Experimentally, the data were in the form of ML/-1fmvs. t. Now, for two values of J f t / ; M , , note that
where 71, t l are the values of dimensionless time and actual t/Mm)l. Therefore, the ratios of time, respectively, a t (A’ dimensionless time taken a t specified L l f t / M m can be directly compared to the ratios of time taken a t the same values of Jft/Mm.The correct value of /3 was taken to be that which caused best agreement of the computed ratios to experimental ratios for several values of Mt/Mm. By obtainment of the value of /3 in this way, the value of Do/L2was calculated from computing the values of r1 and tl a t given values of (.Ut/.lIm)l, that is, at a given value of (Jft/Afm)l,
The arithmetic average value of Do/L2was taken to be the correct value for a given experiment. Nomenclature
a A
= = c = c,, = c, = C = D = Do = H = L = illz = Jf = P = Po = P, =
gas-film interaction parameter in (mol/cc)-l film area concentration in moljcc initial film concentration in mol/cc final film concentration in mol/cc dimensionless concentration defined in Equation 7 diffusion coefficient in cm2/sec preexponential factor in cm2/sec solubility coefficient in mol/cc, mm H g half the thickness of the film in ern amount of gas desorbed a t time t in mol total amount of gas desorbed in mol pressure a t time t in mm H g initial pressure in bomb in mm Hg pressure a t which film is initially in equilibrium in mm Hg
p , = final pressure of system in mm H g R = gas constant in (mm/Hg)(cc)/(mol)(OK) t = time in sec 5“ = temperature in OK V , = polymer volume in cc V, = surroundings volume in cc z = distance from center of film in ern 2 = dimensionless distance defined in Equation 7
GREEKLETTERS CY = volume ratio defined in Equation 7 /3 = dimensionless gas-film interaction parameter defined in Equation 7 6 = initial ratio of wall concentration to equilibrium concentration defined in Equation 7 7 = dimensionless time defined in Equation 7 SUBSCRIPTS f = final 0 = initial s = equilibrium t = a t time t w = surface = surroundings or a t time t Literature Cited
Friedlander, H Z., Rickles, R . N., Anal. Chem., 37, 27A (1965). Li, S . N., Ind. Eng. Chem. Prod. Res. Develop., 8 , 282 (1969). Li, N . N., Long, R.B., AIChE J., 15, 73 (1969). Li, X. N., Long, R. B., “Plasticizing Effect of Pymeates on Membrane Permeation and SeDaration.” in Progress in Separation and Purification,” Vdl 3, E. S. Pery, Ed:, Interscience, New York, NY, 1971. Matulevicius, E. S., Li, N. N., manuscript in preparation (1973). Michaels, A. S.,Bixler, H. J., J . Polyrn. Sci., 5 0 , 413 (1961). w l . Phus., 34, Michaels, A. S., Vieth, W. It., Barrie, J. A., J . A .. 13 (1963). Stannett, V., Szwarc, AI., Bkrgawa, R. L., Meyer, J. A,, lleyers, A. W., Rogers, C. E., Permeability of Plastic Films and Coated Paper to Gases and l.‘apors,” TAPPI AIonograph Series, No. 23, 1962. RECEIVED for review December 17, 1970 ACCEPTEDMarch 20, 1972
Polymerization of C-5 Dienes on Active Surfaces-Catalyst Life Studies Lakis Georgiou Shawinigan Chemicals Division, Gulf Oil Canada Limited, Ste. Xarie Road, Ste. Anne de Bellevue, Quebec, PQ, Canada
A m o n g the by-products formed in the cracking of crude oil to produce ethylene are C-5 dienes (mostly isoprene and cyclopentadiene) and other C-5 hydrocarbons. The ethylene and other desirable products are recovered from the cracked oil by fractionation. The valuable C-5 dienes cannot be separated in a pure state by straightforward fractionation because they have similar boiling points to the other C-5 hydrocarbons. Consequently, an enriched C-5 cut is normally obtained containing small amounts of C-4 and C-6 hydrocarbons. During 316
Ind. Eng. Chem. Prod. Res. Develop., Vol. 1 1 , No. 3, 1972
fractionation some of the cyclopentadiene may dimerize to dicyclopentadiene which may be present in such a fraction. I n some commercial processes this C-5 cut is hydrogenated and mixed with gasoline; in others pure isoprene is obtained by extractive distillation techniques. Such a petroleum fraction represents an inespensive C-5 diene source, and it was of commercial interest to polymerize it. Although the heterogeneous polymerization of C-5 dienes with active surfaces as catalysts has been previously reported
The feed polymerized was a petroleum fraction containing essentially C-5 dienes, olefins, paraffins, dicyclopentadiene, and some C-6 hydrocarbons, the major reactants being the C-5 dienes and dicyclopentadiene. Clays, acid-treated clays, and cracking catalysts were used at 1 0O-20O0C, the product being a highly unsaturated, low-molecular-weight resin. Catalyst life was short (ranging from a few hours to a few days). Unlike acid-treated clays, clays and cracking catalysts could b e regenerated.
