catalytic reforming

1Catalytic Reforming

CATALYTIC REFORMING Process,Catalysts and Reactors

CATALYTIC REFORMING Process,Catalysts and Reactors

Mohan Lal

Axens India Private Limited(Private Limited Company formed under theCompanies Act, 1956)

on

Petroleum Federation of IndiaIndian Oil Corporation Ltd. (Haldia Refinery),

&Lovraj Kumar Memorial Trust


World context:High octane gasoline requirement

Introduction


World context:

Low sulfur content, Low benzene content,

Limited aromatics content,Limited olefins content,

No lead

Introduction


European Gasoline specifications trends2000 2005 Soon* UltimateSeverity**

Sulfur, ppm max 150 50 10 5Aromatics, vol% max 42 35 30 25Olefins, vol% max 18 18 14 10Benzene, vol% max 1 1 1 1Oxygen, wt% max - 2.7 2.7 2.7Vapor pressure, kPa

max90 60 60 50

C5+ ethers, vol%*** 15 15 15 15Lead, ppb max 5 5 5 5RON/MON, min 95/85 95/85 95/85 95/85

* Assumed ** Projected final limits 2015 ***banned in several states of USA

Introduction


Gasoline Pool specificationsBharat

III

Sulfur, ppm max 150

Aromatics, vol% max 42

Olefins, vol% max 21

Benzene, vol% max 1

Oxygen, wt% max -

Vapor pressure, kPa max 60

RON/MON, min 91/81

Introduction


New gasoline specifications require:

Maintaining a high octane level

Meeting reduced sulfur specifications

Meeting reduced Aromatics and Benzenespecifications

Introduction


Constraints from straight run gasoline: Initial fractionation of crude oils gives gasoline cuts with a low octane number

Light gasoline (C5-C6) : RON between 60 and 70

Heavy gasoline (C7-C10) : RON between 30 and 50

Refiners have to considerably improve the quality of gasoline cuts to meet RON/MON specifications

Introduction


RON/MON is increased by chemical transformation

Light gasoline : Isomerization processn-paraffins i-paraffins

Ex: n-Hexane (RON= 24.8) 2,2-DM Butane (RON= 91.8)

Heavy gasoline: Catalytic Reforming processn-paraffins, naphtens aromatics

Ex: Cyclohexane (RON = 83) Benzene (RON = 108)

Introduction


OutlineOutline Fundamentals of Catalytic Reforming

Objective Reactions desirable and undesirable

Process Semi Regenerative Reforming Dualforming Continuous Catalytic Regenerative Reforming Process Variables

Reforming Catalyst Types Poisons

Some Recent Advances in Reforming Update on CCR Technology / Catalyst Update on SR Technology/ Catalyst / Debottle-necking

Options


Fundamentals Fundamentals


Purpose of reformer

Purpose of reformerPurpose of reformer The purpose of Reforming process is to produce :The purpose of Reforming process is to produce :

-- high octane number reformate, which is a main component for mhigh octane number reformate, which is a main component for motor otor fuel, aviation gasoline blending or aromatic rich feedstock. fuel, aviation gasoline blending or aromatic rich feedstock.

-- hydrogen rich gashydrogen rich gas

-- Due to the nature of the reactions, reforming process produces aDue to the nature of the reactions, reforming process produces also:lso:

LPG LPG FG FG 600 psig steam with the waste heat boilers600 psig steam with the waste heat boilers


Purpose of reformer

Reformer feed Reformer feed pretreatmentpretreatmentDue to the presence of contaminants in all cases and to Due to the presence of contaminants in all cases and to the specific characteristics of cracked naphtha,the specific characteristics of cracked naphtha, Naphtha Naphtha PretreatingPretreating unit(sunit(s)) is(areis(are) always necessary.) always necessary.

Reformer feed is either:- Low quality straight run naphtha - or cracked naphtha, generally mixed with straight run naphtha.


Chemical Reactions


Chemical reactions

Two types of reactions Two types of reactions involved in the involved in the OctanizingOctanizing process:process: Desirable reactionsDesirable reactions, which , which

lead to a higher octane lead to a higher octane number and to high purity number and to high purity hydrogen production. They hydrogen production. They are the reactions to are the reactions to promotepromote

Adverse reactionsAdverse reactions, which , which lead to a decrease of lead to a decrease of octane number and a octane number and a decrease in hydrogen decrease in hydrogen purity. They are the purity. They are the reactions to minimizereactions to minimize

RONRON MONMON

CyclohexaneCyclohexane == 8383 77.277.2

MethylcyclohexaneMethylcyclohexane == 74.874.8 71.171.1

1.3 1.3 dimethylcyclohexanedimethylcyclohexane == 71.771.7 71.71.

