How to Increase Gasoline Octane Number from Naphtha: Process Design, Catalyst Selection and Equipment Manufacturing Guide

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Introduction: Increasing Gasoline Octane Is More Than Choosing a Better Catalyst

For refiners, increasing the gasoline octane number is rarely a matter of simply changing the catalyst.

When a refinery wants to convert naphtha into higher-octane gasoline, the actual challenge is much broader:

Is the naphtha feed suitable for the selected process?

Should the refinery use isomerization, catalytic reforming, or a combination of both?

How should C5/C6, C7 and C8+ molecules be managed?

What pretreatment is required before the catalyst?

Is the reactor properly designed for the catalyst and operating conditions?

Can the heat exchanger network provide the required thermal efficiency?

Are fractionation and recycle systems correctly configured?

Can the equipment manufacturer control welding, heat treatment, dimensional accuracy and inspection?

Will the equipment remain stable after years of operation?

A high-octane gasoline production system is therefore a process integration problem, not a single-equipment problem.

Modern naphtha upgrading schemes can combine hydrotreating, fractionation, light-naphtha isomerization and heavy-naphtha reforming to maximize the octane contribution of different hydrocarbon fractions. For example, integrated gasoline complexes separate naphtha into streams and direct C5/C6 toward isomerization and heavier fractions toward reforming.

This is also where the engineering and manufacturing capabilities of an equipment supplier become important.

GYRO provides engineering design, equipment fabrication, installation, modification, maintenance and technical services for chemical and petrochemical projects. Its product scope includes reactors, pressure vessels, towers, heat exchangers and customized petrochemical equipment.1. What Determines Gasoline Octane Number?

Octane number represents a gasoline fuel's resistance to knocking in a spark-ignition engine.

For refinery engineers, however, the more useful question is:

Which hydrocarbon molecules in the naphtha feed should be converted into higher-octane molecules, and how can that conversion be achieved economically?

Naphtha contains different types of hydrocarbons, including:

Normal paraffins

Isoparaffins

Naphthenes

Aromatics

Olefinic components

Small amounts of sulfur, nitrogen and other contaminants

These molecules do not contribute equally to gasoline octane.

For light naphtha, one of the most important strategies is converting low-octane normal paraffins into branched isoparaffins.

For heavier naphtha, catalytic reforming can transform suitable hydrocarbons into higher-octane reformate while also generating valuable hydrogen.

Therefore, a refinery should not simply ask:

"Which catalyst gives the highest octane?"

A better engineering question is:

"Which combination of feed separation, pretreatment, catalyst, reactor design and downstream separation gives the required octane at the best overall yield and operating cost?"

2. The Main Routes for Increasing Gasoline Octane from Naphtha

There are several possible approaches, but two technologies are particularly important in refinery gasoline production:

2.1 Naphtha Isomerization

Naphtha isomerization is primarily used for light naphtha containing C5/C6 paraffins.

The basic reaction converts straight-chain paraffins into branched-chain isomers.

For example:

n-pentane → isopentane

n-hexane → branched-chain hexanes

Branched molecules generally have higher octane numbers than their corresponding normal paraffins.

The major advantage is that isomerization can significantly improve the octane value of light naphtha while maintaining a high liquid yield.

Commercial isomerization technologies use different catalyst and operating-temperature systems. UOP, for example, describes multiple isomerization catalyst families for light paraffin applications, with emphasis on activity, conversion, yield and catalyst life.

2.2 Catalytic Reforming

Catalytic reforming is particularly important for heavier naphtha fractions.

Instead of primarily rearranging normal paraffins, reforming promotes reactions such as:

Dehydrogenation of naphthenes

Dehydrocyclization of paraffins

Isomerization

Hydrocracking under certain conditions

The resulting reformate can provide a significant octane contribution to the gasoline pool.

Catalytic reforming also produces hydrogen, which can be valuable for other refinery hydrotreating processes. Commercial reforming technology is widely used to convert heavy naphtha into high-octane gasoline blending components and aromatics.

2.3 Integrated Octane Management

For a modern refinery, the best solution may not be choosing between isomerization and reforming.

Instead, the refinery can manage molecules according to their properties.

