Ind. E n g . Chem. Res. 1987,26, 1284-1286
1284
particularly of time-on-stream correlation; however, the combination of reactants, catalysts, and modifiers considered here is sufficiently varied to indicate that such effort would be worthwhile.
Greek Symbol 7 = weight time, wt of catalyst-time/vol of fluid Registry No. H3C(CHJ4CH3, 110-54-3;H3C(CH2)&H3, 14282-5; P t , 7440-06-4; Re, 7440-15-5;C, 7440-44-0.
Acknowledgment
Literature Cited
This work was supported by the Walter P. Murphy Fund of Northwestern University, the Mobil Foundation, and Amoco Oil Company. J.B.B. is indebtted to the Alexander von Humboldt-Stiftung for assistance.
Nomenclature a, b = proportionality constants, eq 7 and 8 CA, C R = concentrations of reactant and product, mol/vol C, = coke on catalyst, wt 9’0 FAo= feed rate of reactant, mol/time k = rate constant for reaction, vol/(wt of catalyst-time) k = rate constant for deactivation, l/time m, n = reaction orders -rA = rate of reaction of A, mol/(wt of catalystdime) s = catalyst activity variable t = time W = weight of catalyst WHSV = weight hourly space velocity, l/time x = reactant conversion
Corella, J.; Asua, J. M. Ind. Eng. Chem. Process Des. Dev. 1982,21, 55. Franck, J.-P.; Martino, G. P. “Deactivation of Reforming Catalysts”, In Deactivation and Poisoning of Catalysts; Chemical Industry Series 20; Oudar, J., Wise, H., Eds.; Marcel Dekker: New York,
1985.
Froment, G. F.; Bischoff, K. B. Chem. Eng. Sci. 1961,10, 189. Levenspiel, 0. J. Catal. 1972, 25, 265. Mahoney, J. A. J . Catal. 1974,32, 247. Mieville, R. L. J. Catal. 1986, 100, 482. S h u n , V. K.; Butt, J. B.; Sachtler, W. M. H. J.Catal. 1986,99, 126. SzBpe, S.; Levenspiel, 0. Proceedings of the European Federation, 4th Chemical Reaction Engineering, Brussels; Pergamon: New York, 1970; p 265. Voorhies, A. Ind. Eng. Chem. 1945,37, 318. Wojciechowski, B. W. Catal. Rev. 1974, 9, 1974.
Received for review J u n e 21, 1985 Revised manuscript received October 1, 1986 Accepted April 1, 1987
Characterization of Petroleum Resins by Nuclear Magnetic Resonance Spectrometry Jasenka Muhl,* Vlasta Sriba, Vida Jarm, and Margita KovaE-Filipovib INA-Industrija
N a f t e , Research and Development, Zagreb, Yugoslavia
In this paper an approach to resin structure determination using IH and I3C NMR spectrometries is presented and briefly discussed. The analyzed resin samples are prepared by catalytic and thermic polymerization of the liquid byproducts, obtained by pyrolysis of primary gasoline. The results point out the differences in resin structures depending on crude oil types as well as on the applied polymerization conditions in connection with their physical properties. There is a growing tendency in using low molecular synthetic resins (LMSR) based on crude oil. This is due to their ability to replace scarce natural resins, or expensive synthetic resins, obtained from pure monomers. On the other hand, LMSR provide better utilization of crude oil byproducts from which they are produced. The dificulties in structural analysis of resins derive from the fact that these resins have complex structure consisting of a large number of monomers. Therefore, the resins are usually characterized by their physical and applicational properties. A small number of papers has been published dealing with resin characterization using pyrolythic gas chromatography (Luke, 1973), thin-layer chromatography (Penrifoy et al., 1970) liquid chromatography (Gaya and Suatoni, 1980),thermic analysis (Tsachev and Ruschev, 1978), mass spectrometry (Muchinskii et al., 1979), IR spectrometry (Talpus et al., 1980; Butufei et al., 1979), and a combination of IR and ‘H NMR spectrometry and gelpermeation chromatography (Cheristakudis and Rentrop, 1978): NMR spectrometry is commonly used for the functional group analysis of petroleum and its products due to their compositional complexity. This approach is not typical in synthetic polymer analysis because of relative simplicity as well as known chemical composition of these 0888-5885/87/ 2626-1284$01.50/0
samples. NMR spectrometry in such cases is mostly applied for microstructural analysis as well as for quantitative determination of individual copolymer components. However, it is impossible to analyze the LMSR based on crude oil in such a way but the functional group analysis seems to be very suitable, giving a number of relevant data in determining the structure of these samples. In this paper an approach to resin structure determination using lH and 13CNMR spectrometries is presented and briefly discussed. The analyzed resin samples are prepared by catalytic and thermic polymerization of the liquid byproducts, obtained by pyrolysis of primary gasoline. The results point out that there are expected differences in resin structure depending on crude oil types as well as on the applied polymerization conditions in connection with their physical properties.