BenzeneBenzene == 114.8114.8 > 100> 100

TolueneToluene == 120120 103.5103.5

mm--XyleneXylene == 117.5117.5 115.115.

RON: Research Octane NumberMON: Motor Octane Number


NaphthenesNaphthenes dehydrogenationdehydrogenation Naphthenic compounds dehydrogenated into aromatics with productiNaphthenic compounds dehydrogenated into aromatics with production on

of 3 moles of H2 per mole of of 3 moles of H2 per mole of naphthenenaphthene Promoted by the metallic functionPromoted by the metallic function Highly endothermicHighly endothermic Thermodynamically Thermodynamically favored by high temperature, low pressurefavored by high temperature, low pressure and high and high

number of carbonsnumber of carbons Kinetically favored by high temperature, high number of carbon; Kinetically favored by high temperature, high number of carbon; not not

affected by the hydrogen partial pressureaffected by the hydrogen partial pressure At the selected operating conditions, reaction is very fast and At the selected operating conditions, reaction is very fast and almost almost

totaltotal

Cyclohe xane Benzene

CH

CH

CH

CH HC

HC

CH 2

CH 2

CH 2

H C 2

H C 2

+ 3H 2

CH2

Desirable reactions with hydrogen production


Paraffin's Paraffin's dehydrocyclizationdehydrocyclization

Multiple step reactionMultiple step reaction

Promoted by both acidic Promoted by both acidic and metallic functionsand metallic functions

Kinetically favored byKinetically favored by high high temperaturetemperature, and, and low low pressurepressure

Dehydrogenation step Dehydrogenation step becomes easier as paraffin becomes easier as paraffin molecular weight increases,molecular weight increases, but is competed but is competed by hydro crackingby hydro cracking

At the selected operating At the selected operating conditions, muchconditions, much lower lower rate than that of rate than that of dehydrogenationdehydrogenation

Methylcyclohexane

CH2 CH2

CH CH2 CH3 CH3

CH

CH2 CH2

CH2 CH2

CHCH3 H C2

C H 7 16

+ H 2

C H 7 14

CH2 CH2 CH2

CH2 CH2 CH3 CH3

CH

CH3 CH3

CH2 CH2

CH2 CH

H C2

CH2 CH2

CH2 CH2

CH CH3 CH3

CH CH

CH CH

HCC

+ 3H2




Linear paraffin's Linear paraffin's isomerizationisomerization Promoted by the acidic functionPromoted by the acidic function Slightly exothermicSlightly exothermic FastFast Thermodynamically dependant on temperature; pressure has no Thermodynamically dependant on temperature; pressure has no

effecteffect Kinetically favored byKinetically favored by high temperature;high temperature; not affected by the not affected by the

hydrogen partial pressure hydrogen partial pressure

C H7 16 C H7 16

Carbon atomCarbon atom C4C4 C5C5 C6C6 C7C7 C8C8

% % IsoparaffinIsoparaffin at at 500500CC

4444 5858 7272 8080 8888


NaphthenesNaphthenes isomerizationisomerization Desirable reaction because of the subsequent dehydrogenation of Desirable reaction because of the subsequent dehydrogenation of the the

alkylcyclohexanealkylcyclohexane into an aromaticinto an aromatic Difficulty of ring rearrangement and high risk of ring opening (Difficulty of ring rearrangement and high risk of ring opening (paraffin paraffin

formation)formation) At the selected operating conditions, theoreticallyAt the selected operating conditions, theoretically low rate but low rate but

subsequent dehydrogenation shifts the reaction towards the desirsubsequent dehydrogenation shifts the reaction towards the desired ed directiondirection

Slightly endothermicSlightly endothermic Easier reaction for higher carbon numberEasier reaction for higher carbon number

RONRON MONMON

EthylcyclopentaneEthylcyclopentane == 67.267.2 61.261.2

MethylcyclohexaneMethylcyclohexane == 74.874.8 71.171.1

TolueneToluene == 120120 103.5103.5



Adverse reactions

HydrocrakingHydrocraking HydrocrackingHydrocracking affects either affects either

paraffinsparaffins or olefinsor olefins Promoted by both acidicPromoted by both acidic

and metallic functionsand metallic functions Favored byFavored by high temperature high temperature

and high pressureand high pressure Exothermic Exothermic

((risk of runawayrisk of runaway reactions)reactions) At the selected operatingAt the selected operating

conditions, hydro crackingconditions, hydro cracking reaction could be complete,reaction could be complete, but is limited by kineticsbut is limited by kinetics

