catalytic reforming technology

Gerard B. Hawkins Managing Director, CEO

Catalytic Reforming: Catalyst, Process Technology and Operations Overview

www.gbhenterprises.com

Fundamentals of Catalytic Reforming Objective Reaction Chemistry and Mechanisms Desirable and Undesirable Reactions

Process Variables Reactor Temperature Reactor Pressure Space Velocity Hydrogen / Hydrocarbon Ratio Feedstock Yield Charts

Reforming Process Flow Sheets (PFDs) Fixed Bed reforming Semi Regenerative Reforming (CCR) Continuous Catalytic Regenerative Reforming Octanizing Dualforming RZ Platforming

Contents


Reforming catalyst

Catalyst Types Catalyst Poisons Catalyst Distribution Catalyst Sampling Catalyst Regeneration

Catalytic Reforming Economics Comparison Key Energy and Environmental Facts Conclusions

Contents, con’t

Fundamentals of Catalytic Reforming


Presenter

Presentation Notes

Catalytic reforming unit is a key process unit in refinery and petrochemical industry. Statistical data shows that 717 refineries are operated all over the world with a total capacity of 4,103 Mt/a, where the total capacity of catalytic reforming units is up to 485 Mt/a, making up to 11.0% of the total crude processing capacity.


Basic catalytic reforming scheme with three heaters, three reactors and recycled hydrogen; the excess H2 is later used in other refining plants.

Presenter

Presentation Notes

Fixed bed semi-regeneration reforming process remains a dominating process in the world, for which the processing capacity amounts to around 65% of the total. Fixed bed semi-regeneration reforming processes include Platforming Process developed by UOP, Magna Reforming Process developed by Engdlhard and ARC, Powerforming Process developed by ExxonMobil and Rheniforming Process developed by Chevron. As a pioneer, UOP developed its Platforming Process in 1949.


Presenter

Presentation Notes

Semi-Regeneration and Cyclic Regeneration Reforming Processes Fixed bed semi-regeneration reforming process shows a feature that the undesirable coke will be deposited on the catalyst when process unit is operated for a certain period, leading to reduced catalyst activity, increased reaction temperature and subsequently poor product quality. Continuous Catalytic Reforming (CCR) Process As a new solution to increasingly stringent requirements for reforming technologies, continuous catalytic reforming (CCR) process was first employed in Platforming unit by UOP in 1971. Since then, CCR process is widely popularized in refinery industry, for which the processing capacity amounts for about 25% of the total. CCR process is mainly characterized that individual continuous catalyst regeneration system is provided in the process unit to enable a continuous regeneration of fouled catalyst to provide higher activity. At present, CCR processes include CCR Platforming Process developed by UOP (USA) and CCR process developed by IFP (France).


Generalized Platforrming reaction scheme


Chemical Reactions


Major Reactions Occurring in the Reforming Unit Desirable Reactions


Major Reactions Occurring in the Reforming Unit Undesirable Reactions


Desirable reactions with hydrogen production


Adverse Reactions


Chemical Reactions

Processes Variables


Processes Variables


Process variables that may be adjusted by design or during operation include:

Reactor temperature Pressure Space velocity Hydrogen / hydrocarbon ratio Feedstock characteristics

The relationships of the variables generally apply to both fixed-bed reforming and continuous reforming.

