386
Energy & Fuels 1991,5, 386-394
therefore, higher temperatures were required for their removal than for the nonhindered pyridines. This is consistent with a previous fiiding that hindered pyridines were difficult to remove from shale oils by catalytic HDNSn Hydrodenitrif'ication of Methylcarbazoles. Figure 5 shows the selective detection of the MH+ ions at m / z 182 for the four methylcarbazole isomers found in the polar preparative LC fractions of the catalytic cracker feed from a Shell refinery; (distilled cut 555-640 O F ) and the HDN product (distilled cut 557-650 OF), respectively. The samples of similar boiling ranges were selected in order to compare the relative concentrations of the same alkylcarbazole homologues in the feed and the HDN product. The relative percent of each methylcarbazole isomer in the feed and the hydrogenated product is given in Table IV. Note that the relative concentration of the 1-methylcarbazole (peak 1 in Figure 5 ) is higher in the product than in the feed. The opposite was observed for the 3- and 4-methylcarbazoles (peaks 3 and 4 in Figure 5 ) , while for the 2-methylcarbazole (peak 2) the relative concentrations (27) Holmes,S. A.; Thompson, L. F. Symposium on characterization and chemietry of oil shales presented before the Divisionsof Fuel and Petroleum Chemistry, ACS Meeting, St. Louis, April 8-13, 1984.
are about the same in both the feed and the product. These results clearly reflect the influence of steric hindrance in the HDN process. In the case of 1-methylcarbazole, the nitrogen atom is sterically shielded by a methyl group which results in a slower rate of removal of this compound relative to nonhindered isomers. Consequently, the concentration of the 1-methylcarbazole increased in the HDN product relative to the other isomers.
Conclusions Daughter ion mass spectra of the MH+ ions from the partially hydrogenated 2,6-dimethylquinoline and acridine, obtained by the use of combined NH3/CI and GC/MS/ MS, have shown that the spectra can differentiate intermediates of the same molecular formula. Since the spectra were able to distinguish the hydrogenation on the heterocyclic ring from that on the adjacent aromatic rings, the daughter ion mass spectra are expected to enhance the future development of the HDN catalysts. Furthermore, the additional results have shown that NH,/CI GC/MS is highly useful in the study of steric hindrance effects which influence the removal of nitrogen by the HDN catalyst.
Polycyclic Aromatic Structure Distributions by High-ResolutionMass Spectrometry Kent L. Chasey* Exxon Research and Engineering Company, P.O.Box 4255, Baytown, Texas 77522-4255
Thomas Aczel Exxon Research and Engineering Company, Route 22 East, Clinton Township, Annandale, New Jersey 08801 Received December 18, 1990. Revised Manuscript Received March 18, 1991
Polycyclic aromatic compounds are an important component of many high-boiling petroleum products. A detailed analytical description of the polycyclic aromatic structure distribution is useful for assessing the exact effects of refining processes, such as solvent extraction and hydrotreating, that alter or remove these compounds. High-resolution, low-voltage mass spectrometry was used to characterize the clay gel aromatics fractions of a petroleum vacuum distillate and three lubricant base oils that are derived from it. Proprietary methods were used to extract and hydrotreat the distillate, and different levels of severity were employed. The measurements were made with a Kratos MS50 mass spectrometer, using Exxon proprietary computer programs for data analysis. The programs allow the determination of concentrations for as many as 5OOO individual carbon number homologues and over 100 compound types. The polycyclic aromatic structure distributions of the oils are defined by the use of 2-number terminology and side-chain carbon number distributions. Structures specifically identified are the most probable ones, although other isomers cannot be totally excluded from consideration.
Introduction Most of the physical and toxicological properties of lubricant base oils are significantly affected by polycyclic aromatic compounds (PACs). As a result, the effects of refining processes such as solvent extraction or hydrotreating on PAC structure distributions are of considerable importance to producers of lubricant base oils. These 0887-0624/91/2505-0386$02.50/0
compounds are defined here as any polycyclic structures containing aromatic or partially aromatic condensed-ring systems. Because the array of PAC structures in lubricant base oils is extremely complex, rigorous analytical descriptions of it are difficult to obtain. The distribution of PAC structures in a refined base oil product is dependent on (a) the PAC distribution in the 0 1991 American Chemical Society
Polycyclic Aromatic Structure Distributions RELATIVE EXTRACTION SEVERITY
RELATIVE HYDROTREATING SEVERITY
Energy & Fuels, Vol. 5, NO.3,1991 387 HYDROCARBON RlNQ SYSTEMS (CnH2.-z) SAMPLE IDENTIFICATION
VACUUM HIGH
LOW
c
INCREASED HT SEVERITY INCREASED E X 1 SEVERITY
e
18
12
Figure 1. Processing historiea for petroleum vacuum distillates. Table I. Clay Gel Aromatics and Heteroatom Contents for Whole Oils clay gel aromaprocessing history ticsa sulfurb nitrogene dewaxed distillate 44.15 1.76 470 sample A 42.47 0.97 224 (lowest est/ ht severity) sample B 41.74 0.70 170 (increased ht severity) sample C 37.40 0.45 86 (increased ext severity) Weight percent aromatics by ASTM D2007. *Weight percent total sulfur by X-ray fluorescence. e ppm total nitrogen by chemiluminescence. a
10
14
THIOPHENE RING SYSTEMS (CnHin-zS)
1o/s
18/S
Figure 2. Examples of 2-number terminology for polycyclic aromatic compounds. Table 11. Ring-Number Distributions for Clay Gel Aromatics Fractions weight percent?vb dewaxed component distillate sample A sample B sample C Hydrocarbon Ring Systems 1 ring 9.05 13.93 16.94 17.69 2 ring 10.37 11.48 13.25 11.56 3 ring 5.89 5.41 5.10 4.22 4 ring 2.49 1.76 2.51 1.39 5+ ring 0.80 0.31 0.81 0.63 total 28.60 32.89 38.61 35.49 Thiophene Ring Systems 1 ring traces traces traces traces 2 ring 6.72 2.87 traces traces 3 ring 6.99 5.49 2.80 1.62 4 ring 1.32 0.77 0.33 0.00 5+ ring 0.31 0.06 0.00 0.00 total 15.34 9.19 3.13 1.62 ~
crude oil from which the base oil is derived and (b) the types and severities of refining employed. Accordingly, a determination of the exact effects of various refining histories on the PAC structure distribution requires the production of a series of oils from the same crude oil distillate. The PACs in the oils can then be measured and compared. In this paper we illustrate a methodology for PAC measurement that is based on high-resolution mass spectrometry. The technique is useful for studying the effects of refinery processing on the PAC structure distribution in base oil products, and examples of this application are given.
