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Chem. Prod. Res. Dev., Vol. 17, No. 3, 1978
Courty, P., et al., Bull. Soc. Chim. Fr., 4816 (1968). Courty, P., German Offen, 2 112 144 (Sept 30, 1971). Cowty, P., (to Institute Francais du Petrole) U.S. Patent 3 716497 (Feb 13, 1973). Courty, P., Ajot, H., Delmon, B.,German Offen, 2005099 (Nov 5, 1970). Courty, P., Ajot, H., Marcilly, C., Powder Techno/., 7, 21 (1973). Courty, P., Delmon, B., C . R . Acd. Sci., Paris, Ser. C , 268, 1874 (1969). Covty, P., D e l m , B., Marclliy, C., S u m , A. (Commissariat a I'Energle Atornique et I n s h t e Francais du PeWde des Carbtrams et Lubriflants),Brevet &Invention No. PV 157,487, July 2, 1968. Dietz, H., Klostermann, W., Akad. Wss.(Berlin),Kl. Mafh., Phys., Tech., Abh., No. 1, 221 (1966). Erman, E. L., et al., Russ. J . Inorg. Chem., 9, 1175 (1964). Fransen, T., React. Kinet. Catal. Lett., 5 , 445 (1976). Gregg, S . J., Sing, K. S. W., "The Adsorption of Gases on Porous Solids", E. Matijovic, Ed., "Surface and Colloa Science", Vol. 9, Chapter 4, Wiley, New York, N.Y., 1976. Hlllis, M. R., et al., Trans. Faraday Soc., 62, 3570 (1966). Holmgren, J. D., et al., J. Nectrochem. Soc.. 111, 362 (1964). Kehl, W. L., et al., (to Gulf Research and Development Co.) US. Patent 3 639 647 (Feb 1, 1972). Kilieffer, D. H., Linz, A., "Molybdenum Compounds", p 91, Intrscience, New York, N.Y., 1952. Lamprey, H., Ripley, R. L., J . Nectrochem. SOC., 109, 713 (1962).
Lavrenko, V. A., et al., Izv. Akad. Nauk SSSR, Met., No. 4, 7 (1975). Marcilly, C., Courty, P.. Delmon, B., J . Am. Ceram. SOC.,5 3 , 56 (1970). Marcilly, C., Delrnon, B., C . R . Acad. Sci., Paris, Ser. C , 268, 1795 (1969). Massoth, F. E., J. Catal., 30, 204 (1973). Paris, J. M., Paris, R. A., Bull. SOC. Chim. Fr., 1138 (1965). Pilipenko, F. S . , et al., Kinet. Katal., 14, 752 (1973). Plyasova, L. M., Kefell, L. M., Inorg. Mater. (USSR), 3, 812 (1967). Sinfelt, J. H., Yates, D. J. C., Nature (London), Phys. Sci., 229, 27 (1971). Spretnak, J. W., Speiser, R., "Protection of Molybdenum Against Corrosion at High Temperattres," p 9, Ohio State University, Report No. 12, ONR Contract N6onr-22528 (NR039-005), Jan 31, 1955. Sutugin, A. G., Fuks, A. N., Fiz. Aerodispersynkh Sist., No. 3 , 21 (1970). Szabo, G., Paris, R. A., C . R . Acad. Sci., Paris, Ser. C . , 266, 513 (1969). Tsigdlnos, G. A., Hallada, C. J., McConnell, R. W., (to AMAX Inc.) U.S. Patent 3912660 (Oct 14, 1975); (to AKAX Inc.) German Patent 2451 778 (May 28, 1976). von Destinon-Forstmann, J., Can. Metall. Q . , 4, 1 (1965). Wetzlar, K-E., ASTM Card File 18-879. Zabala. J-M.. et al., C . R. Acad. Sci. Paris, Ser. C , 279, 561 (1974).
