Alkylasi, Reforming, Dan Isomerisai

PRESENTATION MATERIAL FOR ISOMERISATION,

PLATFORMING, AND ALKYLATION

Bandung, 20 April 2011

Crude Distillation Column

Desalter

Vacuum Distillation Column

Desalter

VacuumGas Oils

Vapor Recovery Units

Desalter

VacuumGas Oils

Saturate Vapor Recovery

Unsaturate Vapor Recovery

Sulfur Removal

Sulfur Removal

Hydrotreating Units

Desalter

VacuumGas Oils



Hydrotreating Unit

Hydrotreating Unit

Hydrotreating Unit

Sulfur Removal

Hydrotreating Unit

Sulfur Removal

Hydrotreating Unit

Catalytic Reformer

Desalter

VacuumGas Oils



Hydrotreating Unit

Hydrotreating Unit

Hydrotreating Unit

Sulfur Removal

Catalytic Reformer

Hydrotreating Unit

Sulfur Removal

Hydrotreating Unit

Isomerization Unit

Desalter

VacuumGas Oils



Hydrotreating Unit

Hydrotreating Unit

Hydrotreating Unit

Sulfur Removal

Catalytic Reformer

Hydrotreating Unit

C5/C6 Isomerization

Sulfur Removal

Hydrotreating Unit

Fluid Catalytic Cracking Unit

Desalter

VacuumGas Oils



Hydrotreating Unit

Hydrotreating Unit

Hydrotreating Unit

Sulfur Removal

Catalytic Reformer


Hydrotreating Unit

C5/C6 Isomerization

Sulfur Removal

Hydrotreating Unit

Hydrocracking Unit

Desalter

VacuumGas Oils



Hydrotreating Unit

Hydrotreating Unit

Hydrotreating Unit

Sulfur Removal

Catalytic Reformer

Hydrocracking Unit


Hydrotreating Unit

C5/C6 Isomerization

Sulfur Removal

Hydrotreating Unit

Alkylation Unit

Desalter

VacuumGas Oils



Hydrotreating Unit

Hydrotreating Unit

Hydrotreating Unit

Sulfur Removal

Catalytic Reformer


Hydrocracking Unit Alkylation

Hydrotreating Unit

C5/C6 Isomerization

CatalyticCondensatio

n

Sulfur Removal

Hydrotreating Unit

Residual Units

Desalter

VacuumGas Oils



Hydrotreating Unit

Hydrotreating Unit

Hydrotreating Unit

Sulfur Removal

Catalytic Reformer



Hydrotreating Unit

C5/C6 Isomerization


n

Sulfur Removal

VisbreakingThermal Cracking

AsphaltAsphalt

Oxidation

Hydrotreating Unit

Coking Unit

Desalter

VacuumGas Oils



Hydrotreating Unit

Hydrotreating Unit

Hydrotreating Unit

Sulfur Removal

Catalytic Reformer



Coking

Hydrotreating Unit

C5/C6 Isomerization

Sulfur Removal


n

Hydrotreating Unit

Focus of Discussion

Desalter

VacuumGas Oils



Hydrotreating Unit

Hydrotreating Unit

Hydrotreating Unit

Sulfur Removal

Catalytic Reformer



Coking

Hydrotreating Unit

C5/C6 Isomerization

Sulfur Removal


n

Hydrotreating Unit

ParaffinIsomerization

Paraffin Isomerization Background• WWII requirement for iso-butane for alkylation• 1941 – 1st unit based on Friedel-Craft chemistry

– Used corrosive aluminum chloride catalyst– High costly maintenance– 38 units fulfilled needs of the time

• 1950s – Development of high temperature dual function, reforming-like catalyst systems

• 1959 – 1st C4 unit based on low temperature dual function catalyst systems

• 1969 – 1st C5/C6 unit; • 1970s - Industry-wide lead reduction created need to

upgrade C5-C6 octane.• 2000s – Benzene reduction added benefit

Paraffin Isomerization• Conversion of normal paraffins to iso-paraffins is

one type of isomerization• Principal application of isomerization is the

conversion of normal C4, C5 and C6 material

• Butane (C4) Isomerization provides iso-butane feed to an alkylation process or MTBE Complex

• Pentane (C5) – Hexane (C6) Isomerization provides higher octane (82-91 RONC) components to the gasoline pool– Gasoline is less aromatic when C5/C6 isomers are added– Benzene saturation side reaction helps meet aromatic

concentration standards

Component Blended Octane ValuesComponent RONC MONC iC4 100.2 97.6 nC4 95.0 93.5 iC5 93.5 89.5 nC5 61.7 61.3 Cyclopentane 102.3 85.0 22 DMB 94.0 95.5 23 DMB 105.0 104.3 2 MP 74.4 74.9 3 MP 75.5 76.0 nC6 31.0 30.0 MCP 96.0 85.0 Cyclohexane 84.0 77.2 Benzene 120.0 114.8 Feed C7- 55.0 55.0

C5 - C6 Isomerization Terms

• Product Ratios, wt% or mol%– iC5/C5P = iC5/(iC5+nC5) x 100%– 2,2DMB/C6P = 2,2DMB/C6 Paraffins x 100%– 2,3DMB/C6P = 2,3 DMB/C6 Paraffins x 100%– C6 Paraffins = 2,2DMB + 2,3DMB + MP + MCP + CH + nC6

• PIN (Paraffin Isomerization Number), wt%– Σ (iC5/C5P + 2,2DMB/C6P + 2,3DMB/C6P)

• Feed X-factor, wt%– Σ (MCP + CH + BZ + C7+)

Component Iso Ratios

Lt SR Naphtha Product Octane 72 RONC 83 RONC iC5/C5P 40 77 22 DMB/C6P 2 32 23 DMB/C6P 5 10 2 MP/C6P 31 30 3 MP/C6P 19 17 nC6/C6P 43 11

C5 - C6 Isomerization Process Benefits

• High C5+ product yields (99-100 volume%) • 100% benzene saturation• Low severity reactor operations

– Typical: 450 psig (31.5 kg/cm2(g))– 250-400°F (120-204C)