Experimental Section Pyrocondensate Fraction Characterization. The fractions (I-IV) of liquid byproducts obtained by pyrolysis of primary gasoline (130-200 “C) are analyzed by GC/MS technique. It has been noted that the samples are mixtures of saturated and unsaturated hydrocarbons with 30 or more components. The basic components polymerizing in the pyrocondensate I are identified as cyclic monosa1987 American Chemical Society
Ind. Eng. Chem. Res., Vol. 26, No. 7, 1987 1285 T a b l e I. P h y s i c a l P r o p e r t i e s of Resins" samule T.,"C 374 I-T 430 11-T 858 11-P 91.0 600 11-C 90.0 860 111-T 69.2 1470 95.3 111-P 668 111-C 74.1 750 IV-T 60.8 1170 IV-P 98.5 780 IV-c 91.0
a"
a
Har
.-
FHaih
Br no. 117.00 28.96 17.50 8.40
6.00 7.50 3.00
T = thermic, P = peroxide initiated, C = cationic polymeriza-
tions.
turated hydrocarbons. In the pyrocondensates 11-IV, these components are identified as styrene, methylstyrenes, and indene (Jarm et al., 1984). Resin Preparation. The samples I-IV are prepared simultaneously by using three methods: cationic polymerization, organic peroxide-initiated polymerization, and thermic polymerization. The cationic polymerization is performed at 50 "C and initiated by 1% AlCl, during 2 h. The polymerization in the presence of 0.5% 2, 4,4-trimethylpentyl 2-hydroperoxide is performed a t 130 "C during 24 h. The thermic polymerization lasted for 10 h a t 130 "C. The resin is separated from the reaction mixture by steam distillation and afterwards dried in open air and in vacuum a t 50 "C until constant weight has been reached. Resin Characterization. The resin average molecule mass is determined by cryoscopic and osmometric methods in benzene. The softening temperature has been determined by ASTM E28 and the unsaturation by ASTM D2710-77. The 'H NMR spectra were recorded by using a Varian EM-390 NMR spectrometer operating at 90 MHz and the 13CNMR spectra by using Jeol FX 9OQFT NMR spectrometer operating at 22.5 MHz. Chloroform-dl was used as solvent and Me,Si as internal standard. The 13CNMR spectra were obtained under the following conditions: spectrum width, 5200 Hz; pulse width, 14 ps (90 "C); pulse repetition, 40 s; gated decoupling. These conditions were verified experimentally as quantitative. The analyses were performed with a number of different pulse spacings. The same quantitative relations are already obtained with pulse repetition of 20 s.