A simplified configuration may look like:

Full-Range Naphtha

↓

Naphtha Hydrotreating

↓

Naphtha Fractionation

↓

C5/C6 → Isomerization

C7 → Specialized Isomerization / Octane Management

C8+ → Catalytic Reforming

↓

High-Octane Gasoline Components

↓

Gasoline Blending

This molecular-management approach is more sophisticated than treating the entire naphtha stream as one feedstock. Integrated gasoline schemes can combine hydrotreating, naphtha splitting, C5/C6 isomerization and C8+ reforming to maximize premium gasoline production.

 

 

3. Step One: Feedstock Analysis Comes Before Equipment Selection

One of the most common mistakes in a gasoline octane improvement project is selecting equipment before properly understanding the feed.

A process designer should first evaluate:

Feed boiling range

The boiling range determines whether the material is suitable for:

Light naphtha isomerization

Heavy naphtha reforming

Fractionation

Combined processing

PONA composition

PONA analysis provides important information about:

Paraffins

Olefins

Naphthenes

Aromatics

This information helps determine the realistic octane improvement potential.

Sulfur

Sulfur is particularly important because many noble-metal catalysts are highly sensitive to sulfur contamination.

A feed pretreatment section may therefore be required before the naphtha enters the octane-improvement reactor.

Nitrogen and water

Nitrogen compounds and water can also affect catalyst performance, especially for catalyst systems requiring tightly controlled feed conditions.

Benzene and aromatics

A high-octane product is not automatically a better gasoline product.

The refinery must also consider fuel specifications, including limitations on benzene and aromatics.

Therefore, the target should not simply be:

Maximum octane.

It should be:

Maximum commercially useful octane at the required product specification and acceptable yield.

4. Step Two: Naphtha Pretreatment Protects the Octane-Upgrading Catalyst

Catalyst selection receives considerable attention in refinery projects, but catalyst protection is equally important.

A catalyst can only perform according to its design if the feed conditions are controlled.

Depending on the selected process, pretreatment may include:

Hydrodesulfurization

Denitrification

Water removal

Chloride management

Stabilization

Filtration

Feed fractionation

For example, some low-temperature chloride-containing isomerization catalyst systems require particularly strict control of water and sulfur because these contaminants can deactivate active sites. GYRO's gasoline-type catalyst information describes low-temperature Pt/Cl-Al₂O₃ systems as requiring strict dehydration, desulfurization and denitrification.

This creates an important engineering principle:

Catalyst performance begins upstream of the reactor.

If the pretreatment section is poorly designed, purchasing a more expensive catalyst may not solve the problem.

5. Step Three: Select the Right Isomerization Catalyst

There is no universal "best" gasoline isomerization catalyst.

The correct catalyst depends on:

Feed composition

Target RON

Operating temperature

Operating pressure

Hydrogen availability

Feed contaminants

Desired catalyst life

Regeneration strategy

Capital cost

Operating cost

Three broad catalyst/process concepts are commonly considered for naphtha isomerization.

Low-Temperature Pt/Cl-Al₂O₃ Isomerization

A platinum-supported chlorinated alumina catalyst can provide high activity at relatively low reaction temperatures.

Typical characteristics include:

High catalytic activity

Strong octane improvement potential

High sensitivity to water and sulfur

Chloride management requirements

More demanding corrosion-control requirements

GYRO's gasoline catalyst technical material describes this type of system as suitable for C5/C6 light naphtha and identifies typical reactor inlet temperatures in the approximate 120–175°C range, depending on the process and operating conditions.

This technology can be attractive when high octane improvement from light naphtha is a priority.

However, the associated reactor, piping, separation and corrosion-management design must be considered as one system.

Medium-Temperature Pt/Zeolite Isomerization

Zeolite-based catalysts provide another route.

Compared with chloride-based systems, zeolitic systems can offer:

No continuous chloride supplementation

Simpler process operation

Different feed tolerance characteristics

Potentially easier long-term operating management

GYRO's technical information describes Pt/zeolite systems operating at higher temperatures than chloride-alumina systems and identifies their use for C5/C6 isomerization and other paraffin isomerization applications.

The trade-off is that higher operating temperature changes equilibrium limitations and can influence conversion, recycle requirements and overall equipment design.

 

 

6. Reactor Design Directly Influences Catalyst Performance

A catalyst cannot compensate for a poorly designed reactor.