• Excellent catalyst stability – Up to 10-15 year catalyst lives

• Capable of processing wide range of feedstocks

Isomerization Feedstocks

• C4 Isomerization– Vapor Recovery Unit Butane– Alkylation Product Butane

• C5/C6 Isomerization– Light Straight Run Naphtha– Feed Fractionation

• Feed should consist of C5 and C6 material

• C7 material should be kept to a minimum

Chemistry

• Isomerization• Benzene Saturation• Ring Opening• Hydrocracking

Reactions take place over a dual function catalyst- Metal function (platinum)- Acid function (chloride)

Isomerization Reactions

C

Methylcyclopentane (MCP)

96.0 RON

Cyclohexane (CH)84.0 RON

C-C-C-Cn-Butane (nC4) Isobutane (iC4)

C-C-CC

C-C-C-C-Cn-Pentane (nC5)

61.7 RONIsopentane (iC5)

93.5 RON

C-C-C-CC


C-C-C-C-C-Cn-hexane (nC6)

31.0 RON

2-Methylpentane (2MP)74.4 RON

C-C-C-C-CC

3-Methylpentane (3MP)75.5 RON

C-C-C-C-CC

2,3-Dimethlybutane (2,3DMB)105.0 RON

C-C-C-CC

C2,2-Dimethylbutane (2,2DMB)

93.5 RON

C-C-C-CC

C


• Requires metal and acid functions• Equilibrium limited• Slightly exothermic• No hydrogen consumed• Increases octane

Benzene Saturation• Benzene saturates to cyclohexane• Cyclohexane (CH) in equilibrium with

methylcyclopentane (MCP)

C

MCPentane96.0 RON

Cyclohexane84.0 RON

Benzene120.0 RON

100% 40-60%3H2 + Pt

Benzene Saturation Reaction

• Immediate with platinum sites and presence of hydrogen• No acid sites required• 100% complete• Highly exothermic (25x isomerization, 5x hydrocracking)• Consumes 3 moles H2 per mole of benzene• Reduces octane (120 Bz 84 CH & 96 MCP)• Limit Bz in feed to ~5 vol%

– ~20ºF (11ºC) rx bed deltaT / 1 vol% Bz– ~100ºF (55ºC) total deltaT / reactor

Lead Rx

DT 1DT 2

DT 4DT 3Lead Rx

DT 1DT 2

DT 4DT 3

Ring Opening Reactions

• CH and MCP open to C6 paraffins• Cyclohexane (CH) in equilibrium with

methylcyclopentane (MCP)

C

MCPentane96.0 RON

Cyclohexane84.0 RON

Benzene120.0 RON

100% 40-60%3H2 + Pt

C-C-C-C-C-C

30% 30%

Ring Opening Reactions

• Competes for the platinum sites• Moderately exothermic• 20-40 wt% opening• Consumes 1 moles H2 per mole of ring opened• Reduces octane• Necessary to prevent cyclic buildup with DIH• Increases with lead reactor temperature increases• Higher temperatures favor MCP

Hydrocracking

• Longer chain molecules break to smaller ones

R-C-C-C + H2 R-H + C-C-CC

H

C

Hydrocracking• Triggered by high reactor temperatures and catalyst

acid sites• Exothermic• Consumes 1 moles H2 per mole of cracked material• C5 and C6 paraffin hydrocracking is minimal• About 50% of C7+ paraffins hydrocrack to C4 and C3

paraffins• C5+ yield loss• Caused by:

– Higher C7+ in feed– Higher rx temperatures pushing equilibrium– Temperature excursion

Isomerization Catalyst• Dual function catalyst (metal/acid)

– Metal is always platinum– Acid is always chloride

• Metal impregnated on a high surface area alumina-oxide• Active sites are bound alumina-chloride• Gray extrudate or gray trilobe extrudate

• Dual function balance is maintained by:– Perchloroethylene injection

• Sensitive to contaminants and non-regenerable

Cl

Pt

Cl

Pt

Cl

Pt

Cl

Pt

Cl

Pt

ClCl

Pt

Catalyst Promotor - Chloride

ClClCl-Cl-

HH++ClCl--

Cl-Cl-Cl-Cl-

Cl-Cl-Cl-Cl-

H2H2C5C5

C6C6

C5, C6, H2, HClC5, C6, H2, HCl

• Continuous chloride injection required to maintain activity.

- Hydrogen and hydrocarbon can strip bound chlorides from the catalyst if the partial pressure of chloride

surrounding the catalyst is too low.• Low or loss of chloride injection will permanently

deactivate the catalyst.

Reactor Feed ContaminantsContaminant Effect Limit

Total sulfur Attenuates metal activity, reduces benzene saturation, reversible

0.1 wtppm max.

Nitrogen Organic/Basic

Neutralizes acid sites, deactivates catalyst, irreversible; NH4Cl fouling

0.1 wtppm max.

Water Removes bound chloride, blocks active sites, plug flow, irreversible1 lb H2O kills 100 lb catalyst

0.1 wtppm max.

Oxygenates OH groups displace Cl, neutralizes acid site, irreversible

0.1 wtppm max.

Fluorides Displaces chloride, less acidic, irreversible (very rare)

0.1 wtppm max.

Metals Block active sites, attach Pt, plug flow, irreversible (Mercury, Co, Ni)

ppb

Makeup Gas ContaminantsContaminant Effect Limit

Sulfur (H2S) Attenuates metal activity, reduces benzene saturation, reversible

1 molppm

Nitrogen Organic


0.5 molppm

Water Removes bound chloride, blocks active sites, plug flow, irreversible1 lb H2O kills 100 lb catalyst

0.1 volppm

CO + CO2 CO2 irreversibly adsorbs on drier sieve hence higher spec, less reactive than CO on catalyst

10 molppm max.

CO Attaches to metal, similar to sulfur, eventually methanates with H2, somewhat reversible

1 molppm max.