Receiued for review November 22, 1977 Accepted May 8, 1978
Oligomerization of C3-C4 Olefins Using a Navel Nickel-Aluminosilicate Catalyst Paul G. Berclk, Kirk J. Metrger, and Harold E. Swift" Gulf Research & Development Company, Pittsburgh, Pennsylvania 15230
By proper sulfiding it has now been found that nickel-substituted synthetic mica-montmorillonite (Ni-SMM) is a very active catalyst for oligomerizing C3and C4 olefins to desirable products. For example, from a mixed C4 stream isobutene can be selectively converted to a high octane dimer while 1-butene is concurrently isomerized to 2-butene. This could be of interest as a processing scheme to complement HF and H,SO,-catalyzed isobutane alkylation processes. Isobutylene dimer gasoline has a high clear, RON blending value of about 117 and could be used as a "trim" agent in lead-free gasoline blending. Also, propylene can be converted to a dimer-trimer mixture which offers a route to a high octane product without requiring expensive isobutane for alkylate production. This catalyst can also convert propylene to C12-C18and C2,+ isoparaffinic fractions (after hydrogenation)for use in such applications as jet fuel and low pour hydraulic and transformer oils. Ni-SMM is a noncorrosive catalyst, which can give long cycle lives and can be used to process feedstocks containing relatively high levels of sulfur impurities.
Introduction An earlier paper reported that synthetic nickel layered-lattice clays are highly active for catalyzing light hydrocarbon hydroisomerization and hydrocracking reactions (Swift and Black, 1974). The layered-lattice dioctahedral clay, without incorporated nickel, is known as synthetic mica-montmorillonite (SMM) which can be represented as where each layer group is separated by cation-exchange sites to maintain charge neutrality (Capell and Granquist, 1966). The aluminum ion is in tetrahedral (tetra) coordination in the silica-alumina layers and in octahedral (oct) configuration in the alumina layers. Incorporation of nickel in the SMM structure occurs mainly by substitution for octahedral aluminum and results in some rather striking changes. For example, the surface area increases as does surface acidity, as evidenced by large increases in catalytic activities for hydroisomerization and hydrocracking C5-Cs hydrocarbons. It has been suggested that the catalytic activity of SMM is due to particle edges and faces (Wright et al., 1972). Electron micrograph studies have shown that SMM exists 0019-7890/78/1217-0214$01.00/0
Table I. Composition of Feedstocks feedstock component butadiene 1-butene cis- 2-butene ethane ethylene isobutane isobutylene isopentane 2-methyl-1-butene 2-methyl-2-butene n-butane n-pentane 2-pentene propane propylene trans-2-butene
A
B
0.2 0.0 11.4 0 . 1 10.4 0.1 0.0 24.3 33.6 0.0 11.1 3.4 1.0 0.1 24.0 10.4 0.1 0.2 12.1 1.6 39.3 1.5 0.0 14.9
C 0.2 12.0 10.3
E 0.3 7.5 6.4 0.1
32.3 22.3 11.7 7.5 3.5 0.5 1.0 0.0 10.5 7.5 0.1 0.3 1.6 9.4 1 . 5 29.0 15.0 9.4
D 9.9 26.6 51.1
10.6
1.8
as platelet-like particles having an average diameter of lo00
A. The average number of layers per platelet is five, corresponding to an average platelet thickness of 50 A.
Exactly how nickel incorporation enhances catalytic activity is not known. Besides having a much higher surface area, it may be that nickel-substituted material crystallizes 0 1978 American Chemical Society
Ind. Eng. Chem. Prod. Res. Dev., Vol. 17, No. 3, 1978
in smaller platelets, thus having more exposed edges and resulting in increased activity. Because of the type of surface described and the high acidity of Ni-SMM, it was thought that Ni-SMM would be an excellent catalyst for oligomerizing low molecular weight olefins to gasoline and distillate boiling range materials. This paper reports the results of such an investigation of Ni-SMM for oligomerizing C3-C4 olefins. Experimental Section The catalyst used to process feedstocks A and E (Table I) was a Ni-SMM containing 13.8 wt % nickel and 3.6 wt % fluoride. This catalyst was made by using NiF2 and NH4F.HF in the synthesis as described in a recent patent (Black et al., 1976). The catalyst used for processing feedstocks B and D was a Ni-SMM containing 14.0 wt YO nickel and 4.0 wt % fluoride. The nickel source for the synthesis of this material was nickel acetate. Previous research revealed that there was little or no difference between materials made from NiFz or Ni(C2H,02)2for hydrocracking or hydroisomerization