+ H 2

C H 7 14 C H 7 16

(m)

+ H 2 C H 7 14

(a) +

C H 4 8

C H 3 8

+ H 2

C H 4 10

C H 4 8

(m)


Consequences of cracking:Consequences of cracking:

Decrease of Decrease of paraffinsparaffins and increase of aromatics and increase of aromatics proportion (i.e. increase in octane) in the reformate proportion (i.e. increase in octane) in the reformate and aand a loss of reformate yieldloss of reformate yield

Decrease in hydrogen productionDecrease in hydrogen production (cracking reactions(cracking reactions consume hydrogen)consume hydrogen)

Increase of light endsIncrease of light ends production and low molecular production and low molecular weight weight paraffinsparaffins

Adverse reactions


+ H 2 C H

7 16

CH4

C H 6 14

+ H 2 C H

7 16

C H2 6

C H 5 12

or

+

+

HydrogenolysisHydrogenolysis Promoted by metallic functionPromoted by metallic function Favored byFavored by high temperature and high pressurehigh temperature and high pressure Exothermic (risk of runaway reactions)Exothermic (risk of runaway reactions)

Adverse reactions


HydrodealkylationHydrodealkylation Breakage of the branched radical of an aromatic ringBreakage of the branched radical of an aromatic ring Promoted by metallic functionPromoted by metallic function Favored byFavored by high temperature and high pressurehigh temperature and high pressure Consumes hydrogen and produces methaneConsumes hydrogen and produces methane But at the selected operating conditions, and with the selected But at the selected operating conditions, and with the selected catalyst, catalyst,

this reaction is not significantthis reaction is not significant

+ H 2

Xylene Toluene

+ CH 4

+ H 2

Toluene Benzene

+ CH 4

Adverse reactions


AlkylationAlkylation Addition of an olefin molecule on an aromatic ringAddition of an olefin molecule on an aromatic ring Promoted by metallic functionPromoted by metallic function leads to heavier molecules which mayleads to heavier molecules which may increase the increase the

end pointend point of the productof the product High tendency toHigh tendency to form cokeform coke; must be avoided; must be avoided

Benzene Propylene Isopropylbenzene

HC

CH3

+ CH = CH CH 3 2

CH3

Adverse reactions


TransalkylationTransalkylation (alkyl (alkyl disproportionationdisproportionation) ) DismutationDismutation of 2 toluene rings to produce benzene and of 2 toluene rings to produce benzene and xylenexylene Promoted by metallic functionPromoted by metallic function Favored byFavored by very severe conditions of temperature and pressurevery severe conditions of temperature and pressure At the selected operating conditions, and with the selected At the selected operating conditions, and with the selected

catalyst, this reaction is negligible catalyst, this reaction is negligible

+

XyleneBenzene

+

Toluene Toluene

Adverse reactions


CokingCoking Results from a complex group of reactions. Detailed Results from a complex group of reactions. Detailed

mechanism not fully known yetmechanism not fully known yet Linked to heavy unsaturatedLinked to heavy unsaturated products (products (polynuclearpolynuclear aromatics) aromatics)

and heavy olefins traces or and heavy olefins traces or diolefinsdiolefins present in the feed or inpresent in the feed or in CCR reactionsCCR reactions

Coke depositCoke deposit reduces active contact areareduces active contact area and reduces and reduces catalyst activitycatalyst activity

Favored by low pressureFavored by low pressureIn In OctanizingOctanizing operating conditions, necessity of a operating conditions, necessity of a continuous regeneration to maintain a low level of continuous regeneration to maintain a low level of coke coke

Adverse reactions


All these reactions occur in series and parallel to each other pAll these reactions occur in series and parallel to each other producing aroducing a complicated reaction schemecomplicated reaction scheme.. IIn an effort to simplify the scheme n an effort to simplify the scheme according to the reaction rates the main reactions take place inaccording to the reaction rates the main reactions take place in the the following order:following order:

1st reactor1st reactor DehydrogenationDehydrogenationIsomerizationIsomerization

2nd and 3rd reactors2nd and 3rd reactors DehydrogenationDehydrogenationIsomerizationIsomerizationCrackingCrackingDehydrocyclizationDehydrocyclization

