Bromination of Kerosene Obtained from Kuwait Oil Fields Mousa J. Ijam* and Shaikha Y. AI-Qatami Chemistry Department, Kuwait University, Kuwait
No systematic studies have been reported correlating t h e physical properties of brominated kerosene with t h e degree of bromination. T h e present paper represents such a study for a kerosene fraction boiling between 180 and 220°C obtained from a Kuwait oil field and having a low aromatic content (high furfural miscibility temperature). This kerosene was brominated from 6.5 to 36% bromine content in steps of approximately 0.2 mol of bromine. T h e products have been checked for purity by gas chromatography and characterized by their ir, uv, and n m r spectra. T h e measurements comprise elementary analysis, refractive index, surface tension, furfural point, kinematic viscosity, specific gravity, and molecular weight. These data are correlated with t h e degree of bromination and t h e average molecular
composition obtained.
Introduction Chlorination and bromination of petroleum hydrocarbons and their utilization are becoming increasingly important and have received considerable impetus in recent times. Both the physical and chemical properties of the chlorinated and brominated products of lower molecular weight fractions have been extensively studied and recorded in the literature. However, not much can be found on the bromination of the heavier petroleum fractions. For the latter group the industrial applications have far outstripped studies on fundamental physical and chemical properties. In fact, for certain fractions, data are lacking entirely. This is due to the increased complexity of some of the lighter petroleum fractions extending beyond the gasoline range. Although lack of knowledge of the exact chemistry of bromination of the higher petroleum fractions has not impeded their present industrial applications, it is generally agreed upon that such data would substantially broaden their scope. On the other hand, lack of physical data does markedly hinder progress in this field, since such data are needed for plant design and control of operation of the bromination procedure. Only fragmentary data have appeared in the literature on the physical properties of the brominated kerosene fractions. In 1964, the bromination of n-decane a t its boiling point (at 115 mm) had been carried out a t Shell Research Laboratories (Shell, 1966), the reaction mixture being irradiated with uv light. The work-up of the reaction mixture gave 66% decyl monobromide and 32% unreacted material. Blouri, et al. (1962), studied the bromination of n-heptane and long-chain aliphatic hydrocarbons present in the white spirit. These reactions were carried out in the gas phase, and the contact time of 0.2 sec was found sufficient for complete halogenation a t 300°C. They reported that, in the case of n-heptane, 2-bromoheptane was the predominant product. The aim of the present work is to present a systematic investigation on the preparation and study of the physical properties of brominated kerosene fractions (i.e., the commercial fractions of petroleum which are rich in longchain aliphatic hydrocarbons). Experimental Section Kerosene (bp 169-256°C) was obtained from Kuwait National Petroleum Company (K.N.P.C.) as a distillate fraction of crude oil from the Burgan oil field. A portion of kerosene was washed successively with sulfuric acid, sodi350
Ind. Eng. Chem., Process Des. Develop., Vol. 13, No. 4, 1974
um hydroxide solution, and water, then distilled under atmospheric pressure. The distillate which had a boiling point of 180-220°C was used for subsequent bromination. Table I summarizes its physical properties. The elementary analysis and molecular weight determination indicated the kerosene to have the average composition CllH24. Ir (Beckman IR-12), uv (Unicam SP-800, 200-450-nm range), and nmr spectra (cf. Jaffk, 1966; Nakanishi, 1966; Roberts, 1959) were used to determine the hydrocarbon type and structural group (14.3% aromatic compounds expressed as R-C6H4-H where R = CH3, and 85.7% aliphatic compounds with secondary (H)s/primary (H)s = 1.88). 1. Method of Bromination. Kerosene (200 g, 1.27 mol) was treated with bromine (37.6 g, 0.235 mol) inrthe liquid phase a t 85°C. A uv lamp was used as the source of 350nm radiation to initiate the reaction. The weight of yield after bromination was 219.0 g and the product had teargas properties (lackrymator). .Physical properties of this product are as follows: n25D, 1.4408; sp gr, 0.8263 (25°C); viscosity, 1.413 (25°C); surface tension, 29.942 ("(2); and molecular weight, 166.0. The degree of bromination was determined by repeating the same procedure and conditions mentioned above for ten different experiments a t various bromine concentrations (from 0.235 to 2.0 mol). The results of percentage increase in weight in a series of bromination of kerosene (experiment no. 1-10) are given in Table 11. 2. Analytical Procedure. The following analytical procedures were applied to determine the physical properties and the general structure of the feedstock and other brominated products. Refractive indices were determined on an Abbe refractometer using the sodium D line (A.S.T.M. Standard D 1218-52 T). For surface tensions a t 2 5 T , the capillary rise method was used (Findlay, 1965). Viscosities were obtained kinematically by the method of Ruh, et al. (1941). Specific gravities were determined pycnometrically under thermostatically controlled conditions a t 25°C (Ellis and Mills, 1953). Mean molecular weights were determined by the freezing point depression method (Rall and Smith, 1936). Furfural miscibility temperatures were obtained by the method of Rice and Lieber (1944). The variations of these properties with the bromine content in brominated kerosene products are presented in graphical form in Figures 1-6. Results a n d Discussion 1. Efficiency of Bromination at Constant Tempera-
6
e
f
t
'V
371
1.460
iiI
E
26
1
o
a
5
1
5
2
0
2
5
a
3
5
u
)
Brmin
P-l
Figure 2. Variation of surface tension at 25°C in dynjcm with
bromine content in brominated kerosene.