Chloride (HCl) Adsorbs on drier sieve, irreversible 0.5 molppm

Note: Limits at drier inlet except water spec

Contaminants – Final Words• CO/CO2 & HCl are the most common makeup gas

problems• Cyclics can act as temporary poison

– Adsorbs on the catalyst– Inhibits isomerization equilibrium & hence conversion– Monitor X-factor

WATER, WATER, WATER!

Water Ingress Mitigation Techniques• Acidizing of all equipment in the reactor circuit• Dry nitrogen blanketing of reactor circuit equipment

– If exposed to air during maintenance, must be re-acidized

• Tube rolling and strength welding to charge heater exchanger tubesheet

• Catalyst handling & loading under inert atmosphere• All liquid feed MUST be charged directly from NHT

stripper bottoms or naphtha splitter overhead after NHT• Regenerative driers on makeup gas and feed streams• Moisture analyzers between lead & lag driers.• Dry hydrogen as feed surge drum pressure medium

Prevention is much easier than curing the problem

Isomerization Unit Basics• Feed and makeup hydrogen driers• Switchable lead/lag reactors• Reactions under nominal hydrogen atmosphere

– Isomerization reaction hydrogen neutral

• Exothermic equilibrium and saturation reactions require inter-reactor cooling

• To maintain product quality, severity (temperature) must be gradually increased– Performance gradually deteriorates– Catalyst non-regenerable

• Fractionation (stabilizer) to remove acid gas

Butane Isomerization Process(UOP Hydrogen Once Through Butamer)

Receiver

Isomerate

Stabilizer

Reboiler

Treated Butanes

Condenser

Gas to Scrubbingand FuelSteam

C2Cl4

MU GasDriers

Reactors

Make-upHydrogen

LiquidDriers

Pentane-Hexane Isomerization (UOP Hydrogen Once Through Penex)

Receiver

Isomerate

Stabilizer

Reboiler

Fresh/SpentCaustic

Gasto Fuel

Scrubber

MU GasDriers

Reactors

LiquidDriers

Make-upHydrogen

LightNaphtha

SurgeDrum

C2Cl4

SteamHeater

CCFEHCFE

Pentane-Hexane Isomerization (UOP Recycle Gas Penex)

Receiver

Isomerate

Stabilizer

Reboiler

Fresh/SpentCaustic

Gasto Fuel

Scrubber

MU GasDriers

Reactors

LiquidDriers

Make-upHydrogen

LightNaphtha

SurgeDrum

C2Cl4

SteamHeater

HCFE CCFE

Pentane-Hexane Isomerization with DIH

Increased Octane – More C6 isomers producedBetter for RVP limits

Increases LHSV – recycle offsets

ProductSide DrawMPs, n-C6

Deisohexanizer (DIH)

Bottoms C7+, min n-C6

OverheadC5p, DMB

LP Stm

Receiver

Isomerate

Stabilizer

ReboilerFresh/Spent

Caustic

Gasto Fuel

Scrubber

MU GasDriers

Reactors

LiquidDriers

Make-upHydrogen

LightNaphtha

SurgeDrum

C2Cl4

SteamHeater

CCFEHCFE

H.O.T. Penex

Light Naphtha - FractionationComponent Boiling Point F [C]

Relative Volatility

iC5 82 [28] 3.18 nC5 97 [36] 2.71 22 DMB 122 [50] 1.90 23 DMB 136 [58] 1.59 2 MP 140 [60] 1.53 3 MP 146 [63] 1.42 nC6 156 [69] 1.26 MCP 161 [72] 1.21 Bz 176 [80] 1.25 CH 177 [81] 1.00

Process Variables

C4 Unit C5/C6 UnitPressure 500 psig

(34 bars) 250-500 psig (17-34 bars)

Temperature 300-350F (150-175C)

280-330F (138-166C)

H2/HCBN Ratio 0.05 mol/molAt Outlet

0.05 mol/molAt Outlet

LHSV, hr-1 2-4 1-4Chloride Promotor ~150 wt ppm ~150 wt ppm

Paraffin IsomerizationProcess Variables

• Reactor Temperature– Main process variable– Higher iso ratio (octane) possible at lower temperature– Reaction rate faster at higher temperature– Higher temperature increases cracking and reduces

catalyst life– Lead reactor outlet temperature runs higher than lag

reactor outlet temperature

iC5/C5P

iC4/C4P

Equilibrium Curves

0

20

40

60

80

100

200 250 300 350 400Temperature (F)

Prod

uct R

atio

s (m

ol%

)

MCP/(MCP+CH)(2MP+3MP)/C6P

2-3 DMB/C6P

2-2 DMB/C6P

nC6/C6P

121 C 149 C 177 C

Lag

Rx

Lead

Rx

Octanes of Equilibrium Mixtures

Total C5-C6

C5 Paraffins

C6 Paraffins

7072747678808284868890

100 150 200 250 300Temperature, °C

RO

N

302ºF 392ºF

Lag

Rx

Lead

Rx

Lead and Lag Rx IC5 Product Ratio

400330

EOR

EOR

350240

SOR

SOR

77

45

72

Reactor Outlet Temperature, F

IC5 Product Ratio Equilibrium

IC5/

C5 P

ARAF

FIN

S PR

OD

UCT

RAT

IO, W

t%

Feed (Minimum)116 C 167 C 204 C

Reactor Temperature ProfileExample

100

110

120

130

140

150

160

A Inlet

A Outl

et

B Inlet

B Outl

et

Tem

pera

ture

, C

© 2006 UOP LLC. All rights reserved.

Paraffin IsomerizationVariations

Isomerization Octane Portfolio

556065707580859095

LightNaphtha

Feed

Par Isom Penex PenexDIH

PenexMolex

DIP PenexDIH

RO

NC

60-7060-70

8585

Once Through Hydrocarbon Recycle

8888 89899191

8181

Relative Erected CostsIsomerization Flow Schemes

3.03.0R

elat

ive

Ere

cted

Cos

t 2.52.5

1.51.5

1.01.0

00Par-Isom

Penex Penex/

DIH

PenexMolex

DIP/Penex/DIH

2.02.0

0.50.5

© 2006 UOP LLC. All rights reserved.