Presenter

Presentation Notes

Reactor Temperature Once a process unit has been installed, the primary mechanism to adjust product octane number is that of adjusting reactor operating temperatures. Typical reactor inlet temperatures range from 490°C to 550°C. With the other operating conditions held constant, a higher reactor inlet temperature results in a higher product octane number. Higher temperatures also increase operating severity and cause more rapid Catalyst deactivation. Reactor Pressure Reactor operating pressure can practically vary from 3.5 to 30 bar, although there are no theoretical limits. As a consequence of the typical catalyst distribution between the reactors, the last reactor inlet pressure provides a close approximation of the average pressure in the overall catalyst bed. The lower the operating pressure, the higher the reformate and H2 yields. Low operating pressure results in more severe conditions, causing higher catalyst deactivation rates. The lowest operating pressures are typically only practiced in continuous reforming units. Space Velocity Space velocity is the ratio of the feed rate to the amount of catalyst. It is typically measured in volumetric terms as Liquid Hourly Space Velocity (LHSV) in units of h-1. Space velocity affects the temperature required to achieve a desired product quality. Lower space velocity entails larger catalyst volumes, signifying that lower temperatures are required to achieve the same product quality. High space velocity, a more severe condition, results in higher temperature requirements for the same product quality. Following the construction of a reforming unit, the LHSV can only be adjusted by varying the naphtha charge rate. �Hydrogen / Hydrocarbon Ratio The hydrogen/hydrocarbon ratio, or H2/HC, is the measure of moles of hydrogen charged to the reactor as a ratio of the moles of feed naphtha. As mentioned earlier, hydrogen is recycled to the reactors to maintain catalyst stability. The amount of the hydrogen or H2/HC can be adjusted by the rate of recycled gas at a given operating pressure. The hydrogen purity of the separator gas also has a direct effect on H2/HC. A higher H2/HC results in a less severe operation and thus a lower catalyst deactivation rate. Operation at higher H2/HC must be balanced with the utility cost associated with recycling the separator gas. Feedstock Feedstock can be characterized by the relative proportions of paraffins, naphthenes and aromatics (PNA) in the feed along with its distillation range. The fastest reactions are those of naphthene dehydrogenation. Feedstocks rich in naphthenes require less severe conditions to reach a product octane number target or aromatic concentration. Feedstocks that are lean in naphthenes and correspondingly higher in paraffins require more severe operating conditions to obtain a specific quality product. A feedstock with a wide boiling range or one with a higher end point will also require more severe conditions to reach product targets. When reformate is produced for the purpose of feeding an aromatics complex, the boiling range of the feedstock tends to be more narrow, limited to the range that results in the desired aromatic species.

Processes Variables


Processes Variable: Pressure


Presenter

Presentation Notes

Reactor operating pressure can practically vary from 3.5 to 30 bar, although there are no theoretical limits.

Processes Variable: Pressure


Presenter

Presentation Notes

As a consequence of the typical catalyst distribution between the reactors, the last reactor inlet pressure provides a close approximation of the average pressure in the overall catalyst bed. The lower the operating pressure, the higher the reformate and H2 yields. Low operating pressure results in more severe conditions, causing higher catalyst deactivation rates. The lowest operating pressures are typically only practiced in continuous reforming units.

Processes Variable: Temperature


Presenter

Presentation Notes

Once a process unit has been installed, the primary mechanism to adjust product octane number is that of adjusting reactor operating temperatures. Typical reactor inlet temperatures range from 490°C to 550°C.



Presenter

Presentation Notes

With the other operating conditions held constant, a higher reactor inlet temperature results in a higher product octane number. Higher temperatures also increase operating severity and cause more rapid catalyst deactivation.

Processes Variable: Space Velocity


Presenter

Presentation Notes

Space velocity is the ratio of the feed rate to the amount of catalyst. It is typically measured in volumetric terms as Liquid Hourly Space Velocity (LHSV) in units of h1. Space velocity affects the temperature required to achieve a desired product quality. Lower space velocity entails larger catalyst volumes, signifying that lower temperatures are required to achieve the same product quality. High space velocity, a more severe condition, results in higher temperature requirements for the same product quality.



Presenter

Presentation Notes

Following the construction of a reforming unit, the LHSV can only be adjusted by varying the naphtha charge rate.

Processes Variable: Hydrogen to Hydrocarbon ratio


Presenter

Presentation Notes

The hydrogen/hydrocarbon ratio, or H2/HC, is the measure of moles of hydrogen charged to the reactor as a ratio of the moles of feed naphtha. As mentioned earlier, hydrogen is recycled to the reactors to maintain catalyst stability. The amount of the hydrogen or H2/HC can be adjusted by the rate of recycled gas at a given operating pressure.

Processes Variable: Hydrogen to Hydrocarbon ratio


Presenter

Presentation Notes

The hydrogen purity of the separator gas also has a direct effect on H2/HC. A higher H2/HC results in a less severe operation and thus a lower catalyst deactivation rate. Operation at higher H2/HC must be balanced with the utility cost associated with recycling the separator gas.

Processes Variable: Feed Quality Chemical composition


Presenter

Presentation Notes

Feedstock can be characterized by the relative proportions of paraffins, naphthenes and aromatics (PNA) in the feed along with its distillation range. The fastest reactions are those of naphthene dehydrogenation. Feedstocks rich in naphthenes require less severe conditions to reach a product octane number target or aromatic concentration. Feedstocks that are lean in naphthenes and correspondingly higher in paraffins require more severe operating conditions to obtain a specific quality product.