4th reactor4th reactor CrackingCrackingDehydrocyclizationDehydrocyclization

Chemical reactions


Catalyst Distribution

Highly endothermic transformation Reaction rates vary widely

The overall amount of catalyst needed for the transformation is distributed not equally among several adiabatic reactors in series with intermediary heaters providing the required heat energy input


Temperatures and Compositionsinside Reactors

T0T0 - 25

T0 - 50

R1 R2 R3

AromaticsParaffinsNaphthenes

P0 = 60N0 = 30A0 = 10

H1 H2 H3R1 R2 R3

Position in Reactor

Composition, Vol%

Reactor Temperature, C


The catalyst distribution is:The catalyst distribution is: R1R1 == 10%10% R2R2 == 15%15% R3R3 == 25%25% R4R4 == 50%50%

REACTIONSREACTIONS HEAT OF HEAT OF REACTIONREACTION

(1) KCAL/MOLE (1) KCAL/MOLE

RELATIVE RATERELATIVE RATE (2) APPROX.(2) APPROX.

NaphthenesNaphthenes dehydrogenationdehydrogenation -- 5050 3030

Paraffin Paraffin dehydrocyclizationdehydrocyclization -- 6060 1 (base)1 (base)

IsomerizationIsomerization:: ParaffinsParaffins + 2+ 233NaphthenesNaphthenes + 4+ 4

CrackingCracking + 10+ 10 0.50.5

Chemical reactions

(1) Heat of reaction < 0 = endothermic reaction.(2) For pressure below 15 kg/cm2.


Reforming ProcessesReforming Processes


Fixed bed reformer

Feed

Separator

RecycleCompressor

StabilizedReformate

1 2 3

Fuel GasLPG

A

B

C

Interheater 1 Interheater 2

The most frequent type of unit Current licensors

Axens, UOP In the old days (Chevron, Amoco, Exxon,

Engelhard)


Feed

Separator

RecycleCompressor

BoosterCompressor Hydrogen-

Rich Gas

UnstabilizedReformate

RecontactingDrum

1 2 3

Conventional Unit


DualformingDualforming

FeedRecycle

Compressor

HydrogenRichGas

UnstabilizedReformate

1 2 3

RegenC2

CCRRX

BoosterCompressor

RecontactingDrum

Packinox

12b

Texicap+ RG682

Last Reactor Catalyst Continuously Regenerated Provides excellent option for the revamp of existing SR reformers


Continuous Catalytic Regenerative Reforming





ElutriatorUpper Hoppers

ReductionChamber

H2

LowerHopperLiftPot

Regenerator

LockHopper

UpperSurgeDrum

Reactors R1 R3 R4R2

N2

FC

Coke

H2H2 N2FC

LC

FC

LC

FC

LC

LC

FC

Catalyst Continuously Regenerated With advanced catalysts longer catalyst life and less makeup

rates possible


Objectives of Regeneration Section

Recover initial catalyst activity

Coke removal 2 Burning zones Metal redistribution &

chloride adjustment Oxychlorination

Catalyst drying Calcination

Each zone independently optimized


RegenC

PrimaryBurn

FinishingBurn

Calcination

Oxychlor-ination

CombustionGasfrom Dry Loop

AdditionalAir

ChloridingAgent+ water

Oxychlorination Calcination Gas

Spent Catalyst

Regenerated Catalyst

To Dry BurnLoop

To EffluentTreatment

Burning with dry gas control:%O2, tem perature

Catalysts specific area is maintained

Oxychlorination control: % O2, temperature

and m oisture

Optimum Pt dispersion


RegenC Catalyst Regenerator

CombustionGas Inlet

Air Inlet

CombustionGas Outlet

Oxychlorination Outlet

Calcination GasInlet

Primary Burning

Finishing Burning

Oxychlorination

Calcination

Chloriding AgentInlet

Coked Catalyst

Regenerated Catalyst


Processes VariablesProcesses Variables


Pressure

Temperature

Space velocity

Hydrogen partial pressure (H2/HC)

Quality of the feed

Operating Parameters Summary


Each of themEach of them can be fixed by the operatorcan be fixed by the operator -- within within the operating range of the equipment the operating range of the equipment -- independently from the othersindependently from the others

For one setFor one set of independent variables, for same feed of independent variables, for same feed characteristics, there is onlycharacteristics, there is only one performance of the one performance of the unitunit i.e. one set of values for:i.e. one set of values for: Product yieldsProduct yields Product quality (Octane)Product quality (Octane) Catalyst stability (coke make)Catalyst stability (coke make)