Catalytic Reforming

History• Development during and after WWII• Commercialized in 1949 to meet increase demand for

motor fuel post-WWII– Mono-metallic catalyst (platinum)

• Bi-metallic catalyst introduced in 1969• Continuous catalyst regeneration (CCR) introduced in

1970• Licensees have different names but all are reforming

processes

Catalytic Reforming

• Catalytic reforming upgrades low octane naphthas to higher octane motor fuel by promoting specific groups of chemical reactions, primarily to produce high octane aromatics

• Reforming is the mainstay of almost all fuels refineries• Originally, reformate was used to upgrade the gasoline

pool• Today the reforming process is also designed to

produce specific aromatic hydrocarbons for use in the petrochemical industry

• High purity hydrogen and LPG are important and valuable byproducts

Process FeedstocksProcesses feed stocks from various sources

Hyd

rotr

eate

r

Ref

orm

er

S.R. Naph.FCC Naph.T.C. Naph.Coker Naph.H.C. Naph.

Reformate

Contaminates

Lt. HCBN

Hydrogen

Feedstock Properties

• Feed is normally a C6 to C11 fraction for motor fuel applications– 170-400F (77-204C) D-86 Distillation Range– Sulfur 0.25-0.5 wt-ppm min– Nitrogen less than 0.5 wt-ppm– No olefins, metals, halides or oxygenates

• Narrow range, e.g. C6-C8, for petrochemical applications• Difficulty of reforming basically set by distillation and

PONA (paraffins, olefins, naphthenes, aromatics)– Lean naphtha

• High paraffin, low naphthene content– Rich naphtha

• Low paraffin, high naphthene content

Feed Type Impact on Product Yield

• Conversion of lean and rich naphthas to moderate octane reformates at constant operating conditions

P

N

AA

P

A

P

N

A

P

A

}

}

}}}

}

}}

}}

}

LeanNaphtha

RichNaphthaReformate Reformate

Loss Loss

NFrom P

From NFrom A

From P

From N

From ALegendP = ParaffinsN = NaphthenesA = Aromatics

Loss: Due to both cracking and shrinkage

NP

N

AA

P

A

P

N

A

P

A

}

}

}}}

}

}}

}}

}

LeanNaphtha


Loss Loss

NFrom P

From NFrom A

From P

From N



N

Reforming Chemistry• Aromatics

– Pass essentially unchanged through the reactors• Naphthenes

– Almost complete conversion to aromatics, above 90 RONC– Cyclohexanes easier to convert than cyclopentanes

• Paraffins– Some conversion to aromatics– Some isomerization to more highly branched isomers– Some cracking– Many remain in product as paraffins

• Difficulty generally increases with decreasing number of carbon atoms

RONC = Research Octane Number, Clear

Reforming Catalyst• Dual function catalyst (metal/acid)

– Metal is always platinum– Acid is almost always chloride

• Other metals usually added for stability and/or yield improvement

• Metals impregnated on a high surface area alumina-oxide base. Bases are usually 1/16-1/8 inch (1.6-3.2 mm) diameter spheres or extrudates of various configurations and lengths.

• Regenerable• Dual function balance maintained by:

– Water-chloride control– Regeneration technique

Reforming Reactions

• Naphthene dehydrogenation• Naphthene isomerization• Paraffin isomerization• Paraffin dehydrocyclization• Hydrocracking• Demethylation• Aromatic dealkylation

Naphthene Dehydrogenation

• Formation of an aromatic from cyclohexanes• Reaction is easy and very rapid• Reaction is very endothermic (consumes heat)• Hydrogen is produced• Reaction is promoted by the catalyst metal function• Reaction favored by high temperature and low pressure

SR R

+ 3H2

Naphthene Isomerization

• Enables N5 napthenes to convert to aromatics• Naphthene isomerization converts branched

alkylcyclopentanes to alkylcyclohexanes, then to aromatics• Ring opening occurs, so paraffins may be produced• Reaction is promoted by both acid and metal functions• Reaction favored by low temperatures; little pressure influence.

S R SR'

Paraffin Isomerization

• Paraffin isomerization occurs readily• Branched isomers are higher in octane than straight chained

molecules• Reaction is slightly exothermic and equilibrium limited• Hydrogen neutral• Reaction is promoted by both acid and metal functions• Reaction favored by low temperatures; little pressure influence.

– Low temperatures favor higher iso-/normal ratios– Higher temperatures increase the reaction rate

R-C-C-C-C-C-C R-C-C-C-C-CC

Paraffin Dehydrocyclization

• Ring closure - conversion of paraffins to naphthenes– Required for conversion of paraffins to aromatics

• Slowest and most difficult reforming reaction to promote• Reaction is endothermic• Hydrogen in produced• Reaction promoted by both acid and metal functions• Reaction favored by high temperature and low pressure

R-C-C-C-C-C-C

R'

SR"

+ H2

+ H2

S

Hydrocracking

• Splitting of longer, chained molecules into shorter, lighter compounds– Reduces reformate yield– Increases light ends yield– Serves to concentrate aromatics; therefore, increases octane

• Reaction is exothermic and hydrogen is consumed• Reaction is promoted by the catalyst acid function• Reaction favored by high temperatures and pressures

R – C – C – C + H2

CRH + C – C – C

C

H

Demethylation

• Removal of methyl groups from branched compounds• Only occurs in severe operations or on initial startup• Reaction is exothermic and consumes hydrogen• Promoted by the catalyst metal function• Reaction favored by high temperature and pressure

R–C–C–C–C + H2 R–C–C–CH + CH4

andR-C + H2

RH+ CH4

Aromatic Dealkylation

R+ H2

R'+ R"

• Removal or splitting of alkyl groups from aromatic compounds

• Reaction is exothermic and consumes hydrogen• Promoted by the catalyst acid and metal functions

• Reaction favored by high temperature and pressure

Reaction Scheme

Acid M = Metal =

CrackedProducts

N-Paraffins

M or A M / A

M / AM or A

CyclopentanesA

A

NaphtheneIsomerization

Cyclohexanes

Dehydrogenation

Aromatics

Dealkylationand

Demethylation

LighterAromatics

M M or A

Isoparaf fins

I II III Predominant Active Sites: A

Legend:

