CATALYTIC REFORMING OF NAPHTHA TO GASOLINE

BY

SONI O. OYEKAN RESEARCH SECTION HEAD PETROLEUM PROCESS SECTION RESEARCH AND DEVELOPMENT DEPARTMENT ENGELHARD INDUSTRIES DIVISION

OUTLINE

• INTRODUCTION TO THE CATALYTIC REFORMING PROCESS

• CATALYTIC REFORMING CHEMISTRY WITH EMPHASIS ON PLATINUM/RHENIUM CATALYSIS

• COMPARISON OF CATALYTIC REFORMING TECHNOLOGIES

• ADVANCES IN CATALYTIC REFORMING

THE MAIN OBJECTIVES OF CATALYTIC REFORMING ARE:

• TO UPGRADE LOW OCTANE NAPHTHAS TO HIGH OCTANE GASOLINE COMPONENTS

• TO MAKE AROMATICS (BENZENE, TOLUENE AND XYLENES)

• TO MAKE HYDROGEN

CRUDE OIL -'" ~

~ SIMPLIFIED REFINERY CONFIGURATION

CRUD E UNIT GASES

STRAIGHT NAPHTHA RUN FRACTI ONATOR

NAPHTHA (400°F)

STRAIGHT DISTILLATE RUN

DISTILLATE (550°F)

GAS OIL r---' (850°F) j AGO I ., L ---i ~ HIT I -

I L_ ---I

ATMOSPHERIC

RESIDUUM

-....

NAPHTHA - HIT

DISTILLATE • HYDROTREATI NG

1

FLUID

CATALYTIC

CRACKER

r--I

Ir

CATALYTIC - REFORMING

~ ALKYLATION FEED

~ .. -

--...

...

)SATURATE GASES

REFORMATE

DISTILLATE

CAT CRACKER GAS

CAT CRACKER NAPHTHA

DISTILLATE

-----~ NAPHTHA

---~ I ..1:--'"

OISTILLATE

ATMOSPHERIC RESIDUUM ... HYDROTREATING FUEL OIL

THE CATALYTIC REFORMING PROCESS

• FEEDS CAN BE VIRGIN, CRACKED NAPHTHAS OR HYDROCRACKATES

• BOILING RANGE: 160 - 380°F

FRONT END CUT ELIMINATES HEXANES AND LIGHTER COMPOUNDS

BACK END CUT ELIMINATES HEAVIER COMPOUNDS WHICH INCREASE COKE BUILD-UP

• MOLECULAR TYPES: PARAFFINS, NAPHTHENES, AROMATICS

• CONTAMINANTS

SULFUR: NITROGEN: WATER: MUA~:

DEACTIVATES CATALYST; PROMOTES SCALE FORMATION DEACTIVATES CATALYST; LEADS TO HIGHER GAS MAKE STRIPS CHLORIDE; PROMOTES SELECTIVITY INSTABILITY ARSENIC, SODIUM, LEAD, IRON, NICKEL : PERMANENT POISONS

I I

• OCTANE NUMBER IS A MEASURE OF THE ANTI-KNOCK QUALITY OF GASOLINE

• SCALE CHOSEN IS SUCH THAT 100 OCTANE = 100 VOL. % ISOOCTANE (2,2,4-TRIMETHYL PENTANE)

o OCTANE = 100 VOL % N-HEPTANE

• RESEARCH OCTANE NUMBER (RON) CORRELATES BEST WITH ENGINE PERFORMANCE UNDER MILD CONDITIONS AT LOW SPEED

• MOTOR OCTANE NUMBER (MON) CORRELATES BEST WITH ENGINE PERFORMANCE UNDER HEAVY LOAD CONDITIONS SUCH AS HILL CLIMBING

OCTANE NUMBERS OF SELECTED PURE HYDROCARBONS (2)

COMPOUND PARAFFINS N-BUTANE N-PENTANE N-HEXANE N-HEPTANE 2,2,4-ISOOCTANE

NAPHTHENES CYCLOPENTANE METHYLCYCLOPENTANE CYCLOHEXANE HIGHER ALKYLCYCLOPENTANES

AND ALKYLCYCLOHEXANES

OCTANE NUMBER ACTUAL BLENDING(l) BOILING PT .. OF

93 62 25 o

100

101 91 83

70-80

ll3 62 19 o

100

141 107 llO

32 96.8

156.2 208.4

120.2 161.6 177.8

190-270

I. BASED ON 20 VOL % OF THE COMPOUND IN 80 VOL % OF A 60:40 MIXTURE OF ISOOCTANE AND N-HEPTANE

2. REFERENCE: "HETEROGENEOUS CATALYSIS IN PRACTICE" - SATTERFIELD, C. N., PAGE 241 - TABLE 9-2

OCTANE NUMBERS OF SELECTED PURE HYDROCARBONS (2) (CONTD.)

