Components of Gasoline Produced -
by Catalytic Cracking
AUGUSTUS R. GLASGOW, JR., CHARLES B. WILLISGHAJI, AKD FREDERICK D. ROSSIYI .Vationnl Bureau of Standards, Washington, D . C . T h i s report describes the analysis, with respect to individual hj-drocarbon components, of a gasoline produced by the catalytic cracking process. The analysis was made by utilizing the processes of distillation and adsorption.
A
S P A R T of its war research program, the American l'etro-
leum Institute Research Project 6 a t the Sational Bureau of Standards was requested by the Aviation Fuels Division of thc Cooperative (Automotive) Research Council, through IT-. J. Sweeney of the Standard Oil Development Company, t o determine the hydrocarbon components in certain aviation fuel components. This report presents the results of the analysis, with respect t o individual hydrocarbon components, of :I gasoline produced by the catalytic cracking process. MATERIAL 93VD >SETHOD OF ANALYSIS
The material analyzed in this investigation tws a gasoline produced by :L catalytic cracking process of the fixed-bed type of Iloudry design. This process is one in which material of the gaxoil or heavier distillate r a n g is cracked in the presence of a catalyst in a fixed bed, with the gasoline fraction from the first operation repassed through a similar operation. A general discussion of the catalytic cmcking process is given in references ( 1 , 14). The analysis of this material was made by combination of the data from the following experimental operat,ions: .Inslytical distillation (1 7 ) at, high efficiency x i t h high reflux ratio, of the original material, x i t h nicasurc:nients of boiling point (to *0.01 a C.) and refractive indexes (to *O.OOOl) of the fractions of distillate Scparatioii by adsorption of the original material into an aromatic portion and a paraffin-cycloparaffin portion; cycloparafh is used synonymously with the term naphthene Analytical distillation of the aromatic portion Similar analytical distillation of the paraffin-cycloparaffin portion Determination of the amount of p-xylene in the Cg aromatic portion by measurement of the freezing point Determination of the sulfur content and of the bromine absorption on selected fractions suspected of containing olefins 3Ieasurement of the density of selected fractions of the paraffincycloparaffin distillate .inalytical adsorption experiments to determine accurately thc total aromatic content and also t o obtain an indcperident cstiniate of the olefin content
occurred in the distillate, was made on the basis of the property of refractivity intercept, n-d/2. This property has characteristically different values for paraffins and for cycloparaffins (IS,16). On the fractions from the analytical distillation of the original gasoline, determinations were made of the refractive index of each fraction whole and also of the refractive index of the aromatic-free portion of each fraction. This latter determination was made b y filtering a small volume (about 1 ml.) of the fraction of whole distillate through a small column (about 0.2 X 20 cm.) of silica gel adsorbent (28 to 200 mesh) and letting the first several drops (which is material free of aromatics and olefins) fall on the prism of the relractomkter for measurement. The simple apparatus used is shown in Figure 1.
A small cotton plug - - is sucked bv vacuum into the position shown. The column is packed with silica gcl and stoppered a t A (several such columns can thus be prepared a t the same time for a number of adsorption separations). With the upper portion of column A open to the atmosphere, 1 ml. of hydrocarbon is added and allowed to filter. (For volatile fractions the opening a t A is restricted by a cork stopper having a small vent. K h e n the sample has filtered down t o the cotton plug, pressure is applied t o the column by attaching, a t A , the connection t o the air pressure and closing the air release a t C with a finger until the prism is covered with a liquid film. This slight pressure is required because evaporation of the drops on the prism may exceed the slow filtering rate.) The trap shown in the figure serves to remove oil from the air stream. The small diameter of the tip and the cotton plug holds the next portion of filtrate for a time sufficient t o permit readings of the refractive index of successive filtrate portions.
The apparatus and procedurw for the operations involving analytical distillations, boiling points, and refractive indexes o i the fractions of distillate, and the reduction of the data from the plots of boiling point and reiractivc indes of distillate as a function of its volume are described ( 6 , 1 7 ) ; and the method and apparatus for the measurement of freezing point are described (,F, 18). T h e measurements of density lvere made as described (2); the separation by adsorption of the original gasolinc material into an aromatic portion and a paraffin-cycloparaffin portion was performed as described (4,8, l a ) ; and the analytical adsorption experiment8 m r e performed as described ( 7 , 9). The calculation of the relative amounts of the paraffins and cycloparaffins in the C8 and higher portions, in those regions of .narrow boiling range where several unidentified components
2292
ar ._
release
cotton plug
refroctometer prim
*
~41 0
-
Figure 1. Adsorption Column for Small .4mounts (About 1 411.)
