Ron McGihon (ExxonMobil)

FCC Naphtha 

Desulfurization –

New Developments

Why Reduce Sulfur in Petrol

0

100

200

300

400

500

600

700

800

900

1000

Pre 2000 2001 BS II 2005 BS III 2010 BS IV

Petrol

Diesel

•Low sulfur in petrol reduces emissions of toxins into atmosphere

50 ppm
Sulfur In Gasoline 

FCC Naphtha the Primary Source

FCC 

Naphtha

Reformate

Alkylate

& Other

Oxygenates

Portion of 

Gasoline 

volume

Sulfur 

contributed

EMRE Technologies for Quality Fuels 

HDC +

MIDW

EMRE HYDROFINING

Distillate Waxy Feeds Heavy Feeds

ULSD HDC

LCO 

Upgrading

MDDWTM MIDWTM

GO-finingTM

ULSD +

HDHDC

ULSD +

MAXSATTM

Residfining

Naphtha

FCC Naphtha

OCTGAINSM

Hydrofining

SCANfiningTM
FCC Naphtha Desulfurization - Topics

♦ Technology Overview

♦ Chemistry and Catalyst

♦ Design Flexibility

♦ Ongoing Improvements

Desulfurizing FCC Naphtha 

♦ FCC naphtha contains olefins that contribute 

high octane to gasoline pool

♦ Conventional hydrodesulfurizing of FCC naphtha 

results in olefin saturation and octane loss

♦ SCANfining uses a very selective catalyst to 

minimize olefin saturation and thus minimize 

octane loss
SCANfining Flow Scheme 

PRODUCT

C-4

OFFGAS

Product

Stripper

Main 

Reactor

Recycle

Gas

Zeromer

Reactor

Amine

Scrubber

PURGE

Diolefin

Saturator

FEED

FEED REACTION

PRODUCT RECOVERY

GAS RECYCLE

H2

10-15

100.1

Hydrogen, Nm3/m3

Naphtha yield, vol %

95-98

15-25

0.6 – 1.5

Sulfur reduction, %

Olefin reduction, %

Octane loss (R+M)/2

500-1500

10-50

Feed Sulfur, ppmw

Product Sulfur, ppmw

Typical single 

stage design

Typical Performance
Sulfur Removal Chemistry

Recombinant Recombinant

Mercaptans

Octane

Loss

Mercaptans Mercaptans

Thiophenes Thiophenes

Olefins Olefins

R-H + H2S Hydrotreat

R-R Hydrotreat

R-SH Reversion

R-H + H2S Hydrotreat

R-SH

R = R

R = R

S R

H2S +

Mercaptans Limit SCANfining I Selectivity

♦ Reversion mercaptan levels governed by process conditions

♦ Alternative process designs control mercaptan content in product

SCANfining I Processing Full Range Cat Naphtha: Low S, High Olefins

% Olefin Saturation

0

20

40

60

80

100

120

140

0 10 20 30 40 50 60 70

wppm Sulfur

Total Sulfur

Non-Mercaptan Sulfur

Mercaptan Sulfur
Preferred Regions for SCANfining Options Feed Sulfur

Two Stage Preferred

SF I Preferred

Technology Selection Depends on Feed Sulfur and Olefins 

For Ultra-Low Product Sulfur Targets

Feed Olefins

ZEROMER

SCANfining Flow Scheme 

PRODUCT

C-4

OFFGAS

Product

Stripper

Main 

Reactor

Recycle

Gas

Zeromer

Reactor

Amine

Scrubber

PURGE

Diolefin

Saturator

FEED

Feed Reaction Product Recovery

Gas Recycle

H2
Selective HDS Catalysts

The Heart of the SCANfining Process

♦ RT-225 designed specifically for selective FCC naphtha HDS

 Minimizes olefin saturation / octane loss

 Proven activity and selectivity maintenance

 First commercial SCANfining use began in early 1995

♦ Ongoing Catalyst Development Program 

 Next generation catalyst for main reactor commercialized 

 Higher activity and selectivity

 ExxonMobil is committed to support own refineries and licensees 

♦ Process Design Improvements

 Designs tailored to specific situations

 Installed units utilize single-stage, Zeromer and multi-stage designs

7-10

X *0.5

Y * 0.5

95-98

10-15

0.3 – 0.8

500-1500

10-40

Typical 

Zeromer

10-15

X

Y

Hydrogen, Nm3/m3

Treat Gas, Nm3/m3

Catalyst volume, m3

95-98

15-25

0.6 – 1.5

Sulfur reduction, %

Olefin saturation, %

Octane loss (R+M)/2

500-1500

10-40

Feed Sulfur, ppmw

Product Sulfur, ppmw

Typical single 

stage

Typical Performance – with Zeromer
Zeromer Advantage

♦ Significant reduction in CAPEX & OPEX

 Reduced compressor size

 Reduced reactor size

 Better octane preservation

 Lower hydrogen consumption

♦ Ability to handle high sulfur feeds without feed 

fractionation

Reliability Reliability

Reliability and Commercial Experience
Port Jerome SCANfining Unit

5 years on first charge

Port Jerome SCANfiner First Cycle

Unit has been 100% available since December 1999 startup

End of Run Temperature (Design) 

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

Years on Oil

Reactor Temperature

for Constant % HDS

Automatic Bed Bypass Technology

Run Length Protection

♦ Fouled catalyst bed bypass technology 

♦ Developed to mitigate pressure drop buildup 

across catalyst bed

♦ Proprietary ExxonMobil technology
Automatic Bed Bypass Technology 

Bed Segment

with Bypass

Main Catalyst Bed(s)

Liquid and Gas

Liquid and Gas

Automatic Bed Bypass Internals

Applied Commercially in Many Different Services

♦ Key design feature for run length 

assurance 

♦ Proven in numerous ExxonMobil 

and licensee units

 Naphtha hydrotreaters

 Diesel hydrotreaters

 Cat feed hydrotreaters

 Hydrocrackers

 Vacuum Residfiner 

♦ Eliminated fouling limitations

0

20

40

60

80

100

120

140

0 5 10 15 20 25

Relative Time

Relative Reactor Pressure 

Drop

w/o bypass 

w/ bypass 
Commercial Experience - 38 Units

New Retrofit

ExxonMobil Licensees

SCAN I SCAN II ..

FR Naphtha ICN and/or HCN

N. America Europe, Asia, ME

New/retro

Ownership

Design

Feed

Location

In Summary

♦ FCC naphtha must be desulfurized

 To meet emissions standards 

 Special technology needed

♦ ExxonMobil-KBR offer low cost reliable solution 

for sulfur reduction

♦ Continuing developments to enhance 

technology
Thank you very much...

Questions?