COO POU ND

OLEEINS vs PARAFFINS 2-METHYL-1-HEXENE 2-METHYLHEXANE 3-METHYL-2-PENTENE 3-METHYLPENTANE

AROMATICS BENZENE TOLUENE M-XYLENE

OCTANE NUMBER ACTUAL BLENDING(l) BOILING pT .. OF

91 195.8 42 194.0 97 154.4 74 145.4

> 100 120 117

99 124 145

176 231.8 282.2

1. BASED ON 20 VOL % OF THE COMPOUND IN 80 VOL % OF A 60:40 MIXTURE OF ISOOCTANE AND N-HEPTANE USING A LINEAR SCALE

2. REFERENCE: "HETEROGENEOUS CATALYSIS IN PRACTICE" - SATTERFIELD, C.N. PAGE 241 - TABLE 9.2.

,

• TYPICAL CATALYTIC REFORMING REACTIONS

• DEHYDROGENATION OF CYCLOHEXANE NAPHTHENES

0"<:""",--' 0 + 3H 2

(83) (100)

FAST, SELECTIVE, ENDOTHERMIC

~ ISOMERIZATION OF ALKYL CYCLOPENTANES

6~) ·0 (91) (83)

SLOWER ,SOME HYDRO CRA CK lNG, E X OTHER MIC

• •

• ISO MER I Z A T I ON 0 F PAR A F F·I N S

CH3

I CH CH CH CH CH CH -~> CH - C-CH-,CH

3 3 2 . 2 2 .2 3 3 I 2 .

(25) CH

3

(85)

MUCH SLOWER/SOME HYDROCRACKING, EXOTHERMIC

• HYDROCRACKING OF PARAFF I NS

CH CH CH CH CH CH--7) 2 CH:- CH -CH 322223 3 23

(25) ( 1 12)

SLOW, EXOTHERMIC

PARAFFIN AROMATIZATION

HEPTANE AROMATIZATION: PROPOSED MECHANISM

(0) C H

2 5

___ A_. __ 0 COKE ~d V

• DUAL FUNCTIONALITY

CH . CH 3 3 :

,A (M).'OI U' ~ . (120) ,

• PROVIDES REACTION PATHWAY FOR COKE FORMATION

( G.A . MILLS, H. H E IN E MA N N, T. H.M ILLIK EN,A NO .A.G . OBALD.IND. ENG. CHEM. 45,134 (1953) )

DUAL FUNCTIONALITY OF CATALYTIC REFORMING CATALYSTS

AS EMPHASIZED IN THE PRECEDING SLIDES, DUAL FUNCTIONALITY IS REQUIRED FOR THE REACTIONS TO OCCUR:

1. A HYDROGENATION/DEHYDROGENATION FUNCTION

2. ACID CATALYZED ISOMERIZATION ACTIVITY

• HYDROGENATION/DEHYDROGENATION FUNCTION IS PROVIDED BY METALS (PLATINUM, PALLADIUM, RHENIUM, IRIDIUM, TIN, GERMANIUM, ETC.)

• ISOMERIZATION IS PRIMARILY ACID CATALYZED. HOWEVER, PLATINUM IS REQUIRED TO FORM OLEFINS WHICH CAN BE ISOMERIZED OVER ACIDIC ALUMINA SITES

• HYDROCRACKING CAN BE CATALYZED BY INSUFFICIENTLY SULFIDED PLATINUM AND RHENIUM, AS WELL AS BY EXCESSIVELY ACIDIC ALUMINA

PLATINUM/RHENIUM CATALYSIS IN NAPHTHA REFORMING

• THE MOST WIDELY USED REFORMING CATALYST IS PLATINUM/RHENIUM/CHLORIDE/y-ALUMINA (1,2)

HYDROGENATION/DEHYDROGENATION PLATINUM/RHENIUM ACIDIC FUNCTION CHLORIDE/y-ALUMINA

• CONTROVERSY EXISTS OVER THE EFFECT OF THE RHENIUM MODIFIER

(1) KLUKSDAHL, H. E. U.S. PATENT 3,415,737 (2) KLUKSDAHL, H. E. U.S. PATENT 3,558,477

PREVAILING HYPOTHESES ON THE EFFECT OF RHENIUM

• PROMOTES MORE SATISFACTORY DISPERSION OF PLATINUM AND STABILIZATION DURING REFORMING OPERATION. KOZLOV, N. S., SKRIGAN, E. A. ET AL. NEFTEKHIMIYA 15 (1) 69-73 (1975).

