Fluorosulfonic Acid Promoters in HF Alkylation - ACS Symposium

3

Fluorosulfonic

Acid

Promoters

in

HF

Alkylation

ROBERT A. INNES

Downloaded by STONY BROOK UNIV SUNY on June 4, 2018 | https://pubs.acs.org Publication Date: June 1, 1977 | doi: 10.1021/bk-1977-0055.ch003

Gulf Research and Development Co., P. O. Drawer 2038, Pittsburgh, PA 15230

High octane blending stock for gasoline i s produced by the strong acid catalyzed a l k y l a t i o n of C to C o l e f i n s with i s o butane. Alkylate t y p i c a l l y comprises 10 to 15 percent of the gasoline pool. Although a l k y l a t i o n has been an important r e finery process for more than t h i r t y years, substantial improve ments can still be made. In p a r t i c u l a r , refiners would l i k e to increase the octane ratings of t h e i r alkylate to help compensate for the removal of lead from gasoline. This can be accomplished by c o n t r o l l i n g the many side reactions which accompany a l k y l a t i o n . For example, a t y p i c a l refinery produces 92 RON alkylate from a C3-C5 feedstock. It i s t h e o r e t i c a l l y possible to produce 95 RON alkylate from the same feedstock by eliminating those side reactions which are detrimental to alkylate quality and encouraging those which are b e n e f i c i a l . Such fine tuning of the a l k y l a t i o n process requires modification of the acid c a t a l y s t . This paper describes how the c a t a l y t i c properties of HF may be enhanced by the addition of minor amounts of trifluoromethane sulfonic acid (CF SO H) or fluorosulfonic acid (FSO H). (1,2) 3

3

3

5

3

Experimental Methods Apparatus and Procedure. Blends of C P . Grade isobutane with various o i e f i n i e feedstocks were reacted i n the continuous flow apparatus shown i n Figure 1. The reactor was a small stainless s t e e l autoclave equipped with a magnetically driven s t i r r e r . A polyethylene-lined sight glass was employed as a s e t t l i n g vessel for the separation of acid catalyst from hydrocarbon product. Acid blends were stored i n a s t a i n l e s s s t e e l bomb. The system was pressurized to 50 psig with nitrogen p r i o r to the s t a r t of each run. A portion of the acid blend was then transferred to the reactor using the sight glass to gauge the amount. The acid l e v e l was adjusted so that the autoclave would hold approximately equal volumes of acid and hydrocarbon under reaction conditions.

57

Albright and Goldsby; Industrial and Laboratory Alkylations ACS Symposium Series; American Chemical Society: Washington, DC, 1977.

INDUSTRIAL

AND LABORATORY

ALKYLATIONS


58



3.

Fluorosulfonic Acid Promoters

INNÉS

59

The reactor was then pressurized to 200 psig and the run begun, Isobutane-olefin feed was pumped into the autoclave. The reactor was s t i r r e d at 1600 RPM, intimately mixing the acid and hydrocarbon phases. Contact times (half the reactor volume divided by the hydrocarbon feed rate) ranged from 0.3 to 3.0 minutes. The temperature inside the reactor was controlled by passing water or antifreeze solution from a controlled temperature reservoir through the jacket of the autoclave. The r e action temperature was monitored by a sheathed thermocouple i n serted into the autoclave just below the s t i r r e r . A stream of acid-hydrocarbon emulsion passed continuously from the autoclave to the s e t t l e r . The acid catalyst settled to the bottom and returned to the reactor by gravity flow. The hydrocarbon product passed out the top of the s e t t l e r through a pressure cont r o l valve which maintained the reactor at 200 psig. After passage through a bed of Ascarite and alumina beads to remove dissolved HF, the a l k y l a t i o n product was collected at -78°C. The c o l l e c t i o n of the products reported herein was not begun u n t i l the volume of feed pumped equaled 15 times the reactor volume. At t h i s point the product composition was changing very slowly, i f at a l l . The duration of a run was three hours. A n a l y t i c a l Methods. Liquefied samples of the feed and r e actor effluent were analyzed by gas chromatography. A l l gas chromatographs were t i e d to a chromatographic data processing system which determined peak areas and calculated sample compositions. Sample components were i d e n t i f i e d on the basis of their retention times. Response factors were determined experimentally, using synthetic blends resembling actual a l k y l a tion feeds and products. Except i n those cases where RON was to be determined on a test engine, n-hexane was added to the samples as an i n t e r n a l standard. A l l samples were analyzed using a gas chromatograph equipped with a flame i o n i z a t i o n detector and a 200' χ 0.01" squalane-coated c a p i l l a r y column. Analyses were also made on conventional packed columns i n chromatographs equipped with thermal conductivity detectors. Feeds were analyzed on a s i l v e r nitrate-benzyl cyanide column. Products were analyzed on a 10 χ 1/4" column packed with 25% hexatriacontane on Chromosorb R. After the Ce's had been eluted, the h e x a t r i acontane column was backflushed through the detector to deter mine the heavies content of the sample. 1