This procedure is satisfactory for concentrations of aromatics up to about 50% by volume. For higher COIIcentrations of aromatics, :L longer tube with an ndsorption scction 60 cm. iri length and 0.2 cm. in dinmeter is used with an appropriately larger volume of sample (about 1 t o 3 ml.). The column is packed with silica gel (200 to 300 mesh) and is equipped with a pressure connection [see Figure 1, reference ( 7 ) for details] to increase the speed of filtration. The use of these columns makes possiblc also the determination of the refractive index of the aroniat,ic portion by desorption withethanol. The principles here involved are the same as described on a larger scale in (7, 8).
October 1949
INDUSTRIAL AND ENGINEERING CHEMISTRY
T E M P E R A T U R E
--
I
-
IN
"C
( B
P
AT
725
MM
Hg
2293
)
AoLLFLN% --
r n'
- T d ~PENTANE -A ---y=f+CYCLCPEhTANE AND 2,2-DIMETNYLBUTANE 2 3 - DIMETHYLBUTANE + -
I X
D
1
k 2 - METHYLPENTANE
< 0
r C
3 rn
z
z
r
IIMETHYLCYCLOHEXANES" nOLEFINS - O C T A N E TNAPHTHENES
1...
DIMETHYLHEPTANES L....
'"-... hi ENTAHPYHLTBHEENNZEESN E .......,
~..
I
...
...... ~. ,
\ ...
F i g u r e 2.
1..
.... ,
. -,
. -
......
...__ .+"-NONANE :ISO-AND n
\
-
1PROPY L B E N Z E N E
R e s u l t s of Distillation of O r i g i n a l Gasoline
Ordinate scale on right gives refractive indexes of fractions of distillate (solid curve refers to refractive indexes of paraffin-cycloparaffin part of fraction and dashed curve t o whole fraction). Ordinate scale on left gives boiling point of distillate a t 725 min. Scale of abscissas gives volume of distillate. Amounts b y volume of various components are indicated in upper portion of figure.
INDUSTRIAL A N D E N G I N E E R I N G C H E M I S T R Y
2294
From the values of the refractive indexes OF the original material, the paraffin-cycloparaffin portion, and the aromatic portion, it is possible to calculate the amount of each. The correct,iorifor the nonideality of mixing between the aromatic portion and the portion containing paraffins and cycloparaffins is obtained by measuring the refractive index of known mixtures.
TABLE I. ANALYSISBY TYPEOF HYDROCARBOSS Type of Hydrocarbons Normal paraffins Isoparaffins Cycloparaffins Aromatics Olefins
Amount, Yo]. % Entire sample hfaterial above pentanes 4 . 4 *1.6 47. *&, 4 . 2 i1 . 5 4 2 , 7 *5.4} 3 0 . 5 4 . 5 } 3 4 , 7 15.5 1 6 . 8 5-B. 4 21.015.5 31.9*0.3 3O.9 t 0 ,4 4.2*0.4 4 . 4 *0.5
-
~
Total
100.0
TABLE 11. Boiling Point a t 1 Atm., O C. 49.3 49.7 58.0 60.3 63.3 49-69
68.7 69-81
87.5
89.8
90.1 90.8 91.9 92.0 81-101 98.4 100.9 101-112 103.5 105.0 106.8 109.1 109.4 107-112 110.6 112-117 112.0 115.6 117.6 117.7 118.9 119-126 125.# 112-146 126-135 130-137 136 2 135-141 138.4 139.1 137-145 137-145 114.4 141-150 8 150.8 152.4 139.2 >150.8
>130.8 > 146 181 3 162.1 164.7 165.2 169.1 169.3 172.9-177.3 >177.3
RESULTS
100.0
.&SALYSIS BY
COMPONENTS
The aromatic content of the entire sample was determined to be 32.2*0.2% by volume by analytical adsorption with silica gel
FOR
51 4TERIAL
Cyclopentane 2,2-Dimethylbutane 2 3-Dimethylbutane 2:Methplpentane 3-Methylpentane
Amount, Yol. c;b ____ _____ Ra-ed on aro natir Based on paraffin-cycloparaffin co nlji(~nents components ~
3.5t0.8 8.310.5
...
1.3+0.4
Olefins n-Hexane
1.4-0.3 0.5-0.3
Olefins hfethylcyclopentane Benzene 2 2-Dimethylpentane 2:4-Dimethylpentane} Cyclohexane 1,l-Dimethylcyrlopentane 2 3-Dimethylpentane 2:Methylhexane trans-l,3-Dimethylcyclopentane trans-1,2-Dimethylcyclopentane0 3-Blethylhexane
0.610.3 0.4t0.2 0 . 1 0 t 0 ,06
hIay include some cis-l.3-dirnctl~ylcyclopentane.