Results Three experimental base oil samples were prepared by using laboratory pilot units,as illustrated by the proceasing schemes shown in Figure 1. The feedstock was a petroleum vacuum distillate, having a mid-boiling point of 780 OF. Two levels of extraction severity and two levels of hydrotreating severity were employed. Samples A and B were subjected to the same extraction conditions and samplea A and C were subjeded to the same hydrotreating conditions. Sample A represents the lower levels of extraction and hydrotreating severity. Samples B and C differ from sample A by increased hydrotreating severity and increased extraction severity, respectively. All three of the oils, as well as the distillate feedstock, were solvent dewaxed to comparable pour points and then analyzed. The effects of these varying degrees of refinement on the aromatics and heteroatom contents of the whole oils are listed in Table I. Both samples B and C have lower clay gel aromatics, total sulfur, and total nitrogen contents than sample A. However, the increase in extraction severity (sample C) has a greater impact on these properties than the increase in hydrotreating severity (sample B). The clay gel aromatics fractions were analyzed by high-reaolution,low-voltage mass spectrometry, as detailed in the Ekperimental Section. In the discussion of the mass spectrometry results that follows, 2-number terminology and side-chain carbon number distributions are used to explain the effects of refining on the PAC structure distribution. The 2 number is a measure of the relative hydrogen deficiency of a condensed-ring system when compared with its totally saturated analogue. The 2
total grand total
0.21 44.15
Furan Ring Systems 0.40 traces 42.47 41.74
~~~
0.30 37.40
Average Values for Grand Total dewaxed distillate sample A sample B sample C molecular weight 333 330 340 353 14.8 2 number 13.6 12.4 13.3 24.8 carbon number 25.6 24.9 26.5 12.2 13.3 carbon atoms in side 13.5 15.5 chains atomic C 86.58 87.33 88.53 88.35 9.88 10.49 10.63 11.18 atomic H atomic S 3.51 2.13 0.43 0.84 0.03 0.04 atomic 0 0.00 0.05 a All values normalized to reflect concentrations in whole oils. bTraces means less than 0.005%; 0.00 means not detected, less than 0.001% (10 ppm).
number provides an indication of condensed-ringstructure, but is not affected by attached carbon side chains. Examples of 2-number terminology for hydrocarbon ring systems (C,H,) and thiophene ring systems (C,Hb-&3) are shown in Figure 2.
Discussion An overview of the ring-number distributions for the aromatics fractions is given in Table 11; the data for hydrocarbon, thiophene-containing, and furan-containing ring
Chasey and Aczel
388 Energy & Fuels, Vol. 5, No. 3, 1991 0.3
-
0.25
-
8
- DEHUIXED DISTILLATE
7
6
W 1 %
5 4
3
2 1 0
8
10
12
14
16 18 2 NUMBER
20
22
Figure 3. Effects of extraction on the concentration of hydrocarbons having 2 numbers 8-24. s 20
0A
I D E C
0 0
24
(LOWEST EXT/HT SEVERITY)
5
10 15 20 SIDECHAIN CARBONS
25
30
Figure 5. Impacts of extraction on the side-chain carbon distribution for the phenanthrene series (2= 18).
7
0A
(LOWEST EXTIHT SEVERITY),
6
15 I N
:
R B 0 N s
10
5
0 8
10
12
14
16 18 2 NUMBER
20
22
24
Figure 4. Effects of extraction and hydrotreating on the average number of eidachain carbons for hydrocarbons having 2 numbers
8
10
12
14
16 18 2 NUMBER
20
22
24
Figure 6. Effects of hydrotreating on the concentration of hydrocarbons having 2 numbers 8-24.
8-24.
systems are listed individually. Both extraction and hydrotreating result in a net increase in the total concentration of hydrocarbon ring systems and a net decrease in the total concentration of thiophene ring systems, while furan ring systems are, in all cases, a negligible component. Increases in one-ring and two-ring aromatic hydrocarbons account for most of the overall increase in hydrocarbon ring systems. This result is explained in the sections that follow, in which the effects of extraction and hydrotreating on the polycyclic aromatic structure distribution are treated separately. The average values listed in Table I1 are also referenced. Effects of Extraction. The effect of extraction on the 2-number distribution for hydrocarbon ring systems is shown in Figure 3. A comparison of sample A with the dewaxed distillate shows the combined effects of low-severity extraction and low-severity hydrotreating. A comparison of sample C with sample A shows the effects of increased extraction severity. The results clearly indicate that, during extraction, the concentration of components having 2 numbers 8-16 was either maintained or increased, while the concentration of components having higher 2 numbers was decreased. Actual concentrations of the components in each 2-number series, as well as possible structures, are given in Table 111. The effect of extraction on the distribution of 2-number series for thiophene ring systems is also given in Table 111. With the exception of some of the dibenzothiophene structures, the increased extraction severity for sample C resulted in the total removal of thiophene ring systems. This lowers the total aromatics content and further con-
centrates the onering and two-ring aromatic hydrocarbons. The average 2 number for all ring systems (Table 11) decreases from 13.6 (sample A) to 12.4 (sample C),and this change is consistent with all of the results described above. The effect of extraction on the side-chain carbon number distribution for hydrocarbon ring systems is shown in Figure 4, and actual values are reported in Table IV. A comparison of sample C with sample A shows an increased average side-chain carbon number for all 2 numbers. Average values given in Table I1 for carbon number, and related properties such as molecular weight and number of carbon atoms in side chains, verify that the trend toward higher carbon numbers occurs in all ring systems. Increased extraction severity narrowed the total carbon number distribution (Table V). Some of the specific effects of extraction are illustrated in Figure 5 for the phenanthrene series (2= 18). The overall reduction in polycyclic hydrocarbons is shown by the decreased area under the curves for samples A and C when compared to the dewaxed distillate curve. The overall increase in average side-chain carbon number is shown by the shift of the curves for samples A and C to the right. This type of analysis can be applied to any 2 number of interest. Effects of Hydrotreating. The effect of hydrotreating on the 2-number distribution for hydrocarbon ring systems is shown in Figure 6. A comparison of sample A with the dewaxed distillate shows the combined effects of low-severity extraction and low-severityhydrotreating. A comparison of sample B with sample A shows the effects of increased hydrotreating severity. In contrast to the extraction results described above, the hydrotreating results