reactions. The catalyst used to process feed D was a Ni-SMM containing 9.7 wt % Ni and 0.82 wt % fluoride which was made from nickel acetate. Based on preliminary screening studies little difference was observed for Ni-SMM catalysts containing between 6 and 15 wt % Ni and 0.5 to 4 wt YO fluoride for oligomerizing C3 and C4 olefiis. Thus, this was not considered a major variable for which to report data. All of these materials were heat treated in air at 1000 O F for 10 h to accomplish deammination to give the hydrogen form of the structure previously shown. These materials were all extruded in the form of 1/16-in.particles. A 1-in. i.d. stainless steel reactor attached to a semiautomated pilot unit was used in all experiments. The sizes of the catalyst charge for processing feedstocks A, B, C, D, and E were 268.5, 190.2, 155.2, 64.0, and 306.8 g, respectively. For processing feedstocks A, B, C, and E the following two-step sulfiding katalyst pretreatment was used. After the catalyst was loaded it was heat treated at 927 OF, 25 psig, and a space velocity of 805 standard gas volumes of dry air per hour per volume of catalyst for 2 h. The calcined catalyst was then presulfided at 649 O F , 600 psig, and a space velocity of 287 standard gas volumes of 98.5 vol YO hydrogen and 1.5 vol % hydrogen sulfide per hour per volume of catalyst for 24 h until an exposure of 1.0 g of sulfur/g of nickel in the catalyst was obtained. In a second sulfiding step, the catalyst was treated with isobutane containing 1.8 wt YO methyl mercaptan for 10 h a t 140 O F , 600 psig, and a space velocity of 0.92 liquid weight per hour until 0.63 g of sulfur had been exposed to each gram of nickel in the catalyst composition. For processing feedstock D, the catalyst was loaded and then heated in the reactor for 2 h at 956 O F , 25 psig, and a space velocity of 318 gas volumes per hour of dry air. Following this, the catalyst was cooled in nitrogen to the oligomerization run temperature. Results In earlier work using a 3% Ni-2% F silica-alumina catalyst it was found that a two-step sulfiding was necessary to obtain good product quality, Le., increased isobutene dimer concentration, less n-butene polymerization and enhanced octane value (Bercik and Metzger, 1974). Table I1 summarizes the results of this work. The two-step sulfiding resulted in a sulfur-to-metal mole ratio of a t least 0.55. This two-step sulfiding also improved the quality of product formed using Ni-SMM catalysts. Thus, this procedure was employed in most of the experiments reported in this paper.
215
Table 11. Isobutylene Oligomerization from a C, Hydrocarbon Feed Using a 3% Ni-2% Silica-Alumina (Triple A) Catalyst one-step sulfiding
two-step sulfidine
% isobutylene
conversion
98.3
100
% n-butene
polymerization temperature, F LHSV product quality dimer trimer tetramer pentamer RON clear a
23.8 102 1.0
1.7 142 1.0
47.1 40.4 11.6 0.9 99.0
59.7 35.5 4.6 0.2 101.6
ks described in Experimental Section.
Table 111. Oligomerization of Butenes from an FCC Butane-Butene Stream yield % wt C,-C, conversion, wt % olefins 12.1 _propylene 17.2 butenes 70.9 isobutylene 82.3 1-butene -35.9 2-butene 0.9 total NC, 91.8 butadiene 17.4 total C,-C, olefins 16.7 C', oligomer
__
__ __ __ ___ __
__
dimer trimer tetramer pentamer hexamer
OP, " F EP, "F
63.8 29.6 4.7 1.1 0.7 140 "F (60 "C) 475 "F (246 "C)
% condensed
at 760 mm 5 10
20 30 40 50 60 70 80 90 95
recovery % residue % loss %
204 "F (96 "C) 215 " F (102 " C ) 225 " F (107 "C) 229 " F (109 " C ) 239 "F (115 "C) 249 " F (121 "C) 265 " F (129 "C) 302 " F ( 1 5 0 "C) 351 " F ( 1 7 7 "C) 373 "F (189 "C) 426 " F (219 "C) 97.0 2.0 1.0
A. Butylene Oligomerization. The first butylene feed evaluated was a butane-butene stream made in an FCC unit and having the composition given in Table I, feed B. This feed was water washed to lower the nitrogen content to 0.2 ppm and then dried by 3-A sieves to less than 5 ppm of water. The stream contained 58 ppm of sulfur after water washing. The oligomerization was conducted isothermally for 17.5 days at 218 O F , 600 psig, and 1.0 LHSV. Analysis of the product revealed that the conversion values given in Table I11 were accomplished. There was a high conversion of isobutylene to dimer and trimer, and only a small amount of normal butenes were polymerized. The 2-butene formation (via isomerization) accounted for 96 YO of the total 1-butene conversion. The 2-butene concentration in the normal butene product was 94.5% which is close to the equilibrium value of 95.6%; 70.9% of the