Determination of Octane Numbers. In some cases Research and Motor octane numbers were estimated from alkylate com positions, using the formula,


60

INDUSTRIAL

Ν

est

A N D LABORATORY

ALKYLATIONS

Σ .W.N. - u i Z.W. ι

ι


where Wi i s the weight of component i and Ni i s the ASTM (clear) octane number (3,4) of component i i n i t s pure form. The octane ratings of the "heavies" portion of the alkylate were taken as 87 RON and 84 MON. Otherwise, RON was determined experimentally on a test engine. The reactor effluent was d i s t i l l e d to remove isobutane then submitted to our Product Evaluation D i v i s i o n for deter mination of RON by the standard ASTM method. Results and Discussion Refiners normally charge a mixture of o l e f i n s to t h e i r a l k y l a t i o n units. However, i n studying a l k y l a t i o n , i t i s often i n s t r u c t i v e to alkylate individual o l e f i n s . Accordingly, to demonstrate the e f f e c t of temperature on alkylate composition, we ran the HF a l k y l a t i o n of various pure o l e f i n feeds at 4°C and 45°C. The results are shown i n Tables I and I I . The con tact time was 3.0 minutes for the runs at 4°C and 1.0 minute for those at 45°C. The isobutane-olefin molar r a t i o was 24 when a l k y l a t i n g diisobutene and 12 when a l k y l a t i n g other o l e f i n s . The product names are abbreviated: IP for isopentane, 23DMB for 2,3-dimethylbutane, 224TMP for 2,2,4-trimethylpentane, 23DMH for 2,3-dimethylhexane, and so on. If a l k y l a t i o n were a s e l e c t i v e process, one would expect to obtain 23DMP from propylene, 23DMH from l-butene, 224TMP from isobutene and diisobutene, and a mixture of TMP s from c i s - or trans-2-butene. (5,6,, 7) These are the products which predominated at 4 C. The many other products l i s t e d i n Tables I and II are the result of the various side reactions which accompany a l k y l a t i o n . At 45°C, the y i e l d of primary a l k y l a t i o n products was greatly reduced. A l k y l a t i o n yielded increased amounts of 24DMP and 224TMP from propylene, mixed TMP's from l-butene, DMH s from the other C4 o l e f i n s , and heavy and l i g h t ends from a l l feedstocks. Thus, as the reaction temperature was increased, side reactions became increasingly important. From an octane number standpoint TMP s are the most de sirable a l k y l a t i o n product, while the formation of DMH's and heavy and l i g h t ends should be avoided. When a l k y l a t i n g pro pylene, i t i s important to note that 23DMP has a higher octane rating than 24DMP. Accordingly, most side reactions are detrimental to alkylate quality. Two exceptions to t h i s rule are the hydrogen transfer and butene isomerization reactions. Hydrogen transfer converts propylene and isobutane to propane and isobutylene, 1

e

1

1


Albright and Goldsby; Industrial and Laboratory Alkylations ACS Symposium Series; American Chemical Society: Washington, DC, 1977. 3