Energy & Fuels, Vol. 5, No.3,1991 389
Polycyclic Aromatic Structure Distributions
8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44
Table 111. Concentration6 and 2-NumberClassifications of Various Compound T m r weight percentOb dewaxed possible structure(s) distillate sample A sample B Hvdrocarbon Ring Svstems 6.45 6.35 indans, tetralins 3.40 5.55 3.09 4.30 dinaphthenobenzenes 4.13 2.74 3.48 naphthalenes 3.44 4.37 3.68 acenaphthenes, diphenyls 4.75 4.19 4.32 fluorenes 3.54 3.14 3.02 phenanthrenes 2.26 2.08 2.35 naphthenophenanthrenes 1.62 1.01 0.80 pyrenes, fluoranthenes 1.13 0.70 0.89 chrysenes 0.17 0.07 0.37 cholanthrenes, benzo[h,i]fluoranthenes 0.64 0.19 0.05 dibenzopyrenes, benzofluoranthenes 0.13 0.09 0.20 benzchrysenes 0.15 0.01 0.09 benzo[ghi]perylenes 0.00 0.12 0.03 dibenzopyrenes 0.00 0.06 0.08 coronenes 0.00 0.04 0.01 0.00 0.01 0.03 additional seven- and eight-ring condensed aromatic hydrocarbons 0.00 traces traces 0.00 0.00 traces
81s 101s 121s 141s 161s 181s 201s 221s 241s 261s 2815 301s 3215 341s
dinaphthenothiophenes benzothiophenes naphthenobenzothiophenes dinaphthenobenzothiophenes dibenzothiophenes thiophenoacenaphthenes thiophenofluorenes thiophenophenanthrenes thiophenonaphthenophenanthrenes thiophenopyrenes thiophenochrysenes thiophenocholanthrenes thiophenobenzpyrenes thiophenobenzochrysenes
Z no.
I
sample C
_
6.90 5.23 3.92 3.60 4.03 2.34 1.89 0.83 0.42 0.14 0.48 0.13 0.02 0.01 0.00 0.00 0.00 0.00 0.00
Thiophene Ring Systems traces 3.48 1.90
1.34 4.11 1.92 0.96 1.04 0.29 0.10 0.03 0.13 0.04 traces
0.00 1.24 1.46 0.17 3.12 1.76 0.61 0.58 0.19 0.02 0.01 0.03 traces 0.00
0.00 0.00 0.00 0.00 2.65 0.01 0.14 0.33 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00 1.61 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Furan Ring Systems 0.00 0.00 0.02 0.00 dinaphthenofurans 0.00 0.05 traces 0.00 benzofurans 0.00 0.00 0.00 traces naphthenobenzofurans 0.00 0.03 0.00 0.01 dinaphthenobenzofurans 0.10 0.13 0.00 0.08 dibenzofurans 0.00 0.07 0.12 0.05 naphthencdibenzofurans 0.00 0.02 0.03 0.01 fluorenofurans 0.00 0.07 0.00 0.03 phenanthrenofurans 0.00 0.00 0.04 0.02 naphthenophenanthrenofurans 0.01 0.00 0.00 0.01 pyrenofurans 0.00 traces 0.00 traces chryaenofurans traces 0.00 0.00 0.00 cholanthrenofurans 0.00 0.01 0.00 traces benzopyrenofurans 0.00 0.00 0.00 traces benzochrysenofurans 0.00 0.00 traces traces benzkhi]perylenofurans a All values normalized to reflect concentrations in whole oils. bTraces means less than 0.005%; 0.00 means not detected, less than 0.001% (10ppm).
810 1010 1210 1410 1610 1810 2010 2210 2410 2610 2810 3010 3210 3410 3610
show that the concentrations of Components in all 2number series were either maintained or increased during this process. Actual concentrations of the components in each 2-number series are given in Table 111. The effect of hydrotreating on the 2-number distribution for thiophene ring systems is also given in Table 111. A comparison of the results for samples B and C shows that the increased hydrotreating severity was leas effective than the increased extraction severity in the removal of dibenzothiophenes and other thiophene ring systems. The average 2 number for all ring systems (Table 11) is only marginally reduced (from 13.6 for sample A to 13.3 for sample B), consistent with all of the above observations. The effect of hydrotreating on the side-chain carbon number distribution for hydrocarbon ring systems is shown in Figure 4, and actual values are given in Table IV. A
comparison of sample B with sample A shows a decreased average side-chain carbon number for the Components in almost all 2-number series. Average values for all ring systems (Table 11)confirm that carbon number, molecular weight, and number of carbon atoms in side chains were all decreased by increased hydrotreating severity. Increased hydrotreating severity narrowed the total carbon number distribution (Table V). Conclusions. The mass spectrometry analysis of the PAC structure distributions provides important insight into the exact impacts of refining on the aromatic composition of lubricant base oils. Both extraction and hydrotreating result in significant increases in the concentrations of one-ring and two-ring aromatic hydrocarbons. Solvent extraction reaulta in a relative enrichment of the least aromatic components, because the more aromatic
Chasey and Aczel
390 Energy & Fuels, Vol. 5,No.3,1991 Table IV. Average Number of Sidechain Carbons for Major Series* average value dewaxed SamDle c samde B distillate samDle A Z no. Hydrocarbon Ring Systems 17.6 8 17.4 17.3 16.3 16.7 16.2 17.6 i7.6 10 16.3 15.1 15.8 15.7 12 14.3 13.0 12.1 13.1 14 13.6 12.8 11.8 12.6 16 11.6 10.6 9.4 10.1 18 11.4 10.5 8.7 20 8.9 11.1 7.9 8.7 22 6.9 8.5 6.9 9.3 5.7 24
101s 121s 141s 161s 181s 201s 221s
14.9 12.8 12.6 8.2 6.8 5.7 3.4
Thiophene Ring Systems 14.7 13.0 12.8 9.1 7.1 7.9 5.0 7.6 4.7 5.5
9.8
aValueslisted only if series concentration is greater than 0.05%. Table V. Total Carbon Number Distributions for Clay Gel Aromatics Fractions weight percent of totala total carbon dewaxed no. distillate sample A sample B sample C 9 0.01 0.02 10 0.08 0.04 11 0.11 0.04 12 0.12 0.10 13 0.18 0.07 0.06 0.26 14 0.48 0.14 0.68 15 1.01 0.51 1.25 0.91 0.29 16 1.50 2.14 2.04 0.69 17 2.43 1.52 3.02 2.80 18 3.67 4.22 2.56 3.92 19 4.77 3.45 4.48 4.88 20 5.54 5.58 5.23 6.58 21 6.01 6.35 7.07 5.78 22 6.94 6.42 23 7.54 7.33 8.48 8.42 9.97 7.45 24 8.03 9.92 7.97 9.38 25 8.08 8.64 10.69 8.17 26 8.33 10.16 9.22 27 7.36 8.21 9.07 7.81 7.45 28 5.97 6.47 7.04 6.79 29 4.69 5.25 5.16 30 4.46 5.84 3.54 4.11 2.75 31 3.18 2.74 32 2.41 3.15 2.25 2.83 2.51 33 1.88 1.30 0.71 34 1.34 1.83 0.40 0.22 35 1.36 1.01 0.09 1.03 36 0.79 0.71 37 0.59 0.53 38 0.41 0.30 39 0.18 0.17 40 0.14 0.05 41 0.06 a
Maxima are underlined.