• ALTERS THE SELECTIVITY OF CHEMICAL REACTIONS AND REDUCES COKE AND GAS YIELDS JACOBSON, R. L. AND MC COY, C. S., HYl)ROCARBON PROCESSING ~ (5) 109-112 (1970)

liME. ~OURS

0.5 1.0

16.0

DISPERSION OF THE METALS IS DEPENDENT ON THE REDUCIBILITY OF RHENIUM(l)

PT/RElCL/y-AL203

CO C~EMISQRPIION ~8LUES {cc COs1ELGf12 800DF 900DF lOOQDE

0.2963 0.3311

0.3154, 0.3228

0.4393 0.6926, 0.6848 0.5140

0.7215, 0.6879 0.4689

(1) THE FOLLOWING REFERENCES DISCUSS REDUCIBILITY OF RHENIUM (A) MC NICOL, B. D., J. CATAL. ~, 438-440 (1977) (B) JOHNSON, M. F. L. AND LEROY, V. M., J. CATAL. ~ 434-440 (1974)

EFFECT OF RHENIUM IN THE REFORMING OF NAPHTHA OVER PT/RE CATALYSTS

935°F, 200 PSIG, 5000 SCF/B; FEED: P = 69.05; N+A = 30.90 VOL %

DISC~ABGED CAIALYSI I~SEECIIO~S

REL. RHENIUM CONTENT., C5+ YIELD FOR wu.

AT 100 RON. VOL % ACTIVITY CUKE SULFUR CHLORIDE 1.0 70.8 85.0 8.4 0.03 0.88 1.5 71.2 83.0 9.2 0.05 0.98 2.0 70.7 81.0 8.5 0.07 0.83 2.7 70.3 95.0 7.3 0.12 0.90 3.9 69.9 109.0 7.3 0.14 0.90

GENERAL OBSERVATIONS ON PLATINUM/RHENIUM CATALYSIS(l)

• CATALYST ACTIVITY INCREASES AS THE CATALYST RHENIUM CONTENT INCREASES

• THERE IS AN OPTIMUM RHENIUM/PLATINUM RATIO FOR MAXIMUM SELECTIVITY

• HIGHER RHENIUM LEADS TO LOWER COKE MAKE

• HIGHER RHENIUM LEADS TO HIGHER BTX YIELDS AT THE EXPENSE OF C9+ AROMATICS

• HIGHER RHENIUM LEADS TO HIGHER GAS MAKE, LOWER HYDROGEN AND LOWER C5+ YIELD

• EQUILIBRIUM CATALYST SULFUR IS DEPENDENT ON THE CATALYST RHENIUM LEVEL

(1) OYEKAN, S. 0., PRIVATE NOTES, AND DATA FROM OTHER STUDIES

PARAFFIN AROMATIZATION

HEPTANE AROMATIZATION: PROPOSED MECHANISM

'C H5 C H CH . CH

M/Ao2 M 02

5 A 63

(M). 63

: CH CH CH CH CH CHCH..."'> ........ ~ .. -::", ... '> ~ I

3 2 2 2 2 2 3 ( 120) ,

(0 ) C H

2 5

___ A_. __ 0 COKE ~4 V

• DUAL FUNCTIONALITY

• PROVIDES REACTION PATHWAY FOR COKE FORMATION

( G.A. MIL LS. H.H E I N E MAN N. T. H. MIL LI KEN.A N D .A.G.OBALD.IND. ENG. CHEM. i.§..134 (1953) )

COMPARISON OF CATALYTIC REFORMING PROCESSES

SEMI -REGENERATIVE:

CYCLIC REGENERATIVE:

CONTINUOUS REGENERATIVE:

CONVENTIONAL, FIXED-BED, IN SITU REGENERATION AT END OF EACH CYCLE. HIGHER PRESSURE (150 -500 PSIG). LOW SEVERITY OPERATION.

FIXED-BED. CAPABILITY TO SELECTIVELY REGENERATE REACTOR AND TO VARY REGENERATION FREQUENCY. LOW PRESSURE (125 - 300 PSIG). HIGH SEVERITY OPERATION.

CATALYST CIRCULATION AND REGENERATION, LOW PRESSURE (150 - 200 PSIG), HIGH SEVERITY OPERATION. HIGH YIELDS OF HYDROGEN AND REFORMATE.

•

F-201

,--, -_>.

R-201

P-201

~£R ~

•

PROCESS FLOW DIAGRAM

4 REACTOR CONVENT! ONAl REFORMER

F-202 F-203

,- - ~--, , --"I- --~

R-20 -20

F-204

,--, -_'I.

