Table IX. Analysis of Known Blends Compound Type Alcohols Ketones Acids Esters Lactones Diols
Blend A (wt %) Known Analysis 68.0 4.4 3.2 0.1 5.0 19.3 100.0
69.5 4.7 2.4 0.0 4.8 18.6 100.0
Blend B (wt %) Known Analysis 65.2 4.7 2.0 0.1 5.3 22.7 100.0
blends are compared with known composition in Table IX. Mean deviations for these blends provided the principal information about absolute accuracy. These results also indicated a slight bias in the method as shown in Table I X where alcohols are seen to be systematically high by 1.2%) whereas diols are low by the same amount. Additional information was obtained during development of the method and actual analysis of experimental samples. Very briefly, miscellaneous known blends were analyzed by individual techniques. In addition, internal checks were obtained by independent measurements on a given sample. Diols were frequently found by G C and MS, for example. Both the mass spectrometer and titration provided acid concentrations on many samples; lactones were measured by mass spectrometry as well as infrared analysis. These miscellaneous checks agreed well with the errors as found for the blends of Table IX. Estimated errors based on all of this information are shown
65.5 5.1 2.0 0.1 4.9 22.4 100.0
Blend C (wt %) Known Analysis 65.6 12.3 2.1 0.1 4.0 15.9 100.0
66.7 12.4 2.1 0.1 4.6 14.1 100.0
Blend D (wt %) Known Analysis 67.3 11.8 2.8 0.1 1.8 16.2 __ 100.0
69.2 11.2 2.8 0.1 2.4 14.3 100.0
in Table VIII. The bias in alcohols and diols has already been noted. Mean deviations vary from 0 . 3 x for lactones to 1.O% for esters. ACKNOWLEDGMENT
Helpful discussions of this work were held with J. R . Livingston (Esso Research and Engineering Co., Linden, N. J.) and R. L. Heinrich (Esso Research and Engineering Co., Baytown, Texas). R . F. Stubbeman (Celanese Corp., Corpus Christi, Texas) was responsible for the high resolution mass spectral measurements. Applications of the techniques in this work were achieved through the efforts of E. S. McBride, W. D. Henriques, F. J. Cassidy, G. F. Roberts, T. H. Sara, P. J. Patterson, and D. E. Bachert. RECEIVED for review April 28, 1967. Accepted July 26, 1967. Division of Petroleum Chemistry, 153rd Meeting, ACS, Miami, Fla., April 1967.
Determination of c 3 - c 8 Hydrocarbons in Naphthas and Reformates Utilizing Capillary Column Gas Chromatography Roger E. Leveque British American Research and Development Co., 2489 North Sheridan W a y , Sheridan Park, Ontario, Canada
An analytical capability is described which determines the C3-Cs compositional analysis of naphthas and reformates. A high degree of resolution is obtained with a capillary column using a binary stationary phase in a single run at ambient temperature. Of the 32 cycloparaffins, only one is unresolved and its estimated concentration is small. The capability is extensively automated to minimize data handling; peak areas are digitized by means of an electronic integrator coupled to a teletypewriter equipped with a paper tape perforator. A computer program has been prepared for the calculations and compilation of data.
EXPERIMENTAL
Chromatographic Equipment. The design of the detector and the sample splitter cannot be overemphasized if maximum performance from the capillary column is to be realized. All sample splitters should be checked for linearity, particularly where wide boiling sample mixtures-such as naphthasare employed. Data Handling System. An Infotronics electronic integrator Model 11HS/42X with an automatic base line drift corrector and extended range was coupled to the chromatograph to digitize the areas. Digital readout of retention
CAPILLARY COLUMN gas chromatography ( I ) has found useful application in the resolution of complex petroleum mixtures. It is particularly applicable in providing detailed compositional data on hydrocarbons in the naphtha range, and the literature (2-7) cites a variety of column combinations and systems to resolve the C4 to C7 hydrocarbons but only partial resolution of the CSrange is reported. An instrumental system is described which extends the resolution of hydrocarbons through the C8 range, utilizing a capillary column and a data handling system comprised of an electronic integrator and a computer to provide rapid analyses.
