Pilot Plant Production of 2,3=Dimethylbutane CLARK HO L LOWAY, JK.. AND W. S. BONNELL’ Gulf Research & Developmeni Company, Pittsburgh, P a .
4)f the many products manufactured by the petroleum industry, few can be classified as pure chemicals, and many of the remainder defy analysis. Toluene, butbdiene, and 2,2,4-trimethylpentane (isooctane) are notable pure hydrocarbons from petroleum; this paper describes the pilot plant development of a process for another pure hydrocarbon, 2,J-dimethylbutane, In addition to showing data on the value of the material as a “rich mixture” blending agent, the paper discusses the effects in its pioduction of hydrogen chloride concentration, catalyst activity, space’velocity, mixing power, reaction temperature, isobutane/ethene ratio, and diluents in the feed on ethene converdon, yields, yield efficiency, and catalyst life.“The photograph reproduced above shows an aluminum chloride isomerization unit which is used for preparing alkylation plant isobutane feed (courtesy, the Lummus Company).
T
HE rich mixture rating of an aviation fuel is ameasure of the
power output that can b e secured in flight during operation a t rich mixture, and the rich mixture response is a measure of the increase in power that can be obtained in going from lean to rich mixture operation. Lean mixture corresponds t o cruising conditions, whereas rich mixture is employed for take-offs or military combat, when maximum speed and power are essential. A fuel which performs well under these conditions is said to have good rich mixture response. Aromatics in general are good from the rich mixture standpoint but have other inherent disadvantages when used to excess in fuel. Paraffins in general show poor rich mixture response, even though the octane number may be highfor example, the hydrocarbon which has 100 octane ratin@;by definition, 2,2,Ptrim‘ethylpentane, shows low rich response. There are, however, two members of the paraffin series which have been to have exceptional response. These are 2,3Present address, Gulf Oil Corporation, Port Arthur, Texas
dimethylbutane and triptane (trimethylbutane), which has only recently been reported synthesized by a method economical enough to permit commercial operation (8, 4) and which does not occur naturally in large enough quantities to be isolated for use. The preparation of the former was studied in an extensive series of batch runs in this laboratory early in 1936 and has also been reported by Alden et al. (1). Although Alden and co-workers report operating conditions and results similar t o those of this paper, the alkylation reactors were completely different. The present work describes how to use extremely active aluminum chloride catalyst with a minimum of the side reactions normally associated with such catalysts. This was done by precise regulation of the degree of catalysthydrocarbon contacting in a jet mixer. CATALYST
The catalyst most commonly’ known to be effective for the alkylation of isobutane with ethylene is aluminum chloride, and a commercial grade, Alchlor, was used throughout the present work. The use of solid aluminum chloride as catalyst in a continuous, liquid-phase process is attended with difficulties, however, since the catalyst cannot easily be charged or withdrawn continuously from the reaction system. These investigations chiefly made use of a fluid sludge which was prepared from aluminum chloride and sulfuric acid alkylate bottoms. The sludge, which ie a relatively permanent dispersion of aluminum chloride in ahminum chloride-hydrocarbon complex, is