Chemicals from Petroleum Fractions. 1. Benzene’ Amir Badakhshan, Amir H. Azimipour, Farrokh Kamali, Aramais Nerssisian, Morteza Hashemi, Nasser Alizadeh, and Parviz Sarram National Iranian Oil Co., Research Center, Tehran, Iran
A narrow fraction (boiling range 6 5 9 5 ° C ) of south Iranian crude oil was reformed over platinum catalyst in a catalytic reforming pilot plant to produce benzene. Higher molecular weight aromatics such as toluene, ethylbenzene, and xylenes were also produced. The work was conducted under several reforming conditions. Severe reforming conditions were also investigated to study dehydrogenation reaction on the light feedstock having more thah 80 wt yoof paraffin hydrocarbons. The yield of aromatics increased from 26.043.0 wt of Cj+ yield fbr the range of mild to severe conditions. The conversion of paraffins to benzene b y dehydrocyclization reaction showed a small increase from 2.7-3.0 wt for the same range of conditions, while the total conversion of paraffins to aromatics (benzene, toluene, xylenes, and ethylbenzene) increased from 15.5-20.0 wt yo b y dehydrocyclization.
7 0
7 0
T o d a y , catalytic reforming of petroleum fractions is the main source for product’ioii of aromatic hydrocarbons. Reforming of light aiid heavy naphthas (boiling range about 100-150°C aiid 150-200°C) has been widely used in the oil industry (“Reforming,” 19681, but preparation of be~izeneby catalytic reforming of light gasoline (boiling range about 60100°C) is still under iiivestigatioii (Smol’nik et al., 1968). Since 1958 a number of patents 011 this process have been taken out by petroleum companies (Erigel and Waldly, 1966; Skraba, 1964). The majority describes reforming a fraction having boiliiig range-e.g., of 65-85°C in t’he presence of platiiiuni catalyst (Haensel, 1959)-some using reactor temperatures and pressures in the range of 480-510°C (Coley et al., 1958), 21-42 kg/cm* (Drehman and Hepp, 1966). The yield of beiizeiie from cyclohexane of feedstock approaches l007,, but coiiversioii of methylcyclol~eiitaiie to benzeiie is relatively lo^ (Honeycutt, 1962). According to Selsoii (1969) the worst benzene, tolueiie, and xylene feedstocks are those froin Middle East crude oil. This was also coiifirmed by coniparing Rfaslyaiiqkii mid 13arkaii’s work (1969) with the experiments. The yield of beiizeiie obtaiiied by Maslyanskii and 13arkaii was higher thaii that obtained 011 a south Iraiiiaii fraction because of the high 1ial)htheiiic coiiteiit of the feedstock used. The experiments carried out are of special interest since they investigate dehydrocyclization of paraffins using a light gasoliiie fraction which has high paraffin content. Reforming of light fractioiis having such high paraffin contents as are used here has not been performed previously. ~
Experimental
The experiments were carried out on a light fraction of Aga-Jari crude oil iii the following pilot plants. The light gasoline fractioii, boiliiig range of 65-95”C and contaiiiiiig CS to C,hydrocarbons, was prepared iii an atmospheric batch distillation pilot plant having a still capacity of 300 liters. Feedstock impurities were removed iii a 24-literjday hydrotreating pilot plant. Results are shown in Table I. Corre.pondence should be addressed to 31.Shahab, liebearch IXvibion, National Iranian Oil Co., Tehran, Iran. 330
Ind. Eng. Chem. Prod. Res. Develop., Vol. 10, No. 3, 1971
Some laboratory reformiiig ruiis were carried out in a bench scale coiitiiiuous unit, where the range of procchs vaiiables was choqeii for the o1)eratioii of a reforming iiilot phiit. The reformiiig study was carried out i i i the catalytic reformiiig pilot plant having a capacity of 24 litcr.;/day aiid equipped for gas recycle operations a i d continuous distillation of reactor products. The reactioiis were isothermally 1)er-
Table 1. Properties
of Feedstock after Hydrotreating AAST.\II)i.tillatioii, “C
113P Vol yo recovered 5 10 20 30 40 50
60 70 80
90 95
FI31’ Sp gr at 60/60°F Sulfur content, ppni r\fercaptan sulfur coiitent, ppni 13romine No., g/100 g Octane S o . . F1 clear
64 0 67 69 70 71 72 72 73 75 79 85 32 96
0 0 0 0 0 5 5 7 0 0 0 0
0 6835 27 5 0 54
Hydrocarboii-Type =iiialysiy, n’t yo Xaphthenes 11 04 Cyclohexane 3 54 ~Iethyleyclopeiitaiie 7 50 .lromatics 5 51 I3eiizene 3 68 Toluene 1 83 Paraffins 83 45 n-Paraffins 40 00 iso-Paraffin43 45
0 6 1 5
as
Recycle Gas
-
I
I
-
O
Ih
Figure 1. a.
b. c. d. e.