(1) L. S. Ettre, “Open Tubular Columns in Gas Chromatography,” Plenum Press, New York, 1965. (2) D. L. Ahlburg and J. Q. Walker, Hydrocarbon Process. Petrol. Refiner, 40, 338 (1961). (3) L. R. Durrett, M. C. Simmons, and I. Dvoretzky, Division of Petroleum Chemistry, ACS, St. Louis, Preprint B-63, March 1961. (4) L. R. Durrett, L. M. Taylor, C. F. Wantland, and I. Dvoretzky, ANAL.CHEM.,35, 637 (1963). (5) R. L. Martin and J. C . Winters, Ibid., p. 1930. (6) A. G. Polgar, J. J. Holst, and S . Groennings, Ibid., 34, 1374 (1962). (7) R. 0. Schwartz and D. J. Brasseaux, Zbid., 35, 1374 (1963). VOL. 39, NO. 14, DECEMBER 1967
1811
The column was coated with a binary stationary phase consisting of 4.35 parts of n-hexadecane and 1 part of Fluorolube Oil LG-160 available from Fisher Scientific Co. This volumetric ratio was highly critical in terms of optimum column resolution, with slight alterations greatly magnifying the cycloparaffin and aromatic selectivity of the column. Because of their high viscosity, the weights of the liquid phase were recorded to verify the correct volumetric ratio. The tubing was coated by preparing 10% solutions by volume of the stationary phases in pentane. A reservoir containing the coating solutions was connected to one end of the column and a 150-foot Nylon capillary tubing (0.03inch i.d.) was connected to the opposite end. The column was filled with solution by pressuring with helium; following this, the reservoir was disconnected and the solvent was evaporated with helium at a pressure sufficient to maintain a velocity of 2 cm/second in the column. The velocity was
times and areas was through a Model 33ASR teletypewriter with an attached paper tape perforator. The paper tapes were the means of transmitting data to the computer center. Hydrocarbons. The hydrocarbons used for peak identification and quantitative studies were obtained from : Philips Petroleum Co., Bartlesville, Okla., API Standards, the Carnegie Institute, Pittsburgh, Pa., Chemical Samples Co., Columbus, Ohio, and Fisher Scientific Co. Preparation of Columns. The columns were prepared from stainless-steel capillary tubing supplied by the Superior Tube Co. to the following specifications: 400-500 foot coils of Type 316 stainless steel, 0.01- X 0.0625 inch, free of drawing compounds, and with a bright finish. The tubing was cut to a length of 240 feet, coiled into a 4-inch helix; to ensure the complete absence of drawing compounds, methylene chloride, acetone, and pentane in that order were flushed through the column.
nC4 I
r
CII
MCP
MCll
3MH
I
Bel
ne
CP
I I m
::
n
M
-.ilJ 2,ZDMB
U
f
r
Fa
a a
I N
i
r
-m
z N
L za
1D
0
n u w
Ym
50
ECII
6
-s
Y,
%
Ethylbenzene
u,
70
80
Figure 1. Compositional column Dimensions: 240-feet X 0.01-inch I.D. Liquid phase: Fluorolube and hexadecane Temp.: Ambient
18 12
e
ANALYTICAL CHEMISTRY
90
kept approximately constant by decreasing the helium pressure to compensate for the drop in back pressure as the solution was forced from the column. Solution flow was calculated by observing the velocity of the gas bubbles in the transparent Nylon tubing. This tubing also aids in maintaining a back pressure and a constant flow in the column. Conditioning of the column consisted of passing helium through the column for several hours at ambient temperature. The progress of the conditioning was checked over the final hours with the column installed in the chromatograph at ambient temperature. DISCUSSION
Figure 1 is a chromatogram of a naphtha sample illustrating the extensive resolution of the hydrocarbons through CS obtained with this column. The six alkylbenzenes and the
toluene
normal paraffins in this range are separated as well-resolved peaks. Separation of the cycloparaffins from the paraffins has been accomplished with only one exception, 1,cis-2,cis-4 trimethylcyclopentane. This exception is not considered serious for its estimated concentration in a naphtha is low. Some difficulty can be encountered with the resolution of 1,l-dimethylcyclohexane,eluted as a shoulder on the 3methylheptane peak. Methane and ethane are also resolved on this column when they occur. Separation on the column is rapid, requiring slightly less than 1.25 hours through Ce,excluding the CSalkylbenzenes. Column life is variable but some have lasted 6 months. The life of the column can be extended by keeping it away from heat, turning off the carrier flow when not in use, and having one or two spare columns available at all times.