0.8 4.2 98.4 95.6

3.0 1.9 1.0 0.6 0.4 3.2 98.6 95.9

37.7 5.9 1.1 2.7 0.2 13.3 84.3 85.8

0.4 0.5 0.4 0.1

0.6 13.6

91.3 89.0

225 TMH Heavies

Est. RON Est. MON

DMH DMH DMH DMH

23 24 25 34

1.5 45.0 13.8 25.2

0.9 18.7 5.5 10.2

0.2 11.5 1.6 2.0

TMP TMP TMP TMP

223 224 233 234

2.4 2.0 1.1 0.4

1.4 42.6 13.5 25.6

0.5 1.0 0.2

0.5 0.9 0.2

0.2 0.5 0.3

56.5 5.4 0.1

23 DMP 24 DMP Other C7

1.0 0.3 0.2

0.8 0.3 0.2

trans C4H8-2

0.5 0.7 0.1

1.7 0.9 0.2

8

2.7

4

cis C H -2

1.7

23 DMB 2 MP 3 MP

C4H8-I

1.0

6

3.9

C H

IP

Component, Wt %

Olefin

ALKYLATE PRODUCED FROM PURE OLEFIN FEEDS AT 4°C

Table I


8

0.8 59.7 6.4 10.7

1.2 54.7 6.5 9.6

96.1 94.6

1.8 9.7

96.9 95.4

1.5 6.8

1.1 2.5 1.7 0.2

0.9 1.5 0.2

1.2 1.7 0.3

1.3 2.7 1.7 0.2

1.5 0.5 0.2

3.7

244-TM1

1.7 0.6 0.3

4.7

4

iso C H


0.5 20.9 2.8 3.6

TMP TMP TMP TMP

DMH DMH DMH DMH

223 224 233 234

23 24 25 34 0.7 3.6

90.6 89.1

225 TMH Heavies

Est. RON Est. MON

0.8 1.2 1.0 0.2

33.6 19.7 1.9

2.5 1.2 0.4


5.0

IP

C3H6

23 DMB 2 MP 3 MP

Component, Wt %

Olefin

88.4 88.4

0.8 11.3

11.8 9.7 5.0 1.4

1.2 35.4 6.0 7.2

1.0 2.1 0.6

1.2 0.9 0.3

4.1

C4H8-I

94.6 92.6

1.6 5.8

2.9 4.4 3.7 0.6

2.1 42.3 10.7 12.5

1.2 2.3 0.5

1.9 0.1 0.3

5.6

cis C4H8-:

2.0 5.4 94.6 92.9

9.8 2.4 4.1 3.5 0.5

12.1 3.1 4.6 3.6 0.6 1.4 4.6 94.8 92.9

1.8 46.4 9.1

1.3 2.5 0.5

2.2 0.9 0.3

6.6

iso C4H8

2.3 44.3 11.0

1.2 2.3 0.5

1.8 0.8 0.3

5.1

trans C4H8-2

ALKYLATE PRODUCED FROM PURE OLEFIN FEEDS AT 45°C

Table I I


1.8 5.7 94.6 92.9

10.6 2.5 4.1 3.5 0.5

1.8 46.3 8.9

1.3 2.4 0.5

2.1 0.9 0.3

6.6

244-TMP-l

£ d

3 Ά Ζ g

f

g

ζ,

g

>

>

Ι

g

g

3.