For an isomerization reactor, the equipment designer should consider:

Design pressure

Design temperature

Operating pressure

Operating temperature

Catalyst volume

LHSV

Hydrogen-to-hydrocarbon ratio

Pressure drop

Feed distribution

Catalyst support arrangement

Internal diameter

Bed height

Inlet distributor

Outlet collector

Thermal expansion

Inspection requirements

Catalyst loading and unloading

The reactor must provide an appropriate environment for the catalyst while maintaining stable flow distribution.

Why flow distribution matters

If liquid or vapor distribution across the catalyst bed is uneven, some areas may experience:

Excessive local reaction

Insufficient contact

Higher pressure drop

Local hot spots

Uneven catalyst utilization

The result may be lower overall conversion even when the catalyst itself is technically capable of higher performance.

This is why reactor internals are process equipment, not simply mechanical accessories.

7. Equipment Manufacturing Quality Can Affect Process Economics

From a buyer's perspective, it is tempting to compare equipment suppliers based only on:

Price + delivery time.

For high-pressure refinery equipment, that is rarely sufficient.

The actual lifecycle cost is influenced by:

Material quality

Welding quality

Heat treatment

Dimensional accuracy

NDT coverage

Pressure testing

Internal surface condition

Nozzle accuracy

Flange alignment

Equipment cleanliness

Manufacturing traceability

GYRO operates its own petrochemical equipment manufacturing facility and reports more than 150 manufacturing and processing machines, including plate rolling machines, large-capacity cranes, hydraulic pressing equipment, heat-treatment facilities, CNC cutting machines and welding equipment.

Its quality and inspection capabilities include certified pressure-vessel welders and qualified NDT personnel covering RT, UT, MT and PT inspection methods.

For a reactor or pressure vessel, these capabilities matter because the final equipment must satisfy both process requirements and mechanical integrity requirements.

8. Heat Exchangers: The Hidden Factor in Gasoline Octane Improvement Projects

The reactor receives most of the attention in many technical discussions.

But the heat exchanger network can have a major influence on the overall economics of a naphtha processing unit.

Heat exchangers may be used for:

Feed/product heat recovery

Reactor feed preheating

Reactor effluent cooling

Condensation

Reboiling

Stabilization

Fractionation

Hydrogen recycle cooling

Process stream temperature control

A well-designed heat integration system can reduce external heating and cooling requirements.

For example:

Hot reactor effluent → Feed preheating → Reactor feed

instead of:

Hot reactor effluent → Cooler → Cold feed → Fired heater

The first arrangement can recover valuable process heat.

Therefore, when evaluating an equipment supplier, the buyer should not ask only:

"Can you manufacture a heat exchanger?"

A better question is:

"Can you manufacture a heat exchanger that matches our process duty, pressure, temperature, materials, fouling conditions and maintenance strategy?"

GYRO's product portfolio includes shell-and-tube and customized process heat exchangers for petrochemical and chemical applications.

9. Fired Heaters Must Be Designed Around the Process

Where external heating is required, the fired heater becomes another critical piece of equipment.

A refinery fired heater must balance:

Heat duty

Outlet temperature

Fuel consumption

Tube metal temperature

Pressure drop

Burner performance

Heat flux

Radiation/convection balance

Emissions requirements

Maintenance accessibility

In naphtha processing and reforming applications, incorrect heater design can create excessive tube temperature or insufficient heat transfer.

GYRO provides customized fired heaters for refinery, petrochemical and chemical process units, with designs based on process heat load and operating requirements.

This is another example of why process equipment should be selected as part of the overall process system rather than as isolated mechanical packages.

10. Fractionation Is Essential to Efficient Octane Management

A refinery cannot maximize octane economically if all naphtha molecules are processed in the same way.

Fractionation allows the refinery to direct different boiling-range fractions toward different processing routes.

For example:

Light C5/C6 fraction

→ Isomerization

Middle fraction

→ Appropriate octane upgrading / further processing

Heavy C7+ or C8+ fraction

→ Reforming or other downstream processing

The exact cut points depend on the refinery's feed properties, product targets and licensed process configuration.

Fractionation equipment therefore becomes an important part of the octane-improvement system.