I rdDMCH
I
ICjDMCH
so
40
100
110
60
120
VOL. 39, NO. 14, DECEMBER 1967
e
1813
Compound Methane Ethane Propane n-Butane Isobutane n-Pentane Isopentane 2,2-Dimethylpropane n-Hexane 2-Methylpentane 3-Methylpentane 2,2-Dimethylbutane 2,3-Dimethylbutane n-Heptane 2-Methylhexane 3-Meth ylhexane
3-Ethylpentane 2,ZDirnethylpentane 2,3-Dimethylpentane 2,4-Dimethylpentane 3,3-Dimethylpentane 2,2,3-Trimethylbutane n-Octane 2-Methylheptane 3-Methylheptane 4-Methylheptane 3-Ethylhexane 2,ZDimethylhexane 2,3-Dimethylhexane 2,4-Dimethylhexane 2,5-Dimethylhexane 3,3-Dimethylhexane 3,LCDimethylhexane 2-Methyl-3-ethylpentane 3-Methyl-3-ethylpentane 2,2,3-Trimethylpentane 2,2,4-Trimethylpentane 2,3,3-Trimethylpentane 2,3,4-Trimethylpentane 2,2,3,3-Trimethylpentane
Table I. Physical. and Gas Chromatography Sensitivity Data-Paraffins Specific Vapor F.I.D.c weight gravity pressure at Researchb sensitivities 60” F/60” F 100” F in psi octane number (n-Heptane = 1) 0.3 ... ... 0.80 0.3771 800 111.4 0.90 0.5077 190 112.1 0.92 0.93 0.5844 51.6 93.8 0.93 0.5631 72.2 101.3 0.6312 15.570 61.7 1.04 0.6248 20.44 92.3 1.05 0.5967 35.9 85.5 0.6640 4.956 24.8 1.03 6.767 73.4 1.05 0.6579 6.098 74.5 1.04 0.6690 9.856 91.8 1.04 0.6540 7.404 103.5 1.03 0.6664 1.620 0.0 1.oo 0.6882 2.271 42.4 1.02 0.6830 2.130 52.0 1.02 0.6915 2.012 65.0 1.02 0.7026 3.492 92.8 1.02 0.6783 2.351 91.1 0.99 0.6994 3.292 83.1 1.02 0.6772 2.773 80.8 1.03 0.6977 3.374 112.1 1.02 0.6945 0.537 (-18) 0.97 0.7068 0.768 20.6 0.97 0.7021 0.731 26.8 1.01 0.7101 0.765 26.7 1.02 0.7090 0.748 33.5 1.oo 0.1179 1.221 72.5 1.01 0.6996 0.861 71.3 0.99 0.7165 1.097 65.2 0.99 0.7047 1,101 55.2 1.01 0,6986) 1.030 75.5 1.02 0.7143 0.797 76.3 0.99 0.7236 0.874 87.3 0.98 0.7237 0.834 80.8 0.98 0.7315 1.142 109.6 1.02 0.7203 1.708 100.0 1.00 0.6963 0.967 106.0 1.01 0.7304 0.976 102.5 0.99 0.7233 ... 0.83 ... ...