a Yellow Pasty fluid having about the consistency of molasses. The sludge is immiscible with hydrocarbons, settles readily from hydrocarbons, and it is sufficiently fluid t o flow through ordinary piping. Since the Purpose of converting aluminum chloride into sludge form is mainly to permit continuous addition and withdrawal of catalyst from the reaction system, the least drastic conditions compatible with forming a fluid sludge were employed in order to retain as much of the activity and life of the original aluminum chloride 1231
INDUSTRIAL AND ENGINEERING CHEMISTRY
1232
Vol. 38, No. 12
DESCRlPTlON OF FLOW AND APPARATUS
a
E T HI L E NE
ROE-TANK
PUMP
ALKYLATE
possible. Although the complex compounds of alurnitiuni chloride and hydrocarbon possess catalytic activity, they 1111doubtedly have less activity and shorter life than solid .4lchlor. I n some runs a n improved method of handling fresh catalyst addition Tvas used, which consisted of dissolving the solid aluminum chloride in the liquid isobutanc feed stream. The advaritages are threefold: ( 0 ) the sludge manufacture step is eliniinated, ( b ) no catalyst, activity is loet in sludge preparation, henc~, catalyst life for the alkylation is improved, aiid (c) the necessity fur relatively complicated fresh sludge pumping means is eliminated. Khen charging fresh aluminum chloride in thimanner, the sludge formed in the course of the alkylation reaction was allowed to build up in the reactor t o the desired extent: after that the sludge volume was held constant by periodic vithdravial of spent catalyst sludge. This self-formed sludge TVW substantially equivalent, in appearance and act,ivit'y to the prilformed sludge. A standard method of preformed sludge preparation wafi drveloped which gave uniform results both with respect t o physical properties of the resulting sludges and vr-ith respect to thcir catalytic activity. Sulfuric acid alkylate bottoms lvere used iii preparing the sludge since it is a readily available paraffinic material aiid avoids introducing complicating foreign components into the reaction system. Typical analyses of the reactants and of the aluminum chloride sludge are listed in Table I. During the preparation of the sludge appreciable gas is evolved due to cracking of the alkylate bottoms, and, as is typical with aluminum chloride cracking, the main constituent of the C I and light'er hydrocarbon fraction is isohutane. iis
I t !\-as cwic.luded from preliminary runs, in \vliich the isobutaiir-cth\lcne charge \vas bubbled upward through n l , i - f o ~ ~lrg t of aluminum chloridt. sludge, that agitation wis required if cmentially complete ethylene conversion together viitli se!ec*tivereaction was t o be secured. Previous expeiiencc obtained in conducting other pilot plant reactions viith aluminum chloride sludge catalyst in a mechanical agitator indicnted that it would be desirable t o develop a reaction system in which it would be possible t o eliminate packing gland troubles, as well ab the difficulty of continuously settling catalyst from the reactor effluent stream and recirculating the separated sludge to the reaction systeni These objective. were attained by using jet reactors, where the fresh feed plus the hydrocarbon recycle stream entered the reactor through an orifice, so that the stream was directed a t high velocity against the slanting bottom and violently agitated the aluminum- chloride sludge-hydrocarbon mixture in the reactor. Other advant,agt:$ over t,he mechanical agitator are (1) minimum erosion and corrosion problems, since close