0.7 1 0 . 3 0 . 41 0 . 3 ) 6.4.tl.0
i
1.1*0.8
8.5-0.4 0.4-0.2 0.8-0.5
9.710.4
2.9*l.l]
6.6k0.8
... ...
3.0*0.8
... ..
t 1
0.7*0.4 1 . 9 1 0 . 5 0.21.0.1 1.1+0.6 2.510.7 1.4*0.8
... 20.5*1.0
... 5 , 3*2.01 5,2*2,0 1.5*0.7
0.8*0.4
1.0to.s;i 0.9=J=0.4 1 . 6~ 0 . 4 1 l.lt0.61 3.4-0.2 23.5*0 3 8 810.3 l.itO.8, 4.0*0.3/ 1.0*0.5, 0 . 7 -0.4) 0 . 4 *0.21 5.7-0.4 1.8*l.Oi 2.8+1.01
...
2.3 10.5
4.2-1.0
1.0t0.6
1.4==0.4
t
12.o.to.9
...
...
1 . 71 0 . 8 1 1.610.8l
t
10.0 k 0 . 7
1.9 10.91 1 4 1 . 0 7)
1.0*0.5
0.5-0.2
3.8-0.3
..
'3.3*0.8
2 . 5 -0.3
...
6.410.8
3.6-0.3
...
9,410.7
0 7-0.3 1.0*0.3
100.0 e Dctcrlllined f r o m freezing point iiiraxureincnts.
f I'rrscnt only in small amount ( 0 . 2 ' Z ) , Iu-Butylbenzene
...
4.410.5
1 . 6 -0.6
3.910.4 0.9*0.4
0.6-0.3 0.8-0.5
*
h l a v include some 3.4-dimethylhexane. d 3Iay include some methylethylcyclopentane.
...
0.4 1 0 . 2 1 . 3t 0 . 4 2 , 6 + O , 4)
Toluene Trimet hylcyclopentanea 3 3-Dimethvlhexane b 2:3-Dimeth; Ihexane} 2 - h I e t l i ~lheptaneC 4-Methj lheptane 3 - X l e t h ~lheptane Dimethylcyclohexanes n-Octane Olefins Saphthenes Dimethylheptanes Ethvlbenzene Naphthenes p-Xylene* m-Xylene Dimethylheptanes\ J Alethyloctaneb o-Xylene Saphthenes n-Sonane Isopropylbenzene n-Propylbenzene Saphthanes Paraffins Olefins l-hleth~1-3-eth~lbenzene l-.\Iethyl-4-ethylbenzene} 1 3 5-Trimethylbenzene 1 l:
- 1.42
AROMATIC PORTION S A M P L E NO. 31
,yo-
-141
o
a
-
Lz
90-
K W
a I
-
I-
I-
a
LLi
-140
LL
71.39
a
i
w
ao
LA!
O F
!-
PURE
COMPOUNDS
60
I37
0
200
$00 Figure 4.
6 00
800
V O L U M E
IN
1000
1200
1400
ML.
Results of Distillation of .Ironlatic Portion
Ordinate scale on right gives refractive indrxe, of fractions of distillate, and o n loft gives boiling point of distillate a t 125 mm. Scale of abscissas give- v o l u m e of distillate. Ilorizontal r o w of numbers ncnr middle of chart refer t o lots blended h y spectrographic esamination. A m o u n t s br volume of various coniponcnta are indicatrd i n upper portion of figure.