F.I.D.c liquid volume sensitivities 0.24 0.3394 0.4692 0.5435 0.5237 0.6564 0.6560 0.6939 0.6908 0.6958 0.6802 0.6864 0.6882 0.6967 0.7053 0.7167 0.6919 0.6924 0.6907 0.7186 0.7084 0.6856 0.6810 0.7172 0.7232 0.7179 0.7066 0.7093 0.6977 0.7050 0.7286 0.7163 0.7092 0.7169 0.7347 0.6943 0.7377
Reference (11). Value in parentheses is a calculated blending number extrapolated from an ASTM rating of 20 hydrocarbon 4-80 60 :40 mixture of isooctane-n-heptane to a hypothetical 100 concentration (IO). c F.I.D. liquid volume sensitivity factor is the multiplication product of the weight sensitivity factor (12) by the specific gravity. a
z
b
Quantitative Analysis. The column is operated at ambient temperature and a t a carrier gas flow of 2.65 ml/minute. To avoid overloading of the columns, sample splitter ratios are adjusted according to the distillation range of the sample. No prior treatment of naphtha-type samples is required other than the addition of the internal standard which is 2,2,4trirnethylpentane added a t a concentration level of 4% by volume. This hydrocarbon is present in negligible quantities in naphthas and reformates and is well resolved in an advantageous position in the chromatogram. With the injection of the sample into the chromatograph, the integrator is started and from this point on the run is essentially automated. The computer calculates the liquid volume composition of the sample including a research octane number and specific gravity through Ca. The required physical constant data (Tables 1-111) are retained in the computer program. In many cases, the analysis accounts for most of the sample composition, examples being light naphthas and most re18 1 4
ANALYTICAL CHEMISTRY
z
formates. In those cases where the samples contain compounds above Cs,the gas chromatographic analysis is combined with a mass spectrometric, modified PONA, analysis (8, 9) and the Cs+ content of the sample on a group-type basis is obtained by difference. The computer calculates
(8) ASTM (Am. SOC.Testing Materials) “Standards on Petroleum Products and Lubricants, Special Compilation, Proposed Test for Hydrocarbon Types in Low Olefinic Gasolines by Mass Spectrometry,” Vol. 1, Oct. 1961. (9) ASTM D1658, Aromatic Compounds in Naphthas. (10) ASTM Special Tech Pubin. No. 225, Knocking Characteristics of Pure Hydrocarbons, Developed Under American Petroleum Institute Project 45, May 1958. (11) ASTM Specia/ Tech. Publn. No. 109A, Physical Constants of Hydrocarbons C1 to Clo, Prepared by ASTM Committee D-2, July, 1963. (12) N. Brenner, J. E. Callen, and M. D. Weiss, Gas Chromatography, Third International Symposium, 307, June 13, 1961, Academic Press, New York.
Table 11. Physical0 and Gas Chromatography Sensitivity Data-Cycloparaffins
Specific gravity 60" F/60" F
Vapor pressure at 100" P in psi
Cyclopentane Cyclohexane Methylcyclopentane Ethylcyclopentane 1,l-Dimethylcyclopentane l-cis-2,-Dimethylcyclopentane 1-truns-2-Dimethylcyclopentane 1-cis-3-Dimethylcyclopentane 1-trans-3-Dimethylcyclopentane Methylcyclohexane
0.7505 0.7834 0.7535 0.7710 0.7593 0.7774 0.7562 0.7496 0.7535 0.7740
9.914 3.264 4.503 1,409 2.561 1.648 2.192 2.291 2.209 1,609
101.3 83.0 91.3 67.2 92.3
n-Prop ylcyclopentane Isopropylcyclopentane 1-Methyl- 1-ethylcyclopentane
0,7807 0.7808 0.7854 0.7896 0.7733 0.771 0.771 0,7771 0.7528 0.7836 0.7580 0.7518 0,7749 0.776 0.7680 0.7922 0.7854 0.8006 0.7803 0.7704 0.7892 0.7873 0.7670
0.471 0.601 0.726 0.550 0.72 0.71 0.74 0.999 1.393 0.69 1.14 1.162 0.85 0.84 0.881 0.483 0.820 0,540 0,707 0.783 0.651 0.661 0.821
31.2 81.3
Compound
1-Methyl-cis-2-ethylc yclopentane
1-Methyl-trans-2-ethylcyclopentane 1-Methyl-cis-3-ethylcyclopentane 1-Methyl-trans-3-ethylcyclopentane 1,1,2-Trimethylcyclopentane 1,1,3-Trimethylcyclopentane 1 ,cis-2,cis-3-Trimethylcyclopentane 1,truns-2,cis-3-Trimethylcyclopentane 1,truns-2-cis-4-Trimethylcyclopent ane 1:cis-2-trans-3-Trimethylcyclopentane 1,cis-2-cis-4-Trimethylcyclopentane 1,cis-2-rruns-4-Trimethylcyclopentane Ethylcyclohexane 1,l- Dimethylcyclohexane 1,cis-2-Dimethylcyclohexane 1,truns-2-Dimethylcyclohexane l,cis-3-Dimethylcyclohexane 1,trans- 3-Dimethylcyclohexane 1,cis-4-Dimethylcyclohexane 1,rrans-4-Dimethylcyclohexane b
Research octane number
...