Process variables


Pressure


Pressure

Pressure is the basic variable because of its Pressure is the basic variable because of its inherentinherent effect on reaction rateseffect on reaction rates

Effect of pressure on reactionsEffect of pressure on reactions Low pressures enhanceLow pressures enhance hydrogen producinghydrogen producing reactions: reactions:

dehydrogenation, dehydrogenation, dehydrocyclisationdehydrocyclisation, coking, coking CrackingCracking rate is reducedrate is reduced

The lower the pressure, the higher the yields of The lower the pressure, the higher the yields of reformate and hydrogen for a given octane number. reformate and hydrogen for a given octane number. But high coking rate (compensated by continuous But high coking rate (compensated by continuous regeneration)regeneration)


Pressure

Average catalyst pressure used, close toAverage catalyst pressure used, close to last last reactor inlet pressurereactor inlet pressure

During transient conditions (start up, During transient conditions (start up, shutdown, upsets) it is recommended to shutdown, upsets) it is recommended to increase the pressure to lower coke increase the pressure to lower coke formationformation

Limits of operators actionLimits of operators action Pressure rise limited byPressure rise limited by equipments design pressureequipments design pressure

Pressure lowering limited byPressure lowering limited by recycle compressorrecycle compressor design power and intake volumedesign power and intake volume


Temperature


Temperature

Most important andMost important and most usedmost used operating parameter with operating parameter with space velocityspace velocity

Catalyst activityCatalyst activity is directly related to reactor temperature. By is directly related to reactor temperature. By simply raising or lowering reactor inlet temperatures,simply raising or lowering reactor inlet temperatures, operators operators can raise or lower product quality and yieldscan raise or lower product quality and yields

It is commonly accepted to consider the weight average inlet It is commonly accepted to consider the weight average inlet temperature (WAIT)temperature (WAIT)

Where Where Ti1, Ti2, Ti1, Ti2, are inlet temperature of reactorsare inlet temperature of reactors(wt of catalyst R1)(wt of catalyst R1) are weight of catalyst in reactorsare weight of catalyst in reactors

( ) ( ) ( ) catalyst of wt Total

4Ti x 4RCatalyst wt + ....2Ti x 2RCatalyst wt +1Ti x 1Rcatalyst ofwt = WAIT


AnAn increase of temperatureincrease of temperature (i.e. WAIT) has the following (i.e. WAIT) has the following effects:effects: Increases octaneIncreases octane Decreases the yield (of C5+ fraction)Decreases the yield (of C5+ fraction) Decreases the H2 purity.Decreases the H2 purity. Increases the coke depositIncreases the coke deposit

AA slight increaseslight increase of temperature (WAIT) through theof temperature (WAIT) through the life of life of the catalyst makes upthe catalyst makes up for this activity lossfor this activity loss

Larger and temporary changes in temperature are required:Larger and temporary changes in temperature are required:

To change octane To change octane -- at constant feed quality and quantityat constant feed quality and quantity To change feed quantityTo change feed quantity and still maintain octaneand still maintain octane To change feed qualityTo change feed quality and still maintain octaneand still maintain octane

Temperature


Space Velocity


Space velocity

Weight hourly space velocity:Weight hourly space velocity:

Liquid hourly space velocity:Liquid hourly space velocity:

Linked to residence time of feed in the reactor andLinked to residence time of feed in the reactor and affects the kinetics of the Reforming reactionsaffects the kinetics of the Reforming reactions

reactorsin catalyst ofWeight hour)(per feed ofWeight WHSV =

reactorsin catalyst of Volumehour)(per C15at feed of VolumeLHSV =

Space velocity

residence time

higher severity

Octane increased Lower reformate yield Higher coke deposit


Operators must bear in mind thatOperators must bear in mind that each time each time liquid feed rate is changed, a temperature liquid feed rate is changed, a temperature correction must be appliedcorrection must be applied if octane is to be if octane is to be maintained.maintained.