components (i.e., PACs having the most highly condensed ring systems and the smallest number of side-chain carbons) are selectively removed. Aromatic and naphthenoaromatic structures corresponding to 2 numbers of 8-16 are therefore concentrated, and the average number of side-chain carbons is increased for all 2 numbers. Hydrotreating also results in a relative enrichment of the least aromatic components, but not because of the concentrating effect that is seen with extraction. Instead
of removing the more aromatic components, the hydrotreating process converts these PACs (via hydrogenation, hydrodesulfurization, and other reactions) into different PACs that appear elsewhere in the structure distribution. The reductions in average side-chain carbon number that occur during hydrotreating are due to hydrocracking. Finally, increased extraction severity (sample C versus sample A) produces a greater reduction in the grand total of ring systems than increasing hydrotreating severity (sample B versus sample A).
Experimental Section A modified version of the ASTM D2007 procedure was used for the isolation of clay gel aromatics fractions. Aromatics were carefully collected by extraction of the column with hot toluene in an inert atmosphere. In all cases,total material balances were 98% or more. High-resolution, low-voltage analyses of the aromatics fractions were carried out with a Kratos MS50 ultrahigh-resolution mass spectrometer using proprietary Exxon technology for component identification and quantitation. Major parts of this methodology have been presented or published previously." The brief summary given here serves as an update and as an aid to better understanding of the analytical data. Component Identification. Aromatic fractions were run in the electron impact, low ionization voltage mode at a dynamic resolving power of 15-20000 throughout the mass range (m/z 100-700+). Samples were introduced through an all-glass batch inlet system, heated to 310 "C. The low-voltageconditions resulted in limitingthe spectra to essentially molecular ions. Low-voltage conditions were controlled operationally, using the ratio of mlz 106 to m/z 91 in the spectrum of m-xylene to assure ourselves of the effective voltage. In addition to the meter reading of 10-12 eV, this includes a fraction of the repeller voltage. A value of 100 or higher for the above ratio is the optimum; lower ratios (30-50) had to be accepted in this work in order to detect smaller components. Component concentrations ranged from about 10 to 5OOO ppm, with a theoretical dynamic range of peak areas in the order of 50000 (a component at the 50% level, if present, would not have saturated the detection system). About 500 components were determined in each fraction. Mass measurements were carried out with the aid of a known blend of halogenated aromatics added to the sample. This blend yields abundant molecular ions at low voltages that are easy to recognize with a computer program, given their mostly negative mass defects and theoretical isotopic abundances. A second set of internal standards, Cll to C W naphthalenes, was also used in order to limit the interval between reference standards to less than 14 atomic mass units. These are also recognized automatically if present in the sample, taking advantage of the fact that the exact masses of the naphthalene homologues, CnHb-12 series, will have the highest positive deviation from integer masses and will thus always appear as the highest mass members in the mass multiplets at 142,156, 170, and so on, through m/z 688. Precise masses were determined by using the time constant equation
where T is the time constant, tl and t2 are the Occurrence times of the bracketing standards, Msl and M% are the precise masses of the bracketing standards, t, is the occurrence time, and M, is the precise mass of the unknown sample peak. Bracketing standards are those closeat to the peak to be measured-one at the low-maas side, the other at the high-mass side. Precise "sea in this context indicate masses in atomic mass units, with = (1) Johnson, B. H.; A m l , T. Anal. Chem. 1967,39,682.
( 2 ) Aael, To; Allan, D. F.; Harding, T. H.; Knipp, E. A. Anal. Chem.
1970, 42,
341.
(3) Aczel, T. Enddhl Kdhle, 1973, 26 (l), 27.
Polycyclic Aromatic Structure Distributions
SERIES
CNHZN
CNHZN-2
CNH2N-4
Energy & Fuels, Vol. 5, No. 3, 1991 391
CNH2N-6
CNH2N-8
CNHZN-10
CNH2N-12
CNH2N-14
CNH2N-16
CNHZN-16
CNH2N-20
CARBON NO.