Processes Variable: Feed quality Distillation range


Presenter

Presentation Notes

A feedstock with a wide boiling range or one with a higher end point will also require more severe conditions to reach product targets. When reformate is produced for the purpose of feeding an aromatics complex, the boiling range of the feedstock tends to be more narrow, limited to the range that results in the desired aromatic species.

Operating Parameters Summary


Processes Variables


Evolution of the relationship between liquid reformate yield versus unleaded RON from the 1950s to the 1990s.


Reforming Process PFDs


Reforming Process PFDs Catalytic Reformers Utilize Multiple Reactor Beds

Presenter

Presentation Notes

Selection of Reforming and Catalyst Regeneration Technologies Catalytic reforming process is operated to convert most of naphthene and part of paraffin in naphtha feed into aromatics at specified hydrogen partial pressure and operating temperature in presence of reforming catalyst in high activity. Conventional catalytic reforming technologies include semi-regeneration reforming process and CCR process. In the 1960s, single Pt catalyst was mainly used for catalytic reforming units. As single Pt catalyst has poor stability, catalytic reforming units shall be operated at higher reaction pressure. This greatly constrained technical improvement and economics for catalytic reforming units. From the 1970s, as Re catalyst and Pt-Re catalyst with satisfactory stability were developed and commercialized in catalytic reforming units, they contributed to significantly reduced reaction pressure and increased product yield. As a result, satisfactory economic benefits were seen. As continuous catalyst regeneration system provided for CCR process is correlated with the reaction system, this ensures constant catalyst activity without any constraint from severe operating conditions. As such, significant improvement of both yield and quality for products (reformate and H2) is seen. The second generation CCR process, which could be operated at much lower reaction pressure, was developed in the 1980s. And in recent two years, the third generation CCR process was developed based on the second generation CCR process where regeneration system is significantly improved. Along with the development of new generation CCR technologies and improvement for operating conditions, both product yield and quality are being improved, and thus more and more satisfactory economics are seen in CCR units. As a key part for CCR process, continuous catalyst regeneration technologies are mainly monopolized by UOP and IFP.


Fixed bed reformer

Presenter

Presentation Notes

The most frequent type of unit: Semi-regenerative reforming As the catalyst deactivates in fixed-bed reforming, the reactor inlet temperatures are gradually increased to maintain product octane number. Semi-regenerative reforming is the original method of management of deactivation, introduced by UOP in 1949. UOP’s RZ Platforming process is another fixed-bed system that uses semi-regenerative reforming technology. Current licensors Axens, UOP [In the old days (Chevron, Amoco, Exxon, Engelhard)


Conventional Unit

Presenter

Presentation Notes

In a typical semi-regenerative reforming unit, treated naphtha feed is combined with recycled hydrogen gas and heat exchanged against reactor effluent. The combined feed is then raised to reaction temperature in the charge heater and sent to the reactor section. Down-flow or radial-flow reactors are arranged in a conventional side-by side pattern.


Semi-Regenerative Catalytic Reformer Unit

Courtesy: UOP


Cyclic Regenerative Reforming

Presenter

Presentation Notes

Cyclic regenerative reforming is an extension of the semi-regenerative paradigm. In cyclic reforming, fixed-bed reactors swing in and out of reforming service and are regenerated individually. This allows for nearly continuous operation of the reforming unit. Typically, there are five or six reactors and large valves permit the removal of any reactor from the process for regeneration. Cyclic operation allows higher severity (hence, higher RON) than semi-regenerative reforming. The regeneration is often suboptimal.


CCR with stacked reactors

Courtesy: UOP

Presenter

Presentation Notes

The conventional CRU type is the SR fixed-bed reforming unit, which is used for limited octane improvement. The unit is operated at high pressure to mitigate carbon formation. As carbon laydown increases, reactor temperatures are raised to achieve the target octane at the expense of reformate yield. A cyclic regenerative process with a swing reactor system is used for higher severity and octane operation. With CCR reforming (see Slide 51 and Slide 55) extremely high severities are obtainable without frequent shutdowns due to catalyst deactivation. The units operate at a low pressure with the associated yield benefits of higher reformate and hydrogen yields. The catalyst regeneration system in a CCR reformer performs two functions: catalyst regeneration and catalyst circulation. These days, all regeneration steps, except for reduction, occur in the regenerator. The reduction takes place in the reduction zone above the first reactor. The catalyst exits the zone and flows by gravity to the first reactor.