...
79.2 80.6 74.8
... ...
...
57.6 57.6
...
87.7
...
... ... 89.2
...
89.2 46.6 87.3 80.9 80.9 71.7 66.9 67.2 68.3
F.I.D.b weight sensitivities (n-Heptane = 1)
F.I.D.b liquid volume sensitivities
1.04 1.01 1.01 1.00 1.03 1.oo 1.01 1 .oo 1.oo 1.01
0.7805 0.7912 0.7610 0.7710 0.7821 0.7774 0.7638 0.7496 0.7535 0.7817
0.97 0.98 1.02 1.00 1.01 1.00 0.97 1.03 1.04 0.99 1.00 0.98 0.98 1.oo 0.99 1.01 1.03 0.99 1.01 1.oo 1.01 1.00 0.99
0.7573 0.7652 0.7933 0.7896 0.7810 0.7710 0.7479 0.8004 0,7829 0.7758 0.7580 0.7368 0.7594 0.7682 0.7603 0.8001 0,8090 0.7926 0.7881 0.7704 0.7971 0.7873 0.7593
Reference (11). F.I.D. liquid volume sensitivity factor is the multiplication product of the weight sensitivity factor (12) by the specific gravity.
Table 111. Physical. and Gas chromatography Sensitivity Data-Alkylbenzenes
Specific gravity 60" F/60" F
Vapor pressure at 100" F in psi
Blendingb research octane number
F.1.D.c weight sensitivities (+Heptane = 1)
F.I.D.0 liquid volume sensitivities
Benzene Toluene
0,8845 0.8719
3.224 1.032
(98) (124)
1.12 1.07
0.9906 0.9329
Ethylbenzene ortho-Xylene
0.371 0.264 0.326 0.342
124)
para-Xylene
0.8717 0.8848 0.8687 0,8657
1.03 1.02 1.04 1.oo
0.8979 0,9025 0,9034 0.8657
n-Propylbenzene Isopropylbenzene 1-Methyl-2-ethylbenzene 1-Methyl-3-ethylbenzene 1-Methyl-4-ethylbenzene 1,2,3-Trimethylbenzene 1,2,4-Trimethylbenzene 1,3,5-Trimethylbenzene
0.8666 0.8663 0.8852 0.8690 0.8657 0.8987 0.8802 0.8696
0.141 0.188 0.106 0.124 0. I24 0.066 0,088 0.104
1.01 0.97 1.02 1.01 1.oo 0.98 0.97 0.98
0.8753 0.8403 0.9029 0.8777 0.8657 0.8807 0.8538 0.8522
Compound
me fa-Xylene
( 120)
(145) (146)
Reference (11). Values in parentheses are calculated blending numbers extrapolated from an ASTM rating of 20% hydrocarbon f 80% 60:40 mixture of isooctane-n-heptane to a hypothetical 100% concentration (IO). F.I.D. liquid volume sensitivity factor is the multiplication product of the weight sensitivity factor (12) by the specific gravity. a
VOL. 39, NO. 14, DECEMBER 1967
1815
Table IV.
Carbon Average No. value
Compound 3-Methylpentane Methylcyclopentane Benzene Cyclohexane 3-Methylhexane 2,2,CTrimethylpentane n-Heptane Methylcyclohexane 1,1,3-Trirnethylcyclopentane Toluene
True value
Deviation
6 6 6 6 7 8 7 7
5.49 5.16 4.32 8.23 7.34 6.84 7.26 9.14
5.63 5.00 4.37 8.04 7.41 6.80 7.16 9.16
0.14 0.16 0.05 0.19 0.07 0.04
8 7
5.82 8.76
5.94 8.67
0.12 0.09
Table Va.
