Industrial and Laboratory Alkylations

4 Isoparaffin/Olefin Trifluoride

Alkylation

over

Resin/Boron

Catalysts

T. J. HUANG

Downloaded by EAST CAROLINA UNIV on November 7, 2016 | http://pubs.acs.org Publication Date: June 1, 1977 | doi: 10.1021/bk-1977-0055.ch004

Mobil Research and Development Corporation, P. O. Box 1025, Princeton, NJ 08540 S. YURCHAK Mobil Research and Development Corporation, Paulsboro Laboratory, Paulsboro, NJ 08066

Conventional s u l f u r i c a c i d and HF a l k y l a t i o n processes (1,2,3) employ l i q u i d - l i q u i d c a t a l y t i c systems which are expensive and troublesome because o f such problems as maintaining an acid/hydrocarbon emulsion, product s e p a r a t i o n and waste d i s p o s a l (H2SO4 process o n l y ) . A s o l i d c a t a l y s t should e l i m i n a t e many o f these problems. I n view o f t h e i r h i g h a c t i v i t y , z e o l i t e s have been used by a number o f workers (4 _5,6,2) catal y z e i s o p a r a f f i n / o l e f i n a l k y l a t i o n w i t h v a r y i n g degrees of success. Z e o l i t e s appear t o have l i m i t e d a t t r a c t i v e n e s s because they age r a p i d l y and cannot perform e f f e c t i v e l y a t h i g h o l e f i n space v e l o c i t i e s . M a c r o r e t i c u l a r a c i d i c i o n exchange r e s i n s represent a c l a s s o f m a t e r i a l s a v a i l a b l e w i t h a r i g i d pore structure. While they have shown good low-temperature a c t i v i t y f o r a number o f a c i d - c a t a l y z e d r e a c t i o n s , they are i n e f f e c t i v e f o r i s o p a r a f f i n / o l e f i n a l k y l a t i o n since they lack hydride t r a n s f e r c a p a b i l i t y . I t may, however, be p o s s i b l e t o i n c r e a s e the a c i d i t y o f i o n exchange r e s i n s by forming a complex between the a c i d groups o f the r e s i n and a Lewis a c i d . T h i s approach was taken by K e l l y (8) who found t h a t i s o p a r a f f i n / o l e f i n a l k y l a t i o n could be c a t a l y z e d by a gel-type a c i d i c ion exchange r e s i n i n the presence o f BF3. The e f f i c i e n c y o f t h i s c a t a l y s t system seems t o have been impaired by the non-swelling nature o f g e l - t y p e r e s i n s i n hydrocarbons. Such l i m i t a t i o n s are not imposed on m a c r o r e t i c u l a r ion exchange r e s i n s . In t h i s paper, we present some o f our data on the use o f m a c r o r e t i c u l a r ion exchange r e s i n s t o c a t a l y z e the a l k y l a t i o n o f isobutane with butene i n the presence o f BF3. t