INNÉS

C-C=C + H

C-C-C +

C-Ç-C

63

-> C-C-C

Ç-C c-ç-c

> C-C-C + C-£:-c

> C-Ç=C + H

+


while butene isomerization converts l-butene to 2-butene. + C-C-C=C + H

C-C-C-C

+

> C-C-C-C

> C-C=C-C + H

The product o l e f i n s y i e l d TMP's when alkylated rather than the lower octane 23DMP or 23DMH, expected from the s t a r t i n g o l e f i n s . A comparison of Tables I and I I demonstrates the importance of side reactions i n determining alkylate quality. The quality of the alkylates produced from isobutene, diisobutene, c i s - 2 butene, and trans-2-butene was greatly improved when side r e actions were reduced by lowering the reaction temperature to 4°C At 45°C, the alkylates obtained from these o l e f i n s were remarkably s i m i l a r i n composition. The estimated RON s ranged from 94.6 to 94.8. Reducing the reaction temperature to 4°C inhibited the formation of DMH's and increased the y i e l d of TMP's, boosting octane ratings 1.5 to 4.0 RON. Reducing side reactions does not always mean greatly improved octane ratings. Propylene alkylate was only s l i g h t l y improved at the low temperature, because the hydrogen transfer reaction was i n h i b i t e d along with undesirable side reactions. A decrease i n the y i e l d of 24DMP and other undesirable products was o f f s e t by a decrease i n the y i e l d of 224TMP. The quality l-butene alkylate at low temperatures was very poor because the desirable butene-l isomerization reaction was i n h i b i t e d . At 45°C most l-butene isomerized to 2-butene p r i o r to a l k y l a t i o n and TMP s were the major product; but, at 4°C, less than half the l-butene isomerized and 23DMH predominated. The same e f f e c t s were seen with mixed o l e f i n feeds. The refinery stream described i n Table I I I was blended with C P . Grade isobutane to obtain a 9.0-to-1.0 isobutane-to-olefin molar r a t i o . This feed was alkylated at temperatures ranging from 4°C to 45°C The contact time was held constant at 1.0 minutes. The results are shown i n Table IV. The alkylate compositions include pentanes derived from the feed, but only 1

1


INDUSTRIAL

A N D LABORATORY

ALKYLATIONS

Table I I I C3-C5 REFINERY STREAM

Component


Ethane

Vol % 0.06

Propane

13.26

Propene

27.34

Isobutane

19.55

N-butane

4.71

Butene-l

4.44

Isobutene

4.64

Trans-butene-2

5.20

Cis-butene-2

3.40

Isopentane

12.28

N-pentane

0.61

Pentene-1

0.60

Cis and trans pentene-2

1.26

2-methylbutene-l

1.35

2-methylbutene-2

0.90


Albright and Goldsby; Industrial and Laboratory Alkylations ACS Symposium Series; American Chemical Society: Washington, DC, 1977. 15