Crude oil source Sample type
2,3,4-Trimethylcyclopenlane 2-Methyl-3-ethylpentane 3-Methylheptane 1,trunx-2-Dimethylcyclohexane 1,rruns-3-Dimethylcyclohexane n-Octane Cs aromatics (4 isomers)
55. I 115-305 86.4 (10.51)
...
(0.17)
2,Z-Dimethylbutane 2,3-Dimethylbutane 2-Methylpentane 3-methylpent me
2,2-Dimethylpentane 2,CDimethylpentane 3,3-Dimethylpentane 2,2,3-Trimethylbutane 2-Methylhexane 2,3-Dimethylpentane 3-Methylhexane 3-Ethylpentane Total isoheptanes +Heptane 2,ZDimethylhexane 2,5-Dimethylhexane 2,CDimethylhexane 2,2,3-Trimethylpentane 3,3-Dimethylhexane 2,3,4Trimethylhexane 2,3,3-Trimethylhexane 2-Methyl-3-ethylpentane 2,3-Dimethylhexane ZMethylheptane 3-Methyl-3-ethylpentane 3,CDimethylhexane 4-Methylheptane 3-Ethylhexane 3-Methylheptane Total isooctanes n-Octane
1
+- Paraffins Ca + Olefins C9
ANALYTICAL CHEMISTRY
4.30 3.32 2.51
4.26 3.37 2.60
0.04
8
1.12
1.18
0.06
8 8 8
1.45 5.14 13.80
1.48 5.16 13.77
0.03 0.02 0.03
58.7 150-312
0.05
0.09
52.4 130-330 88.3 (5.68)
* * .
(1.16)
0.08 0.62 2.79 2.19
0.28 0.88
(16.01)
(15.55)
(21 ,08)
0.04 0.28 2.50 2.24
1.02 0.88 4.68 3.77
0.12 0.78 4.21 3.19
1.02 1.18 6.21 4.88
10.35 5.66
8.30 7.25
13.29 7.79
(23.41)
(18.79)
(15.18)
(13.87)
0.14 0.58 0.08 0.06 3.02 2.40 4.48 0.93
0.27 1.57 0.46
0.39 0.59 0.24 0.15 3.10 1.03 3.27 0.39
0.37 0.70 0.36 0.13 3.42 1.04 4.04 0.37
0.01
3.45 2.62 5.20 0.82 11.69 11.72
C8 Paraffins
8 8 8
(12.13)
5.06 7.07
Total isohexanes n-Hexane C7Paraffins
Deviation
Nigerian Crude Oil Naphtha Reformate
1.39 3.26 3.62 2.24
0.02 0.15
CSParaffins
True value
Detailed Compositional Analysis-Paraffins
61.2 180-300
Propane Isobutane n-Butane Isopentane n-Pentane
a
0.10
0.02
Carbon Average No. value
Compound
Western Canadian Crude Oil Mixture Naphtha Reformate
Gravity, OAPI Distillation range, OF Research octane number, clear Light ends
1 816
Estimation of Accuracy
9.16 6.02
14.40 4.39
10.43 3.44
(11.99)
(5.51)
(9.03)
(3.86)
0.10 0.44 0.55
0.04 0.19 0.39
0.15 0.35 0.57
0.06 0.17 0.31
0.06 0.09 0.03 0.21 0.40
0.01 0.01 0.01 0.05 0.22
0.15 0.09 0.03 0.09 0.33
0.03 0.02 tr 0.06 0.19
3.13
1.18
2.40
0.76
1.27 0.14 1.39
0.77 0.10 1.09
0.58 0.30 1.86
0.47 0.19 0.89
7.90 3.89
4.06 1.45
6.90 2.13
3.15 0.91
(1.26)
(0.41)
(1.98)
(2.11)
(0.30)
(0.80)
(0.10)
(1.00)