(Hainner and Steel?, 1959; Soday, 1946), little has been reported on catalyst life. This problem was investigated with a petroleum fraction csoiitaining the C-5 dienes in both batch and continuous operations. Experimental Polymerizations. Bat,ch polymerizations were carried out in a 300-ml stainless steel, electromagnetically stirred autoclave. The air in the autoclave was flushed wit'h purified nitrogen before heating t'he contents. For a pelleted catalyst a basket of stainless steel screen attached to the stirrer was used to hold the catalyst. The apparatus used for continuous fixed-bed polymerizations ill t,he vapor phase is shown in Figure 1. The feed was kept under an atmosphere of purified nitrogen a t -3°C to minimize peroxide formation and dimerization of the cyclopentadiene present in the feed. The calibrated glass contaiiiers ( 3 and 4) weie used to allow part of t'he feed to warm up to room temperature and then be diluted with a known amount of a high-boiling solvent (light Xigerian distillateboiling range 162-270°C) before being pumped to the reactor.
Figure 1
.
Figure 2 shows the apparatus used for continuous liquidphase polymerizations. The pressure in the reactor was maint'aiiied a t 100 psi higher than the vapor pressure of the feed a t t'he reactor temperature, so that' the feed remained in the liquid phase. After separation of t'he reacted solution from the catalyst, the catalyst was washed with benzene, and the unreacted components xere removed by simple distillation up to a pot temperature of 200°C a t 760 torr. I n cases where the feed was diluted with light K'igerian distillate, t'he distillation was carried out a t 30 torr up to a pot temperature of 160180°C. The residue was the resin product. Det,erminat'ioii of the thermal expansion of the feed was carried out by observing the height of the feed level in a vacuum-sealed capillary tube as the temperature was raised. Test Methods and Definitions. Bromine numbers (number of grams of bromine consumed by 100 grams of sample) were determined by use of ASTM Method KO.D1150-61. COP Method 326-58 was used for maleic anhydride values (number of milligrams of maleic anhydride consumed by 1 gram of sample), and -4STM D-154 method was used
Apparatus for continuous vapor-phase polymerization 1. Refrigeration unit 2. Feed tank 3,4. Calibrated glass containers 5. Condensers 6,7. Pumps 8. Flask containing hexyl alcohol 9. light Nigerian distillate storage 10. Preheater stainless steel cannon packing bed 11. Catalyst bed in pyrex glass rector 12. Check valve 13. Glass jacket surrounding reactor 14. Mercury safety manometer Ind. Eng. Chem. Prod. Res. Develop., Vol. 1 1 , NO. 3, 1972
317
I
b T.I.
Figure 2. Apparatus for continuous liquid-phase polymerization B.P.R.
Back pressure regulator Safety valve Temperature indicator Pressure indicator Catalyst bed Condenser
S.V. T.I. P.I. C.B.
C.
Table
I.