o

#

75

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

76

INDUSTRIAL

AND

LABORATORY

ALKYLATIONS


Experimental

In conducting i s o p a r a f f i n / o l e f i n a l k y l a t i o n , part i c u l a r a t t e n t i o n must be given to minimizing the c h i e f s i d e r e a c t i o n — o l e f i n p o l y m e r i z a t i o n . In the l a b o r atory, t h i s can be c o n v e n i e n t l y done by u s i n g a semibatch r e a c t o r with o l e f i n being charged c o n t i n u o u s l y to a pool of isobutane, c a t a l y s t and product. The o l e f i n feed r a t e i s kept low enough so t h a t i t does not accumulate i n the r e a c t o r . In t h i s manner, the b i m o l e c u l a r p o l y m e r i z a t i o n r e a c t i o n r a t e i s minimized. The e x p e r i ment i s continued f o r a time s u f f i c i e n t t o g i v e the desired external i s o p a r a f f i n / o l e f i n r a t i o . This r a t i o bears some s i m i l a r i t y t o the i s o p a r a f f i n / o l e f i n feed r a t i o t o a continuous r e a c t o r employed i n commercial a l k y l a t i o n systems. In accordance w i t h the above, most runs were performed i n a 300 ml, Type 316 s t a i n l e s s s t e e l s t i r r e d autoclave equipped f o r semi-batch o p e r a t i o n with o l e fin. Reactor pressure was s u f f i c i e n t to maintain the r e a c t a n t s i n the l i q u i d phase. In the standard procedure, 7 grams of dry r e s i n (Rohm and Haas, see Table I) was placed i n the r e a c t o r and 93 grams o f isobutane (Instrument Grade, Matheson) was charged i n t o the react o r by N2 pressure. Then about 6-7 grams of BF3 ( P f a u l t y and Bauer) was charged and the contents s t i r red at 1800 rpm. A f t e r the d e s i r e d temperature was reached, butene ( C P . , Matheson) was fed i n slowly f o r the d u r a t i o n o f the run. An o n - l i n e chromatograph, which was equipped w i t h a f l a m e - i o n i z a t i o n d e t e c t o r and a d i g i t a l i n t e g r a t e r , was used t o monitor the course o f a l k y l a t i o n . D e t a i l s on o p e r a t i n g c o n d i t i o n s are given i n the t a b l e s . At the end o f the run, the product was discharged under N2 flow i n t o a metal bomb which was kept at -73 °C. The product was warmed t o room temperature and t r a n s f e r r e d t o the atmospheric pressure weathering system which c o n s i s t e d of two BF3-scrubbers, a s o l e n o i d v a l v e and a t e n - l i t e r gas c o l l e c t o r which was equipped w i t h an automatic pressure c o n t r o l l e r . Both the weathered l i q u i d and the weathered gas were anal y z e d on a Scot Pak column. Resins were p r e t r e a t e d i n the f o l l o w i n g manner: e l u t i o n w i t h methanol; d i s t i l l e d water wash; exchange w i t h 4 percent NaOH, d i s t i l l e d water wash; exchange w i t h 15 percent H2S04# d i s t i l l e d water wash u n t i l a c i d f r e e . Treated runs were s t o r e d i n d i s t i l l e d water. The p r e t r e a t e d r e s i n was d r i e d i n vacuo f o r three hours at 120°C p r i o r t o use. A l l r e s i n s were ground t o pass through 100 mesh unless otherwise s p e c i f i e d .



2

Surface Area, m /g dry

Cross-linkage % d1vinyl benzene

40-50

-20

150

100-120

550-600

-150

-150

f

40-50

80-90

200-600

Avg. pore diameter, Â

28

-150

24

47

42

32

Porosity, %

Maximum Temperature, °C

4.2

3.3

3

3.4

AmberlystXN-1011

4.9

AmberlystXN-1010

Hydrogen i o n concentration meq/g d r y

AmberlystXN-1005

RS0 H

Styrene-DVB

Amberlyst15

Ionic functionality

Skeletal structure

Resin

30-40

-150

400-800

4.5

AmberlystXN-1008

PHYSICAL PROPERTIES OF VARIOUS MACRORETICULAR RESINS

TABLE I


40-50

-20

150

4.3

Amberlite 200

δδ*

3

•3»

4

78

INDUSTRIAL

AND

LABORATORY

ALKYLATIONS

Results and D i s c u s s i o n The C5+ hydrocarbon y i e l d together with chromatographic data and bromine number has been used t o assess the e f f e c t i v e n e s s o f a c a t a l y s t f o r c a t a l y z i n g i s o paraf f i n / o l e f i n a l k y l a t i o n . T h i s y i e l d i s d e f i n e d as the grams o f C5+ hydrocarbon produced per gram o f o l e f i n converted. For butene feed, i f only a l k y l a t i o n occurs, the C5+ y i e l d would be 2.04 g Cs+/g C4 converted; however, i f only p o l y m e r i z a t i o n occurs, the C5 y i e l d would be 1.0 g C$ /g C4 converted. The 04= WHSV i s defined as g C4=/g c a t a l y s t / h o u r . =

+

=


+

I.