Detailed Compositional Analysis-Cycloparaffins and Aromatics Western Canadian Mixture Nigerian Mixture Reformate Naphtha Naphtha Reformate (0.27) (0.17) (0.68) (0.68) Cyclopentane (12.18) (2.36) (2.27) (9.24) C6 Cycloparaffins 1.63 4.80 6.56 2.20 Methylcyclopentane 5.52 0.64 0.16 4.44 Cyclohexane (22.83) (4.05) Ci Cycloparaffins (19.59) (0.62) 0.96 0.16 1.00 0.05 1,l-Dimethylcyclopentane 2.66 0.24 1.91 1-cis-3-Dimethylcyclopentane 0.11 3.15 0.86 1.68 1-trans-3-Dimethylcyclopentane 0.11 5.38 1.02 2.71 0.15 1-trans-2-Dimethylcyclopentane 0.69 0.13 0.44 0.03 1-cis-2-Dimethylcyclopentane 9.06 1.43 10.99 0.10 Methylcyclohexane 0.93 0.21 0.86 0.07 Ethylcyclopentane (1.63) (IO. 58) (0.04) C8 Cycloparaffins (9.94) 0.65 0.11 0.90 1,1,3-Trimethylcyclopentane 0.01 1.38 0.17 l-trans-2-cis-4-Trimethylcyclopentane 1.00 0.01 0.38 2.39 1.25 l-trans-2-cis-3-Trimethylcyclopentane .. 0.01 0.19 0.31 1,1,2-Trimethylcyclopentane ... tr 0.03 l-cis-2-trans-4-Trimethylcyclopentane 0.02 ... 0.03 tr 0.04 1-cis-2-trans-3-Trimethylcyclopentane 0.46 0.08 1,l-Dimethylcyclohexane 0.45 ... 2.01 3.40 1-trans-4Dimethylcyclohexane 0.40 tr 1-cis-3-Dimethylcyclohexane 0.22 0.03 1-Methyl-cis-3-ethylcyclopentane 0.20 ... 0.22 0.70 1-Methyl-trans-3-ethylcyclopentane 0.02 1.03 1-Methyl-trans-2-ethylcyclopentane 1-Methyl-1-ethylcyclopentane 0.13 0.62 1-cis-24s-3-TrimethyIcycIopentane 1.06 1 trans-2-Dimethylcyclohexane tr 0.21 1-trans-3-Dimethylcyclohexane 0.55 ... 1-cis-4Dimethylcyclohexane 0.02 Isoprop ylcyclopentane 0.01 0.02 1-Methyl-cis-2-ethylcyclopentane 0.01 *.. 0.05 0.01 1-cis-2-Dimethylcyclohexane 0.05 ... 0.09 0.54 Ethylcyclohexane 0.54 ... 0.09 n-Prop ylcyclopentane 0.09 (0.15) Cs+ Cycloparaffins (1 .07) (1.57) (0.87) (6.20) Benzene (1.42) (5.14) (12.44) (21.10) Toluene (4.98) (4.94) (21.33) (10.70) C, Aromatics (1.29) (1.64) (12.26) 0.42 Ethylbenzene 1.39 0.47 1.56 0.17 2.03 p-X ylene 0.27 2.60 0.51 4.74 rn-Xylene 0.68 5.35 0.19 2.54 0-Xy lene 0.22 2.75 (1.60) CSAromatics (0.68) (1.70) C,, Aromatics *.. ... (0.10) 100.00 100.00 Total liquid volume 100.00 100.00 Accounted for compositionally 97.37 97.04 95.67 94.22 491-14318 PQNA 51/1/8/40 431-144113 47/1/4148 Table Vb.
5
-
i
t
I
and compiles the gas chromatographic and the mass spectrometric analyses and outputs the individual component results and a summarized copy (Figure 2). The accuracy of the method was estimated by blending a 20-component mixture of the hydrocarbon types covering a distillation range of 145 '-292" F. The results are tabulated in Table IV. Application. Table V a and b contain a tabulation of the composition of two naphthas and their corresponding reformates. The value of these analyses in characterizing naphthas makes possible certain predictions concerning aromatic yields and the ease of reforming a given naphtha. Observations can be made on the conversion level of the hydrocarbon types by comparing a reformate and its corresponding
Table VI.
Reformate Reformate Reformate Reformate Reformate Naphtha Naphtha Naphtha
.
.