Examples of Feed Compositions
Component
C-4 hydrocarbons Isopentane Neopentane n-Pentane Pentene-1 2-hlethylbutene-1 1-4 Pentadiene Trans-pentene-2 cis-Pentene-2 2-Methylbutene-2 Isoprene 2-Methylpentane Trans-1-3 pentadiene Cis-1-3 pentadiene Cyclopentene Cyclopentadiene C-6 hydrocarbons Benzene Unknown high boilers Dicyclopentadiene
1-
A
Feed, wt B
% r
c
D
0.4
0.7
1.7
0.2
9.9
6.5
9.8
6.2
11.2 3.6
8.7 4.2
11.8 3.9
6.4 7.6
7.3
6.7 5.1 3.3
2.4 1.6 2.6 16.7 1.9 5.7 3.6 3.5 11.5 1.2 8.7 1.1 6.2
2.8 13.3 2.0 4.0 5.0 4.3 11.9 1.6 8.6 1.7 9.8
8,s 3.0 1.9 3.0 19.8 1.4 7.0 4.8 3.1 20.2
10.1
..,
4.3 2.7 3.6 22.2 1.4 6.9 5.3 4.1 17.4 1.2
...
...
...
196.1, Siemens, IT. Germany). The disappearance of the monomers was followed by means of gas-liquid chromatography. For the C-5 components a 20-ft X 1/4-iii. (20 wt % Ucon oil LB-550-X on Chromosorb P) column was used a t 78OC and a helium flow rate of 50 ml/min. For dicyclopentadiene a 7-ft X 1/4-in. (3 ft of 12 wt 7*silicone oil DC-704-314 on Fluropak, 4 ft of 12 w t % Ucon oil LB-135 on Fluoropak) column was used a t llO°C and a helium flow rate of 60 ml/ miri. A Hewlett Packard (Quebec, Canada) gas chromatograph (F & 11 720) with a hot filament-type thermal conductivity detector was used with bcth columns. Cracking catalysts used were zeolite XZ-36, eta-alumina, silica-alumina (SlIR-1171 grade 979, l / d in. long X 0.19-in. diameter, 13% d1203), and silica-alumina (25% h1203) from Davison Chemical Co., Xaryland, L-.S..i. Also used Iyere alumiiium silicate pigment ASP-400 and fuller's earth from Debro Chemicals, Quebec, Canada. Acid activated montmorillonite clays K-10-SF and KSF were from Chemetron Chemicalb, Kentucky, T-3.X. Filtrol-13 (an acid-treated clay) was from Filtrol Corp., Los dngeles, CX, C.S.A., and Zeo-karb ion-exchange resin from Permutit Co., S e w York, U.S.A. Results and Discussion
for determination of the solids content (the w t 7, of residue remaining from a 1.2 f 0.1-gram resin sample after being in a n oven for 3 hr a t 105 i 2°C. Yumber average molecular weights were determined cryoscopically in benzene. Surface area measurements were carried out b y use of standard nitrogen techniques on a Suminco-Orr surface area analyzer (Model MIC-103, Kumec Instrument and Control Corp., PA, L7.S.A.). X-ray fluorescence studies were carried out on a Siemens Crystalloflex IV instrument (Model 318
Ind. Eng. Chem. Prod. Res. Develop., Vol. 11, No. 3, 1972
Batch Polymerizations. T h e feed (see Table I for examples) used in the polymerizatlons contained about 0-2 wt yo C-4 hydrocarbons, 10-20 wt 7,C-5 hydrocarbons, 30-50 wt % C-5 conjugated dienes, 20-35 wt % unsaturated C-5 hydrocarbons (apart from the conjugated dienes), 0-12 wt % dicyclopentadiene, and 1-12 mt 70C-6 hydrocarbons (mainly benzene). The thermal expansion of the feed \vas considered in carrying out batch runs and the autoclave filled accordingly. As much as a 30Y0 increase in volume was observed in varying the temperature from 25-200°C. Table I1 lists some of the results obtained with the catalysts tried in
Table
II.
Batch Polymerizations
Using feed A; see Table I
Catalyst used
Zeokarb (ion-exchange resin) Fluid zeolite cracking catalyst XZ-36 Aluminum silicate pigment ASP 400 Eta-alumina Silica-alumina cracking catalyst (25% &oO) Fuller's earth (Attapulcus clay) Silica-alumina cracking catalyst 13% Al2o3 Acid-activated Montmorillonite clay K-lOSF
% (Wton
W t % on charge catalyst
Reaction time, hr
10.0
3.5
10.0
3.5
10.0 10.0
Reaction temp, OC
charge) resina yield
R Yield I"
Wt% solids content of resina
(wton charge) nonvolatile product
Br no. of resina
Maleic anhydride value of resina
No. av mol wt resina