clearances, high impeller speeds, and ~ eliminated, and (2) elimination of internal obstruction to f l o are c-ooling, since heat of reaot,ion can be readily removed from the recycle stream. Contiriuous liquid phase aluminum chloride sludge alkylation runs were made in tv-o unit? equipped with jet reaction systems, and with alkylate produetion capacities of substantially 2 and 20 gallons per day, respectively. A Aom sheet of the smaller unit is shoim in Figure 1. The isobutane chargc was pumped through an activated alumina drier to the absorber, where thc desired amount' of ethylene mas dissolved, and the resulting solution m-as charged to the reaction hystem. The jet react'or \vas equipped nith an integral settling zone; a settling zone height of approximately 11 times the rcactor diameter was employoti in order t o eliminate catalyst carry-over due to channeling and uneven distribution of tlic, hydrocarbon flon-. The ina,iur portion of the duminum chloride sludge settled out of t h e liydrocarbon stream before reac~hing the settling zone of tho actor, or in the settling set-tion Fig,lre 2. J e t itself, and the small amouiit of catalyst remaining in the hydrocarbon effluent from the reactor was removed by glass wool filters. The hydrocarbon efP,uent T Y ~ Sre let by tivo 1-inch diameter piston pump ~ i t concentrated h sulfuric acid-oil seals i: ficulty of packing against light hydrocnrbons. The produc*t, taken from the filtered recycle stream :ln where the alkylate plus n small amouiit o mntinuously >is hottoms, i ~ l i i ki-nitanw And 1ightc.i. \wre takctll
2
r13-
Gravity, il.P.1. 54. 1 A.S.T.U. distn., O F. Initial b . p . 322 E n d point 486 10% o\-er 342 362 50% 384 90% Recovery, r/o 9s 0 Residue, % 2 0 Compn., vol 'i; Paraffin 98 4 Olefin 1 6 Total
100 0
Ilensity a t 60' F., ('hen!. anal., w t . AlCla Fe&. h l z 0 ~ Hydrocarbona
'Tutal
Centrifugal annlysii. vel. c~: Liquid 41 Solid 59
._
Total
100
INDUSTRIAL A N D ENGINEERING CHEMISTRY
December, 1946
ETHYLENE ALKYLATION RUNS TABLE11. TYPICAL 243A 252 27 Run No. . 26 138 Reaction temp., O F. Space velocity, (vol. fresh feed/hr.)/ 23.2 vol. catalyst sludge 4.2 Mixing power, h.p./barrel catalyst 4.7 Isobutans-ethvlene. mole ratio 90.1 Ethylene conversion % Yield of alkylate, w6. % of ethylene 268.5 charnd Yield-~~>,3-dimethyIbutane, wt. % 184 of ethylene charged 66.7 Yield efficiency %” Catalyst cpnsukption, Ib. AICla/gal. 0.09 debutanized alkylate 2 Alkylate production, gal./day Insuections of debutaniaed caustio washed alkylate 77.8 Gravit A P I. 6.5 R v. . r ’ l b /sq’in. A:s.$:M. ciist;., 0 F. Initial b.p. 126 End point 300 133 148 Over 225
132 10.9 0.94 6.2 79.9
136 10.0 1.8 4.2 96.6
130 7.4 1.1 3.2 89.8
236
271
285
166 67.8
174 68.9
172 82.2
0.06 2
0.08 20
ciprocating pumps were used in handling the liquid hydrocarbons, and.the pressures on the reaction systems and towers were controlled by means of motor-operated valves. The following table gives pertinent data on the isobutane and ethylene charged to the units. These materials were neighed into the system on sca1es.accurate to 0.01 pound.
132 314 138 149 219
78.1 6.7 127 311 135 147 215
0.07 20
tanes 2,2,5-Trimethylhexane HR~VV
Isobutane
132 370 142 161 240
‘6 a
b
5.5 64.6 7.0 (23.0)
..... ..... ..... ..... ..... .....
..... .....
2.5 62.4 4.5 (30.6) 2.6 2.6 5.0 3.6
..... ..... 5 . 0 . . . . . . . . . . . . . . . 1.5 10.6 . . . . . ...... 8.4 ---s -5.8
100.0
Total
2.2 70.9 4.9 (22.0)
100.0
100.0
100.0
of 2.3-dimethylbutane producedX 100 3.07 X wt. of ethylene converted ‘
Efficiency = Reid vapor pressure.