I II III= Hydrocracking and Demethylation (M) = Paraf fin Isomerization = Dehydrocyclization

Metal/Acid Sites – for dehydrocyclization, hydrocracking, dealkylation

Properly Balanced Catalyst

DesiredDesiredMetal-AcidMetal-Acid

BalanceBalance(Pt)(Pt)

Increasing MetalIncreasing MetalFunctionFunction

DemethylationDemethylation

(Cl)(Cl)Increasing AcidIncreasing Acid

FunctionFunction

CrackingCracking

DehydrogenationDehydrogenationDehydrocyclizationDehydrocyclization

IsomerizationIsomerization


Total sulfur Attenuates metal activity, suppresses dehydrogenation, reversible

0.25-0.5 wtppm min

Total Nitrogen


0.5 wtppm max

Water Affects water/chloride balance ~1 wtppm

Oxygen (Dissolved and Combined)

Forms water, affects water/chloride balance

2 ppm as oxygen

Fluorides Displaces chloride, less acidic, irreversible

<0.5 wtppm

Metals Block active sites, attach Pt, plug flow, irreversible (Arsenic, Pb, Cu)

ppb

Catalytic Reforming Basics• Multiple reactors in series• Reactions under hydrogen atmosphere

– Hydrogen producer

• Endothermic reactions require inter-reactor heaters• To maintain product quality, severity (temperature)

must be gradually increased– Performance gradually deteriorates– Catalyst regeneration periodically required to return catalyst

quality back to acceptable levels

• Fractionation (stabilizer or debutanizer) to ‘stabilize’ products– Gasoline RVP adjustment

Types of Reforming Process Units

• Fixed Bed (semi-regen unit)– Unit must be shut down and complete catalyst

inventory is regenerated

• Cyclic Reformer– Catalyst is regenerated one reactor at a time– Unit is on stream continuously

• CCR Platforming Unit– Continuous Catalyst Regeneration– Unit is on stream continuously

Fixed-Bed Semi-Regeneration Reforming

• Catalyst is stationary in separate reactors• Reactors are normally separate and in series• A high H2/HC ratio is used

– Typically between 6-9 mol/mol

• Moderate to high pressure – 300 to 600 psig (21 to 42 bars)

• Water/chloride injections used to balance catalyst performance

Fixed-Bed Semi-Regeneration Reforming

H2O/Cl-

Injection

Net GasFuel Gas

LPG

Reformate

Feed

Reactors

Separator

Debutanizer

CombinedFeed

Exchanger

HH H

H

Cyclic Catalytic Reforming

Flue Gas

Air

Inert Gas Furnace

Furnace Furnace Furnace

Separator

Reformate

Overhead

PretreatedNaphtha

SwingReactor

Reactor Reactor Reactor

H2-Rich Gas

Flue Gas

Air

Inert Gas Furnace

Furnace Furnace Furnace

Separator

Reformate

Overhead

PretreatedNaphtha

SwingReactor

Reactor Reactor Reactor

H2-Rich Gas

UOP CCR Platforming Unit• Catalyst is circulated through the reactor and

regenerator sections– Reactors are stacked with free flowing piping between them– Special equipment used to transport catalyst

• Constant regeneration means a constant catalyst performance throughout most of its life

• Operations at more severe conditions– Lower pressure, less catalyst, higher temperatures, less hydrogen circulation, higher octane

• Reformate product is high quality and consistent

– More hydrogen produced and at higher purity

UOP CCR Platforming Unit with Two-Stage Counter-Current Recontact

LegendRC = Recontact DrumREC = ReceiverCON = Convection Section

RCR

C

Fresh Catalyst

Net Gas

LPGSpentCatalyst

FeedH H

SEP

REC

CON

StackedReactors

H

Debutanizer

Reformate

H

CombinedFeed

Exchanger

LegendRC = Recontact DrumREC = ReceiverCON = Convection Section

RCR

C

Fresh Catalyst

Net Gas

LPGSpentCatalyst

FeedH H

SEP

REC

CON

StackedReactors

HH

Debutanizer

Reformate

H

CombinedFeed

Exchanger

UOP CCR Platforming Unit Atmospheric Catalyst Regeneration Section

LiftEngager

No. 1

CatalystCollector

DisengagingHopper

RegenerationTower

CatalystLift Lines

DustCollector

Lift GasBlower

Hydrogen Lift Gas

SurgeHopper

NitrogenLift Gas

ReductionZone

PlatformingReactors

LockHopper

No. 1

FinesRemovalBlower

LiftEngager

No. 2

Flow ControlHopper

CatalystAdditionHopper

LockHopper

No. 2

RegenerationTower

LockHopper

ReductionZone

SpecialElbows

N2 Seal Drum

DustCollector

IsolationValves

CatalystCollector

Booster Gas

Lift GasL-Valve Assemblies


DisengagingHopper

Nitrogen

Reactors

N2 Lift Gas

IsolationValves

RegenerationTower

LockHopper

ReductionZone

SpecialElbows

N2 Seal Drum

DustCollector

IsolationValves

CatalystCollector

Booster Gas

Lift GasL-Valve Assemblies


DisengagingHopper

Nitrogen

Reactors

N2 Lift Gas

IsolationValves

UOP CCR Platforming Unit CycleMax Regeneration Section

Process Variables• Feed Stock Quality

– Boiling range – 170-400F (77-204C) D-86 – Paraffin/naphthene/aromatic content (PNA)

• Catalyst Type• Reactor Temperature

– 890-1020F (477-550C)– Mostly endothermic reactions

• Space Velocity– 0.8-3.0 hr-1

• Reactor Pressure– 50-600 psig (3.4-42 bars)

• H2/HC Ratio– 2-9 mol/mol

Feed Type Impact on Product Yield

• Conversion of lean and rich naphthas to moderate octane reformates at constant operating conditions