216
Ind. Eng. Chem. Prod. Res. Dev., Vol. 17,
No. 3, 1978
Table IV. Butene Oligomerization yield 95 wt conversion wt 3'% propylene butenes isobutylene 1-butene 2-butene total NC, butadiene total C,-C, olefins C,' oligomer
4.1 18.8 69.5 77.7 -32.6 2.9 91.8 18.7
__
dimer trimer tetramer pentamer hexamer
OP,"F EP, "F
c3-c,
olefins
__ ____ ___ __ __ __
17.9
66.7 28.9 3.8 0.7 0.0 186 " F ( 5 8 "C) 470 "F (243 "C)
% condensed
at 760 mm 5 10 20 30 40 50 60 70 80 90 95
217 220 223 227 237 247 259 285 333 378 441
recovery % residue % loss %
"F (103 "C) "F (104 " C ) " F (106 "C) "F (108 "C) "F (114 "C) "F (119 "C) "F (126 " C ) O F (141 "C) "F (167 "C) " F (192 "C) "F (227 "C) 96.5 1.5 2.0
isobutylene fraction was polymerized to c6+ oligomer product (16.7 wt % yield of C3-C4 olefins). The distribution of this c6+product is also given in Table 111, which reveals that almost all of the product was dimer and trimer. This c6+product had an API gravity of 58.7 and a clear Research octane number of 101.8. Table I11 also gives the results of distilling this fraction. The next experiment was conducted using a similar feedstock (Table I, feed C) but this time the oligomerization was conducted adiabatically over a 34.5 day period. The conditions were the same as the first run with an average temperature of 221 OF (spread was from 208 to 243 OF). Table IV shows what conversions occurred. Only 2.9% of the normal butenes were polymerized and the 2-butene yield increased from 32.6% due to isomerization
of 1-butene. 2-Butene constituted 92.6% of the normal butenes (95.5 is the equilibrium value); 69.5% of the isobutylene was polymerized to give a C,+ product (17.9 w t % yield of C3-C4olefins) having a distribution as shown in Table IV. This product had an API gravity of 58.2 with a clear Research octane value of 101.7. Table IV gives the results of distilling this product. The clear octane blending numbers for isobutylene dimer gasoline in a Gulf Coast Refinery lead-free gasoline pool were also determined. Five experimental blends which covered 90.1 to 96.6 research and 81.8 to 85.0 motor octane clear ranges were made. Clear blending octane values were then calculated using a clear gasoline blending model which had previously been developed for this Gulf Coast Refinery. The clear RON and MON octane blending numbers for the isobutylene dimer gasoline were 117 and 88.7, respectively. The clear RON and MON bonuses, defined as the blending number minus the lab number, were +15.7 and +3.7, respectively. These high clear blending octane numbers indicate that isobutylene dimer gasoline could be used as a "trim" agent in lead-free gasoline blending. Here, the isobutylene dimer gasoline could have an intangible benefit over its value as a gasoline component. To illustrate this point, the clear octane of an East Coast Refinery lead-free gasoline pool was "trimmed" by the addition of 5 and 10 vol % of an isobutylene dimer gasoline. The results, summarized in Table V (study A), show that the clear, RON of the pool was increased significantly from 91.0 to 92.1-93.5. The clear, MON of the pool was also increased somewhat from 84.0 to 84.6-84.8 on the average. These data clearly show that small amounts of isobutylene dimer gasoline are useful as a "trim" agent for increasing clear RON with a slight increase in clear MON. The other data (study B) in Table V show that isobutylene dimer gasoline could be useful in making premium gasoline blends with alkylate. The two blends made are representative of the relative amounts of dimer and alkylate that might be obtained in a dimerization with subsequent alkylation of a butane-butene stream from a refinery fluid unit. This shows that such additions of isobutylene dimer gasoline to alkylate substantially increases clear, RON from 92.7 to 97.4-99.2. Although a much smaller but significant loss in clear MON occurred, the road octane number, even when conservatively defined as 0.25 multiplied by RON plus 0.75 multiplied by MON, increased from 91.5 to 92.5. A continuous polymerization run was made using a sulfur-free hydrocarbon feed (Table I, feed D) and with
Table V. Clear Octane Blending Values of Some Isobutylene Dimer Gasolines clear, research octane number
clear, motor octane number
(MOW
(RON) blend studv descrbtion A. East Coast Refinery lead-free gasoline pool dimer blend blend duplicate blend