R-204

. E-205

E-205

01

T-201

OW' V . V-202

P-202

'------.0. H. L1ll.

F-205

P-203

'---- ~E%::=;=d~----<~-20~ ~R~ E-208 cr.('E r·v\TE

I~ TO __ ~ ____ -.. r-----.. HYDro: TREATER

E- 3

•

I------~.~ GftS

•

•

E-20l

P-201 fX

•

PROCESS FLOH D IAGRAr1 t1AGNAFORMER

F-201 F-202 F-203 F-204

~-- ,,- -, , --~ -->

R-20l ,-204

E-20

E-202

C-201

E- 03

E-206

C\·

T-201

E-207

-202 L----+,O.H.

LIQ.

P-203 R. RE-~~:=;=_ 2~08--C--(\~~209 ~f~fE

rlET 1---- ------+~ ro1jlJ<E

Gffi

•

•

CATALYST FROM REGENERATOR

CONTINUOUS PROCESSING SECTION - -

SIMPLIFIED FLOW DIAGRAM

CATALYST FKOM REGENERATOR

Low RECYCLE

To FUEL GAS AND

LIGHT END RECOVERY

•

PRESSURE COMPRESSOR

CATALYST To REGENERATOR

REACTORS

•

SEPARATOR

NET SEPARATOR CHARGE &

INTERHEATERS FEED GAS

CATAL T To REGENERATOR

REACTOR

HIGH PRESSURE SEPARATOR

r---4'=':~:1 STAB 1-LIZER

PLAT TE TO STORAGE

•

, ,

PARAFFIN AROMATIZATION

HEPTANE AROMATIZATION: PROPOSED MECHANISM

C H5 C H CH . CH 2 2 5 3 3 :

CH CH CH CH CH CHCH,M/1';': ,M ,~,~<A==>6~Mk~

3 2 2 2 2 2 3 ~ ~ ~ (120) ,

(0) C H

2 5

___ A_. __ fA COKE ... V

• DUAL FUNCTIONALITY

• PROVIDES REACTION PATHWAY FOR COKE FORMATION

( G.A .MILLS,H.HEIN EM ANN, T .H.MILLIK EN ,A NO A.G.OBALD.IND. ENG. CHEM. 45,134 (1953) )

W 0:::

= ~ 0::: W CL ::E W I-

L!:l

980

=940 (/)

Cl: W 0::: U z:

STABILITY ENHANCEt1~NT IHTH LOW SULFUR OPERAUOJI~_

100

DISTILLATION

IBP . 16CPF 50% 284 95% 392

COMPONENT ANALYSIS

P =' 46.0 VOL % N + A =; 54.0 "

1. CAT. A/UNTREATED NAPHTHA

2. CAT. A/SULFUR GUARD TREATED NAPHTHA

3. CAT. A/DOUBLY TREATED NAPHTHA

200 300 400

II ME ON STREAM

--l

RECENT ADVANCES IN CATALYTIC REFORMING

MULTIMETALLIC CATALYSTS • PLATINUM/IRIDIUM PLUS SELENIUM, TELLURIUM, MANGANESE, TUNGSTEN, RHENIUM, ETC. • PATENTS ISSUED TO AMOCO, EXXON, IFP, UOP, ENGELHARD

STAGED CATALYST SYSTEMS • OPTIMIZATION OF NAPHTHENE DEHYDROGENATION AND PARAFFIN DEHYDROCYCLIZATION

CAPABILITIES • KEY PATENTS TO ENGELHARD: US 3,660,271, US 3,705,095, US 3,658,691, US 3,705,094

ON STAGING OF PLATINUM AND RHENIUM CATALYSTS • OTHER PATENTS ON METAL CONCENTRATIONS, HALOGEN CONTENT AND COMPOSITIONAL

DIFFERENCES

LOW SULFUR NAPHTHA REFORMING • REQUIRES USE OF SULFUR GUARDS • TWO TO THREE FOLD IMPROVEMENTS IN CYCLE LENGTHS • IMPROVEMENTS IN GASOLINE YIELD • ENGELHARD. EXXON, CHEVRON

c­• WI'_ .....

-21-ENGE&.HARD

ENGELHARO I NDUSTRIES O IV ISION IHQIELH""O " ' HI""1..1 • CHIEMtCALI CO",.O" ... TIOH

Analytical S.rvice Departmen t

METALLOGRAPHY SECTION

PLATE 6

SCHEMATIC OF ISOTHERMAL UNIT

ISOTHERMAL TUBULAR REACTOR

l----~~ ... (SIM'T."', _.

& .

o .. .. c .. &

DItC" I'rNIl

no ......