Simplified flow diagram of catalytic-reforming pilot plant f.
Fresh hydrogen for start-up Feedstock De-oxo catalyst for 0 2 removal Drier Overhead condenser
g.
h. i. j.
Deareator Bottom cooler Molecular sieve Preheater Reactor
k.
Recycle gas compressor Gas separator Stabilizer
I. m.
Table II. Operating Conditions and Products, Case 1 Run ~
1
2
~
~
~
~~~
~~~~~~~~~~~~~~
~~~
3c
4
Conditions Reactor temp, "C 500 Reactor pressure, kg/crn2 20 LHSV, hr-l 2.08 Hydrogen to hydrocarbon,. mol ratio 6.0 No Loss Product Yields, Wt
H2
0.92 2.06 4.59 6.66 2.39 1.78 3.60 2.60 75,40 Total CS+Yield
c1 C'?
clt i-c4 n-C,
i-cj n-C5 ('e+-
Wt yo of charge Vol yo of charge Octane S o . , F1 clear
IBP Vol Yo recovered 5 10 20 30 40 50 60 JIaterial balance checks available
520 20 2.05 5.2
530 20 2.08 4.5
0.93 1.46 3.62 8.62 3.67 2.97 3.75 2.70 72.28
0.92 1.81 5.OG 10.99 4.79 4.61 3.90 2.78 65.14
0.76 4.18 8.71 6.00 4.15 4.G 4.19 2.95 64,fjl
71.82 69.3 0.7291 82.5
71,75 G7.2 0 . i254
31.5
24.5
38.5 42.5 50.5 56.0 62 0 67.0 72.0
33.5
81.60 78.73 79.75 74.0 0 . 7089 0.7139 79.2 81.1 ASTN I)istillatioii, "C 25.5 26.5
Sp gr a t 60/6O0F
a
510 20 2.05 5.7 yo of Feed.
35.5 42.5 51.5 59.0 64.0 70.0 75.0 fl. of feedstock, it was coiicliided that: Optimum coiiditioiis for protluctioii of benzene from the fraction used are Reactor temp., " C Reactor pressure, kg/cm2 LHSV, hr-l H2/HC, mol ratio
510 20 2.05 5 7
a t which the yield of benzene and total aromatics are
13e1izeiie Total aroniatic\
Vol % of C,' yield
VOl % of feed
W t % of feed
15 30 29 20
11 30 21 60
14 0 26 5
Reduction of working prensure from 20-18 and 15 kg/cm2 a t 52OOC in the reforming leads to decrease in total aromatic products from 34.5-20.4 vol % of C6+yield. Conversioii of methylcyclopentane to aromatics in this
Table V. Estimated Conversions in Production of Aromatics in M i l d and Severe Conditions Mild conditions, 510"C, 20 kg/cm2 Wt % Conversion, of feed %
.Ironlatic from cyclohexane Aromatic from methylcyclopentane .ironlatic in the feed Aromatic from dehydroc yclization of 1)araffiirs Total yield of aromatics
Severe conditions, 530°C, 20 kg/cm2 Wt % Conversion, of feed %
._______
3.54
100
3.54
100
4.50
60
4.87
65
5 . 5 1 lTnchairged 12.95 26.50
15.5
5.51 t'iichnngcd 16.88 _ __ 30.80
20.2
process was about 60% in the mild and 65% in the severe conditions. From the yield of benzene produced in the mild and severe conditions, the ratio of reformillg pactiolis could have beell as shown in Table IV. From the yield of aromatics produced in the mild and severe conditions, the reactions as shown in Table V probably took place.