Stacked CCR Catalytic Reformer Unit

Courtesy: UOP


Stacked CCR Catalytic Reformer Unit


Side-by-Side Arrangement

Courtesy: Axens


CCR with side-by-side reactors

Courtesy: Axens

Presenter

Presentation Notes

SR and cyclic reformers utilize fixed-bed reforming reactor(s) for regeneration, while a CCR reformer has a dedicated moving-bed regenerator with associated piping and equipment. In SR operation, the catalyst is allowed to coke up and needs to be regenerated periodically in-situ. A cyclic reformer has a swing/spare reactor to allow unit operating severity to be maintained while one reactor is being regenerated. A cyclic or CCR reformer is more robust to feed upsets, as it is regenerated on-line. The reactor operating pressure is lower than with SR operation, which is beneficial to reformate/aromatics yield. Although the lower operating pressure accelerates coke laydown, this is taken care of by on-line regeneration.

www.gbhenterprises.com Courtesy: Axens


Presenter

Presentation Notes

Reducing energy consumption has been a major goal seemingly in contradiction to other objectives; for examples, the desired lower operating pressures and higher octane requirements would normally lead to an increase in the size and energy consumption of the recycle compressor, an increase in the heat requirements, and losses of reformate in the hydrogen rich gas. In order to counteract these effects, IFP has designed a very low pressure drop reaction section, improved the heat recovery on the heat exchange between the reactor effluent and feed, and optimized the recovery of the C5 plus fractions from the hydrogen rich gas under economical conditions. This has been achieved by some equipment developments: the specification of low pressure drop box-type heaters the utilization of new welded sheet feed/effluent heat exchangers which allows both substantial improvement in the thermal approach (i.e., difference between the temperature at the outlet of the last reactor and the temperature at the inlet of the first heater) and very small pressure drop the optimization of the design of the radial reactors, in order to reduce the pressure drop, while maintaining a satisfactory distribution of the hydrocarbons on the catalyst the optimum separation of reformate from hydrogen off gas through the use of efficient yet inexpensive refrigeration systems.

www.gbhenterprises.com Courtesy: Axens


Presenter

Presentation Notes

IFP regenerative technology reportedly allows faster circulation of the catalyst and as a consequence, increased regeneration frequency as required by the more severe operating conditions. It is characterized by a number of unique features listed below. Side-by-side arrangement of the reactors which leads to a number of advantages : Inexpensive, it provides each reactor with its own integrity, thus it is safe and easy to maintain (easy access to any reactor). It eliminates problems of thermal stresses. It is very well adapted to high severities which require increased reactor heights. There is no problem to use four reactors since there are no height limitations. Accurate control of catalyst regeneration and reduction Very accurate control of operating parameters during the various phases of catalyst regeneration and reduction, ensures complete coke burning, good adjustment of the chloride level and utilization of non-purified hydrogen for the reduction. Absence of valves operating on circulating catalyst The patented lift system permits catalyst circulation without using valves and so considerably simplifies maintenance. One of the key IFP process features, it allows even control of the catalyst velocity in the lift lines. Irregular flows or pulsations of catalyst are avoided and as a consequence the attrition is very low.


SR and CCR hybrid process

Courtesy: Axens

Presenter

Presentation Notes

The decision to convert high pressure SR catalytic reformers to CCR-type units hinges entirely on economics. Some reforming licensors have developed a hybrid unit, by adding a CCR reactor and regenerator to an original SR reforming unit. Typical examples are shown in Slide 58 and Slide 59. The conversion could cost less than half that of a new CCR and increases throughput and/or cycle length. To some refiners, a complete conversion to CCR remains economically attractive relative to a hybrid unit, due to the higher on stream factor, lower operating pressure, and higher yields of hydrogen and naphtha. Virtually all new reforming units are of the CCR design.