Results and Discussion The physical properties of the resins obtained from pyrocodensates I-IV by thermic polymerization (T),peroxide-initiated polymerization (P), and the cationic polymerization (C) are presented in Table I. The lH NMR spectra signals of resins are wide and nonresolved. It is possible to determine the hydrogen content for the following functional groups only: aromatic ring (6.0-8.5 ppm, Hw), olefinic double bond (4.5-6.0 ppm,
8
6
7
5
4
3
2
I
Holef),and alkyl groups (0.5-3.5 ppm, Halk). In aromatic resin spectra, the signal at 2.2 ppm which belongs to the a-methyl groups of the aromatic ring has appeared. The quantitative part of this signal cannot be determined due to its overlap with other alkyl group signals. The 13CNMR spectra are significantly better resolved and therefore give more information. They provide the following quantitative determination: unsubstituted aromatic carbon atoms (100-130 ppm, C,-H), aromatic carbon atoms substituted by alkyl groups (130-150 ppm, Car-C), a-methyl group carbon atoms to aromatic ring (18-22 ppm CCH3),and other saturated carbon atoms (22-60 ppm, C a d . The results in Table I1 indicate that resin I is aliphatic with a high unsaturation level which is supported by the high bromine number obtained. Resins 11-IV are aromatic; among them, resin I1 has the lowest aromatic content. Practically all the 13CNMR resin spectra signals belong to the structural units of styrene, 0-,m-, and p-methylstyrene, and indene, as was indicated by 13CNMR spectra analysis based on the reference data, dealing with polystyrene (Farrall and FrBchet, 1979) and poly(methy1styrene) (Ebdon and Huckerby, 1976) and by analogy with polyindene (Pratsch et al., 1976), directed toward individual component identification (Table 111). The ratio among the spectra signals provides information concerning the individual components contribution. Despite the quantitative differences in structural composition of aromatic resins 11-IV (Table II), the similarity of the resins prepared by the same polymerization type
T a b l e 11. Carbon-Hydrogen F u n c t i o n a l Groups Distribution Determined by 'H a n d 13C NMR Spectrometries sample I-T 11-T 11-P 11-c 111-T 111-P 111-c IV-T IV-P IV-c
H,
(Holef.)
(10.2) 41.9 46.8 37.9 47.7 46.9 43.8 47.4 44.5 43.5
Halk
89.8 58.1 53.2 62.1 52.3 53.1 56.2 52.6 45.5 56.5
Har/Halk
0.72 0.87 0.61 0.91 0.88 0.78 0.90 0.81 0.76
0p m
F i g u r e 1. 'H NMR spectra of resins 11: (a) thermic, (b) organic peroxide-initiated, and (c) cationic polymerizations.
Ca7-H ( C o l d (13.9) 48.1 52.0 57.4 62.6 59.3 55.5 49.6 65.4 53.8
Cm-C
Calk
(CCHs)
20.2 17.2 13.1 15.6 15.9 18.5 20.6 11.1 16.9
86.1 31.7 30.8 29.4 21.8 24.8 26.0 29.8 23.5 29.3
(5.9) (4.5) (4.1) (6.2) (6.0) (6.3) (4.8) (5.5) (5.2)
2.1 2.2 2.4 3.6 3.0 2.8 2.4 3.2 2.4
1286 Ind. Eng. Chem. Res., Vol. 26, No. 7, 1987 Table 111. Basic Structural Aromatic Resin Units and Chemical Shifts of lsCNMR Spectra"
-c-c-7
0
s no. 1 2 3 4 5 6 7 8 9 10
S 145.3 128.0-127.8 128.0-127.8 125.7 128.0-127.8 128.0-127.8 42.4-45.5 40.7
-c-c-
-c-c-
M (o,m.p)
O-M 143.8 136.4 130.5 125.8-126.2 125.8-126.2
m-M 145.4-146.5 128.4-129.1 137.1-137.3 126.5-126.9 127.8-128.2 124.7-124.8 42.6-44.2 40.5-40.6 21.5
43.8-47.0 34.3-34.9 18.3-19.2
"S = styrene; M(o,m,p) =
I
P-M 142.6-143.0 127.7 128.7 134.6-134.8 128.7 127.7 42.7-44.5 40.1-40.7 21.1
I 143.9 143.9 125.9 124.2 124.2 125.9 43-47 32.8
0-,
m-, p-methylstyrene; I = indene.