Important recommendationImportant recommendation Always decrease reactor inlet temperature first and Always decrease reactor inlet temperature first and

decrease feed decrease feed flowrateflowrate afterwardsafterwards Always increase feed Always increase feed flowrateflowrate first and increase first and increase

reactor inlet temperature afterwardsreactor inlet temperature afterwards

Space velocity


Hydrogen to hydrocarbon ratio



H2/HC ratioH2/HC ratio: : ==

WhereWhere RR is the recycle flow in Kg/h (or lb/h)is the recycle flow in Kg/h (or lb/h)MM is the recycle gas molecular weightis the recycle gas molecular weightFF is the feed rate in Kg/h (or lb/h)is the feed rate in Kg/h (or lb/h)mm is the feed molecular weightis the feed molecular weightYY vol. fraction of H2 in the recycle gasvol. fraction of H2 in the recycle gas

The recycle gas MW is obtained by chromatographic The recycle gas MW is obtained by chromatographic analysis, as well as the H2 vol. fraction (Y)analysis, as well as the H2 vol. fraction (Y)

The feed MW is obtained by chromatographic analysis The feed MW is obtained by chromatographic analysis or by correlation from its distillation range and specific or by correlation from its distillation range and specific gravitygravity

)(mole/hour rate flow Naphtharecyclein )(mole/hourhydrogen Pure = HC

H 2 H2 HC = R

M x YFm


Operators can change the H2/HC ratio by lowering Operators can change the H2/HC ratio by lowering or increasing theor increasing the recycle compressor flowrecycle compressor flow

For a given unit, the amount of recycle isFor a given unit, the amount of recycle is limited by limited by the recycle compressorthe recycle compressor characteristics (power, characteristics (power, suction flow)suction flow)

The H2/HC ratio hasThe H2/HC ratio has no obvious impactno obvious impact on the on the product quality or yieldproduct quality or yield

But a high H2/HC ratioBut a high H2/HC ratio reduces the coke build upreduces the coke build up

It is strictly recommended to operate with a H2/HC It is strictly recommended to operate with a H2/HC ratio equal to (or higher than) theratio equal to (or higher than) the design figuredesign figure



Feed quality


Feed quality Chemical composition

Characterization of the Characterization of the feedstocksfeedstocks by:by: With a higher 0.85 N + AWith a higher 0.85 N + A

The same Octane content will be obtained at a lower severity The same Octane content will be obtained at a lower severity (temperature) and the(temperature) and the product yield will be higherproduct yield will be higher

Or for the same severity (temperature),Or for the same severity (temperature), the Octane content will be the Octane content will be higherhigher

Higher Higher naphtenicnaphtenic content. Tcontent. The endothermic reaction heat is he endothermic reaction heat is increased and the feed flow rate will beincreased and the feed flow rate will be limited by the heater design limited by the heater design dutyduty

With lower With lower 0.85 N + A0.85 N + A Higher paraffin content. Higher paraffin content. The hydrogen purity of the recycle gas The hydrogen purity of the recycle gas

decreases and operation will bedecreases and operation will be limited by the recycle compressor limited by the recycle compressor capacitycapacity

ImpuritiesImpurities Temporary or permanent reduction of catalyst activity by poisonsTemporary or permanent reduction of catalyst activity by poisons

contained in the feedcontained in the feed

0.85 N + A


The feed distillation range is generally as follows: The feed distillation range is generally as follows: IBP (Initial Boiling Point)IBP (Initial Boiling Point) 7070--100 100 CC EP (End Boiling Point)EP (End Boiling Point) 150150--180 180 CC

Light fractions: Light fractions: CyclizationCyclization of C6 more difficult than that of C7of C6 more difficult than that of C7--C8C8

The lighter the feed, theThe lighter the feed, the higher the requiredhigher the required severityseverity for a given Octanefor a given Octane

Heavy fractions:Heavy fractions: high naphthenic and aromatics contenthigh naphthenic and aromatics content

Lower severityLower severity to obtain good yieldsto obtain good yieldsBut polycyclic compounds which favorBut polycyclic compounds which favor coke depositcoke deposit

Feed quality Distillation range

EP higher than 180C are generally not recommended


Operating Parameters Summary

Hereafter the theoretical effect on the unit performance of Hereafter the theoretical effect on the unit performance of each independent process variable taken separatelyeach independent process variable taken separately::

IncreasedIncreased RONCRONC Reformate yieldReformate yield Coke depositCoke deposit

PressurePressure

TemperatureTemperature

Space velocitySpace velocity

H2/HC ratioH2/HC ratio

Naphtha Naphtha QualityQuality

A + 0.85 NA + 0.85 N

End boiling pointEnd boiling point

Initial boiling pointInitial boiling point


CatalystsCatalysts


The main characteristics of a catalyst other than its physical and mechanical properties are :

The activityo catalyst ability to increase the rate of desired reactionso Is measured in terms of temperature

The selectivityo Catalyst ability to favor desirable reactionso Practically measured by the C5+ Reformate and Hydrogen

yields

The stabilityo Change of catalyst performance ( activity, selectivity )with

timeo Caused chiefly by coke deposit and by traces of metals in feedo Measured by the amount of feed treated per unit weight of

catalyst. C5+ wt reformate yield is also an indirect measure of the stability.