2.8 10.1

2.7 10.6

225 TMH Heavies

2.5 9.5

3.9 1.6 0.7 0.5 0.1

4.6 1.5 0.7 0.5 0.1

4.6 1.6 0.7 0.5 0.1

4.9 1.3 0.6 0.5 0.1

23 DMH 24 DMH 25 DMH 34 DMH Other C8 2.9 11.0

0.5 20.1 3.7 6.9

0.5 16.3 3.4 6.7

0.4 15.4 3.2 6.7

0.3 14.7 3.2 6.3

25.9 3.0 0.2

27.7 2.7 0.2

28.4 2.5 0.2

223 224 233 234

1.8 0.6 0.2

2.0 0.7 0.2

2.2 0.7 0.2

2.0 0.6 0.2

17.3 0.9

198 92.6

18.2 0.8

30.5 2.3 0.1

TMP TMP TMP TMP

12 185 92.4

18.3 0.9

179 92.4

10

18.3 0.8

172 92.3


23 DMB 2 MP 3 MP

IP Ρ

Alkylate Composition, Wt %

Y i e l d , Wt % RON

Temperature, °C

2.8 9.2

4.1 1.8 0.8 0.5 0.2

0.5 20.0 3.9 7.1

24.9 3.8 0.2

1.8 0.6 0.2

16.9 0.8

193 92.6

20

45

2.3 1.0 0.4 16.6 9.8 1.0 0.6 19.9 3.9 5.4 2.2 2.7 1.7 0.4 0.3 3.3 9.6

2.0 0.8 0.3 17.5 8.1 0.8 0.5 21.0 4.1 6.8 2.0 2.4 1.6 0.4 0.2 3.0 10.2

18.0 6.4 0.5 0.5 22.0 4.1 6.5 3.0 2.3 1.2 0.4 0.2 3.1 10.2

18.9 5.1 0.4 0.5 22.5 4.0 6.5 3.4 2.4 1.1 0.4 0.2 3.0 10.1

1.8 0.7 0.3

1.9 0.7 0.3

204 91.8

18.2 0.8 18.0 0.8

38 208 92.

32 207 92.4

18.1 0.8

18.0 0.8

206 92.5

27

HF ALKYLATION OF C3-C5 REFINERY FEED WITHOUT PROMOTER

Table IV


AND

LABORATORY

ALKYLATIONS


INDUSTRIAL


3.

INNÉS


67

the net increase i n these materials was considered i n c a l c u l a t i n g the y i e l d of a l k y l a t e . As with the pure o l e f i n feeds, lowering the reaction temperature i n h i b i t e d side reactions. The y i e l d of primary alkyl a t i o n products such as 23DMH and 23DMP increased, as the formation of other DMH isomers and 24DMP was i n h i b i t e d . TMP s are both a primary product and a byproduct. Thus, TMP s from i s o butene and 2-butene increased as TMP's from propylene and 1butene decreased. The t o t a l TMP y i e l d was optimized at 27°C. The net e f f e c t on alkylate quality was that RON increased from 91.8 to 92.6, then f e l l back to 92.3. The t h e o r e t i c a l y i e l d of alkylate based on o l e f i n i n the feed was 220 wt %. Below 27°C, o l e f i n conversion was incomplete. Unreacted o l e f i n s were detected i n the reactor effluent and alkylate y i e l d s were considerably below the t h e o r e t i c a l value. From 27°C to 45°C, the o l e f i n feed was completely reacted. In this temperature range the o l e f i n y i e l d averaged 206 wt %. Small amounts of added CF3SO3H dramatically changed the c a t a l y t i c properties of the HF phase. Tables V, VI, and VII show the e f f e c t at low temperatures with propylene, l-butene, and mixed-olefin feeds, respectively. The f i r s t two feeds contained 95 wt % isobutane and 5 wt % o l e f i n . The t h i r d feed, prepared from C P . Grade isobutane and the C3-C5 refinery stream shown i n Table I I I , had an isobutane-olefin molar r a t i o of 12. With HF alone, the y i e l d of primary a l k y l a t i o n products was very high. The addition of CF3SO3H s e l e c t i v e l y restored the hydrogen transfer and butene isomerization reactions. TMP y i e l d s were enhanced at the expense of 23DMP and 23DMH without unduly i n creasing undesirable byproducts such as 24DMP. As a r e s u l t , substantial increases i n alkylate quality were recorded for a l l three feedstocks. Most importantly, the octane rating of the alkylate produced from the C3-C5 refinery stream was boosted from 92.1 to 93.9 RON. Furthermore, reaction rates i n the presence of CF3SO3H were several times those obtained with HF alone. The increased alkylate y i e l d s r e s u l t i n g from CF3SO3H were due i n part to i n creased o l e f i n conversions. In an extension of the experiments i n Table VII, contact time was varied at several temperatures and promoter l e v e l s . The alkylate y i e l d s were plotted against contact time as i n Figure 2. An estimate of the r e l a t i v e r e action rates was made by comparing the contact times required to achieve a 195 wt % y i e l d of a l k y l a t e . The Figure shows that the enhancement of reaction rate by CF3SO3H was more than enough to compensate for a reduction i n temperature from 38°C to 4°C. The e f f e c t of FSO3H on HF a l k y l a t i o n was very much l i k e that of CF3SO3H. The 9-to-l blend of isobutane with refinery o l e f i n s , alkylated e a r l i e r with HF alone (Table IV), was used to study the c a t a l y t i c properties of HF-FSO3H blends. Table VIII gives the r e s u l t s of runs made at 4°C and 1.0 minute 1