overhead through a wet test meter, sampled, and discarded. The alkylates from the official test periods were completely debutanized in a small batch column packed with 5 feet of No. 18 jack chain; then they were analyzed by fractionation in glass .columns. Streams containing n-butane and lighter were analyzed by fractionation in low temperature microcolumns. The operations on the large unit producing 20 gallons per day of alkylate were the same as those outlined, except that a debutanizer and depropanizer were used in order that unconverted isobutane could be recovered and recycled. Since a deisobutanizer was not available, sufficient butane was removed with the alkylate to prevent build-up of n-butane in the system. Fresh catalyst was added hourly to both units by displacement with alkylate bottoms from a charge bomb, and spent catalyst was withdrawn periodically from the reactor as required to allow maintenance of a constant catalyst volume. The desired reaction temperature was obtained on the smaller unit by circulating oil through a jacket on the reactor, whereas on the 20gallon per day unit the reaction temperature was controlled by an electrical heater on the recycle line. A detailed sketch of the jet reactor on the large unit is presented in Figure 2. A flange with an appropriate “dead man” (not shown) was located near the bottom of the reactor so that corrosion-erosion samples could be put in place and so that the lower portion of the reactor could be visually inspected. All the pressure equipment on both units was constructed of extra-heavy seamless steel tubing of appropriate diameters. Mild steel was used throughout, with the exception of certain critical points in the reactors which were constructed or reinforced with Hastelloy B, as shown in the reactor drawing. Re-
100 0
Total
77.2 6.6
97.6 99.0 99.0 98.5 Recovery, % 0.5 1.6 0.5 1.6 Resjdue, % 0.0 0.0 0.0 0.0 Bromine No. 0.006 0.028 0 , 0 4 3 0 . 0 2 Chlorine, wt. % Gum (AN-VVF-776-E9), mg./100 89.0 4.1 114.3 37.4 ml. Aviation Method 1-C Octane No., 92.6 93.0 92.1 93.0 Clear Comun. of debutaniaed alkylate, 3.5 66.1 4.2 (26.2) 2.1 2.1 4.7 3.1
Typical Analysis, Mole % Methane 1.0 95.7 Ethylene Ethane 3.1 0.2 Propane
Material Ethylene
~
77.4 6.2
1233
Propane Isobutane n-Butane
6.0 91.0 3 0
-
Total
100 0
TYPE OF PRODUCT OBTAINED
The results from four of the liquid phase aluminum chloride sludge alkylation runs are summarized in Table 11. The operating conditions for these runs are considered to be close to the optimum when alkylating isobutane with ethylene in the liquid phase and using preformed aluminum chloride sludge catalyst and the jet reaction system. Yields, quality of alkylate, and catalyst life would all be improved by charging fresh catalyst in isobutane solution instead of as a preformed sludge. Table I1 shows that the gum contents of the alkylates are generally high. It was found that organic chlorides have considerable effect on both tlle lead response and on the gum content of the alkylate. The effect of organic chlorides (3) and their removal from the alkylate (6) have been described. The total alkylate produced in run 25 was batch-distilled in a 25-gallon precision column. Table I11 presents the volume per cent yields, based on debutanized alkylate charged to the still, and the properties of the blended fractions. The total hexane fraction of the alkylate has an Aviation Method 1-C octane number of 92.6 (by A.S.T.M. Tentative Method D-614). This fraction, which contained about 94 volume % of 2,3-dimethylbutane and has been termed commercial 2,3-dimethylbutane, could be separated fairly readily from the alkylate in commercial operation for blending purposes, although this procedure would probably not be desired since the octane number is no highcr
TABLE111. PROPERTIES OF BLENDED FRACTIONS OF DEBUTANIZED ALKYLATE FROM RUN25 Commercial 2,3-Dimethylbutane Vol. % of debutanized alkylate Gravity, O A.P.I. lb./sq. in. ~ : ~ : & ~distn., M . O F. (D86-40) Initial b.p. End point 10% over 20% 30% 40% 50%
Recovery, yo Residue, % LOS%
%
Bromine No. Chlorine, wt. % Gum, mg./100 ml. (AN-VV-F776-E9) A.S.T.M. Motor Method Octane No. Clear Aviatioi Method 1-C Ootane No., Clear
70.3 81.0 7.0
Heptanes and Heavier 26.2 65 9 1.3
Heptanes Nonanes and and Octanes Heavier 17.8 69.1 1.5
8.4 57.8 0.,5
136 141 137 137 137 137 137
208 401 217 220 224 227 232
202 235 208 210 212 214 216
276 460 294 302’ 306 311 316
137 137 138 138
239 249 264 306
218 220 224 228
324 335 354 396
99.5
....