Amberlyst-15 Resin

P r e l i m i n a r y experiments were performed using Amberlyst-15 resin/BF3 c a t a l y s t t o explore the s t o i c h i o metric requirements necessary t o o b t a i n a good a l k y l a t i o n c a t a l y s t . As the r e s u l t s i n Table I I show, BF3 alone, Amberlyst-15 alone and Amberlyst-I5/BF3 c a t a l y s t with a 1:1 e q u i v a l e n t r a t i o o f BF3 t o -SO3H groups i n the r e s i n are not e f f e c t i v e a l k y l a t i o n c a t a l y s t s . However, i n the presence o f a l a r g e excess o f BF3 (BF3/ -SO3H > 2 e q u i v a l e n t / e q u i v a l e n t ) , the c a t a l y s t i s a c t i v e f o r a l k y l a t i o n as i n d i c a t e d by the C5 y i e l d being equal t o 1.92 g C s / g 04= converted (Run 4, Table I I ) , o r 1.95 g C5+/ ; C4= converted (Run 6, Table I I ) . Amberlyst-15 i n the Na+ form (prepared by exchange with NaOH) was used t o determine i f the H on the -SO3H group p a r t i c i p a t e s i n the a l k y l a t i o n . _The r e s u l t s are shown below ( c o n d i t i o n s : 40°C, 2.6 C4" WHSV, and i - C 4 / C = 5): +

+

0

+

=

4

Cation i n r e s i n

H

O l e f i n conversion % C+ 5

yield, 9 C / g C4

100 1.95

=

+

5

+

Na

+

91 0.93

converted

The d i f f e r e n c e i n 05+ y i e l d c l e a r l y demonstrates t h a t the s u l f o n i c a c i d group i s e s s e n t i a l f o r isobutane alkylation. A l s o shown i n Table I I i s the e f f e c t o f o l e f i n space v e l o c i t y . Comparison o f Runs 4 and 6 shows t h a t the Amberlyst-I5/BF3 c a t a l y s t can a l k y l a t e isobutane w i t h butene i n good y i e l d a t an o l e f i n WHSV o f 2.6 g o l e f i n / g r e s i n - h o u r . The a l k y l a t e y i e l d s are s l i g h t l y lower than the t h e o r e t i c a l v a l u e o f 2.04 due t o removal of some o f the r e a c t o r contents v i a the o n - l i n e sampli n g system. The y i e l d s shown are based on the l i q u i d


Albright and Goldsby; Industrial and Laboratory Alkylations ACS Symposium Series; American Chemical Society: Washington, DC, 1977. 5

+

Amberlyst15/BF

=

i - •c4/c4=

100.0

=

2.4

99.2

*Operating c o n d i t i o n s : i -•c4/c4=

3

1.7

5.1 and C

7.5 and C

1.95

1.02

4

4

=

=

< 0.1

—

Alkylation

P r i m a r i l y polymerization

Alkylation



No r e a c t i o n but trace o f o l e f i n polymerization

WHSV = 2.6 f o r Runs 5-6.

WHSV = 0.2 f o r Runs 1-4;