Catalyst Catalyst


Catalyst

Catalyst Chlorinated gamma alumina with nanao

particle of Pt The chlorinated gamma alumina has too

strong acid sites The Pt promotes hydrogenolysis of

Pt + H2


Catalyst

In the 90s Procatalyse (now Axens) launched promoted Pt/Re catalyst RG 582 Then RG 682 in 2000

The promoter provides two benefits Reduced hydrogenolysis by a modification

of the metallic cluster Lower the number of the strongest acid

sites


Catalyst

The stability of Pt has been improved by addition of promoters (Re, Ir)

The hydrogenolysis of Pt has been reduced by addition of promoters

The acidity of the chlorinated gamma alumina has been tuned by addition of promoters


Catalyst

To improve the catalyst stability the Pt sintering has to be hindered

Addition of promoters Rhenium or Iridium

Explanation Re and Ir is alloyed with Pt the boiling point of Pt is increased Sintering reduced

Pt accessiblePt Total

0.75

0.50

0.25

Time, hours0 10 20 30 40 50

Pt + Re

Pt

1.00

Operating conditions T = 650C H2 = 2 000 L/kg/h


Reforming catalysts are bimetallic catalyst consisting of platinum plus promoters on an alumina support, Rhenium and Tin being essentially one of the promoter besides the others.

The main features of these catalysts are :o High purity alumina support - High mechanical resistanceo Platinum associated with Rhenium - high stability &

selectivityo Platinum associated with Tin high selectivity

o High Regenerability

The combination of these qualities give the following advantages:

o High Reformate yieldo High hydrogen yieldo High on - stream factoro Low catalyst inventory

CatalystCatalyst


Catalyst

Platinum (Pt) plus other promoter(s) impregnated on to gamma alumina containing around 1% wt chloride to provide acidity.

Since 1967, bimetallic catalysts have been widely used.

The second metal comes from the groupRhenium (Re)Tin (Sn)Iridium (Ir)Germanium (Ge)


WHICH METAL COMBINATION TO CHOOSE

Depends on what you want from the catalyst - "THE OBJECTIVES"

Stability / cycle life

Selectivity towardshydrogen (H2)liquid reformate (C5+ reformate)benzene yield in C5+ reformate


Stability

Normal causes for catalyst ageing/deactivationNormal causes for catalyst ageing/deactivation

metal sinteringmetal sintering temperaturetemperature metallic phase metallic phase presence of chloridepresence of chloride

deposition of coke on metal and acid sitesdeposition of coke on metal and acid sitesCoking effect can be splitCoking effect can be split

1. Degree of poisoning of deposited coke1. Degree of poisoning of deposited coke 2. Relative coking rate2. Relative coking rate


Desired yields are:Desired yields are: hydrogenhydrogen CC55 + reformate+ reformate low benzenelow benzene

Benzene Benzene yield can be minimised by preyield can be minimised by pre--fractionating the fractionating the

precursors (MCP, CH, nC6P) which are present in the precursors (MCP, CH, nC6P) which are present in the fraction boiling between 70 to 85fraction boiling between 70 to 85CC

benzene is also produced by the hydrodealkylation of benzene is also produced by the hydrodealkylation of alkyl benzenesalkyl benzenes

Loss of desired yields is caused by crackingLoss of desired yields is caused by cracking hydrocracking involving the metal plus acid siteshydrocracking involving the metal plus acid sites hydrogenolysis involving the metal in the presence of hydrogenolysis involving the metal in the presence of

hydrogen hydrogen

SELECTIVITY


Tin and GermaniumTin and Germanium increases selectivity towards desired productsincreases selectivity towards desired products no stability benefitno stability benefit

Rhenium and IridiumRhenium and Iridium increase stabilityincrease stability no major effect on yield selectivityno major effect on yield selectivity

Other effects such as regenerability and tolerance to feedstockOther effects such as regenerability and tolerance to feedstock impurities has led to the PtRe combination being preferred catalimpurities has led to the PtRe combination being preferred catalyst yst

SUMMARY - EFFECT OF SECOND METAL


RG 582 introduced 1994RG 582 introduced 1994 Third metal moderates hydrogenolysis activity to Third metal moderates hydrogenolysis activity to

between that of balanced PtRe and PtSnbetween that of balanced PtRe and PtSn Desired yields increasedDesired yields increased

Hydrogen by 0.1 to 0.15wt%Hydrogen by 0.1 to 0.15wt% CC 55 + by around 1 wt%+ by around 1 wt%

Stability studies in pilot plant show 93 Stability studies in pilot plant show 93 -- 100% of 100% of balanced bimetallic catalyst, but in commercial units balanced bimetallic catalyst, but in commercial units >100% is commonly seen.>100% is commonly seen.