0.5 0.0 0.0019
98.0 2.0
0.0 0.0
0.071
97.5 1.0 0.5 0.0
0,083
96.5 2.5 1.0 0.0
0.052
1.2
37.5
0.5
162.9
92.9
83.5
87.8
75.4
92.6
83.2
86.5
73.8
P.234
INDUSTRIAL AND ENGINEERING CHEMISTRY
TABLEIV. LEAKA N D RICHMIXTURERATINGS , ,Compn., vol. % Commercial 2.3-dimethylbutane 0.0 East Texas base stock 33.8 [sooctane 91 48.2 [sopentane 18.0 Total 100.0 '::FR-XFD-BC ratings with 4 cc T.E.L.", 708-2 in hIb or cc. T.E.L. in S-2 Lean mixture 98.5% Rich mixture 0.05 CFR-AFD-3C Ratings, chlorine and sulfur-free blending stocks Lean mixture Rich mixture a Tetraethyllead. b Reference fuel bl. _
_
10.0 35.0 39.0 16.0 100.0
I
_
15.0 35.0 35.3 14.7 100.0 _
20.0 35.0 31.5 13.5 100.0
_
_
_
0.02 0.44
0.1 0.5
0.15 0.59
0.01 0.56
0.06 0.54
0.23 0.96
Vol. 38. No. 12
preparing the blends are summarized in Table V ; the inspection? and ratings of the blends are shonn in Table VI, and Figure 3 presents curves of lean and rich mixture rating against conrentration of hydrocarbon in the blends The rich mixture curves show that 2,3-dimethylbutane i b about half as effective a rich mixture additive as triptane but i p considerably better than Isooctane 91. As would be expected, triptane was also the best additive for raising the 1-C rating The 1-C rating of the 10% 2,3-dimethylbutane blend was better than the 10% Isooctane 91 blends; the 20y0 blends had the same ratings, and the 30% Isooctane 91 blend had a better 1-C rating than the 30% 2,3-dimethylbutane blend. The abscissa in Figure 3 is the actual volume per cent of the compound in the blend and does not include the isopentane required to bring the compounds to 7-pound Reid vapor pressure. Since 2,3-dimethylbutane has a Reid vapor pressure of 7, and since triptane and Isooctane 91 require isopentane to reach 7, the latter blends, for the same percentage of compound added, actually contain mow added material of high octane number than the 2,a-dimethvlbutane blends. From the curves in Figure 3 it is apparent that blends containing lZ.070 and 31.7c7, 2,3-dimethylbutane in E-100 will be ablc to meet rich mixture specifications of 5-2 plus 1 and 2 cc. of tetraethyllead, respectively; however, as can be seen from the A.S.T.M. distillations in Table VI, the blends containing 20 and 30y0 of 2,3-dimethylbutane do not meet the present aviatinn gasoline distillation specifications.
than that of the total alkylate. The debutanized alkylate from isobutane-ethylene alkylation does not contain much high boiling material, and it is not necessary to rerun the alkylate to remove heavy ends. Precision fractionations were made on 25-gallon charges of alkylate from this run and from run 252 to give the analyses iisted in Table 11. There is no indication of triptane in either product. Since the fractionations were not carried above the octane range, the presence of particular nonanes (other than 2,2,5trimethylhexane) and decanes cannot be stated. I n order to evaluate 2,3-dimethylbutane as a blending stock for aviation gasoline, a large number of lean and rich mixture ratings were obtained on pure 2,3-dimethylbutane and blends of 2,3-dimethylbutane. The results from a number of these REACTION VARIABLES blends n-ill be reviev-ed briefly, and ratings on blends of 2,3-diIn the liquid phase aluminum chloride sludge alkylation of isumethylbutane, isopentanized triptane, and isopentanixed alkylate butane with ethylene using a jet reaction system, the in depend^ with 100 octane number aviation gasoline will also be discussed. ent and