52.4

50.3

< 0.1

6

3

79.2

Amberlyst15/BF

1.92

5

3

100.0

Amberlyst15/BF

4

2.1

-

56.6

1.21

100.0

1.0

Amberlyst15/BF

3

3

25.5

47.8

1.16

96.9

-

v

Comment

CATALYST AT 40°C

Bromine No. o f Product

BF^ alone

Wt % o f Cp i n

No Product f o r A n a l y s i s

Yield

C

2

2

Olefin Conv. %

Amberlyst15 alone

Catalyst

3

3

1

Run No.*

Equiv. Ratio BF /S0 H 0.0

ISOBUTANE/TRANS-2-BUTENE ALKYLATION OVER AMBERLYST-15/BF

TABLE I I



80

INDUSTRIAL

A N D LABORATORY

ALKYLATIONS

recovered from the r e a c t o r a t the end o f the e x p e r i ment. I t i s noteworthy that good performance was achieved a t h i g h o l e f i n space v e l o c i t i e s with low e x t e r n a l isobutane/butene r a t i o . For comparison purposes, s u l f u r i c a c i d a l k y l a t i o n operates a t an o l e f i n space v e l o c i t y o f approximately 0.2-0.4, and an e x t e r n a l i s o b u t a n e / o l e f i n r a t i o o f about 5. HF a l k y l a t i o n , while p e r m i t t i n g o p e r a t i o n a t higher o l e f i n space v e l o c i t i e s than H2SO4 a l k y l a t i o n , requires e x t e r n a l isobutane/ o l e f i n r a t i o o f about 15. I t i s w e l l known t h a t o l e f i n space v e l o c i t y and e x t e r n a l i s o b u t a n e / o l e f i n r a t i o has a pronounced e f f e c t on a l k y l a t e q u a l i t y w i t h both H2SO4 and HF a l k y l a t i o n . A s i m i l a r s i t u a t i o n was obtained with resin/BF3 catal y s t , as shown below ( c o n d i t i o n s : Amberlyst-I5/BF3 and 40°C): i-C /C =

C = WHSV

Wt. % o f TMP i n C

10

0.7

60

10

1.4

54

5

1.4

45

5

2.6

41

4

4

4

+ 5

C l e a r l y , the a l k y l a t e q u a l i t y , as measured by the trimethylpentane (TMP) content o f the a l k y l a t e , d e t e r i orates as o l e f i n space v e l o c i t y i s i n c r e a s e d . I n a d d i t i o n , a t equal o l e f i n space v e l o c i t y , reducing the e x t e r n a l i s o b u t a n e / o l e f i n r a t i o a l s o lowers the alkylate quality. For H2SO4 and HF c a t a l y s t s , three main process v a r i a b l e s a f f e c t a l k y l a t e q u a l i t y : temperature; o l e f i n space v e l o c i t y ; and e x t e r n a l i s o b u t a n e / o l e f i n r a t i o . For resin/BF3 c a t a l y s t , the above process v a r i a b l e s a l s o a f f e c t a l k y l a t e q u a l i t y . However, with the r e s i n / BF3 c a t a l y s t , the surface area o f r e s i n i n a d d i t i o n t o the f u n c t i o n a l group o f the r e s i n , may a l s o play an important r o l e i n d i r e c t i n g a l k y l a t i o n . Some r e s u l t s i l l u s t r a t i n g the e f f e c t o f the r e s i n ' s surface area on a l k y l a t e q u a l i t y are shown i n Table I I I . C l e a r l y , i n c r e a s i n g the r e s i n ' s surface area improves the a l k y l a t e q u a l i t y both i n terms o f the f r a c t i o n o f t r i m e t h y l pentanes i n the C5+ a l k y l a t e and the c l e a r research octane number (RON) o f the C s a l k y l a t e . While t h i s study o f the e f f e c t o f the r e s i n ' s s u r f a c e area was performed by using d i f f e r e n t macror e t i c u l a r r e s i n s , i t i s f e l t that the primary v a r i able being changed i s surface area, s i n c e a l l the +



35

45

45

110

570

Amberlyst XN-1008

Amberlite200

Amberlyst15

Amberlyst XN-1005

Amberlyst XN-1010

69.7

56.5

52.2

52.0

39.4

45.9

Wt. % o f TMP i n C 5

+

88.3

86.4

79.1

80.9

73.1

75.5

Wt. % o f TMP i n Cg

4

*100% o l e f i n c o n v e r s i o n f o r a l l r e s i n s .

28

2

Surface Area m /g dry

Amberlyst XN-1011

Macroreticular:

Type o f Resin

3

9

+

11.6

20.7

19.2

22.0

21.9

19.3

5

Wt. % o f C in C +

+

1.88

1.76

1.89

1.91

1.86

1.88

C Yield 5

C 5

+

96.5

95.6

93.6

93.7

92.4

92.3

RON Alkylate

THE RESULTS OF SCREENING TESTS ON IS OBUTANE/TRANS- 2-BUTENE ALKYLATION OVER VARIOUS RESIN/BF COMPLEXES AT 40°C AND 2.6 c ~ WHSV*. ( E f f e c t o f Surface Area o f Resin) .