i 4 5 6 7 6 10 9 11
12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0
0.0 0.0
0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.098 0.120 0.157 0.345 0.484 0.707 0.948 1.026 0.749 0.743 0.591 0.579 0.318 0.285 0.165 0.116 0. I16 0.076 0.052 0.024 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.053 0 . 059 0.123 0.206 0.370 0.525 0.658 0.701 0.660 0.582 0.567 0.466 0.265 0.197 0.137 0.075 0.077 0.025 0.023 0.019 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0
0.0
0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0
0.0 0.0
0.0
0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0
0.0 0.0
0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.086
0.0
0 . I00 0.146 0.347 0.372 0.602 0.752 0.679 0.880 0.765 0.615 0.457 0.292 0.265 0.182 0.128 0.092 0.042 0.062 0.022 0.0 0.010 0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0
0.0 0.0 0.0 0.054 0.064 0.057 0.073 0.084 0.147 0.186 0.344 0.325 0.446 0.694 0.607 0.798 0.542 0.431 0.354 0.253 0.237 0.158 0.116 0.060 0.057 0.044 0.042 0.0 0.0 0.0 0.0
0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.013 0.024 0.039 0.064 0.070 0.100 0.128 0.156 0.198 0.204 0.485 0.465 0.743 0.863 0.707 0.952 0.517 0.460 0.363 0.306 0.252 0.232 0.127 0.092 0.092 0.041 0.039 0.031 0.017 0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.005 0.015 0.040 0.072 0.100 0.124 0.195 0.274 0.409 0,549 0.736 0.747 0.814 0.624 0,658 0.944 0.662 0.505 0.426 0.329 0.244 0.276 0.161 0.100 0.097 0.082 0,059 0.045 0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0
0.0
0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.026 0.042 0.094 0.263 0.341 0.341 0.396 0.481 0.583 0.608 0,660 0.637 0.598 0.559 0.503 0.326 0.367 0.337 0.197 0.174 0.128 0.104 0.085 0.057 0,049 0.045 0.021 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.011 0.025 0.165 0.306 0.461 0.541 0.531 0.418 0.412 0.406 0.705 0.217 0.004 0.091 0.399 0.197 0.068 0.047 0.076 0.043 0.065 0.044 0.030 0.0 0.039 0.030 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0
Figure 7. Compound type and carbon number distribution for aromatic hydrocarbons in clay gel aromatics fraction. ON STREAM .................................................................
HRLV AROMATICS ANALYSIS-CARBON NO. 0ISTRIBUTION.WT.PCT.
SERIES
CNHZN
CNH2N-2
CNH2N-4
CNH2N-6
CNHZN-8
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.024 0.026 0.054 0.091 0.163 0.232 0.291 0.310 0.291 0.257 0.251 0.208 0,117 0.087 0.060 0.033 0.034 0.01 1 0.010 0,009
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.043 0.053 0.069 0.152 0.214 0.312 0.419 0.453 0.331 0.328 0.261 0.256 0.141 0.126 0.073 0.051 0.051 0.033 0.023 0.011 0.0 0.0 0.0 0.0
CNHPN-10
CNHZN-12
CNH2N-14
CNHZN- 16
CNH2N-18
CNH2N-20
CARBON NO. 1
2 3 4 5
! 6 10 11
12 13 14 15 16 17 18 1s
20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0
0.0 0.0 0.0
0.0
0.0
0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0
0.0 0.0 0.0
0.0 0.0
0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.038 0.044
0.065 0.153 0.164 0.266 0.332 0.300 0.433 0.338 0.271 0.202 0.129 0.117
0.080 0.057 0.041 0.019 0.028 0.010 0.0 0.004 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.024 0.028 0.025 0.032 0.037 0.065 0.087 0.152 0.143 0.197 0.306 0.268 0.353 0.239 0.190 0.158 0.112 0.104 0.070 0.051 0.036 0.025 0.020 0.019 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.001 0.01 1 0.017 0.028 0.031 0.044 0.057 0.073 0.087 0.090 0.214 0.205 0.328 0.381 0.312 0.420 0.228 0.203 0.160 0.135 0.111 0.102 0.056 0.041 0.041 0.016 0.017 0.013
0.008 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.002 0.007 0.018 0.032 0.044 0.055 0.096 0. I21 0.180 0.243 0.325 0.330 0.360 0.364 0.290 0.417 0.292 0.223 0. I68 0.145 0.108 0.122 0.071 0.044 0.043 0.036 0.026 0.020 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.011 0.019 0.042 0.118 0.151 0.150 0.175 0.213 0.258 0.268 0.291 0.281 0.264 0.247 0.222 0.144 0.162 0.149 0.087 0.077 0.057 0.046 0.039 0.025 0.022 0.020 0.009 0.0
0.0
0.0
0.0 0.0
0.0 0.0 0.0
0.0
0.0 0.0
0.0
0.0 0.0 0.0
0.0 0.0 0.0
0.0 0.0 0.0 0.0
0.0 0.0
0.0 0.0
0.0 0.0
0.0 0.0 0.0 0.0
0.0
0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.005 0.011 0.073 0.135 0.203 0.239 0.234 0.184 0.182 0.179 0.311 0.096 0.002 0.040 0.176 0.087 0.030 0.021 0.033 0.019 0.029 0.019 0.013
0.0 0.017 0.013 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0
Figure 8. Compound type and carbon number distribution for aromatic hydrocarbons in whole oil. 12.000000 and measured to an accuracy of at least O.OOO1 units. AB the time constant decrsaeee uniformly with decreasing m / z
values, the calculation ie repeated twice: once to obtain an integer mass using the time constant between bracketing reference peaks,
and then a second time, using a time constant value interpolated to the distance between one of the reference peaks and the integer value of the mass being measured. This procedure greatly increases the accuracy of the mass measurements, yielding values
Chasey and Aczel
392 Energy & Fuels, Vol. 5, No. 3,1991
SOURCE-
3333.