Poor fractionation can cause:

Loss of valuable molecules

Excessive recycle

Increased energy consumption

Lower catalyst efficiency

Increased downstream load

GYRO manufactures customized chemical towers and process columns, including distillation and other petrochemical separation equipment.

11. Why "Maximum RON" Is Not Always the Correct Target

A common misconception is:

Higher RON = better refinery economics.

In reality, the refinery should optimize several variables simultaneously.

A practical optimization objective can be expressed conceptually as:

Gasoline Profit = Product Value – Feed Cost – Hydrogen Cost – Fuel Cost – Catalyst Cost – Utilities – Maintenance Cost

Therefore, increasing RON from 90 to 92 may be attractive.

Increasing it from 95 to 97 may not necessarily be economically attractive if the additional octane requires:

Higher hydrogen consumption

More severe operating conditions

Higher catalyst consumption

More recycle

Higher energy consumption

Lower liquid yield

Greater equipment investment

The optimum point depends on the refinery's economics and product specifications.

12. Catalyst Life Is as Important as Initial Catalyst Activity

A catalyst with extremely high initial activity is not necessarily the best commercial choice.

A refinery should evaluate:

Initial activity

How much octane improvement can be achieved at startup?

Selectivity

How much desired product is produced versus unwanted reactions?

Catalyst stability

How quickly does performance decline?

Catalyst life

How long can the catalyst remain commercially effective?

Regeneration

Can activity be restored, and how complex is regeneration?

Feed tolerance

How sensitive is the catalyst to sulfur, nitrogen, water and other contaminants?

UOP's isomerization catalyst portfolio, for example, emphasizes activity, conversion, high yield and catalyst life as key performance considerations rather than activity alone.

The same principle applies to equipment:

The cheapest reactor is not necessarily the lowest-cost reactor over its operating life.

13. Hydrogen Management Matters in Naphtha-to-Gasoline Systems

Hydrogen can play several roles in an integrated refinery.

It may be required for:

Naphtha hydrotreating

Isomerization

Reforming-related systems

Hydrogen recycle

Protection of downstream catalysts

An integrated reforming process can also become an important hydrogen source for the refinery.

Therefore, gasoline octane optimization should be connected with the refinery-wide hydrogen balance.

A process designer should ask:

How much hydrogen is available?

What purity is required?

What recycle ratio is appropriate?

What compressor capacity is available?

What hydrogen is consumed in pretreatment?

Can reforming-generated hydrogen support other units?

Ignoring hydrogen balance can result in an apparently attractive process that performs poorly economically at the refinery level.

14. The Importance of Materials Selection

The material of construction should be determined by the actual process environment.

Important factors include:

Temperature

Pressure

Hydrogen partial pressure

Sulfur compounds

Chlorides

Acidic components

Water

Corrosion mechanism

Design life

Welding requirements

This is particularly important for chloride-containing isomerization systems.

When a process involves corrosive components, the equipment designer must consider not only the pressure-vessel wall thickness but also:

Material compatibility

Corrosion allowance

Weld procedure

Heat treatment

Internal components

Nozzle areas

Flanges

Gaskets

Inspection requirements

This is where an integrated engineering-and-manufacturing supplier has a practical advantage.

15. Why Design and Manufacturing Should Be Connected

One of the biggest problems in customized refinery equipment procurement occurs when:

Process designer → Engineering company → Equipment broker → Fabricator

creates multiple interfaces.

Each additional interface creates potential misunderstandings concerning:

Design conditions

Materials

Nozzle orientation

Dimensions

Internals

Inspection

Delivery scope

Site installation

GYRO's business model integrates engineering design with equipment manufacturing, installation, modification, maintenance and technical service. The company states that projects can be developed from process data, PFDs, P&IDs, equipment lists, technical datasheets and customer drawings.

For complex process equipment, this integration can simplify communication between the process requirement and the final manufactured equipment.

16. What Should Buyers Ask an Isomerization Reactor Manufacturer?

Before purchasing an isomerization reactor, an EPC contractor or refinery owner should request clear answers to the following:

A professional manufacturer should be able to discuss these questions from both engineering and fabrication perspectives.

17. GYRO: From Process Requirements to Manufactured Equipment

For gasoline octane improvement projects, GYRO's role is not limited to manufacturing a single pressure vessel.