1


INDUSTRIAL

A N D LABORATORY

ALKYLATIONS

Table V


EFFECT OF CF3SO3H ON PROPYLENE ALKYLATION

Wt % CF3SO3H

0

3.8

6.6

Contact Time, Minutes

3.0

3.0

3.0

Temperature, °C

2

3

4

176

199

230

Wt % Y i e l d Est. RON

90.8

92.8

93.5

1.7

2.5

2.5

1.3

2.2

2.4

23 DMP

77.0

51.8

41.6

24 DMP

3.9

9.9

12.2

TMP's

9.5

30.3

37.5

DMH's

0.8

1.5

1.8

225 TMH

0.1

0.1

0.2

Heavies

6.2

2.0

1.8

Alkylate Composition, Wt % C

5

C6


3.

INNÉS


69

Table VI


EFFECT OF CF3SO3H ON BUTENE-1 ALKYLATION

Wt % CF3SO3H

0

3.6

7.0


3.0

3.0

3.0

Temperature, °C

2

3

4

188

198

203

Wt % Y i e l d Est. RON

83.8

90.8

94.5

C5

0.9

1.6

1.6

C

1.2

1.5

2.2

0.9

1.2

1.2

40.2

62.3

75.0

48.9

31.1

18.2

Other Ce

0.3

0.2

0.3

225 TMH

0.1

0.5

0.5

Heavies

7.5

1.2

1.2


6

C7 TMP's 1

DMH s


70

INDUSTRIAL

A N D LABORATORY

ALKYLATIONS

Table VII


EFFECT OF CF3SO3H WHEN ALKYLATING A C3-C5 REFINERY STREAM AT 4°C

Wt % CF3SO3H

0

2.7.

6.5

8.6


1.5

1.5

1.5

1.5

182

Wt % Y i e l d

205

211

217

92.1

92.9

93.9

93.7

19.1

18.8

18.9

17.1

2.3

2.4

2.3

2.0

23 DMP

28.5

23.7

21.5

16.8

24 DMP

2.3

2.9

3.1

4.4

Other C7

0.1

0.1

0.2

0.2

24.3

32.5

36.8

38.7

DMH s

7.3

5.5

4.5

4.4

Other Cg

0.2

0.2

0.1

0.1

225 TMH

2.7

3.0

3.0

3.0

Heavies

13.1

11.0

9.6

13.3

RON

Alkylate Composition, Wt % C5

c

6

TMP's 1


Albright and Goldsby; Industrial and Laboratory Alkylations ACS Symposium Series; American Chemical Society: Washington, DC, 1977. 0.3 14.7 3.2 6.3