SANPLC- TOTAL SILICA-OIL
ARWTICS
CWPOUNO
TYPE _--------CNHZN CWPN- 2 CNHZN- 4 CWZN- 8 CWZN- 8 CNMZN-10 CWZN- 1 2 CNH2N- 14 CNHZN-18 CW2N- 18 CNHZN-20 'CNHZN-22 CNHZN-24 CHHZN-28 CHCIZN-28 CWZN-30 CNHPN-32 CW2N-34 CNHZN-36 CNHZN-38 CNH2N-40 CWZN-42 CNH2N-44 CNHZN- 25 CNHPN- 4 5 CNHZN- 65 CNHZN- 85 CNHZN- 10s CNHZN- 125 CNH2N-145 CNHZN-18s CNHZN-185'
0.0
0.0
0.0
5.789 7.701 7.000
8.205 7.791 9.489
8.012 5.329 3 . 889 1.575 0.394 0.419 0.457 0.344 0.284 0.174
0.0
0.0
0.0 0.0 2.686
0.0 0.0 2.588
3.400 3.091 2.739 3.440 4.189 3.542 2.353 1 .E20
3.400 3.091 2.739 3.440 4.189 3.542 2.353 1 .E20
0.895
0.895
0.174 0.185
0.174 0.185
0.202
0.202 0.152
0.0 0.0 0.0 2.588 3.400 3.091 2. 739 3.440 4.189 3.542 2.353 1 .E20 0.895 0.174 0.185
0.202
0.081
0.152 0.117 0.077 0.037
0.117 0.077 0.037
0.073 0.004
0.032 0.002
0.002
0.032 0.002
0.001
0.001
0.001
0.0 0.0 0.0
0.0 0.0 0.0
0.0 0.0
0.0
0.0
0.007 7.892 4.291 3.030 9.304 4.348
0.0
0.0
0.003 3.484 1 .e95 1.338 4.108 1 .Dl9
0.003 3.484 1 .895 1.338 4.108 1.919
0.003 3.484 1 .E95 1.338 4.108 1.919
0.152 0.117 0.077 0.037 0.032
0.002
0.0 0.0 0.0
0.0 0.0 0.0 28.59
0.0 0.0 0.0
388.28 362.01 382.14 347.85 337.95 328.74 318.90 314.73 298.97
25.70 25.14 24.82 24.06 23.91
17.43 17.58 15.70 13.14 12.82 10.06 8.91
22.93
6.93
308.28
23.73
351.87 408.97 401.35 384.11 399.70 386.08 382.04 401.48 480.80 417.24
28.98
5.73 7.98 11.07 8.81 7.72 8.98 6.15 4.00 3.53 7.91
28.43
28.58
31.07 30.81 29.72 3 0 . 98 30.15 30.00 31.53 35.91
0.0
0.0 0.0 184.00 342.29 352.93 348.89
298.88 304.93
32.95
2.95
0.0 0.0 0.0
0.0 0.0 0.0
10.00
3.00 14.88 12.78 12.84
22.88 8
20.59
23.78 23. 84 20.20 20.78
8.20 8.78
HRLV A R O M A T I C S ANALVSIS-AVERAGE S E R I E S D A T A
...........................................
COMPOUND TYPE
WT.PCT. ON VOLATILES
_____-----
0.101 0.034 0.132 0.044 0.004
0.958 1.035 0.286 0,101 0.034 0. 132 0.044 0.004
0.958 1.035 0.286 0,101 0.034 0.132 0.044 0.004
0.0 0.0 0.0
0.0 0.0 0.0
0.0 0.0 0.0
0.001
CNHZN-ZOS CNHZN-ZZS CNHZN-24s CNH2N-26s CNHZN-ZBS CNHZN-30s CNHZN-325 CNHZN-34S
2.171 2.343 0.647 0.230 0.077 0.298 0.099 0.009
0.958 1.035
CNHZN- 20 CNHZN- 4 0 CNHZN- 60 CNHZN- 80 CNH2N- 100 CNHZN- 120 CNHPN- 140 CNHZN- 180 CNHZN- 180 CNHPN-ZOO CNHPN-220 CNH2N-240 CNHZN-260 CNHPN-280 CNHPN-300 CNHPN-320 CNH2N-340 CNHZN-360
0.0
0.0 0.0 0.003 0.0 0.005 0.017 0.170 0.120 0.023 0.064 0,044 0.014 0.006
0.0 0.0 0.001
0.003
*TRACE AROM TOTALS
MS5O TOTAL IONIZATION=
0.266
0.001
0.001
0.0
0.0
0.0
0.002
0.002
0.002
0.007 0.075 0.053 0.010 0.028 0.019
0,007 0.075 0.053 0.010
0.007 0.075
0.028
0.098
0.019
0.019
0.006
0.006
0.003 0.0 0.0
0.003
0.006 0.003
0.0 0.0
0.0 0.0
0.001 0.001
0.001 0.001
0.001 0.001
0.053 0.010
287.43 282.16 307.56 300.97 305.51 315.21 352.43 352.67
0.0 0.0 0.0 288.00
0.0 336.48 372.76 276.38 283.00 295.03 275.23 315.17 309.50 286.67
0.0 0.0 388.00 373.91
19.67 19.44 21.40 21.07 21.54 22.37 25.17 25.35
0.0
5.67 3.44 4.40 3.07 1.54 1.37 3 . 17 1.35
0.0
0.0 0.0 0.0
20.00
13.00
0.0 0.0
0.0
23.75 26.48 19.74 20.36 21 .36 20.09 23.06 22.82 21.33
13.75 15.48 7.74 6.36 7.36 4.09 6.08 4.82 I .33
0.0 0.0
0.0
29.00 28.14
5.00 4.14
0.0
0.0 0.0 0.0 -----_-_-------------------44.150
44.150
44.150
3539369. O I V I S I O N S
TRACE QUANTITIES OF UNIOENTIFIEO A R O M A T I C S ABOVE CNH2N-44,CNHZN-34S,AND CNHZN-360
Figure 9. (a, top) Average series data for all compound types. (b, bottom) Average series data for all compound types. generally within 0.3-1.0 millimase units of the theoretical ones. Formulas are calculated from the mass measurements using a simple, conventional algorithm but only within two mass units from a reference; all other formulas are calculated by using the 'found" sample peaks as new reference peake for the remaining sample peaks in that mass cluster (multiplet; usually four to six members) and in those within the next two atomic mass units. This 'expert" approach makes formula assignments essentially error free, Options in the program include selection of heteroatom maee groupings to be considered and the use of other homologous series, in addition to the "standard" naphthalenes, as internal reference peaks. Formulas calculated are sorted into the proper homologous seriea (about 100). secondary reference peaks, isotop, fragments,
and noise peaks are recognized as such by using sophisticated computer procedures. At the resolving powers used, one can resolve hydrocarbon doublets (l2C/H , AM = 0.0939),certain hydrocarbon-sulfur doublets ( W 2 H $ S , AM = O.osoS), hydrocarbomxygen doublets (12CH4/160,A M = 0.0364),but not other hydrocarbon-sulfur doublets (s2SH4/1%8,AM = 0.0034). The latter occur generally between n aromatic ring sulfur compounds and n + 1aromatic ring hydrocarbons, such as benmthiophenes, CnHa-& and naphthenophenanthrenea, CnHhm or dibemthiophenes, C,,H,& and cholanthrenes, CnHa-~,or, in general, between homologous series with the general formulas CnH*n-x/CnHln-(z-l~)88 in CnH~-dCnH~-3DS/CnH2n-&~ S/CnH,,n+-&, These types of mas8 multiplets are deconvoluted at present
Energy & Fuels, Vol. 5, No. 3, 1991 393
Polycyclic Aromatic Structure Distributions MSB
HR-LV AROMATICS ANALYSIS-CARBON NO.0ISTRIBUTION SUMMARY-TOTALS OF ALL COMPOUND TYPES ........................................................................................ ON VOLATILES.WT.PCT.