(7 ; : i l l i i 31 .!I niiv l>>- n w : ~ > ~ I w 1 n c ni ~t t rci'r:tcrtivc ' 0.37~ iiidex\c,sof fractions of t h e distillate. Tlic. : L ~ K I ~ I I of I I sulfur i i i thieiitirc: aamplc v a s founc Figures 2, 3, anti 4 till~itioiis~ including nu pni,afIiii-e?.clopara~n spectively. Thew nnal>-tical d i - t i l h t i o i i ~n-ere performed in &tilling columns 1-0s. 2 , 3, and 2 , respc'ctively. Columns 2 and 3. ~~-1iieli are identical, are described ( 1 7 ; . Each of the an:ilytical distillations \\-as performed a t a rate of removal of disti1l:ite of 2 . 3 ml. Der hour, with i: reflux ratio of about 130 t o 1. In the dia-
tillation i i i tlic amnmtics, a kiion-n amount of pure ti-I,utylLciizc~iic: (183 C.) was added as a chaser. Comparison of the distillation plot in Figure 2 wit11 t h t i n Figure 3 shows clearly tlie difference in the behavior on disti1l:it ion of a mixture of paraffins and cyclopwaffins and this s m i e misture with alkylbenzcne- : t ( l c I ~ d . T h e phenomenon of :tzciotrupisrn Ixtween the allq-lbenzenes on the one hand and the paraffins and cycloparafins on the other is clearly shown in the forniatiun of minimum constant boiling mixtures ( I O ) . Table I gives the analysis by type of h>.droearbons for the, entire sample and also for the material a b o r e pentanes. The
INDUSTRIAL AND ENGINEERING CHEMISTRY
October 1949
2297
TABLE 111. RESULTS OF COOPERATIVE ANALYSESOF CO~ R O U A T I C SIN C i ALYTICALLY-CRACKED NAPHTHA, SAUPLE31 Standard Oil Develop- Humble Oil Shell Deiiient Co., and Refining Sun Oil Co., velopment Co.. 2-20-46 Co., 7-17-46 Mean from 10-22-15 2-12-46 (Infrared Plus (Infrared Plus Spectrographic (Raman) (UltraviolAt) Ultraviolet) Ultraviolet) Analyaes
Boiling
A.P.I. Research Project 6, 5-31-45
SoconyVacuum Oil Co., 10-16-46 (Infrared)
Isopropylbenzene tL-Propylbenzene
:!:}
1.0 1 0 . 5
O:S}‘‘o
1-Methyl-4-ethylbenzene 1-3Iethyl-3-ethylbenzene
i:!j:}
9 . 3 r0.8
:::}9.7
::::}9.2
:::}9.5
i:k}8.9
i:i}S.8
:::}9.2
164.7 165,2}
6 . 4 *0.8
:::}6.5
!::}7.1
::68)6.4
p:i}6.8
7:21S.S
;:!j!}6.7
9”:;
9.7a
Point at 1 Atm., ‘C.
Components
1 3 ,%Trimethylbenzene l:~~;IcthyI-?-Ethylbenzene tert-Butylbenzene 1,2,4-Trimethylbensene l , ? ,3-Tri methylbenzene a b
ig;::}
Volume
9.4’*0.7
...
9.,j’*
... ...
j9.9
Z of
Total Aromatics 0.1 0.8)O.Q 1.8
...
...
...
0.8 1.0 Corrected for a small amount of this component in adjacent lot or lots not snalyzed by this laboratory. 176.1
-
...
9.7
0.8
7:A)
1.7
y : i6i1.3s
‘1
...
9.7
;:39.7
0 8
u .8s
tert-Butylbenzene believed t o be small in amount (less t h a n 0.5%).
material above pentanes constitutes 79.8 * 1.0% of the entire sample. Of the material consisting of pentanes and lower boiling material, the amounts are as follom, in volume % of the ent,ire sample: n-pentane, 1.0 * 0.4; isopentane (contaminated with small amount of butanes), 18.5 * 1.0; and olefins, 0.7 * 0.3. Table I1 gives the anall-sisby components of the whole gasoline above pentanes; the anall-sis by components of the paraffincycloparaffin portion, above pentanes; and the analysis b y components of the aromatic portion COOPER.4TIVE SPECTROGRAPHIC ANALYSIS OF Co AROMATICS
The matcrinl containing the CS alkylbenzenes from the analytical distillation of t h e aromatic portion was blended for a cooperative spectrographic analysis b y several different laboratories to obtain values for the relative amounts of the individual C, alkylbenzenes in this gasoline. Such information is important, for comparison with the relative amounts of the CO alkylbenzenes occurring in natural petroleum ( 3 , I S ) and for comparison rrith t h e amounts called for in thermodynamic equilibrium (11). The material vas blended for spectrographic analysis into the lots shoir-n in Figure 4 b y the horizontal row of numbers near the middle of the chart. From each of these twelve lots, five samples of from 2 t o 4 ml. each, and from lots 3 t o 12, one sample of 10 ml., were sealed in glass ampoules. The remaining material was sealed for retairiing. The spectrographic analyses reported by t,he several cooperating laboratories are summarized in Table 111, which includes the dates and kinds of analyses. The results indicate good agreement not only among the laboratories using the same type of spectrometer (infrared), but also among those using different types of spectrometers (Raman, ultraviolet, infrared j. Further, the results from the spectrographic analyses are in good accord with the analyses by this laboratory as given in Table 11. ACKNOWLEDG3IENT
The spectrographic analyses were made possible by the follow ing laboratories and persons t o whom grateful acknowledgment is hereby made: Humble Oil and Refining Company, Baytown, Tex., Sherman 9. Shaff er; Shell Development Company, Emeryville, Calif., Otto Beeck, R . R. Brattain, and D. D. Tunnicliff; Socony-Vacuum Oil Company, Paulsboro, N. J., L. C. Beard, Jr., and F. P. Hochgesang; Standard Oil Development Company, Elizabeth, S. J., W. J. Sweeney, S. C. Fulton, and H. J. Hall; Sun Oil Company, Norwood, Pa., J. Bennett Hill, S. S. Iiurtz, Jr., and E. J. Rosenbaum. The sulfur content and bromine numbers TI-ere determined under the supervision of R. C. Hardy in the Lubrication Section of this Bureau.