SR and CCR hybrid process

Courtesy: UOP

Presenter

Presentation Notes

The decision to convert high pressure SR catalytic reformers to CCR-type units hinges entirely on economics. Some reforming licensors have developed a hybrid unit, by adding a CCR reactor and regenerator to an original SR reforming unit. Typical examples are shown in Slide 58 and Slide 59. The conversion could cost less than half that of a new CCR and increases throughput and/or cycle length. To some refiners, a complete conversion to CCR remains economically attractive relative to a hybrid unit, due to the higher on stream factor, lower operating pressure, and higher yields of hydrogen and naphtha. Virtually all new reforming units are of the CCR design.


Comparison of Semi-Regeneration Reforming Process and CCR Process

Presenter

Presentation Notes

Normally, catalytic reforming technologies can be classified into semi-regeneration reforming process (fixed bed) and CCR process (moving bed), depending on catalyst regeneration modes. Semi-regeneration reforming process shows advantages of simple process flow and less investment. However, it does not allow reformate to have a high octane number so as to extend operating cycle for catalyst. Additionally, reactors must be operated at a higher pressure and a higher hydrogen/oil ratio, which will result in lower liquid yield and H2 yield. Furthermore, catalyst activity will be gradually weakened due to coking on catalyst as operation cycle extends, which gradually reduces C5+ liquid yield and H2 yield. As a result, reaction temperature shall be increased gradually until the process unit has to be shut down for catalyst regeneration. Semi-regeneration reforming process employs semi-regeneration reactor, and the service life of catalyst is normally one year. Over operation cycle, catalyst activity will be gradually weakened as cokes deposit. In order to extend the service life of catalyst, higher reaction pressure (around 1.5MPa) and higher hydrogen/oil ratio (around 6) are required for semi-regeneration reforming process. This process features simple process flow and less investment, and it is preferentially applicable to reforming units in a capacity lower than 400 kt/a where products having an octane number less than 95 are produced.


CCR Platforrming versus Fixed-bed Platforrming

Presenter

Presentation Notes

As an additional continuous catalyst regeneration system is provided for CCR process to enable continuous regeneration for the fouled catalyst to maintain its stable activity, reforming reaction can be operated under severe conditions such as low pressure (around 0.35MPa) and low hydrogen/oil ratio (around 2.5). As such, satisfactory activity and selectivity are available for catalyst to contribute to higher C5+ liquid yield and higher H2 yield (C5+ liquid yield can be increased by about 6% and H2 yield can be increased by about 0.8% for the same octane number), catalyst performance is kept stable, leading to process unit in long-term stable operation.


Advantages of CCR Continuous Reforming Technology

Courtesy: UOP

high utilization of feed due to low operating pressure

on stream factor of more than 95% flexibility to process a wide variety of feedstock only two catalyst lifts for minimal catalyst attrition Stacked reactors for economical design optimized heat and compression integration for

every unit liquid recovery optimized on every unit.

Presenter

Presentation Notes

One of the key factors in maintaining catalyst performance (particularly, constant reformate and hydrogen yields) throughout catalyst life is the ability of the CCR regenerator to completely regenerate the catalyst.


Disadvantages of CCR Continuous Reforming Technology

Courtesy: UOP

CCR process shows disadvantages of complicated process flow and more investment as an additional continuous catalyst regeneration system is provided. Note: However, it can contribute to high octane product, high product yield, long unit operation cycle and flexible operation.

Presenter

Presentation Notes

Normally, the larger the process unit size is, the poorer the feedstock properties are and the more stringent the requirements for product are, the more outstanding the advantages for CCR process will show. At present, most grassroots mega-size reforming units employ CCR process. Normally, CCR process is applicable to all reforming units in a capacity larger than 400 kt/a.


Comparison of CCR Process and Semi-Regeneration Reforming Process

Courtesy: UOP

Basis: Same Feedstock processed.

Presenter

Presentation Notes

To conclude, CCR process shows advantages of good product quality, high product yield and high H2 yield, and it can well balance plant-wide hydrogen and find a solution to provide high octane gasoline component.

www.gbhenterprises.com Courtesy: UOP


Dualforming

Presenter

Presentation Notes

A few mixed semi-regenerative/continuous catalyst circulation configuration units IFP developed and commercialized a process that allows the refiner to revamp a conventional reformer and achieve the goal of higher octane at the minimum capital cost. This process is called Dualforming. The Dualforming process allows for the maximum utilization of existing equipment, while improving both reformate yield and hydrogen production compared to a semi-regenerative unit. In many cases, significant improvement in catalytic reforming flexibility may be realized at less than 50% of the capital investment costs of a new continuous regeneration catalytic reformer. It is well known that reducing operating pressure in a catalytic reforming unit substantially improves the reformate yield and especially hydrogen yield. It is also known that lower pressure operations in fixed bed units increases coke formation on reforming catalyst and significantly reduces cycle life.

