled and sent to gasoline blending. A low-octane C5 and/or C6 isomerate stream is recycled back to the isomerization reactor.

Prefractionation With Recycle of Low-Octane Hexanes

Prefractionation with low-octane recycle can utilize all of the above methods: prefractionation, isomerization, and postfractionation. The prefractionation step consists of deisopentanization of the feed and/or C7+ separation. The postfractionation step consists of separating the high-octane portion of the C5-C6 isomerate and recycling the low-octane C6 isomerate stream.


The SI-2 catalyst provides high conversion rates and a close approach to thermal equilibrium at low temperatures. Key to the technology is the fact that the SI-2 catalyst exhibits superior activity alongside stability, simplicity and safety in operation. Features of the Isomalk-2 technology include:

  • Process capability to produce 81-93 RON
  • Low operating costs
  • Regenerable catalyst with superior tolerance to process impurities and water
  • No chloride addition or caustic treatment needed; no wastes produced
  • Mass yield > 98%, volume yield up to 100%
  • Up to 5-6 year cycles between regenerations
  • Guaranteed service life of SI-2 catalyst of 10+ years
  • Reduced hydrogen consumption




Isomalk-3 is a low-temperature isomerization technology for processing n-butane into isobutane (i-butane), its branched polymer. Isobutane is an important intermediate required for the production of isobutylene or alkylate. Isobutylene can be used to produce MTBE or other high-value petrochemicals such as isoprene through a synthetic on-purpose route.

The Isomalk-3 technology is based on the use of a mixed-metal oxide SI-3™ catalyst with high selectivity to i-butane. Operating at a temperature of 150-170°C (302-338°F), the yield and operating expenses are optimized. The expected lifetime of the SI-3 catalyst is over 10 years. The process eliminates the need for chlorine injection, off-gas caustic scrubbing and associated equipment expenses. Water, sulfur and nitrogen specs for the feed are significantly lowered. Breakthrough of these contaminants is permissible, and catalyst activity can be restored via “in-situ” catalyst regeneration. As with the other catalysts associated with the Isomalk family, operation is simple and reliable; startup, turnaround and shutdown times are minimal due to the high resistance to catalytic poisons and, most important, water.

Configuration Overview

Isomalk-3 can achieve high conversion to isobutane while significantly reducing equipment needs, and it is the only available nonchlorinated process based on n-C4 isomerization technology that has been commercially successful. The SI-3 catalyst provides a close approach to thermal equilibrium at low temperatures and exhibits outstanding stability, simplicity and safety in operation. Isomalk-3 can efficiently separate out C5+ from feeds in a dividing-wall-column deisobutanizer that allows for greater feedstock flexibility. The process can be adapted for reverse isomerization of i-butane to n-butane as well.

The process requires a one-reactor configuration and eliminates the chemical consumption of organochlorides and caustic for operation. Cooling water or refrigerant serves as a medium to recover i-C4 and n-C4 in the stabilizer overhead, depending on the available utilities on site. The subsequent integration of the i-butane with downstream dehydrogenation technology allows the optimal recovery of all products of the isomerization reaction, heat integration, minimized OSBL requirements and plot plan.


Isomalk-3 is the only available nonchlorinated process for n-C4 isomerization that is commercially successful. The SI-3 catalyst provides a close approach to thermal equilibrium at low temperatures and exhibits outstanding stability, simplicity and safety in operation. Features of Isomalk-3 include:

  •  Low operating and capital costs
  • No chloride addition or caustic treatment needed; no wastes produced
  • Regenerable catalyst (SI-3) – ease of operation and long service life of 10+ years
  • Robust design – highly tolerant to process fluctuations resulting in 48 to 60 months between catalyst regeneration
  • High conversion per pass – results in process configuration with only one reactor
  • High selectivity – low hydrogen consumption
  • Low-hydrogen partial-pressure requirement – no recycle gas compressor or separator


Isomalk-4 is a low-temperature isomerization technology for processing C7 paraffins contained in wide-range naphtha streams. In a conventional refinery configuration, C7 paraffins are distributed to the C5-C6 isomerization unit and the reformer. These components tend to reduce the overall yield of the liquid products, to lower RON of the gasoline and to form unwanted amounts of benzene.

This innovative process allows isomerization of the hydrocarbon stream to achieve a low-RVP gasoline component with 84-86 RON while improving the operation of the other naphtha-processing units. By applying Isomalk-4, the wide-range naphtha can yield over 90 wt% liquid having a 95-98 RON, with benzene content < 0.6 vol.% — meeting required gasoline specifications without any additional blending.

The inclusion of Isomalk-4 in the refinery configuration gives a 2.1 wt%. gain of liquids, a higher 1.5 RON value, and lower overall benzene and aromatics. The SI-4™ catalyst provides high conversion rates and approaches thermal equilibrium at low temperatures. The SI-4 catalyst exhibits superior activity alongside stability, simplicity and safety in operation. Features of the Isomalk-4 technology include:

  • Process capability to produce 84-86 RON from the standalone unit
  • Low operating costs
  • Regenerable catalyst with superior tolerance to process impurities and water
  • No chloride addition or caustic treatment needed; no wastes produced
  • Mass yield > 93%
  • Service life of SI-4 catalyst: 8-10 years
Figure 1. MaxFlux Reaction Zone Configuration. A liquid recycle is used to deliver hydrogen and pre-heat the hydrocarbon feed.

MaxFlux Renewable Diesel

The Next Generation of Hydrotreating

MaxFlux® Advanced Hydrotreating Technology is a novel alternative to traditional hydroprocessing. The hydrotreating reactors operate in a high mass ux mode that removes the mass transfer limitation and eliminates the need for large volumes of hydrogen recycle gas as a quench uid.  Instead, hydrogen is dissolved in a recycle liquid stream to deliver more hydrogen to the reactor and stabilize temperature uctuations (Figure 1). As a result, installation of MaxFlux instead of conventional hydrotreating offers signicant capital cost savings, improved yields, and longer catalyst life.

Over the full range of hydrocarbons, MaxFlux can be installed as a grass roots hydrotreating unit or as a revamp in a pretreat conguration. In pre-treating, the MaxFlux reactor accomplishes most of the necessary hydrotreatment, reducing the demand in the existing conventional reactor, which will then operate in a polishing mode. As a result, catalyst deactivation due to coking in the conventional reactor is greatly reduced.

Figure 2. MaxFlux installed as a pretreat reactor in an existing hydrotreater

Process Advantages

  • Lower total capital investment
  • Lower operating expense
  • Longer catalyst life
  • Higher yields

BioFlux is offered by Sulzer GTC in cooperation with Duke Technologies.

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