LITERATURE CITED
(1) .4llender, S. S., WorldPetroleum. 17, 60 (1946). (2) Forziati, A. F., Mair, B. J., and IZossini, F. D., J . Research Natl. Bur. Standards, 35, 513 (1945). (3) Forsiati, A. F., and Rossini, F. D., Ibid., 39, 425 (1947). (4)
Forsiati, A. F., Willingham, C. B., Mair, B. J., and Rossini, F. D., Proc. Am. Petroleum Inst., 24 (III), 34 (1943); J . Research
T a t l . B u r . Standards, 32, 11 (1944). (5) Glssgow, A. R., Jr., Streiff, A. J., and Rossini, F.D., Ibid., 35, 355 (1945). (6) Glasgow, A. It., Jr., Streiff, A. J., Willingham, C. B., and Rossini, F. D., Proc. Am. Petroleum Inst., 26 (III), (1946); J . Research S a t l . B u r . Standards, 38, 537 (1947). (7) Mair, B. J., Ibid., 34, 435 (1945). (8) &fair,B. J., and Forsiati, A. F.,Ibid., 32, 165 (1944). (9) >fair, B. J.. Gaboriault, A. L., and I t o s ~ i n i ,F. D . , ISD.ENG. CHEW., 39, 1072 (1947). (10) Marschner, R. F., arid Cropper, W.P., Ibid., 38, 262 (1948). (11) Rossini, I;. D., arid Epstein, 11. B., S a t l . Bur. American Petroleum Institute IiesenTch Projects
unpublished. (12) Roasini, F. D., >lair, B. J., Forziati, -1.F., Glasgow, A. I i . , Jr., and Willingham, C. B., Proc. Am. Petroleum Inst., 23 (III), 7 (1942); Oi2 Gas J . , 41, 106 (1942); Petrolaim Refiner, 21. 73 (1942). (13) Rossini, F. D., Pitser, K. S., Taylor, W. J., Ehert, J. P., Kilpntrick, J. E., Beckett, C. W., Williams, hl. G . , and Werner, 15. G., Sat2. B u r . Standards Circ. 461 (1947). (14) Sachanen, 1.N., “Chemical Constitution of Petroleum,” New York, Reinhold Publishing Corp., 1945. (15) Streiff, A. J., and Rossini, F. D., J . Research Y a i l . Bur ards, 32, 185 (1944). ~ . d s . ~ r , .ED., (16) Ward, A . L., and Kurta, 9.S . , J r . , IND. 1 3 ~CHEM., 10, 559 (1938). (171 Willingham, C. B., and Rossini, F. D., J . Research S a i l . B U T . Standards, 37, 15 (1946). RECEIVED July 6, 1948. Presented before the Division of Petroleum St. Chemistry at the 114th Meeting of the A V E R I C A NCHESICALSOCIETY, Loui-. 110. This investigation a-as performed a t the National Bureau of Standards as part of the v o r k of the American Petroleum Institute Research Project 6 on the ;\naiysis, Purification, and Propertie? of Hydrocarbons.
* * *
-*;e!process The results of a theoretical study of the fractionatinir adsorption, made on the basis of the same
I
of concepts as are used in t h e theoretical analysis of fiactionating piocesses in general-for example, distillation-were reported t o the Division of Petroleum Chemistry by IIaiI, \\-csthaver, and Rossini of the Sational Bureau of Standards, at the 116th Meeting of A.C.S. (Sept. 18-23, 19.19) at .ltlantic City, S.J. Experimental results were given for the separation factor as a function of concentration for benzene plus n-propylbenzene, benzene plus nhexane, and benzene plus cyclohesane.