TABLE I I I


82

INDUSTRIAL

AND

LABORATORY

ALKYLATIONS

r e s i n s are composed b a s i c a l l y o f a s u l f o n a t e d styrenedivinylbenzene copolymer. II.

Amberlyst XN-1010 Resin

Since the Amberlyst XN-IOIO/BF3 c a t a l y s t produced an a l k y l a t e w i t h q u a l i t y s u p e r i o r to the other r e s i n s t e s t e d , a d d i t i o n a l work was performed w i t h t h i s r e s i n / BF3 c a t a l y s t t o explore the e f f e c t s o f p a r t i c l e s i z e and temperature, and s e n s i t i v i t y to o l e f i n type. Olef i n space v e l o c i t y was kept a t 2.6 grams C4 /gram resin-hour f o r a l l the r e s u l t s reported below. Downloaded by EAST CAROLINA UNIV on November 7, 2016 | http://pubs.acs.org Publication Date: June 1, 1977 | doi: 10.1021/bk-1977-0055.ch004

=

A. E f f e c t o f P a r t i c l e S i z e . The h i g h r e a c t i v i t y of Amberlyst XN-IOIO/BF3 c a t a l y t i c system suggested t h a t a d i f f u s i o n a l l i m i t a t i o n may be imposed i n t h i s system. Therefore, the e f f e c t o f p a r t i c l e s i z e on a l k y l a t i o n was i n v e s t i g a t e d i n order t o d e f i n e a proper p a r t i c l e s i z e range f o r the subsequent work. The r e s u l t s on the e f f e c t o f p a r t i c l e s i z e are summarized below (40°C, i-C4/C4 -2 = 5.1, and 100% o l e f i n conversion) : =

Run Number P a r t i c l e s i z e , mesh

7

8

9

10

30-40

100-200

100+

325+

Wt. % o f TMP

in C +

62.2

68.5

69.7

69.9

Wt. % o f TMP

in C

85.4

88.6

88.3

87.7

5

16.1

13.6

11.6

9.6

alkylate

94.6

95.9

96.5

95.9

5

8

Wt. % o f C9+ i n C + RON

clear of C s

+

For the r e s i n w i t h a p a r t i c l e s i z e o f 30-40 mesh, l e s s TMP and more C g were produced i n the 05+ r e s u l t i n g i n an a l k y l a t e w i t h a lower RON+0. With p a r t i c l e s smaller than 100 mesh, there i s almost no d i f f e r e n c e i n a l k y l a t e q u a l i t y , although the C9+ content seems t o i n crease o n l y s l i g h t l y w i t h i n c r e a s i n g p a r t i c l e s i z e . I t i s concluded t h a t p a r t i c l e s w i t h 100+ mesh are s u f f i c i e n t l y small to overcome the d i f f u s i o n l i m i t a t i o n problem. +

B. E f f e c t o f O l e f i n Feedstock. D i f f e r e n t butènes were used as feedstocks t o determine i f the Amberlyst XN-IOIO/BF3 c a t a l y s t d i s c r i m i n a t e s among them. The r e s u l t s are shown below (40°C, i - C / C 4 % o l e f i n conversion): =

=

5

-

1

a

n

d

1 0 0

4


HUANG

4.

Isoparaffin/ Olefin Alkyhtion

A N D YURCHAK

Run Number

9

O l e f i n feedstock C5

+

11

12

trans-2- 1-Butene Isobutene Butene

+

yield, g C / g C4"" converted 5

Wt. % o f TMP i n C wt. % o f TMP i n C wt. % o f C Downloaded by EAST CAROLINA UNIV on November 7, 2016 | http://pubs.acs.org Publication Date: June 1, 1977 | doi: 10.1021/bk-1977-0055.ch004