RZ Platforrming


Presenter

Presentation Notes

UOP’s RZ Platforming process is a fixed-bed system that is well suited for use in aromatics production facilities, particularly for those producers requiring large amounts of benzene. The RZ Platforming process uses the RZ-100 catalyst. By virtue of its ability to convert the most difficult feed components (C6 and C7 paraffins) to aromatics, the RZ-100 catalyst represents a major step beyond conventional reforming catalyst technology. Although RZ-100 catalyst is similar in many ways to conventional reforming catalysts, it differs greatly in the production of light aromatics (benzene and toluene). The selectivity of conventional reforming catalysts for benzene and toluene is significantly lower than for the C8 aromatics. By comparison, the selectivity of the RZ-100 catalyst for light aromatics is vastly improved. This improved selectivity can be illustrated by comparing its aromatics selectivity to that of conventional low-pressure CCR Platforming catalyst. The RZ Platforming process is primarily used for situations in which higher yields of BT aromatics and hydrogen are desired.

RZ Platforrming


Aromatics yields from raffinate

Presenter

Presentation Notes

Although the continuous reforming process is the most efficient means possible for producing xylenes from heavier naphtha fractions, its conversion of C6 and C7 paraffins to aromatics is normally below 50%, even at low pressure. The RZ Platforming process offers constant aromatics selectivity, in the range of 80% or higher, even when processing the most difficult C6 and C7 paraffin feed components. Illustrations of the improved selectivity of the RZ-100 catalyst for aromatics production and increased hydrogen yield are shown in the Fig. and the Fig. on the next slide.

RZ Platforrming


Hydrogen yield from raffinate.

Presenter

Presentation Notes

The RZ-100 catalyst was compared with CCR Platforming catalyst in a controlled pilot plant test, using raffinate feed consisting primarily of C6 and C7 paraffins. The aromatics yields of both catalysts were measured at the same LHSV and low operating pressure. The reactor temperature was varied to show product yields over a wide range of paraffin conversions. The higher selectivity of RZ-100 catalyst toward aromatics while processing this difficult feedstock is clearly demonstrated, ranging from 25-30 wt% higher over the span of the test. Feedstock to the RZ Platforming unit can range from extraction unit raffinate to BTX naphtha. The RZ-100 catalyst can also be used in parallel with a conventional reforming unit to optimize the production of the desired aromatics by processing different fractions of the hydrotreated feed. In such cases, the conventional reformer can be dedicated to processing the heavier feed fraction, taking advantage of its superior ability to produce xylenes. The light naphtha, which is rich in C6 and C7 components, can be routed to the RZ Platforming unit, where selectivity for converting light paraffins to benzene and toluene is greatest.

Reforming Catalyst


Presenter

Presentation Notes

Catalytic reforming reactions are promoted by the presence of a metal catalyst. Catalysts are typically platinum deposited on alumina, or bimetallic catalysts such as platinum-rhenium on alumina. Some multi-metallic catalysts have also been introduced. Bimetallic catalysts provide results comparable to platinum-alumina catalysts with a lower hydrogen-to-feed ratio and a lower pressure.

Catalyst


Reforming Basics Bi-Functional Catalysts


Catalysis Mechanism


Catalyst



Presenter

Presentation Notes

Chloride-related corrosion control To assure the metallic and acidic functions of a reforming catalyst, chloride is continuously injected into the process. Depending on the levels of nitrogen in the feed to the CRU, ammonium chloride could form and deposit on process equipment, with the risk of corrosion or reduced efficiency (for instance, in compressors). Injections with reformate, naphtha or water are an option for cleaning out salts deposited in the recycle gas compressor.