B. Sulfuric acid alkylate dimer blend blend
dimer vol %
0 100 5 10 10 0 100 12.5 19.1
lab number 91.0 100.5 92.1 93.5 93.5 92.7 102.2 97.4 99.2
dimeP blending number
bonusb for dimer
__
--
___ .
113 116 116
+12.5 +15.5 +15.5
_._-
__ __
130 126.5
+32.6 + 27.3
lab number 84.0 84.7 84.6 85.2 84.4 91.1 84.4 90.9 90.1
dimera blending bonusb number for dimer
__
__
__ __
96 96 88
+ 11.3
_-
__
88.8 87.0
+ 11.3 +3.3
__
_+4.4 + 2.6
a Computed based on a linear volume average as follows: blend octane number = volume fraction of dimer x blending The bonus octane number of dimer + volume fraction of other component x the octane number of the other component. is defined as the blending octane number minus the lab octane number.
Ind. Eng. Chem. Prod. Res. Dev., Vol. 17, No. 3, 1978
Table VIII. Propylene Oligomerization from a Mixed C,-C, Stream
Table VI. Butylene Oligomerization in a Sulfur-Free System
experiment
conversion, yield % wt wt% C, olefins 24.6 79.2 16.0 6.0 8.7 24.6
butenes isobutylene 1-butene 2-butene total NC, total C, olefins C,' oligomer dimer trimer tetramer pentamer hexamer
__
__ __ __
__
temperature, 'F pressure, psig
__
time, days
22.2
65.2 31.7 3.1 0.0 0.0
Table VII. Conditions and Results of Oligomerizing C,-C, Olefins experiment temperature, F pressure, psi
LHSV time, days
1 264.6 600 1.0 40.1
2 280 900 1.0 44.0
yield conver- % w t conver- % wt sion, C,-C, sion, C,-C, wt % olefins wt % olefins
C,-C, propane butanes pentanes propylene butenes pentenes polymer, C, t dimer trimer tetramer pentamer and hexamer heptamer and heavier
dimer trimer tetramer pentamer hexamer OP, "F EP, " F
8.4 20.1 73.5 75.4 -31.8 2.8 100.0 14.8
__
24.2 34.0 90.3 81.0 -15.4 15.8 100.0 29.5
__
wt %
wt%
49.8 41.6 6.6 1.4 0.6
64.3 30.1 4.8 0.5 0.1
1 6 3 " F (73 "C) 509 "F (265 "C)
114 O F (46 "C) 470 "F (243 "C)
217 " F (103 "C) 229 " F (109 "C) 245 "F (118 "C) 259 "F (126 "C) 275 " F (135 "C) 296 "F (147 "C) 324 "F (162 "C) 343 " F (173 "C) 359 "F (193 "C) 395 "F (202 "C) 468 "F (242 "C)
199 "F (93 "C) 216 " F (102 " C ) 231 "F (111 " C ) 244 " F (118 "C) 256 "F (124 "C) 274 "F (134 "C) 303 " F (151 "C) 335 "F (168 "C) 355 "F (179 "C) 400 " F (204 "C) 470 " F (243 "C)
97.9 1.4 0.7
96.0 2.3 1.7
% condensed
at 760 mm 5 10 20 30 40 50 60 70 80 90 95 recovery % residue % loss %
a nonsulfided catalyst. This experiment was conducted for 5.3 days at 132 O F , 400 psig, and 2.0 LHSV. Table VI gives the results of this experiment. From these data it can be seen that isobutylene was selectively polymerized at a much lower temperature and higher space velocity than when using a sulfided catalyst and sulfur containing feed. However, the extent of 1-butene isomerization was much lower and several days of operation was necessary before n-butene polymerization fell below 10% and the amount of tetramer and heavier product fell below 12%.