....................
ON VOLATILES,MOL PCT.
.....................
ON STREAM.WT.PCT.
....................
ON STREAM.YOL PCT.
.....................
CARBON NO. I
i
0.0 0.0
0.0 0.0
0.0 0.0
0.0 0.0
0.0
0.0
0.0 0.0 0.0 0.0 0.0 0.023 0.153 0.200 0.218 0.301 0.774 1.531 2.138 3.291 4.738 5.898 6.559 6.617 7.549 7.800 7.987 8.431 7.698 6.566 5.137 3.882 3.584 2.478 1 .a15 1.378 0.952 0.698 0.531 0.386 0.259 0.113 0.084 0.037 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.004 0.033 0.047 0.053 0.077 0.212 0.447 0.661 1.072 1.620 2.105 2.445 2.659 3.066 3.327 3.543 3.887 3.679 3.247 2.636 2.069 1.967 1.404 1.065 0.831 0.592 0.448 0.349 0.260 0.179
0.0
IO II 13 I2
14 15
I6
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41
42 43 44 45 46 47 48 49 50 TOTALS
0.0 0.0 0.0 0.010 0.075 0. IO6 0.121 0.175 0.481 1.012 1.498 2.429 3.669 4.767 5.53B 6.022 6.944 7.535 8.025 8.804 8.333 7.355 5.970 4.687 4.455 3.179 2.412 1 .e83 1.340 1.014 0.792 0.588
0.405 0.181 0.138 0.082 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.000 0.061
0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.010 0.067 0.088 0.096 0. I33 0.342 0.676 0.943 1.453 2.092 2.604 2.896 3.010 3.333 3.444 3.526 3.722 3.399 2.899 2.266 1.714 1.582 1.094 0.601 0.608 0.420 0.308 0.234 0.170 0.114 0,050
0.028 0.0
0.037 0.017 0.0
0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0
0.0 0.0
0.0 0.0 0.0 0.0
0.0 0.0
- -- -- - -
-- - -- --
-- - - - - -
100.001
100.001
44.150
- - ---
-
44.150
Figure 10. Carbon number distribution summary for all compound types. by the quantitative analysis program discussed below. A significantly more accurate approach, using on-line LC/MS in the high-resolution, low-voltage MS mode is now being developed by Exxon Research and is discussed in the next paper in the Symposium.' Quantitation. Input to the quantitation programs consists of the formulas and intensities (areas) of the identified components, plus additional, optional information, such as data from a chromatographicpercolation (totalsaturata, aromatics, polm, asphaltenes); analyses of the saturates; and GC distillation data on the chromatographic fractions, if available. These data are integrated with the high-resolution, low-voltage analyses of the a r o d t i c s fractions to provide one with a more complete insight into the composition of the total stream.s Quantitation is carried out using a set of calibration coefficients based on experimental data, theoretical considerations, and extrapolations. The set contains calibration coefficients for approximately 5OOO carbon number homologues in 140 homologous series, including one to seven ring aromatics, naphthenoaromatics, aromatic thiophenes, aromatic furans, aromatic nitrogen compounde, and miscellaneous SO, S2,NO, NOz,and N2compounds. Theoretical considerations on molecular sensitivities are summarized below. They are based on the relationship between aromaticity and ionization potential. The relationshipsdiscussed are in terms of gram sensitivities (i.e., signal intensity per unit weight of eample/compound charged to the instrument). Sensitivities increase as a function of aromaticity (number of aromatic double bonds). Sensitivities increase with number of substituents, i.e., xylenes > toluene > benzene. Sensitivities decrease with increasing length and branchiness of alkyl side chains, Le., isopropylbenzene< n-propylbenzene < ethylbenzene < xylenes. (4)Heu, T.S., et ai. Prepr. Am. Chem. SOC.,Diu. Pet. Chem- 196, %5 (4) 649-8152. (6) Aaal, T. Preprints of Symposia,Division of Petroleum Chemistry, American Chemical Society, Vol. 34,No. 2, Dallas, Texas,April 1989 (ACSAward in Petroleum Chemistry Presentation), p 318.
Sensitivitiea of aromatic thiophenes and f u r m are equivalent to those of the correspondent aromatics, i.e., benzothiophenes naphthalenes benzofurm; dibenzothiophenes = Phenanthrenes = dibenzofurans. Sensitivities of pyrrolic N compounds are higher than those of the correspondingaromatics; those of pyridinic N compounds are lower, i.e., pyrroles > benzenes > pyridines: indoles > naphthalenes > quinolines. Impacts of additional aromatic rings, alkyl substitution, heteroatoms, etc., decrease with molecular size; i.e., pyrroles e< benzenes; carbazoles > phenanthrenes. In addition to determiningthe concentrationof each individual component (carbon number homologue), the quantitative analysis is used for calculating several physical properties related to composition, including elemental analysis for C, H,0, S, N molecular weight distribution; distillation characteristics; prediction of the composition of narrow distillate fractions from the analysis of a wide boiling range material (by sorting componenta according to boiling range); density; refractive index; H and C types as would be measured by NMR etc. This is done by associating each individual component with the correspondent value of each additive property such as formula, boiling range, theoretical NMR parameters, etc., and then compositing these values weighed by the corresponding concentrations. Some of the types of data obtained are illustrated (for the aromatics fraction derived from the dewaxed distillate) in Figures 7-1 1 and summarized below. Figures 7 and 8 Compound Type, Carbon Number Distribution. Individual concentrations of up to 2900 hydrocarbon, aromatic thiophene, and aromatic furan carbon number homologues are tabulated in order of compound type (columns) and carbon number (row). Values are given on both an 'aromatics" (Figure 7) and a "stream" (Figure 8) basis. These figures provide us with the database for all parameters calculated in the other figures. Only one page of each set of data is given for illustrative purposes. Figure 9 Average Series Data. (1) Concentration of each of 58 aromatic hydrocarbon, aromatic thiophene, aromatic furan C,H,# compound, or homologous series type (C,Hh to C,H,;
Chasey a n d Aczel
394 Energy & Fuels, Vol. 5, No.3, 1991 MISCELLANEOUS AVERAGES AND SUMMARIES ON VOLATILE AROMATICS
..........................................................