83

+ 9

+ 5

8

inC + 5

RON c l e a r o f C5"*" a l k y l a t e

1.88

2.06

1.82

69.7

64.3

59.0

88.3

83.2

87.4

11.6

14.2

18.4

96.5

93.4

97.7

The unusual f i n d i n g was t h a t isobutene gave lower TMP i n C5 , but with a higher octane number f o r the C5"*" a l k y l a t e (normally, the octane number o f a l k y l a t e p a r a l l e l s t o the TMP content i n 05+). By comparison w i t h conventional HF and H2SO4 a l k y l a t i o n c a t a l y s t s as shown below, Amberlyst XN-IOIO/BF3 showed r e l a t i v e l y much l e s s d i f f e r e n c e among these three o l e f i n isomers. HF a l k y l a t i o n d i s c r i m i n a t e s s t r o n g l y against l-butene w h i l e H2SO4 a l k y l a t i o n g i v e s r e l a t i v e l y poor r e s u l t s with isobutene (2,3). T h i s suggests that the resin/BF3 system i s unique and not r e l a t e d t o conventional systems. +

Wt. % o f TMP i n C c

Resin/BF ***

HF*

H S0 **

2-Butene

74

72

70

1-Butene

22

70

64

Isobutene

59

52

59

2

4

+

3

*At -10°C and 5 min. contact time (see Ref. 2 ) . **At 7°C and 0.2 04= WHSV (see Ref. 2 ) . ***At 40°C, i - C / C = = 5 and 2.6 C = WHSV. 4

4

4

C. E f f e c t o f Temperature. The e f f e c t o f temperature on isobutane/trans-2-butene a l k y l a t i o n over Amberlyst XN-IOIO/BF3 c a t a l y s t was s t u d i e d a t 0°, 20°, 40°, and 60°C. The r e s u l t s are summarized below (i-C /C = 5.1 and 100% o l e f i n c o n v e r s i o n ) : =

4

A


84

INDUSTRIAL

I

1

1

1

100

100 (

90

L

\

\

r

ο ο

80

70


A N D LABORATORY ALKYLATIONS

I -40

-20

80^°

V

-

60L

Ν

0 +20 Temp.°C

-4

70

J

1 60

+ 60

+ 40

Figure 1. Percent of C isoparaffins in alkylate as function of temperature (Amberlyst XN-1010/BF catalyst) 8

3

Run Number

13

Temperature, °C

14 0

9

15

20

40

60

1.96

1.99

1.88

1.81

+

90.3

80.6

69.7

50.6

Wt. % o f TMP i n C 8 Wt. % o f C in C +

97.1

93.5

88.3

77.5

4.2

9.2

11.6

20.7

101.9

99.1

96.5

96.0

C + y i e l d , g C +/ g C^- converted 5

5

Wt. % o f TMP i n C

5

+

g

RON c l e a r o f C +

5

alkylate

As shown, the s e l e c t i v i t y f o r TMP and the RON o f C5 a l k y l a t e increased sharply w i t h decreasing temper ature. An a l k y l a t e w i t h a RON c l e a r o f 101.9 was pro duced a t 0°C and an o l e f i n space v e l o c i t y o f 2.6. The p l o t s o f wt. % o f CQ i n 05+ and wt. % o f TMP i n C3 v s . temperature are shown i n F i g u r e 1, w h i l e the p l o t o f TMP d i s t r i b u t i o n v s . temperature i s given i n F i g u r e 2. I t i s speculated t h a t the r e v e r s e trends o f 2,2,4-TMP and 2,3,4-TMP i n TMP d i s t r i b u t i o n a t 60°C (Figure 2) could be due t o increased degree o f s e l f a l k y l a t i o n and butene d i m e r i z a t i o n , followed by r a p i d h y d r i d e and methyl group t r a n s f e r s . Based on the ex t r a p o l a t i o n s from these two f i g u r e s , the RON o f 05+ a l k y l a t e a t -40°C was c a l c u l a t e d t o be 102.7. The RON +


4.

HUANG A N D YURCHAK

Isoparaffin/Olefin

Alkylation

85


70

4

o f C5 " a l k y l a t e i s p l o t t e d a g a i n s t temperature i n F i g ure 3. The RON-temperature curve appears t o approach a plateau a t about 0°C, i n d i c a t i n g t h a t lower temperature (

Industrial and Laboratory Alkylations

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