223 224 233 234 4.9 1.3 0.6 0.5 0.1 2.7 10.6

23 DMH 24 DMH 25 DMH 34 DMH Other CQ

225 TMH Heavies

TMP TMP TMP TMP

30.5 2.3 0.1

2.0 0.6 0.2


23 DMB 2 MP 3 MP

IP Ρ 18.3 0.8

172 92.3



— 100.0

FSO3H HF

Catalyst Composition, Wt %

2.8 9.6

4.0 1.1 0.5 0.4 0.1

0.3 21.1 4.1 6.3

24.9 3.3 0.1

1.9 0.6 0.2

18.0 0.8

191 93.0

3.3 96.7

3.1 8.2

2.9 0.8 0.5 0.4 0.0

0.2 25.1 4.8 6.0

21.2 4.1 0.1

1.9 0.6 0.2

18.8 0.8

206 93.6

6.6 93.4

3.0 9.9

2.3 1.0 0.4 0.3 0.0

0.5 24.0 5.6 6.6

21.3 4.2 0.3

1.6 0.6 0.2

17.2 0.8

208 93.9

9.7 90.3

3.8 11.6

1.9 1.7 1.2 0.3 0.1

1.4 28.6 6.3 4.7

10.5 5.8 0.7

1.4 0.8 0.3

17.8 0.9

215 93.6

15.7 84.3

4.6 13.1

2.0 1.8 1.5 0.4 0.2

1.7 26.6 5.9 4.2

8.6 5.8 0.6

1.7 1.1 0.5

18.7 0.9

210 93.2

21.8 78.2

5.4 12.0

1.9 2.2 1.9 0.4 0.2

2.4 24.7 6.0 3.7

8.2 6.3 0.9

2.1 1.2 0.4

19.0 0.9

213 92.6

32.4 67.6

EFFECT OF ADDED FSO3H ON THE ALKYLATION OF C3-C5 REFINERY FEED AT 4°C

Table VIII


6.0 13.6

1.8 2.3 2.0 0.4 0.2

2.3 21.0 6.1 3.5

7.4 6.9 1.3

2.2 1.4 0.5

20.1 1.0

204 91.9

50.0 50.0

8.7 15.4

1.4 2.7 2.6 0.4 0.6

2.8 14.2 3.7 2.3

5.8 5.2 1.9

2.7 2.4 0.9

25.5 1.0

204 90.1

100

s:

Ci

I

2


72

INDUSTRIAL

A N DLABORATORY

ALKYLATIONS

contact time. The percentage of FSO3H i n the catalyst blend was varied from 0 to 100 wt %. The highest quality alkylate (93.9 RON) was obtained with a catalyst blend containing 9.7 wt % FSO3H. Once again the promoter s e l e c t i v e l y restored the hydrogen transfer and butene isomerization reactions, boosting TMP y i e l d s at the expense of 23DMP and 23DMH. Above the o p t i mum promoter l e v e l , alkylate quality deteriorated because DMH's, 24DMP, and heavy and l i g h t ends were increasingly formed. With 50% or 100% FSO3H, alkylate octane ratings f e l l below those obtained with HF alone. Reaction i n the absence of promoter was r e l a t i v e l y slow, so o l e f i n conversion was incomplete. The addition of FSO3H markedly increased reaction rates, and alkylate y i e l d s approached the t h e o r e t i c a l value of 220 wt %. Only 6.6 wt % FSO3H was required to achieve complete conversion, so the enhancement of reaction rates was of the same magnitude achieved with CF3SO3H. In Table IX a l k y l a t i o n was carried out at various temperatures with a catalyst blend containing 9.7 wt % FSO3H. As the reaction temperature was raised, undesirable side reactions increased. A comparison of Tables IX and IV shows that above 25°C the addition of 9.7 wt % FSO3H was detrimental to alkylate quality. Conclusion A commercial HF a l k y l a t i o n unit operating at 45°C produces 92.1 RON alkylate from the C3-C5 r e f i n e r y stream used i n these experiments. We have shown that 93.9 RON alkylate can be obtained from the same feedstock by lowering the reaction temperature to 4°C and adding an optimum amount of CF3SO3H or FSO3H promoter. Reducing the reaction temperature increases the s e l e c t i v i t y for primary a l k y l a t i o n products, but i n the absence of promoter this has only a small e f f e c t on RON because both desirable and undesirable side reactions are i n h i b i t e d . The addition of promoter restores hydrogen transfer and butene isomerization without markedly increasing undesirable side reactions. Consequently, alkylate quality i s improved. The addition of CF3SO3H or FSO3H also greatly accelerates the rate of alkylate production. This means that throughputs for a modif i e d HF a l k y l a t i o n process employing one of these promoters would be at least as high as i n conventional HF a l k y l a t i o n , despite the lower reaction temperature. The u t i l i z a t i o n of CF3SO3H or FSO3H as promoters i n HF a l kylation w i l l depend on the value assigned by r e f i n e r s to an incremental octane number. The added value of the alkylate must be high enough to j u s t i f y the i n s t a l l a t i o n and operation of the required r e f r i g e r a t i o n equipment. At present most refiners are s t i l l able to increase the quality of their gasoline pool by less costly methods such as by operating t h e i r reforming units at higher severity. However, i f the demand for high-octane