dependent variables are considered t,o be as follom: Ninety-nine per cent pure 2,3-dimethylbutane plus 4 cc. of tetraethyllead was found to have a rich mixture rating above 5-2 Independent Dependent, 15 cc. of tetraethyllead, and a 25% blend of 2,3-dimethylHC1 concentration Ethylene conversion butane in reference fuel F-3 with 4 cc. of tetraethyllead had a Catalyst activity Yield of alkylate Space velocity Yield efficiency rich mixture rating of F-3 9.0 cc. of tetraethyllead. The 3C Mixing power Catalyst life Temperature ratings of 7-pound Reid vapor pressure-100 octane number blends Isobutane/ethylene ratio containing East Texas base stock, Isooctane 91, isopentane, and Diluents in feed 0 to 2O%-commercial 2,3-dimethylbutane are summarized in Table IT. (The designation for rich mixture ratings a t the time of this Jvork T a s CFRTABLE V. 2,3-DIMETHYLBUTAXE, T R I P T B N E , ISOOCTAKE 91, AND E-100 AFD-3C. The present designation for the same test USEDIN PREPARING BLENDSFOR Lcax ASD RICHMIXTURERATIXQ is CFR-BFD-F4.) Commercial To eliminate any possibility of error due to the 99% Pure 2.3-Dimethyl2.3-Dibutane Isoocpresence of sulfur or chlorine in the blending stocks, tane methyl- (6% Methyl- Triptane butane pentanes) (Eastman) 91a E-100 all of the stocks except the isopentane were passed 81.0 69.4 71.7 81.1 .... over bauxite a t 700" F. and a liquid space velocity 3.2 .... 6.4 7.0 .... of approximately 2. The sulfur contents of the F. 104 136 . . . . C 156 . . . .b East Texas base stock and the Isooctane 91 were 296 141 352 .... .... 132 186 137 .... .... reduced by this treatment from 0.0058 and 0.0061 200 146 137 .... .... weight yo,respectively, t o less than 0.0010 weight 160 210 137 .... .... 176 217 . . . . 137 . . . . %, and the concentration of chlorine in the com194 222 137 .... .... mercial 2,3-dimethylbutane was reduced from .. 227 207 .... 137 60% 0.00290 to 0.00015 weight yo. The 10, 15, and 20yo ,. 233 214 .... 137 70% . . . . 138 , . 241 220 80% 2,3-dimethylbutane blends TTere resubmitted and, as ..., 138 .. 266 229 90% can be seen in Table IT', the rich mixture ratings of Recovery, % 99.5 .... 98.0 99.0 .... 0.0 .... 1.0 0.5 Residue, % the 10 and 15% blends increased slightly, whereas 1.0 0.9 Loss,,% .... 0.5 .... Refractive index, ng 1.3749 .... 1.3893 ... .... the rich mixture rating of the treated 20% blend Freezing point, F. .... .... -24.7 ... .... was 0.37 cc. of tetraethyllead higher than for the Chlorine content, art. yo 0.001 0,0019 0.004 ... .... A.Y.T.N. Aviation Method 1-C untreated blend. 94d 92.6 . . . . ... 81.4 Clear I n order to complete the evaluation of 2,3-di$4 cc. T.E.L. 2.55 .... .... ... 0.02 CFR-AFD-3C RIethod + methylbutane, 7-pound Reid vapor pressure blends 4 cc. T.E.L. S1-A .... ... s-2 Lean mixture 4.86 .... .,.. ... 0.1 of 99y0 pure 2,3dimethylbutane, isopentanixed Rich mixture >15 . . . . .... ... 0.4B triptane, and isopentanized Isooctane 91 with a Sulfuric acid alkylate. 0.0' F. b 50% b.p. 136.0° F. Spread, initial b.p.-50% 100 octane number gasoline (E-100) were rated by 50% b.p. 177.5' F. both Aviation Method 1-C and the CFR-AFD-3C d A.S.T.M. Motor Xethod Octane No. method. The inspections of the materials used in
+
+
8,'
f
.
.
.
.
--
-
.
I
.
INDUSTRIAL AND ENGINEERING CHEMISTRY
December, 1946 TABLE
VI. LEANAND RICH MIXTURE BUTANE,
2,3-Dimethylhutane Blendsl 1 2 3
Blend No. Compn. of blend, vol. % Isopentane 2,3-Dimethylbutane Triptane [sooctane 91 E-100
. . . . . . . . . . . .