................................
ELEMENTAL ANALYSIS BY MS.WT.PCT. ATOMIC ATOMIC ATOMIC ATOMIC
86.59 9.88 3.51 0.03
CARBON: HYDROGEN8 SULFUR* OXYGEN:
CHARACTERISTIC AVERAGES ON SAMPLE
................................. MOLECULAR WEIGHTr CARBON NUMBERi 2 NUMBER (CNHZN-2): C ATOMS I N SIDECHAINS:
332.592 24.771 14.794 12.212
TOTAL: ATOMIC H l C RATIO:
------
TOTALS NDNARDYATICS 1 RING AROMS 2 RING AROMS 3 RING AROMS 4 RING AROMS 5 RING AROMS 6 RING AROMS 7+ RING AROMS
.
------------TOTALS :
0.0
0.0
0.007 15.213 15.821 2.990 0.606 0.108
20.490 23.485 13.351 5.637 0.877 0.782 0.163
0.003 0.192 0.143 0,122 0.006 0.004
-------
- -- ----
- ------
64.785
34.746
0.471
0.007 35.706 39.498 16.485 6.365 0.991 0.786 0.163
- - -- - - -
100.D01
MISCELLANEOUS AVERAGES AND SUMMARIES ON STREAM
............................................... DISTRIBUTION OF AROMATIC RINGS
................................
--__--_-____
HYDROCARBONS NONAROMATICS 1 RING AROMS 2 RING AROMS 3 RING AROMS 4 RING AROMS 5 RING AROMS 6 RING AROMS 7+ RING AROMS
-------------
.
0.0 9.047 10.369 5.894 2.489 0.387 0.345 0.072
COMP. _ - - _ _ _ _ _ _ _ _ _ OXYGEN -----------SULFUR COMP.
0.003 6.716 6.985 1.320 0.267 0.048
0.0 0.001 0.085 0.063 0.054 0.003
0.002
0.003 15.764 17.438 7.278 2.810 0.437 0.347 0.072
- - - - - --
TOTALS :
*
------
TOTALS
44.151
NOTE: NAPHTHENIC AND HETEROCVCLIC RINGS ARE NOT CONSIDERED A S AROMATICS FOR EXAMPLE TETRALINS.BEN2OTHIOPHENES AN0 OCTAHVDROANTHRACENES ARE LISTED
AS 1 RING AROMATICS
Figure 11. Miscellaneous averages and summaries. Table VI. Sulfur Concentrations in Clay Gel Aromatics Fractions weight percent atomic sulfur X-ray mass processing history fluorescence spectrometry dewaxed distillate 3.59 3.51 sample A 2.19 2.13 sample B 1.51 0.84 sample C 1.10 0.43 to C,H,S; C,Hh-20 to CnHHO), thus including essentially all types from one to seven, or more, aromatic rings per molecule, is listed. Concentrations are given on the basis of both volatile aromatics (volatiles)and total stream, i.e., normalized to the value of aromatics in the original stream (sample) as determined by a chromatographic percolation. The portion of sample analyzed is that volatilized at 310 “C and 1 X lod Torr, corresponding approximately to a boiling range of 30-560 OC; hence the reference to “volatiles”. (2) Average molecular weight, average carbon number, and the number of average carbon atoms in side chains for each type are also given. Figure I O Carbon Number Distribution Summary. Concentrations associated with each carbon number in all compound types. Values are given in both weight percent and mole percent, and on both a ‘volatile aromatics” and a “stream” basis. Figure 11; Miscellaneous Averages and Summaries. (1) Elemental analysis (C, H, S, and 0),atomic H/C ratio, average molecular weight, 2 number (hydrogen deficiency), average carbon number, and the average number of carbon atoms in side chains are listed. AU of the above values are calculated on the aromatics. (2) Distributions of aromatic rings according to clam (hydrocarbons, thiophenes, furans) and number of aromatic rings per molecule (one to w e n , or more) are listed. Values are given both
on an “aromatics” and “stream” basis. As mentioned previously, the resolving power used (150002OOOO) is not sufficient to separate certain hydrocarbon and sulfur types, such as benzothiophenes and naphthenophenanthrenes, CnH2n-1,,Sand C,Hzn+ The resolving power required, up to 150OOO in a dynamic scanning mode over a wide mass range, is beyond the capabilities of any commercially available mass spectrometer. Separation of the interfering compound types, CnHw1,,S through C,H-S and from C,H%,p through C,H-, is carried out by using computer programs based on the carbon number distribution and boiling range characteristics. For example, in the case of C,Hzn-l,,S and C,H%-#, homologues, peaks of molecular weights 134-176 are assigned in their entirety to sulfur componenta,as these molecular weights are below that of the first possible C,Hzn-ao homologue (molecular weight 190). Peaks of homologues with molecular weights of 190 and above are prorated between sulfur and hydrocarbon componenta by using as a guide the carbon number distribution curve of naphthalenes at and above m/z 184. Naphthalenes and benzothiophenes of corresponding carbon numbers have very similar boiling points and thus it is reasonable to assume that the carbon number distribution curves are also similar in fossil fuel distillates. Analogous procedures are used for all other interfering sulfur/ hydrocarbon series, and, semiquantitatively, for distinguishing between C,Hh-,S and CnHan4r-lo~Sz series. The validity of the ~ssumptionsused is proven by the good agreement found, in these and hundreds of other samples, between sulfur values measured by X-ray fluorescence and those calculated from the mass spectrometry composition using the above approach. Values obtained from this study are shown in Table VI.
Acknowledgment. We thank Ms. Linda Kwiatek who carried out t h e mass Spectrometry experiments.