OP, " F EP, "F
1
2
314 ___
325 900 0.98 9.7
900 0.96 8.7
LHSV
yield
propylene butenes isobutylene 1-butene 2-butene total NC, butadiene total C,-C, olefins C,' oligomer
217
product analyses, wt % 0.1 12.4 51.6 0.0 8.5 0.1 0.0 27.2 2.3 27.9 28.1
~~
0.2 12.7 52.6 0.0 8.1 0.1 0.1 26.2 2.6 28.3 27.2
28.8
28.4
13.0
13.6
distillation results 111"F (44 "C) terminated at 90.5% condensed
117 " F (47 "C) terminated at 88% condensed
222 " F (106 "C) 260 "F (127 "C) 292 "F (145 "C) 314 " F (157 "C) 340 " F (171 "C) 371 " F (189 "C) 402 F (206 C) 442 " F (228 " C ) 491 "F (255 "C)
214 " F (101 "C) 256 "F (124 "C) 290 " F (143 "C) 315 " F (157 "C) 346 " F (174 "C) 379 " F (193 "C) 416 "F (213 "C) 458 "F (237 "C) 512 "F (277 "C)
% condensed
at 760 mm 5 10 20 30 40 50 60 70 80
Once the catalyst reached some state of equilibrium it gave a c6+oligomer product as shown in Table VI which had an API gravity of 55.4 and octane number of 100.8. B. Propylene-Butylene Co-Oligomerization. Two experiments were conducted using a feed made from a blend of a butane-butene stream made via FCC and a propane-propylene stream used as cumene feedstock (Table I, feed E). The purpose of these experiments was to determine the effectiveness of the catalyst to form C3-C4 oligomer products. This blend contained 64.4 w t 70of the butane-butene stream which had been water washed prior to blending to lower combined nitrogen content of 0.2 ppm. The blended feed contained less than 0.2 ppm combined nitrogen, 16 ppm sulfur, and an equilibrium amount of dissolved water. Table VI1 gives the results of these experiments. As processing severity was increased, the yield of c6+oligomer increased, the dimer-to-trimer ratio increased, the API gravity decreased (59 to 57.3) and the research octane number decreased from 99.4 to 98.1. The 2-butene concentrations in the normal butene products were 91.8 and 92.7 wt 70with respective equilibrium values of 94.4 and 94.1 % C. Propylene Oligomerization. Table I gives the composition of feed A used in this study and Table VI11 gives the conditions employed for the two experiments conducted. For both of these runs the feed was dried over 3-A sieves to less than 5 ppm of water. The feed was also free of trace amounts of combined nitrogen and sulfur compounds. Analyses of the products revealed that 78.4% and 79.5% of the propylene was converted in experiments 1 and 2, respectively. Table VI11 gives analyses of the
.
218
Ind. Eng. Chem. Prod. Res. Dev., Vol. 17, No. 3, 1978
Table IX. Properties of Propylene Oligomers from a Mixed (2-4, Feed ~~
~
oligomer cut dimer inspections gravity, API clear research octane no. clear motor octane no. freeze point AS'L~MD2386 (OF) pour point, ASTM D97 (OF) distillation, ASTM D86 OP, " F EP, " F % condensed at 760 mmHg ( F) 5 10 20 30 40 50 60 70 80 90 95
trimer
tetramer
59.8 98.7 82.0
51.5 98.7 82.1 --112(-80 " C )
-_ -_
-_
pentamer and hexamer 44.8
_-
__
-92(-69
__
C)
236(113 "C) 302(150 "C)
324( 162 'C) 409( 210 C)
422( 234 C) 504( 263 a C)
248( 120 C) 250( 121 C) 254( 123 'C) 258(126 "C) 261(128 "C) 265(130 "C) 268( 131 'C) 271( 133 'C) 275(135 "C) 282( 139 C) 289( 144 'C)
340(171 " C ) 342(172 " C ) 346( 175 'C) 349(176 " C ) 351(177 " C ) 354( 178 " C ) 356(180 " C ) 359(181 "C) 365(184 " C ) 372(189 "C) 377(192 " C )
433(223 " C ) 436(225 " C ) 439(227 "C) 442(229 " C ) 446( 231 C) 450(232 " C ) 455(235 "C) 460( 238 C) 468( 242 C) 478( 248 'C) 486(253 " C )
products obtained. This table also gives the distribution of the oligomer fractions and the results of distilling these fractions by employing the procedure outlined in ASTM D86. Some of the oligomer products from these experiments were cornposited and then fractionated in a precision distillation column to obtain specific oligomer concentrates. The analyses of these concentrates are given in Table IX. These data show that the dimer, trimer, and tetramer fraction exhibit high clear research octane numbers. The oligomer fractions in the kerosine boiling range (tetramer thru hexamer) have very low freeze points and could be hydrogenated to give isoparaffinic high performance jet fuels. The oligomer fractions in the lubricating boiling range, heptamer and heavier, have a very low pour point and after hydrogenation could be useful in preparing isoparaffinic low pour hydraulic and transformer oils. Relative yields of gasoline to kerosine and heavier products can be controlled by the degree of sulfiding of the catalyst. Little or no sulfiding will give predominately dimer-trimer product, whereas, as the degree of sulfiding is increased heavier products are formed.