1.430
1
o
2.L s
a
1
5
x
,
3
bent h i $
0
3
5
4
Q
I
Figure 1. Variation of refractive index at 25°C with bromine con-
tent in brominated kerosene. Table I. Physical Properties of the Kerosene Distil1at.e
Characteristics
Values
BP, "C (mm) Refractive index ( n ' j ~ ) Specific gravity (25°C) Viscosity (25'C) Surface tension (25°C) Furfural point. ("C) Pour point ("C) Flash point ("C) Microanalysis (% C) Microanalysis ( % H) Molecular weight M R D calculated MRn observed a t 25OC
180-220 (760) 1,4284 0.7685 1.285 28.153 94.40 26.65 46.65 85.15 14.55 157.00 52.32 52.45
1.0
I 0
5
15
x)
Lo
Rrmt-
n
0
35
"
Figure 3. Variation of viscosity at 25°C with bromine content in
brominated kerosene.
1.2
i
Table 11. Percentage Increase in Weight in a Series of Brominations of Kerosene
Expt
Bromine,
Final wt,
no.
g
g
Increase in wt, g
37.6 64 .0 96 . 0 128.0 160.0 192 . O 224 .0 256 . 0 288 .0 320 .0
219 . O 232.8 243.0 258.0 265.4 283.4 294.9 297.5 302.8 318.0
9.5 16.4 21.5 29 . O 32.7 41.7 47.9 48.7 51.4 59.0
1
2 3 4 5
6 7 8
9 10
Time required, hr
I 5
3
Br,
-
R-Br
+
HBr
r n 2 5 3 0 z i 4 0 ycrcrnt Brminc
Figure 4. Variation of specific gravity at 25°C with bromine con-
tent in brominated kerosene.
10.5
12 13 17
10). Assuming that the only reaction would be substitution of a bromine atom for a hydrogen atom, the amount of bromine lost during the reaction was calculated according to
+
IO l5
4 5 6.5 7 9.5
ture. Samples of .brominated kerosene containing from about 9.5% to approximately 59.0% bromine by weight were used (Table II) to determine the relationship between the efficiency of bromination and the bromine content in brominated kerosene a t 85°C. (experiment no. 1-
R-H
-.+----
(1)
where R represents a molecule of kerosene or brominated kerosene. Results obtained are listed in Table In.
The efficiency of bromination was determined according to the values obtained from the results of all ten experiments. The amount of bromine in the brominated kerosene was multiplied by 2 to give the total amount of bromine used up in the reaction. This value was then subtracted from the total bromine used in each experiment to give the loss figure. Finally, one hundred minus the loss figure gives the efficiency of bromination. 2. Determination of Bromine Atoms per Molecule of Brominated Kerosene. The calculation of the number of bromine atoms was based upon the assumption that there was no appreciable breakdown or polymerization during the bromination process at constant bath temperature (85°C) and in the presence of uv light. This also takes into consideration that the reaction between kerosene and bromine is a free-radical substitution reaction. From the molecular weight of the original kerosene and the percentage of bromine in the brominated products obtained by microanalysis, the following equation can be derived Ind. Eng.
Chern., Process Des. Develop., Vol. 13, No. 4 , 1974
351
7 ZX)
170
t /
I 0
lsJl
o
s
lo
z o 2 s x ) 3 5 4 0
Rrcml s m m c
Figure 5. Variation of molecular weight with bromine content in brominated kerosene.
% Br in brominated
% Loss of total
kerosene
bromine used
9.5 16.4 21.5 29 . O 32.7 41.7 47.9 48.7 56.5 59 .O
- 1.06
1
2 3 4 5 6 7 8
9 10
no.