P

N

AA

P

A

P

N

A

P

A

}

}

}}}

}

}}

}}

}

LeanNaphtha


Loss Loss

NFrom P

From NFrom A

From P

From N



NP

N

AA

P

A

P

N

A

P

A

}

}

}}}

}

}}

}}

}

LeanNaphtha


Loss Loss

NFrom P

From NFrom A

From P

From N



N

Octane-Barrel Yield Response toProduct Octane and Feed Composition

RONCRONC

Oct

ane

- Bar

rel Y

ield

Oct

ane

- Bar

rel Y

ield

per

100

BB

L F

eed

per

100

BB

L F

eed

90906,5006,500

7,0007,000

7,5007,500

8,0008,000

8,5008,500

(Pressure = Constant)(Pressure = Constant)

9292 9494 9696 9898 100100 102102 104104

N + 2A = 40N + 2A = 40

N + 2A = 80N + 2A = 80

N + 2A = 60N + 2A = 60

Reactor Temperature Profile

1.01.00.50.50.250.250.10.100Fraction of Total Catalyst

Tem

pera

ture

, °

C(°

F)

-80-80(-144)(-144)

-60-60(-108)(-108)

-40-40(-72)(-72)

-20-20(-38)(-38)

InletInlet

Hydrocarbon Types ConversionReactor Profile

Fraction of Total Catalyst

Mol

es p

er 1

00 M

oles

of F

eed

CHCHCPCP

PP

AA6060

4040

3030

2020

1010

00

5050

0.00.0 0.100.10 0.250.25 0.500.50 1.01.0

Effect of Pressure on Yield StructurePr

oduc

t Yie

ld, w

t-%

Prod

uct Y

ield

, wt-

%

C5+ ReformateC5+ Reformate

HydrogenHydrogen

Pressure psig (kg/cmPressure psig (kg/cm22))

00

CC1 1 + C+ C2 2 + C+ C3 3 + C+ C4 4

143143(10)(10)

285285(20)(20)

428428(30)(30)

570570(40)(40)

7070

8080

9090

100100

450450(31.6)(31.6)

Average Reactor Pressure, psig (kg/cm2)

Rea

ctor

C5 +

ΔLV

-% Y

ield

00

FB Reforming

400400(28.1)(28.1)

350350(24.8)(24.8)

300300(21.1)(21.1)

250250(17.6)(17.6)

200200(14.1)(14.1)

150150(10.5)(10.5)

100100

Continuous Reforming

112233445566778899

1010

Liquid Yield Variations with PressureContinuous vs. Fixed-Bed Reforming

Lean Middle East Naphtha 100 RONC

“Perfect” Reformer• Low pressure to max yields• High catalyst activity to max octane and aromatics• High on-stream factor• CCR > cyclic > semi-regen

Catalyst Issues

• Contaminants• Feedstock boiling range• Water-chloride balance• High temperatures• Low space velocity• Low H2/HC ratios

Summary – Reforming• Complex high temperature process• 3 types of reformers• Mechanical issues include compressors,

heaters, fractionators, catalyst handling / regeneration

• Critical to refinery profitability octane pool, hydrogen system, aromatics sales

Alkylation Processes

Background

• Alkylation was developed during WWII to make aviation gasoline

• Today its main purpose is to convert light ends into gasoline

• The gasoline is ideal for ultra low sulfur and RFG premium – high MON – low emissions – very low in sulfur, olefins, and aromatics

What is Alkylation?• Alkylation combines C3-C5 olefins with iso-butane to

produce highly-branched, high-octane C7-C9 isoparaffins

• Reaction is catalyzed by strong acids

– HF– H2SO4

– Solid catalysts (UOP Inalk, Alkylene)– Superacids (BF3, HSO3F, HSO3CF3)

Alkylation Feeds

FCC

Alkylate Product

FCC Feed

AlkylationUnit

n-Butane

MixedButanes from

Hydrocracking, ReformingAnd Crude Units

Butamer

Propane

C3/C4 OlefinRich Stream

FCC Products(Gasoline, etc.)

C3/C4 OlefinCoker

Alkylate Product• Ideal RFG Blending Component

– High Octane (RON & MON)• C3=/C4= Feed

– 91-94 RON / 90-93 MON

• C4= Feed– 94-96 RON / 92-94 MON

– No Aromatics– No Olefins– Low RVP

• 3 - 6 psig• Highly Dependant on Fractionation (nC4,iC5)

– Low Sulfur

• 10-15% of Gasoline Pool

Primary Products and OctanesOlefin Primary Products Research Motor

Propylene 2,3-Dimethylpentane 91 892,4-Dimethylpentane 83 84

Isobutylene 2,2,4-Trimethylpentane 100 100

Butene-2 2,2,3-Trimethylpentane 109 1002,2,4-Trimethylpentane 100 1002,3,3-Trimethylpentane 106 992,3,4-Trimethylpentane 103 96

Butene-1 2,2-Dimethylhexane 72 772,4-Dimethylhexane 65 70 2,3-Dimethylhexane 71 79

Pentenes 2,2,3,4-Tetramethylpentane2,2,4-Trimethylhexane

2,2,5-Trimethylhexane 92 902,2,3-Trimethylhexane2,3,4-Trimethylhexane2,3-Dimethylheptane2,4-Dimethylheptane

Chemistry

Alkylation Reaction:

C-C=C-C + C-C-C iC7-9 Alkylate Olefin isobutane Acid

Hydrogen Transfer Reaction:

Olefin + 2 isobutane iC8 Alkylate + C3-C5 paraffins

• Olefins highly soluble in acid, isobutane sparingly so• Reaction requires 6-15 fold excess isobutane for selectivity• Two liquid phases (emulsion) in reactor, reaction occurs in acid phase• Hydrogen transfer reaction makes iC8, which has higher octane• However, it consumes more isobutane and makes light paraffins• In HF alkylation, hydrogen transfer occurs for all olefins• In H2SO4 alkylation, only for C5 and heavier olefins

C

Catalyst Selection

• The current commercial catalysts HF and H2SO4 each have advantages and disadvantages

• Main difference in processes is reactor cooling– HF uses cooling water– H2SO4 uses integral refrigeration