GYRO provides engineering and manufacturing support for chemical and petrochemical equipment, including:

Pressure vessels

Chemical reactors

High-pressure reactors

Heat exchangers

Distillation columns

Absorption and scrubbing towers

Customized process equipment

Fired heaters

Petrochemical equipment

The company reports a 50+ person design team, 15 engineering and technical specialists, 14 certified pressure-vessel welders and qualified NDT personnel covering RT, UT, MT and PT.

Its manufacturing facility covers approximately 30,000 m², including around 20,000 m² of workshop space, with more than 150 sets of manufacturing and processing equipment.

This manufacturing infrastructure is particularly relevant for projects requiring customized dimensions, pressure-vessel fabrication, large process equipment or multiple equipment interfaces.

18. GYRO's Equipment Scope for Naphtha and Gasoline Projects

Depending on the process configuration, GYRO can support equipment packages involving:

Reaction Equipment

Isomerization Reactors

Hydrogenation Reactors

Chemical Reactors

High-Pressure Reactors

Heat Transfer Equipment

Shell-and-Tube Heat Exchangers

Process Heat Exchangers

Feed/Effluent Heat Exchangers

Separation Equipment

Distillation Columns

Fractionation Towers

Stabilizer Columns

Customized Chemical Towers

Heating Equipment

Fired Process Heaters

Refinery Process Heaters

Pressure Equipment

Medium- and High-Pressure Pressure Vessels

Customized Non-Standard Pressure Vessels

This equipment-oriented capability is important because gasoline production projects often require several interconnected equipment types rather than one isolated reactor. GYRO's EPC project approach specifically covers process requirements, engineering design, equipment configuration, manufacturing, auxiliary integration and technical support.

19. How to Choose the Right Equipment Manufacturer for a Gasoline Octane Improvement Project

Before sending an RFQ, refinery owners and EPC contractors should evaluate suppliers in five dimensions.

1. Engineering capability

Can the supplier understand:

Process data?

Equipment datasheets?

PFD?

P&ID?

Catalyst requirements?

Design pressure?

Design temperature?

Material requirements?

2. Manufacturing capability

Can the factory actually manufacture the equipment rather than outsourcing most of the work?

3. Quality capability

Does the supplier have:

Qualified welders?

NDT personnel?

Welding procedures?

Heat-treatment capability?

Inspection systems?

Material traceability?

4. Project coordination

Can the manufacturer coordinate:

Reactor + Heat Exchanger + Tower + Pressure Vessel + Auxiliary Equipment

rather than treating each item as an independent order?

5. After-sales support

Can the supplier provide:

Installation support

Modification

Maintenance

Technical service

Troubleshooting

These capabilities become increasingly important as project complexity increases.

20. A Practical Strategy for Increasing Gasoline Octane from Naphtha

A reliable project-development workflow can therefore be summarized as:

Step 1 - Analyze the feed

Determine:

Boiling range

PONA

Sulfur

Nitrogen

Water

Benzene

Aromatics

Target gasoline specification

↓

Step 2 - Define the product target

Determine:

Target RON

Gasoline yield

Aromatics limit

Benzene limit

Product sulfur

Required blending properties

↓

Step 3 - Select the process route

Evaluate:

Naphtha hydrotreating

Fractionation

C5/C6 isomerization

C7 upgrading

Catalytic reforming

Recycle strategy

↓

Step 4 - Select catalyst

Evaluate:

Activity

Selectivity

Feed tolerance

Catalyst life

Regeneration

Operating temperature

Hydrogen requirement

↓

Step 5 - Design the equipment

Design:

Reactor

Heat exchangers

Fired heater

Towers

Pressure vessels

Piping interfaces

Hydrogen system

↓

Step 6 - Manufacture and inspect

Control:

Materials

Welding

Forming

Heat treatment

NDT

Dimensional inspection

Hydrostatic testing

Final QA

↓

Step 7 - Install and commission

Verify:

Equipment alignment

Piping connection

Instrumentation

Catalyst loading

Leak testing

Startup conditions

↓

Step 8 - Optimize operation

Monitor:

RON

Conversion

Yield

Catalyst activity

Pressure drop

Energy consumption

Hydrogen consumption

This is the difference between buying equipment and engineering an octane-improvement solution.