1 2
3 4 5 6 7 8
9 10
-2.50 1.04 9.37 17.62 13.12 24.27 23.82 28.61 26.25
x)
35
40
Refractive index (25OC)
Density (25OC)
Viscosity (25OC)
Mol wt
1.4551 1.4498 1.4472 1,4514
0.9412 0 ,9225 0.8943 0.9035
1.664 1.502 1.579 1.561
190 183 175 168
Table VI. Efficiency of Bromination under Different Conditions No. of run 1
2 3
4
% Br
C
H
Br
6.9 12.71 16.89 21.26 24.09 27.84 28.92 32.21 36.33 36.39
10.99 10.96 10.92 10.64 10.63 10.54 10.52 l b .50
21.96 21.70 21.33 21.28 20.64 19.96 19.66 19 .OB 19.45 19.49
0.14 0.28 0.39 0.50 0.59 0.71 0.74 0.88 1.01 1.03
10.06
No. of run 1
Av mol formula
10 .OB
15,mp-,,25
Figure 6. Variation of furfural miscibility temperature with bromine content in brominated kerosene.
2 3 4
Table IV. Calculations of Bromine Atoms per Molecule of Brominated Kerosene Expt
10
Table V. Physical Properties of the Brominated Kerosene under Different Conditions
Table 111. Efficiency of Bromination at Constant Temperature No. of expt
5
79.91% %Br = 157 + 78.916n
(2)
where n is the number of bromine atoms substituted, 157 is the experimental molecular weight of kerosene, and 157 79.916n is the molecular weight of brominated kerosene. Solving the above equation for n yields
+
157 X %Br n = (79.916 X 100) - (78.916 x Br)
(3)
% Br in brominated kerosene
% Loss of total bromine used
29 . O 22.5 21 .o 14.9
9.37 29.68 34.36 53.46
(200 g, 1.27 mol) and bromine (128.0 g, 0.8 mol) under the following conditions: (a) a t 85°C with uv light (run no. 1); (b) a t 85°C without uv light (run no. 2); (c) a t 120°C with uv light (run no. 3); and (d) a t 40°C with uv light (run no. 4). Their physical properties are listed in Table V. The amount of bromine lost was calculated on the same basis as before. The data obtained are listed in Table VI, which show that the efficiency of bromination appears to be greater a t 85°C and in the presence of uv light (which is considered to be one of the most important factors initiating such substitution reactions which follow a chain reaction mechanism). The results were in agreement with Hass rules (Hass, et al., 1935, 1936).
Acknowledgment The authors wish to express their thanks to the staff of the chemistry laboratories of the Kuwait National Petroleum Co. for the supply of crude kerosene and for their help with some of the physical analyses. Literature Cited
where % Br is the experimentally derived value for the brominated kerosene in each experiment. The results of these calculations are summarized in Table IV. 3. Efficiency of Bromination under Different Conditions. To find the relation between the efficiency of bromination and bromine content under different conditions (e.g., heat and light), samples of brominated kerosene were obtained by treating the same quantities of kerosene 352
Ind. Eng. Chem., Process Des. Develop., Vol. 13, No. 4 , 1974
Blouri, B., Cerceau. C., Fauvet, J. E., Bull. SOC.Chim. Fr., 477 (1962). Ellis, R. 6.. Mills, A. P., "Laboratory Manual of Physical Chemistry," pp 15, 23,McGraw-Hill, N e w York, N . Y . , 1953. Findlay. A , , "Introduction to Physical Chemistry," pp 104, 109, 21 1-214, 3rd e d , Longmans, London, 1965. Hass, H . B., McBee. E. T.. Weber, P., Ind. Eng. Chem., 27, 1190 (1935).
Hass, H. P., McBee. E. T., Weber, P., Ind. Eng. Chem., 28, 333 (1936). Jaffe, H. H., Orchin, M . , "Theory and Applications of Ultraviolet Spectroscopy," pp 242, 253, Wiley, N e w York, N. Y . , 1966.
Nakanishi, K., "Practical Infrared Absorption Spectroscopy." pp 14, 20, 26. Holden-Day, San Francisco, Calif.. 1966. Rall, H. T., Smith, H. M.,Ind. Eng. Chem., Anal. Ed., 8, 324, 436 (19361. , - - - /
Rice, H.T.. Lieber, E., Ind. Eng. Chem., 16, 107 (1944). Roberts, J. D., "Nuclear Magnetic Resonance: Application to Organic Chemistry." pp 20, 22, 23, McGraw-Hill. New York, N. Y., 1959.