Albright and Goldsby; Industrial and Laboratory Alkylations ACS Symposium Series; American Chemical Society: Washington, DC, 1977. 0.5 24.0 5.6 6.6

223 224 233 234 2.3 1.0 0.4 0.3 0.0 3.0 9.9

23 DMH 24 DMH 25 DMH 34 DMH Other CQ

225 TMH Heavies

TMP TMP TMP TMP

21.3 4.2 0.3

1.6 0.6 0.2

17.2 0.8

208 93.9


23 DMB 2 MP 3 MP

IP Ρ



Temperature, °C

3.4 9.1

2.2 1.6 1.1 0.4 0.2

2.1 1.5 1.0 0.4 0.1 3.3 9.2

1.1 27.0 5.9 5.1

15.3 6.4 0.7

1.8 0.7 0.3

16.9 0.8

3.7 9.2

2.1 1.9 1.3 0.4 0.1

1.3 26.6 6.0 4.9

13.1 7.3 0.8

1.9 0.9 0.4

17.1 0.8

210 93.2

222 93.5

1.0 27.7 6.0 5.2

15.4 6.2 0.6

1.7 0.7 0.2

16.6 0.8

205 93.7

16

10

4.1 9.4

2.2 2.1 1.5 0.4 0.2

1.5 25.1 5.8 4.6

12.0 7.7 1.1

2.2 1.2 0.4

17.4 0.8

210 92.8

20

3.7 10.4

2.5 2.2 1.7 0.4 0.2

1.4 25.0 5.8 4.7

10.9 7.5 1.0

2.3 1.2 0.4

17.8 0.9

213 92.5

25

3.9 11.9

2.6 2.3 2.0 0.5 0.3

1.5 23.3 5.3 4.0

10.1 7.9 1.2

2.3 1.4 0.4

18.2 0.9

212 92.1

32

HF ALKYLATION OF C3-C5 REFINERY FEED PROMOTED BY 9.7 WT % FSO3H

Table IX


4.2 12.3

2.8 2.6 2.3 0.6 0.3

1.5 22.4 5.0 3.8

9.1 8.3 1.3

2.2 1.4 0.5

18.5 0.9

207 91.7

38

4.5 13.0

3.1 2.9 2.5 0.7 0.4

1.5 19.9 4.9 3.7

8.5 8.7 1.5

2.2 1.5 0.5

19.1 0.9

203 91.3

45

3

3 ο S?

&

Ci

3

i

74

INDUSTRIAL

A N D LABORATORY

ALKYLATIONS

unleaded gasoline increases s i g n i f i c a n t l y , the use of these promoters could be j u s t i f i e d .


Literature Cited (1) Innes, R. Α., U.S. Patent Application S e r i a l No. 501, 664, August 29, 1974. (2) McCaulay, D. Α., U.S. Patent 3, 928, 487 (December 23, 1975). (3) "Knocking Characteristics of Pure Hydrocarbons", ASTM Special Publication No. 225, American Society for Testing Materials, Philadelphia (1958). (4) ASTM Manual for Rating Motor, Diesel, and Aviation Fuels, pp 16 & 37, American Society for Testing Materials, Philadelphia (1971). (5) Schmerling, L., J. Amer. Chem. Soc., 67, 1778 (1945). (6) Schmerling, L., "Alkylation of Saturated Hydrocarbons", Chemistry of Petroleum Hydrocarbons, I I I , 363, Reinhold, New York (1955). (7) Schmerling, L., "Alkylation of Saturated Hydrocarbons", F r i e d e l Crafts and Related Reactions, 2, 1075, Interscience, New York (1964).


Fluorosulfonic Acid Promoters in HF Alkylation - ACS Symposium

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