Calculated us. Measured Data
Research octane number Calcu- Measlated ured 85.1 85.4 80.7 82.0 98.7 98.0 84.0 84.5 86.4 86.4 59.2 56.5 59.3 61.0 68.7 70.4
%
Specific gravity Calcu- Measlated ured 0.751 0.757 0.745 0.744 0.769 0.772 0.751 0.757 0.700 0.709 0.748 0.751 0.750 0.746 0.671 0.670
Accounted for compositionally 90.2 95.2 97.7 94.8 99.5 68.6 68.8 100.0
VOL. 39, NO. 14, DECEMBER 1967
0
1817
COMPOSITE NAPHTHA SOURCE: DATE SAMPLED: PROJECT NO. SHAWINIGAN AUG 22/66 SAMPLE NO. C-53 UN NO. 2350 API GRAVITY 68.0 R.V.P. IBPjlO%/SO %I90 Z/FBP 140/156/182/273/341 MEASURED R.O.N. SUMMARIZED RESULTS
z
CONSTITUENT
0.00 0.00 0.00 Ca 0.02 IC4 0.0s NC4 1.13 IC6 2.50 NC6 3.00 CP Ca PARAFFINS 33.72 ISOHEXANES 21.08 N-HEXANE 12.65 Ca NAPHTHENES 6.11 MCP 5.26 CH 0.85 BENZENE 0.19 21.92 C7 PARAFFINS ISOHEPTANES 15-50 N-HEPTANE 6.43 c 1
c2
%
VOLUME
CONSTITUENT
VOLUME
NAPHTHENES IIDMCP IC3DMCP ITaDMCP ITIDMCP ICzIBMCP MCH ECP TOLUENE Cs PARAFFINS ISOOCTANES N-OCTANE Cs NAPHTHENES Cs AROMATICS ETHYLBENZENE P-XYLENE M-XYLENE 0-XYLENE CQ+ PARAFFINS Cs NA4PHTHENES Cg AROMATICS Cio AROMATICS Cii AROMATICS
2.80 0.14 0.70 0.25 0.34 0.10 0.92 0.37 1.31 7.46 5.70 1.76 1.02 2.76 0 61 0.52 1.33 0.31 7.68 3.78 1.97 0.58 0.02
Cr
+
TOTAL Gg+ 14.03 TOTAL Ci TO Cs 84.02 CALCULATED R.O.N. (UP TO & INCLUDING Cs) 60.3 CALCULATED SPECIFIC GRAVITY 60/60F (UP TO & INCLUDING C,) 0.6977 CALCULATED VAPOUR PRESSURE BOOF PSI (UP TO & INCLUDING CB) 4.654 P.O.N.A. 74.51% 1.95% 16.71% 6.83% Figure 2.
Computer ontput summarized copy
18 18
ANALYTICAL CHEMISTRY
4
naphtha charge under actual processing conditions; a number of the major reforming reactions are apparent, such as the dehydrogenation of cycloparaffins to aromatics, isomerization particularly of the normal paraffins, and the hydrocracking of the higher molecular weight compounds to lower molecular weight. The production of the large amount of aromatics contributes substantially to the improved octane numbers of the reformates (Table VI). Improvement is also attributed to the hydrocracking and isomerization reactions, for example; the alteration of the isoparaffinln-paraffin ratio from 1 in the naphthas to as high as 3 (Table Vu) in the reformates contributes as much as 10 octane numbers. The contribution of the individual compounds can be integrated with respect to a number of physical properties for the purposes of characterization. Table VI contains two examples comparing calculated and measured octane and specific gravities using the data in Tables 1-111. Blending octane values are used for aromatics because their individual values produced low results by as much as three numbers; this evidence supports the fact derived from octane experiments (IO) that blends of aromatics and paraffins produce higher results than can be predicted from individual values. The agreement on comparison in Table VI is good. Deviations will occur for samples containing substantial amounts of e,+, for the calculations apply through Cg only. Among other physical properties that may also be calculated are vapor pressure, molecular weight, carbon/hydrogen ratio, and BTU value. ACKNOWLEDGMENT
The author acknowledges the contributions of Roger Lennox who diligently carried out much of the experimental gas chromatography work, and the help of many members of the Instrumental Laboratories in providing backup analytical data.
RECEIVED June 8, 1967. Accepted September 7, 1967. Paper presented at the Symposium on Instrumental Methods for Analysis of Petroleum Fractions, Division of Petroleum Chemistry, ACS, Miami Beach, April 1967.