• Feedstock, economics and safety control selection

Acid Selection Criteria

• FeedstockHF better on C3

= and iC4 =

H2SO4 better on C5 = and dirty feeds

• Size and LocationHF cheaper for small units HF requires 1/40 as much acid shippingH2SO4 more favorable with on-site acid plant

• Community SafetyH2SO4 does not form aerosols at alkylation conditions

HF safety requirements reduce its capital advantage

Alkylate RON for Feed Olefins

C3=

1-C4=

2-C4=

iso-C4=

C5=

H2SO4

89

96

96

92

91

HF91

91

97

95

89

Alkylation Yields

Sulfuric Acid AlkylationC3Alkylate C4Alkylate C5Alkylate

iC4con/olefin (v/v) 1.27-1.32 1.1-1.16 0.96-1.14Alkylate yield (v/volefin) 1.75-1.78 1.7-1.78 1.55-1.60

R+M/2 88-91 93-95 91-92Acid con (#/bbl alky) 34-42 13-25 25-34

HF Acid AlkylationC3Alkylate C4Alkylate C5Alkylate

iC4con/olefin (v/v) 1.33-1.41 1.14-1.16 1.17Alkylate yield (C5+) 1.78 1.76 1.85

R+M/2 90-91 92-94 90-91Acid con (#/bbl alky) 0.2 0.1 0.2

HF Acid Unit Features

• Good feedstock flexibility• Low operating cost• Lowest capital cost• Low catalyst usage (0.1-0.2 lb/bbl product)• 95F (35C) reactor temperature• HF acid requires special attention

HF Processes

• Accounts for most of the recent new units• Higher iC4 solubility in acid (2.7%)• Does not require refrigeration, can use cooling water (To=100oF)• Mixing easy due to low interfacial tension• Favored by small remote refiners because of poor availability of cheap

sulfuric acid• Acid recovery by distillation at unit (rerun)• Lower acid costs. Higher yield• Consumes more iC4; makes propane, n-butane• Requires dry feed (HF + H2O corrosive)• Stripper column needed to separate HF from hydrocarbon products (HF is

1% soluble in hydrocarbon)• Economically favored • More toxic, corrosive• Area dominated by safety issues

Sulfuric Acid Features• C4 feeds make best alkylate• Acid is handled more easily• 50F (10°C) reactor temperature requires refrigeration

cooling• Catalyst usage is higher and generally requires offsite

regeneration (13-42 lb/bbl product)• Catalyst costs are usually higher• Large quantities of acid are handled

Acid Properties

Sulfuric Acid• Boiling point 640oF at 1 atm• Specific gravity 1.83• Higher surface tension and

viscosity• Isobutane only slightly soluble in

acid (0.1%)• Less corrosive• Sulfuric acid insoluble in

hydrocarbon phase• $15-120/ton, depending on

location

HF Acid• Boiling point 67oF at 1 atm• Specific gravity 0.93• Low surface tension and viscosity• Isobutane solubility about 30 times

higher (2.7%)• HF+water extremely corrosive • HF acid about 1% soluble in

hydrocarbon phase • $1,700/ton + processing costs

Advantages and Disadvantages of the Acids

Sulfuric Acid+ Higher Octane, less iC5 from

Pentenes+ Non aerosoling+ Less corrosive

+ Less product treating+ Tolerates dirty feedstocks- More Expensive to Build

- Requires refrigeration- High Mixer HP Requirement

- Higher Catalyst Use and Cost- Large Acid Requirement

- Higher Energy Use- Higher CO2 Make

HF Acid+ Higher Octane and Yield from

Propylene, Isobutylene + Recoverable

Lower net catalyst cost+ Cheaper to build No refrigeration

Easier to mixFavored for smaller units - Forms Toxic Aerosols (dominated by safety issues)

- More corrosive- Must remove HF, Fluorides from LPG

Alkylation Processes

Alkylation Process Concept

iC4

Olefin

Acid

iC4

Reactor SettlerEffluent

Distillation

Propane

n-butane

Alkylate

H2SO4 Processes

• Exxon/Kellogg Cascade reactor, Kellogg Jet reactor, and Stratco Contactor reactor.

• Accounts for 65% of the worldwide capacity • Accounts for 60% of U.S. capacity• Requires refrigeration (compressors)• More mixing required• Acid is less toxic• Simpler feed treating• Acid is insoluble in hydrocarbon product• Acid recovery in acid plant (off-site or on-site)

H2SO4 Processes

• Stratco Contactor reactor- Refrigerated by flashing effluent through tubes in the

reactor• Exxon/Kellogg and Amoco Cascade reactor

- Auto-refrigerated by allowing the reactor contents to flash into compressor suction in multiple stages

• Older Kellogg Jet and Time Tank reactors- Auto-refrigerated by one-stage flashing of reactor

contents

Stratco Process with Effluent Refrigeration

Propane

Compressor

Flash Drum

SuctionTrap

Dep

ropa

nize

r

Contactor

Recycle Isobutane

Product Treatingand Distillation

60 MBSD

Refrigerant

Fresh Feed

3 MBSD

31 MBSDE

fflue

nt

110 MBSD

28 MBSD

52 MBSD

DIB

24 MBSD

Settler

Emulsion170 MBSD

Acid Recycle

PressureControl Valve

H2SO4 Alkylation Process Variables

• Isobutane concentration– Rx HC effluent > 50% or iC4/Olefin mol ratio > 7– Higher values are highly desirable– Might be limited by effluent pump design and condition – Optimum depends on incremental energy and acid costs versus

octane value

• Temperature– 35-55°F (2-13°C)– T <35°F : acid carryover, high acid consumption– T >55°F : high acid consumption, increased corrosion

• Mixing– Maximize mixing as limited by acid carryover

H2SO4 Alkylation Process Variables• Acidity

– Maximum octane occurs at 93-94 wt% for butylene feeds– Optimum acidity depends on acid costs and octane value– Keep >89% acidity in tail reactor. Units with excellent feed quality

and low water content can be at 88%– Risk of acid runaway at <87%

• Olefin Space Velocity– Olefin feed rate/reactor acid holdup. 0.2 - 0.6 hr-1

– Typically outside the control of the Alky unit– Low is better. However, the economics of alkylate production

generally overrides.