Drehman, L. E., Hepp, H. J. (to Phillips Petroleum Co.), u. s. Patent 3,258,503 (June 28, 1966). Engel, J. H., Waldly, R. W. (to Phillips Petroleum Co.), U. S. Patent 3,280,022 (Oct. 28, 1966). Haensel, V. (to Univ. oil Prod. C0.h u. S.Patent 2,911,451 (Nov. 3, 1959). Haensel, V., Addison, G. E., “Seventh World Petroleum Congress,” Vol. 4, pp. 113-23, Elsevier, New York, N. Y., 1967. Honeycutt, E. 111. (to Sun Oil Co.), U. S. Patent 3,070,637 (Dec. 25, 1962). Rlaslyanskii, G. Tu’., Barkan, S. A,, Int. Chem. Eng.,8 (Z), 218-20 (1969) \ - - - - I
literature Cited
Ciapetta, F. G., Petro./Chenz. Eng., C19-C31, Rlay 1961. Coley, J. It., Evering, B. L., 111cCollum J. D. (to Standard Oil Co.), U. S. Patent 2,861,944 (Nov. 26, 1958). Connor, Jr., J. E., Ciapetta, F. G., Leum, L. N., Fowle, 111. J., Ind. Eng. Chem., 47 ( l ) , 152-6 (1955).
Nelson, W. L., Oil Gas J.,67 (5), 104-5 (1969). “Reforming,” Hydrocarbon Process., 47 (9), 155-62 (1968). Skraba, F. W. (to Phillips Petroleum Co.), U. S. Patent 3,121,676 (Feb. 1964). Smol’nik, Y. E., Bryanskaya, X. G., Vampol’skii, K . G., Shurba, A. S., Cherednichenko, G . I., Sobol, E. P., Khznz. Tckhnol. Topl. lVfaseZ, 13 (6), 10-12 (1968). 1~ECcIvi.ofor review September 9, 1970 ACCEPTEDMay 12, 1971
Reverse Osmosis Performance of Sulfonated Poly(2,6=dimethylphenylene Ether) Ion Exchange Membranes Shiro G. Kimura General Electric Corporate Research and Development, Schenectady, S.Y . 12301
Sulfonated poly(2,6-dimethylphenglene ether] cation exchange membranes show promise as reverse osmosis membranes, having from 8 to 10 times CIS high water permeability as homogeneous cellulose acetate at the same salt rejection levels for 1 % NaCl feeds. Membrane morphologies can b e varied to give u wide range of salt rejections and water permeabilities. Since the principal mechanism of salt rejection is Donnan exclusion, membrane performance is highly dependent on feed composition.
T h e r e exist, basically, two types of reverse osmosis membranes -solutioii-diff usion mcmbraiies with or Ivithout coupled flows and ion exchange membranes. 111 a solution-diffusion membrane, solvelit a i d solute pass through the membrane by first being dissolved in the membrane polymer aiid then diffusing across. Salt rejectioii occurs because solvent and solute solubilities and diffusion coefficients differ. Flow coupling exists when there are membrane imperfections of sufficient size to permit viscous flow and allow solute to be transported by drag fbrces. Cellulose acetate membranes are examples of solution-diff usion membranes. Ion exchange membranes are viscous flow xiiembranes which exclude salt by electrical forces. When ai1 ion eschaiige membrane is immersed in an electrolyte solution, there is a tendency for counterions to diffuse out into the solution and coions to diffuse from the solution into the memhraiie because of concentration differences betweeii the meinbralie aiid the surrouiiding solution. Thus a charge imbalaiice is created, and the membrane takes 011 n potential, the Doimaii poteiitial, which inhibik further coion upt,ake. -1 cation exchange membrane takes 011 a negative charge mid, thus, excludes anions. Since electroiieutrality must be maiiitniiied, coion rejection is equivalent to salt rejection. Sulfonated
poly(2,6-dimcthyl~)liciiylciic cthei,) mein1)raiies are of tliis type. 11IcKelvey et al. (1057, 1964) first iiitroduced the idea of usiiig Doiinnii rcjcctioii as a Iiasis for reverse omobi.;. Experimental Procedure
Sulfonated Poly(2,6-dimethylphenylene ether) Freparation. Poly(2,6-diniethylpheiiyleiic ether) wnb aulfoiiatrd using the procedure of Fox aiid Sheiiian (1966). U l ~ o i iwctioii i with chlorosulfonic acid ~ ~ o l \ ( 2 , 6 - d i m e t h ~ l ~ ) l i c i i yether) l~iic becomes:
r
1
wheie I may vary fiom 0 to 1. Complete sulfoiintioii, .r = 1, correspoiids to aii 1011 e\cliaiige capacity (IEC’) of 5.0 mcy “/gram of dry pols mer. Ind. Eng. Chem. Prod. Res. Develop., Vol. 10, No. 3, 1971
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