Discussion Oligomerization of light olefins on a commercial scale to make polymer gasoline using a solid phosphoric acid catalyst has been practiced for a number of years. Such a process is plagued by corrosion problems and when a severe operation is used for the production of low pour distillates, catalyst life is relatively short. Zeolitic catalysts can also be used for oligomerizing olefins; however, such catalysts suffer from a short cycle life due to the formation of heavy polymer incapable of diffusing from the cage-like cavities. The use of nickel catalysts for olefin oligomerization is well documented in the patent literature (Allum, 1974; Barnett and Glockner, 1970; Choutoer et al., 1964; Lucki, 1976; Pine et al., 1970). In most cases propylene or isobutylene are the olefins which have been studied. The work reported on using nickel-fluoride silica-alumina catalysts is particularly significant (Bercik and Metzger, 1974) for it revealed that with proper sulfiding, product quality can be enhanced and a feed containing significant quantities of sulfur can be used and still maintain good
O
heptamer and heavier
-
catalyst life. Based on this study it was not surprising to find that Ni-SMM is also very active for olefin oligomerization. However, it was unexpected to find that sulfided Ni-SMM could concurrently catalyze a number of desirable reactions from a mixed C4 stream, i.e., good selectivity to a high octane isobutene dimer, near equilibrium isomerization of 1-butene to 2-butene, and the conversion of butadiene to a furnace oil boiling material. The high surface acidity of Ni-SMM is obviously responsible for these results, similar to what was previously reported for the high activity of sulfided Ni-SMM for hydrocracking various hydrocarbon feedstocks (Black et al., 1976). It was surprising to observe that while sulfided Ni-SMM resulted in high activity for catalyzing these concurrent reactions, very little of the undesirable oligomerization of n-butenes occurred. The ability of Ni-SMM to catalyze these reactions has potential commercial significance for use to complement H F and H,S04-catalyzed isobutane alkylation processes. In such a complementary scheme, Ni-SMM would convert isobutene to a high octane dimer and diolefins to high boiling products. Isobutene produces poor alkylation products and has very high acid consumption in sulfuric acid catalyzed alkylations. Diolefins, even though present in low concentrations, greatly increase acid consumption and sludge formation. Thus, after processing over a Ni-SMM catalyst, isobutene oligomers and Clzf hydrocarbons material from butadiene would be separated to leave a C4 stream rich in butene-2, which is desirable in HF-catalyzed alkylations since it gives a much better quality alkylate than butene-1. Sulfided Ni-SMM is also very active for the conversion of propylene from propylene-propane-isobutane or propylene-propane streams to selectively give dimer and trimer of high octane value, i.e., 98.0 RON clear. This is of interest since it gives a route to a high octane gasoline from propylene without the need for expensive isobutane. With short isobutane supplies and projections of a large excess of olefins, particularly in Europe (Bronner et al., 1977), there is current interest in dimerizing olefins. An example is the recent announcement that Total Petroleum, Inc. is constructing the first commercial Dimersol unit (Kohn, 1977). Dimersol is a process licensed by France's Institut Francais du Petrole (IFP),which employs a ho-
Ind. Eng. Chem. Prod. Res. Dev., Vol. 17, No. 3, 1978
mogeneous nickel complex catalyst to convert propylene to isohexenes (97 RON clear) and to dimerize butylene and co-dimerize C3-C4 olefin streams (Andrews and Bonnifay, 1973). A desirable feature of sulfided Ni-SMM in processing light olefins which contain high concentrations of sulfur impurities is that it is a rugged catalyst that can be used under relatively severe processing conditions and still exhibit good aging performance. Thus, it can catalyze the conversion of propylene to a CI2-Cl8 material to give (after hydrogenation) isoparaffinic high performance jet fuels or a CZl+product for preparing isoparaffinic low pour hydraulic and transformer oils. The excellent aging performance of Ni-SMM is probably associated with its catalytic activity being derived from platelet edges and faces as previously described (Wright et al., 1972). This type of surface morphology provides a mechanism whereby product is easily displaced by solvent and/or more reactant to re-expose the catalytic site, thus, resulting in long catalyst life. Polymer gasoline processes which are still in use employ a solid phosphoric acid catalyst for mainly processing C3-C4 olefin feeds. Noncorrosive and sulfur tolerant Ni-SMM can also accomplish this to give an excellent yield of high octane product as revealed by the data reported in this paper. In summary, as a new catalyst Ni-SMM offers considerable potential for processing low molecular weight