Objectives Path to Breakthrough Catalysts


Catalyst


Presenter

Presentation Notes

Pt-Sn catalysts are utilized in CCR reforming units. The presence of tin (Sn) prevents platinum agglomeration or sintering during the regeneration and provides better Pt dispersion. In the reactors, both the metal(s) and the chloride base help catalyze desirable reactions. Optimum catalyst performance requires a proper balance of these two catalytic functions. Catalyst deactivation usually occurs as a result of coke formation covering the active sites of the catalyst. To regenerate the catalyst, the coke must be burned off and the catalyst oxidized (oxychlorinated to redisperse the platinum and restore the chloride balance), dried and finally reduced. Each step of the regeneration procedure is critical to return the catalyst system to its usual high performance and to ensure long catalyst life.

Catalyst


Presenter

Presentation Notes

Catalyst developments continue, with manufacturers constantly introducing catalysts that exhibit a better yield pattern or a higher activity.

Catalyst


Presenter

Presentation Notes

The reforming catalyst consists of noble metals impregnated on an alumina base, with a cylindrical (SR applications) or spherical shape (SR and CCR applications). A wide variety of metals can be used, but platinum is predominantly used. Multi-metallic catalysts composed of platinum (Pt) and rhenium (Re) are the most common type found in a fixed-bed CRU. Rhenium helps to improve catalyst life by retarding coke deposition to prevent deactivation.

State-of-the-Art Catalysts


WHICH METAL COMBINATION TO CHOOSE


SUMMARY - EFFECT OF SECOND METAL


Stability


SELECTIVITY


New Generation of Catalyst


Catalysts Poisons


Catalysts Contaminants


Catalysts Contaminants (Contd…)


Catalysts Distribution


Catalyst Distribution


Temperatures and Compositions inside Reactors


Chemical Reactions

Catalyst Sampler


Catalyst Regeneration


Objectives of Regeneration Section


Presenter

Presentation Notes

The catalyst deactivates over time at reaction conditions. Typical cycle lengths range from six to twenty-four months. Generally, in-situ catalyst regeneration for rejuvenation of the catalyst is conducted. After the catalyst has deactivated to the point where the desired product can no longer be achieved, the unit is taken off-line, the reactors are purged of hydrocarbons and the catalyst is regenerated. Regeneration employs a low concentration oxygen environment that burns the coke from the catalyst. The unit can then be placed back on stream with near new catalyst performance. Over the course of many years and regeneration cycles, the catalyst will loose the ability to be rejuvenated to nearly new performance and it is replaced.

Regenerator Section: RegenC-2


Regen C


RegenC Catalyst Regenerator



Reactor Types

Presenter

Presentation Notes

Reactor design There are three types of reactors predominantly in use in the reforming process. These are spherical, downflow and radial. As catalyst improved over the years, the reactor pressure could be reduced to take advantage of the increased C5+ and hydrogen yields at lower operating pressure. At lower pressure, the pressure drop through the reactor becomes an important consideration; therefore, more modern designs of reforming units employ reactors that are radial flow in design and combine good flow distribution with low pressure Drop.

Typical Radial CCR Reactor


Presenter

Presentation Notes

The combined feed is directed from the reactor inlet nozzle into so-called scallops, which are long, vertical channels positioned along the entire circumference of the reactor. The scallops have holes or, more commonly these days, profile wire screens along the entire length, through which gas passes radially into the annular catalyst bed and inwards to a centre pipe that collects the reactor products and directs them to the reactor outlet. Low flow should be avoided, as it will result in accelerated coke laydown.

CCR Reactor Metallurgy


Presenter

Presentation Notes

Reactor vessels in a SR CRU service are standalone items and can be either hot or cold shell, depending on design preference. In cold-shell designs, an internal refractory lining protects the vessel wall from exposure to the process temperature. In CCR service, the reactors are invariably of the hot-shell design and can be either individually positioned or stacked to form a compartmented single vessel. In a SR CRU, a cold wall (carbon steel with refractory lining) with an inner stainless steel liner is the norm. However, hot shell design necessitates the use of 1.25Cr-0.5Mo, or in some cases 2.25Cr-1Mo, with stainless steel internals suitable for service above 538°C (1000°F) to meet the requirements for both high-temperature strength and resistance to hydrogen attack.

Typical Axial Fixed-Bed Reactors


Typical Radial Fixed-Bed Reactor



Catalytic Reforming Economics Comparison

Economics Reforming Comparison


Key Energy and Environmental Facts—Catalytic Reforming


Summary of Inputs and Outputs of Catalytic Reforming


Estimated Energy Use in Catalytic Reforming


Conclusions


catalytic reforming technology

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