TRI METALLIC CATALYST


Pilot test results Low pressure pilot test

Previous Generation - Bi-promoted catalyst- High Pt content

Selectivity & stability improvement

Axens New series - Multi Promoted Catalyst- Reduced Pt content

- Tri-promoted catalyst- Reduced Pt content

SelectivityC5+ yield

Stability (time)


The catalyst affects reaction rates through its two different functions/type of sites:o Metallic, ando Acidic

Different types of reactions are promoted by these sites as:

o Dehydrogenation Metallico Dehydrocyclisation Metallic + Acidico Isomerisation Metallic + Acidic o Hydrogenolysis Metallic o Hydrocracking Metallic + Acidic

Catalysis MechanismCatalysis Mechanism


Catalysts PoisonsCatalysts Poisons


Temporary poisons

Which can be removed and the proper Activity and Selectivity of catalyst is restored.

The most common temporary poisons ( inhibitors ) are:

o Sulphuro Organic nitrogeno Watero Oxygenated organicso Halogens

Catalyst ContaminantsCatalyst Contaminants


Permanent poisons Which induce a loss of activity which can not be restored.

Catalyst Contaminants (Contd)Catalyst Contaminants (Contd)

Main permanent poisons are

Arsenic Lead Copper Iron Nickel Chromium Mercury Sodium Potassium


Reactor TypesReactor Types


Typical Axial Fixed-Bed Reactors

Typical Axial Fixed-Bed Reactors


Typical Radial Fixed-Bed Reactor

Typical Radial Fixed-Bed Reactor

The design of the upper part of the reactor was made to take into account

- density change (settling)

- possible by-passing of catalyst

- space for mechanical assembly

Bolted metal shroud and cover

CatalystDead Space


Typical Radial CCR ReactorTypical Radial CCR Reactor

CatalystFeed

Effluent


A New Concept of Radial Reactor Internals

A Flexible Flow-guide that molds to the shape of the top of the bed

Texicap TMTexicap TM


Typical Radial Fixed-Bed Reactors

Typical Radial Fixed-Bed Reactors

The design of the upper part of the reactor was made to take into account

- density change (settling)

- possible by-passing of catalyst

- space for mechanical assembly

BEFOREBolted metal shroud and cover

CatalystDead Space


Modifying Radial Fixed-Bed Reactors with Texicap

Modifying Radial Fixed-Bed Reactors with Texicap

Gainedwith

Texicap

BEFORE AFTERCatalystDead Space


Catalyst Sampler

N2 ATM FL

RefillingSampling Box

Draining

Handling Head

Receiving Pot

Drain


CATALYTIC REFORMING Process,Catalysts and Reactors IntroductionIntroductionIntroductionIntroductionIntroductionIntroductionIntroductionOutlineSlide Number 10Slide Number 11Slide Number 12Slide Number 13Slide Number 14Slide Number 15Slide Number 16Slide Number 17Slide Number 18Slide Number 19Slide Number 20Slide Number 21Slide Number 22Slide Number 23Slide Number 24Slide Number 25Slide Number 26Catalyst DistributionSlide Number 28Slide Number 29Reforming ProcessesFixed bed reformer Slide Number 32Slide Number 33Slide Number 34Slide Number 35Slide Number 36Slide Number 37Slide Number 38Slide Number 39Slide Number 40Slide Number 41Slide Number 42Slide Number 43Slide Number 44Slide Number 45Slide Number 46Slide Number 47Slide Number 48Slide Number 49Slide Number 50Slide Number 51Slide Number 52Slide Number 53Slide Number 54Slide Number 55Slide Number 56Slide Number 57Slide Number 58Slide Number 59Catalyst Catalyst CatalystCatalyst Slide Number 64Slide Number 65Slide Number 66Slide Number 67Slide Number 68Slide Number 69Slide Number 70Pilot test results Low pressure pilot testSlide Number 72Slide Number 73Slide Number 74Slide Number 75Slide Number 76Slide Number 77Slide Number 78Slide Number 79Slide Number 80Slide Number 81Slide Number 82Catalyst SamplerSlide Number 84

catalytic reforming

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reforming update

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