is obvious. The lH and 13C NMR spectra of the resins obtained by thermic polymerization, using peroxide and cationic polymerization of sample 11, are exhibited in Figures 1 and 2. The same profile characterizes the spectra of resins obtained by the corresponding polymerization of samples I11 and IV. Combining the 'H and 13C NMR spectra data, it shouid be noted that the resins obtained by thermic polymerization contain more styrene. This is quite obvious from the intensive polystyrene signals in 13C NMR spectra, as well as from the aromatic signal in 'H NMR spectra, showing the characteristic separation of aromatic ring signals for ortho protons and meta + para protons, for a set of styrene units in the polymer. The resins obtained with peroxide polymerization initiators contain less styrene (see 13C NMR spectrum) but the sequences are longer (see lH NMR spectrum). The resins obtained by cationic polymerization contain approximately the same amount of styrene, methylstyrenes, and indene. The 13CNMR spectra characterized by the relative signal increase at 124.2 and 143.9 ppm related to indene. This is supported by the quantitative data presented in Table 11; e.g., in all three resin samples (111-T,111-C, and 111-P),the methyl group carbon content (CcHJ is approximately the same. In the same time, the Calkand Car-C for resins obtained by cationic polyermization are higher than for the resins obtained by polymerization with peroxide or by thermic polymerization. This indicates that the relative indene content in cationic resin 111 is higher. The resins obtained by different polymerization of the same pyrocondensate fraction differ with respect to the composition, the molecule mass, appearance, and softening temperature. In general, the resins obtained by cationic polymerization and with peroxide are characterized more by higher softening point than the resins with higher styrene content, obtained by thermic polymerization. The resins obtained by polymerization with peroxide are characterized by the highest molecular mass and the weakest color.
Conclusion 'H and 13CNMR spectrometries provide a good insight into the chemical structure of petroleum resins. This provides us with a better understanding of the mechanisms
so
!LO
120
100
BO
60
LO
20
0 ppm
Figure 2. I3C NMR spectra of resins 11: (a) thermic, (b) organic peroxide-initiated, and (c) cationic polymerizations.
of their preparation and also supports comparative analysis of the resins and their more useful application.
Acknowledgment We thank Biserka Metelko for 13C NMR spectra. This paper was presented on the 9th Croatian Chemists Meeting, Zagreb Yugoslavia, Feb 11-13, 1985.
Literature Cited Butufei, 0.;Donesen, D.; Mihailescu, M. et al. Rev. Chim. (Bucharest) 1979, 30 (51, 469. Cheristakudis, P.; Rentrop, K. H. Plaste Kautsch. 1978,25 (2), 74. Ebdon, J. R.; Huckerby, T. N. Polymer 1976, 17 (21, 170. Farrall, M. J.; FrBchet, J. M. J. Macromolecules 1979, 12 (31, 427. Gaya, L. G.; Suatoni, J. C. J. Liq. Chromatogr. 1980, 3 (2), 229. Jarm, V.; KovaE-FilipoviZ.,M.; Alajbeg, A.; Svob, V., Presented at the 8th Yugoslav Symposium on Macromolecular Chemistry and Technology, Bled, April 18-20, 1984, p 62. Luke, B. G. J . Chromatogr. Sci. 1973, 11 (8), 435. Muchinskii, Ya. D.; Polyakova, A. A.; Kogan, L. 0. Fiz.-Khim. Methods Issled. Nefteproduktou M 1979, 56. Penrifoy, P. V.; O'Neal, M. J.; Woods, L. A. J . Chromatogr. 1970,51 (2), 227. Pratsch, E.; Seibl, J.; Simon, W. Tabellen zur strukturaufilarung Organischer Verbindungem mit Spektroskopischen Methoden; Springer-Verlag: Berlin, 1976. Talpus, V; Badilescu, S.; Grigore, A. Reu. Chim. (Bucharest) 1980, 31 (7), 705. Tsachev, A.; Ruschev, D. J. Therm. Anal. 1978, 13 (2), 307.
Received for review January 28, 1986 Revised manuscript received February 11, 1987 Accepted March 11, 1987