• Emulsion Quality (Acid Fraction in Rx)– Keep reactor emulsion at a minimum of 35 vol% acid– Alkylate quality improves with increasing acid concentration and is at

a maximum at 65%– Maximize acid recycle rate as limited by acid carryover

HF Processes

• Phillips - Gravity Acid Flow

• UOP- Pumped Acid Flow- Low Inventory

UOP HF Alkylation Process(Propylene & Butylenes)

Saturate C4’s

iC4’sMakeup

Recycle iC4

ButaneAlkylate Propane

KOH Treaters

KOHTreater

AluminaTreater

HFStripper

Acid

DepropanizerIsostripperSettlerReactor

OlefinFeed Acid

Regenerator

Polymer and CBMTo Neutralization

Water

Steam

Saturate C4’s

iC4’sMakeup

Recycle iC4

ButaneAlkylate Propane

KOH Treaters

KOHTreater

AluminaTreater

HFStripper

Acid

DepropanizerIsostripperSettlerReactor

OlefinFeed Acid

Regenerator

Polymer and CBMTo Neutralization

Water

Steam

HF Alkylation Process Variables• Reactor Temperature

– Significant influence on the octane number of the product– All reactors are operated below 100F (38C)– Higher temperatures lead to lower octane number, higher end points,

and excessive isobutane consumption– Above 120F (50C) excessive side reactions occur– Extremely low temperatures (below 60F or 16C) result in incomplete

alkylation

• Acid to Hydrocarbon Ratio– Normally between 1:1 and 2:1– Below 0.8:1, excess polymer forms and alkylation stops– No advantage to operate above 2:1 for HF

HF Alkylation Process Variables• Isobutane to Olefin Mol Ratio

– iC4/Olefin > 8-14– High iso-butane/olefin ratio promotes:

• Higher octane products• Lower end points• Suppression of tar products

– High iso-butane/olefin ratio cost energy

• Acid Strength– Depends on unit design

• Type and quantity of contaminants• Acid inventory• Process operations

– Generally 85-90% (wt) HF– Low acid strengths lead to incomplete alkylation– Maintain H2O content < 1wt%

Process Contaminants

• Water or water forming compounds• Sulfur compounds• Nitrogen compounds• Ethane, ethylene or non-condensables• Diolefins• Amylenes• Affect acid consumption and regeneration, corrosion and

product quality


Total sulfur Affects acid strength, polymer production, acid consumption

20 wtppm max

Total Nitrogen

Affects acid strength, polymer production, acid consumption

10 wt ppm

Water/water forming compounds

Affects acid strength, polymer production, corrosion

3-5 molppm5 wt% in acid max

Ethane, ethylene & non-condensables

Affects isostripper pressure 0.5 mol%

Diolefins Affects acid strength, polymer production, acid consumption

0.5 mol%

Amylenes Affect alkylate octane

InAlk Simplified Process Flow

Alkylation – Hazardous Materials • HF

– Liquefied gas that forms heavy, toxic aerosols that can travel downwind for miles

– Causes deep, sometimes delayed burns that require immediate flushing and medical treatment to stop tissue destruction

– Most burns occur during equipment maintenance

– Anything that has contacted HF causes burn (scale, rags, PPE, equipment, tools …) Use correct PPE and carefully follow procedures

Economics• What is the cost if the unit is not generating?

– Losses are $10/bbl of olefin (fuel vs. gasoline feedstock) when alky is down

– Losses can reach $20/bbl of olefin (or more) when feedstock must be flared

• How does it enhance the value of the product?– Lowers Gasoline Pool emissions as sulfur, aromatics,

olefins increase without Alky– Improves Gasoline Pool MON, avoids RON Giveaway– Alkylate can trade for $4/bbl above gasoline

Alkylation Summary• Alky Keeps the Refinery Out of the Flare• Alkylate is Great Gasoline• Don’t Liquidate the Asset

– Keep the genie in the bottle – Clamps mean something is wrong inside– Follow PSS and Best Practice Documents

CatalyticCondensation

Catalytic Condensation• Also referred to a Polymerization• Developed in early 1930s because of:

– Excess of thermally cracked olefins– Need for higher performance gasoline

• Discovered in lab testing cracked gasoline– Testing for olefin content with H2SO4 acid– Found increase in gasoline yield.

• 1933 1st commercially viable unit started

Main Applications

• Condensation of light olefins to poly gasoline- With mixed olefin feed, RONC of poly gasoline and

alkylate are equivalent- Higher sensitivity than alkylate (∆RONC & MON)- Particularly relevant where isobutane is not available

• Alkylation of aromatics to cumeme, ethylbenzene and cymene

Feedstocks

• Unsaturated Vapor Recovery Unit• FCC, coking and thermal cracking are sources of

light olefins• C3, C4 or mixed C3/C4 olefin streams• Feeds are generally treated to remove nitrogen

and sulfur compounds

Chemistry

• Acid polymerization of olefins

C–C=C + C-C=C C=C-C-C-C-C

• ExothermicC C

Catalyst

• Phosphoric acid on Kieselguhr clay• Catalyst is attacked by water and basic nitrogen

compounds• Higher pressure favors longer catalyst life

Catalytic Condensation Process/Motor Fuel Production(UOP)

QuenchStreams

FeedDrum

OlefinicFeed

ReactorRecycleDrum Stabilizer Receiver

C3C4

Poly GasolineRecycle

C3C4

FlashDrum

Reactor Types

• Tubular– Catalyst contained in tubes surrounded by water to

remove excess heat

• Chamber– Catalyst exists in layers between which there are

quench lines

Operating Conditions• Pressure

– 450-550 psig (32-39 bars)

• Temperature– 320-420F (160-216C)

• Space Velocity– 0.8-1.5 LHSV

• Combined Feed Olefin Content– 25-30 vol-%

Alkylasi, Reforming, Dan Isomerisai

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