10.0
20.0
30.7.
............ ............ 90.0 80.0 69.3 --
.
Total Gravity, A.P.I. R.v.p., lb./sq. in. A.S.T.,M. distn. (D8&-40), Initial b.p. End point ; W & over
7-POUND R.V.P. BLENDSOF, S,&DIMETHYLTRIPTANE, AND ISOOCTANE 91 WITH E-100 RATINQS O F
a
F.
30% 40% 50% 60% 70% 80% 90 % Recovery, % Residue, 70
Loss, %
+
100.0 72.7 6.7
100.0 73.4 6.8
100.0 74.2 6.6
110 295 138 147 160 172 185
112 290 137 146 153 166 176
198 211 219 228 99.0 1.0 0.0 323
190 202 215 224 99.0 1.0
0.0
10 50'3' oints 313 A.S.T.M. A%:tion Method 1-C (4 cc. T.E.L./gal) Isooctane T.E.L. 0.10 0.13 CFR-AFDT3C rating (4 cc. T.E.L./gal.) Lean rating S-2 0.29 T E.L 0.27 1.40 T.E.L.' 0.92 Rich rating,'S-2
+
++
Triptane Blends 4 5 1.2
3.5
Isooctane 91 Blends 1 Y
.2.. 6. . . 5. . .2 . . .7.. 7.
........ 5.0 15.0 ....
. . . . 20.. 30.. 87.4 74.8 62.3 i i : b -- --93.8
100.0 71.7 6.8
100.0 73.1 7.0
100.0 71.7 6.8
100.0 72.1 6.7
100.0 73.2 7.2
116 285 138 144 151 159 168
108 315 141 154 168 183 196
109 283 137 147 159 172 186
101 320 138 153 167 185 200
102 338 139 153 167 185 201
106 291 135 147 163 182 200
180 194 210 225 99.0 1.0 0.0 306
205 213 222 234 99.0 0.5 0.5 337
197 206 215 227 99.0 1.0
211 218 225 238 97.0 1.0 2.0 338
211 218 225 238 97.5 1.0 1.5 340
212 219 227 239 98.0 2.0 0.0 335
--
0.0
323
0.21
0.06
0.21
0.07
0.32 1.94
0.18 0.97
0.17 1.87
0.19 0.83
HYDROGEN CHLORIDE CONCFINTRATION. The continuous, liquidphase aluminum chloride sludge alkylation of isobutane with ethylene was investigated in a tube reactor and a mechanically agitated system as well as in the jet reaction system; in all of the operations it was possible to secure alkylation without the addition of hydrogen chloride. This, of course, is advantageous; consequently no data were accumulated on the effect of varying amounts of the promoter. In the tube reactor study, the isobutane-ethylene charge was bubbled through an unpacked tube filled with sludge, and in the mechanically agitated system the hydrocarbon feed and sludge were charged to a reactor equipped with an impeller turning at 1750 revolutions per minute. Typical results of these operations are given in Table VII. I n this and in succeeding tables the units
I
I 20
HYDROCARBON IN BLEND, V 0 L . x
0.13
-
0.27 0.99
systems.
0.29 0.26 1.31
TABLE VII. COMPARISON OF ALKYLATION CONTACTORS Tube Reactor 131 350 4.4 0.43
Temp., F. Pressure, lb./sq. in. abs. Isobutane/ethylene mole ratio SDace velocitva hiixing powe;, h.p./barrel Contact time, min. Catalyst in reactor, vol. % Catalyst height, ft. HCI addn. Ethylene conversion % Yield of alkylate, wl. % Yield e5ciency, % a Units of Table 11.