219
olefins to a variety of useful products and for use in conjunction with H F and H2S04isobutane alkylate processes. It is a noncorrosive catalyst, can result in long process cycle times even with feedstocks containing relatively high levels of sulfur impurities, and is capable of air regeneration. Literature Cited Allum, K. G. (to British Petroleum Company), US. Patent 3816555 (June 1 1 ,
1974). Andrews, J. W., Bonnifay, P., NPRA Meeting, Paper AM-73-31(Apr 1-3, 1973). Barnett, K. W., Glockner, P. W. (to Shell Oil Co.), U.S. Patent 3 527 839 (Sept
8, 1970). Bercik, P. G., Metzger, K. J. (to Gulf Research & Development Co.), US. Patent 3840474 (Oct 8, 1974). Black, E. R., Montagna, A. A., Swift, H. E. (to Gulf Research & Development Co.), U S . Patent 3 966 642 (June 29, 1976). Bronner, C., Derrien, M., Lassau, C., Hydrocarbon Process., 131 (Jan 1977). Capell, R. G., Granquist, W.T. (to Gulf Research 8 Development Co. and N. L. Industries, Inc.), U S . Patent 3 252 889 (May 24, 1966). Choufoer, J. R., deRuiter, H., vanZoonen, D. (to Shell Oil Company), US. Patent 3 161 697 (Dec 15, 1964). Kohn, P. M., Cbem. Eng., 114 (May 23, 1977). Lucki, S. J. (to Mobil Oil Corp.), U S . Patent 3 959 400 (May 25, 1976). Pine, L. A., Roberts Jr., D. T., Jolley, G. B. (to Esso Research & Engineering Co.), U S . Patent 3518323 (June 30, 1970). Swift, H. E., Black, E. R., Ind. Eng. Cbem. Prod. Res. Dev., 13, 106 (1974). Wright, A. C.. Granquist, W. T., Kennedy, J. V., J . Catal., 25, 65 (1972).
Received for review November 29, 1977 Accepted May 8, 1978
Presented at the Division of Petroleum Chemistry, 175th National Meeting of the American Chemical Society, Anaheim, Calif., March 1978.
Ion-Exchanged Ultrastable Y Zeolites. 3. Gas Oil Cracking over Rare Earth-Exchanged Ultrastable Y Zeolites Julius Scherzer' and Ronald E. Rltter W. R. Grace & Co., Davison Chemical Division, Washington Research Center, Columbia, Maryland 21044
The use of rare earth, hydrogen-exchanged ultrastable Y (RE,H-USY) zeolites as catalysts in gas oil cracking has been investigated. Both microactivity and pilot unit data are presented and discussed. The activity and selectivity of these zeolites is compared to that of ultrastable Y and RE,H-Y zeolites. RE,H-USY zeolites are more active than USY. They show good gasoline selectivity, lower coking rates, and higher olefin selectivity than RE,H-Y. The gasoline fractions obtained over RE,H-USY catalysts have a high content of aromatics, olefins, and cyclic allylic hydrocarbons. A possible reaction mechanism is briefly discussed.
Introduction The preparation and physical properties of lanthanum-hydrogen-exchanged ultrastable Y (La,H-USY) zeolites have been previously described and discussed (Scherzer and Bass, 1977). It was shown that such compounds combine properties characteristic to ultrastable Y zeolites with those of lanthanum-exchanged Y zeolites. Infrared studies have shown the presence of both Bronsted and Lewis type acidity in these compounds. They also have high thermal and hydrothermal stability. Such properties would suggest that these compounds can be used as catalysts in processes involving carbonium ion reactions at elevated temperatures. This paper presents and discusses the results obtained by using different rare earth-hydrogen-exchanged ultrastable Y (RE,H-USY) zeolites as catalysts in gas oil cracking. 0019-7890/78/1217-0219$01 .OO/O
Experimental Section A. Materials. A series of lanthanum, cerium, and mixed rare earth exchanged ultrastable Y zeolites have been prepared by methods previously described (Scherzer and Bass, 1977). Different rare earth-exchanged zeolites were prepared by either (a) acid treatment of the ultrastable Y zeolite at a set pH, followed by rare earth exchange, or (b) exchanging the zeolite with a rare earth chloride solution of a certain acidity. Materials prepared by method (a) bear the notation M,H-USY, (M = La, Ce, RE mixture); those by method (b) are designated M,HUSY,. M,H-USY zeolites were also prepared by direct rare earth exchange of USY, without acidity adjustment. They bear the notation M,H-USY,i,. In this case, the exchange pH was close to 4.0. The lanthanum and cerium chloride used in these preparations was obtained from American Potash and 0 1978 American
Chemical Society