Ruh. E. L., Walker. R. W., Dean, E. W.. Ind. Eng. Chem., Anal. Ed., 13, 346 (1941). Shell International Research, Neth. Pat. Appl., 6,413,449; Chem. Abstr.. 65. 12106a (1966).
Received for review October 23,1973 Accepted April 16,1974
Design of Direct Contact Humidifiers and Dehumidifiers Using Tray Columns Everett C. Barrett* and Stephen G. Dunn Hatch Associates Ltd.. Toronto. Ontario. Canada M4T 7L9
Simultaneous mass and heat transfer equations for dehumidifying or humidifying in direct contact tray towers are presented and a solution procedure outlined which is readily adapted to a digital computer. T h e mass transfer coefficients are calculated from t h e penetration theory and t h e Chilton-Colburn analogy is used for heat transfer coefficients. T h e equations apply to a wide range of systems without t h e limitations of previous methods and can be used for both superheated and supersaturated (fogging) vapors. Analysis of plant data for a hydrogen sulfide-water dehumidifier on sieve trays shows good agreement between measured and calculated values. Design of a hydrogen-water h u midifier/dehumidifier system on grid trays indicates the presence of fogging in t h e dehumidifier. If 50% or more of t h e fog is scrubbed out below each tray, only a small amount of fog remains in the exit gas.
The success of the Canadian nuclear power program is accelerating the growth of Canada's heavy water industry. Direct contact cooling, dehumidification, heating, and humidification of very large gas flows are an important part of heavy water production processes now in use or being developed (Rae, 1971). These involve mass and heat transfer performance of direct contact sieve and grid tray contactors under more severe conditions than treated by previous design methods. The new method reported here was developed during studies of heavy water processes undertaken for Atomic Energy of Canada Limited. Direct gas-liquid contact for gas cooling and dehumidification is used where fouling or pressure drop considerations are of importance or where a low heat transfer resistance is required. With dusty or corrosive gases or with corrosive cooling water, fouling in a tubular heat exchanger may be unacceptable while in applications such as barometric condensers, the pressure drop resulting from a velocity needed to provide a reasonable heat transfer coefficient would be higher than allowed. Problems associated with direct contact heat transfer are the potential incompatibility of the gas and liquid and the absorption of the gas in the cooling liquid. Design methods for direct contact dehumidifying incorporating varying degrees of simplification have been proposed. The enthalpy potential method first developed by Merkel in 1925 and also used in cooling water tower design has been reported by Kern (1950), Bras (1956a), and Olander (1961). The approach is only valid for systems with a vapor mole fraction in the gas below 0.15 as it assumes that mass transfer is proportional to the humidity driving force rather than the vapor partial pressure driving force. It is also restricted to systems such as air-water with a Lewis number of unity. Additional restrictions are detailed by Bras and Olander. In a further article Bras (1956b) developed a method for saturated gas-vapor mixtures with a small gas-liquid A t while Kern (1950) ex-
panded the enthalpy potential method for Le # 1 but still retained the humidity driving force which limits the method to low humidities. Fair (1972a,b) based his method on overall mass transfer coefficients and related them to heat transfer by analogy. To apply this method to tray columns the Carey temperature efficiency must be assumed equal to the Murphree mass transfer efficiency. This approach is not practical for a tray by tray calculation. Olander (1961) proposed a design method based on material and enthalpy balances assuming a constant height of gas phase transfer unit and appropriate heat and mass transfer analogies. His method applies to superheated vapors only. None of these previous methods accounted for the solubility effects of the gas in the liquid phase as they were concerned with relatively insoluble gases in low-pressure systems Because mass and heat transfer performance of direct contact sieve and grid tray contactors under more severe conditions than treated by previous methods was to be examined, a new approach was necessary. The systems to be studied were water-hydrogen at lo00 psia and temperatures of 100 to 625°F and water-hydrogen sulfide a t 200300 psia and temperatures of 80 to 270°F. Because the vapor phase Lewis number of the water-hydrogen system a t high temperatures is greater than 1 the possibility of supersaturation or fog formation had to be considered. In the water-hydrogen sulfide system the solubility of hydrogen sulfide in water and the resulting heat effects had to be accounted for. Mass and heat transfer rate equations for these conditions are developed and applied using the penetration theory for mass transfer coefficients and the Chilton-Colburn analogy for heat transfer coefficients. Mass and Heat Transfer Equations The mass and heat transfer relations developed are based on the gas and liquid flows on the tray shown in Figure 1, and the gas-liquid interface shown in Figure 2. Ind. Eng. Chem.. P r o c e s s Des. Develop., Vol. 13, No. 4 , 1 9 7 4
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