30
Figure 3. .Effect of Various Additives i n E-100 Aviation Gasoline on Lean and, Rich Mixture Ratings
-
are the same as in Table I1 Thelow conversion and efficiency obtained with the tube reactor indicates insufficient contact time and inefficient contacting, respectively. Although adding 2.5 weight % of hydrogen chloride based on hydrocarbon charge increased the ethylene conversion to 98%, the efficiency decreased to 1670, and the yield of alkylate based on ethylene charged wae low because of ethyl chloride formation. Considering the inefficient contacting and short con. tact time which are characteristie of the tube reactor operation, it is not surprising that only 37% conversion and 3oa/, efficiency were obtained in the tube reactor, as compared to 100% conversion and 60-70Y0 efficiency in the mechanical agitator or jet reactor
The sludge used in this work was prepared without the addition of promoter a t atmospheric pressure, and any free hydrogeD chloride formed in the catalyst manufacture would be worked out of the sludge during the cooling and stirring procedure. Further.
1od
IO
P "
7
1233
40'
I
I
4
...
Mechanical Agitator 106 364 5.3 24.1
...
..*
.0. .
0 37 96 30
I
e
... ... ... 0
13.9 35.9
ib:z
I
Jet Reactoi 138 366 4.7 23.2 4.2
100 285 66.5
90.1 269 66.7
I
I
I
I
I
I 16
I 20
1
12
SPACE VELOCITY Figure 4. Effect of Space Velocity on Yields, Conversion, and Yield Efficiency
INDUSTRIAL AND ENGINEERING CHEMISTRY
1236 300 -
5
I b
Vol. 38, No. 12
stant conditioiib. In t,his and the surceedi~igfigurtss, units are its given in Table 11. Variables not accounted for o i i thtn curws were held constant at the follo\viny vahieq:
a
Temperature, F. Mixing power, h.p./barrel catalyst IPobutane/ethvlene i n fresh feed, mole
130 2 *5
latiti
Spaw velocity has been defiiieti :is fresh fwtl rate divided by lyst volume in the reactor: henrar. it follows that, rwirlt:nc*t: time 7' is defined hy t h e rquxtioii
T
=
(I-
-
C ) /c,s
\\.here C ' = catalyst volunie
I-= effective reactioii zone voliinw ,s' = space velocity
4 0'
I 2
I 4
I 6
I
8
MIXING POWER Figure 5 . Effect of Mixing Power on Yields, Conversion, and Yield Efficiency more, Cree hydrogen chloride was not, found in the ratalyst upon analysis. In all of the present investigations, with the exception .of some runs in the 20-gallon per day jet reactor unit, the isobutane charge was dried with activated alumina or by distillation. The alumina content, of t,he sludge did not increase measurnbly in these operations on either unit when the feed was dried and increased only slight,ly in the undried 20-gallon per day operation. Thus it does not appear that appreciable concentrations of free hydrogen chloride could have been present in these runs, although it cannot reasonably be denied that traces, such as would he required in a recently proposed alkylation mrchanism ( 6 ) , wry. This tt,rni tlrpritls upon t'he type of catalyst employed, its original activity, its make-up charge rate, nrid t h r other independent variables, surh as temperature and . ; p a c ~velocity. Although the activity vannot be represented numerically, in this work N single-type catalyst prepared by a standard method was used. Since all other independent vari:ibles (such as temperature) are specifically set in every case, thv catalyst activity for any particular run is fixed by setting thr. catalyst addition rate; t,his rate ic; defined as pounds of aluminum chloride added per galloii of 2, a-diniet,liylbutane which could theoretically be produecd fro The alkylation ruiis n.hich gtbneral groups: those in n.h ate at a low catalyst, addition r:itt, in order t o estimate t,he minimum catalyst consumption, arid those made a t a moderate but nitli a constant catalyst addition Tate in order to permit quick catalyst turnover and thus ensure a representative lined-out catalyst within a reasonable time, the primary purpose here being the assembling of data on t h r other reaction variables. From detailed consideration of the experimental data, it vas possibltx to correct the efficiencies and yields for all high catalyst additioii rate runs to values consistent Tl-ith a low catalyst addition rat
