I n d . Eng. Chem. Res. 1990, 29, 661-669
667
Determination of Sulfonation Conditions of Postdodecylbenzene Bilsen Besergil Central Quality Laboratories, P E T K I M , Petrochemical Corporation, P.K. 12, Izmir, Turkey
Bahattin M. Baysal* Department of Chemical Engineering, Bogazici University, 80815 Bebek, Istanbul, Turkey
High molecular weight alkylbenzenesulfonic acids are starting materials for the production of detergent-dispersant additives for lubricating oils. The raw materials for alkylbenzenesulfonic acids are heavy alkylates which are called postdodecylbenzene. This material is produced as a byproduct during the production of dodecylbenzene. In this work, the sulfonation processes and parameters for postdodecylbenzenesulfonic acid formation are studied. For this purpose, sulfonations are carried out according to two different processes using different concentrations of the sulfonating agent and the diluent. Products are investigated from the point of view of yield, molecular weight, inorganic acid content, and unsulfonable oil. Thus, industrial sulfonation process and sulfonation contitions are determined for PDB.
I. Introduction Postdodecylbenzene (PDB) is a heavy alkylate obtained as a byproduct of plants. It is used as a raw material for the production of lubricant additives, which are the rareearth salts of high molecular weight alkylbenzenesulfonic acids. In previous work, the properties and the composition of PDB were determined, and PDB was found to be a mixture of 30% mono-, 49% m-di-, and 21% p-dialkylbenzenes (Begergiland Baysal, 1989). It is well-known that monoalkyl- and m-dialkylbenzenes are easily sulfonated, whila p-dialkylbenzenes are resistant to sulfonation reactions. In the literature, the sulfonation reactions of various types of alkylates were studied, and different yield values in the range 63-88% were reported (Gilbert and Veldhius, 1958; Lavigne and Huges, 1969). Alkylates containing 36% mono-, 47% m-di-, and 17% p-dialkylbenzenes yield 87% sulfonic acid (Sweeney and Hudson, 1955; Kirk and Shadan, 1956; Gilbert and Veldhius, 1958; Begergil and Baysal, 1989). The sulfonation procedure of PDB used in this work gives a yield of 87%. The sulfonation yields are identical if we compare the composition of our PDB to the alkylate composition cited in the above given literatures.
In the case of process 11, PDB and spindle oil were placed together in the reactor. The same procedure as process I was applied. Tests. To determine the sulfonation efficiency, various test methods were used. For this purpose, the percentages of unsulfonated oils (a), raw sulfonic acids (RSA), pure sulfonic acid ( b ) ,and inorganic acids ( c ) , and the average molecular weights (MWAv)were determined according to the procedures described by Holtzman and Mildwidsky (1965). For acidity values and total acid number (TAN) tests, ASTM D-664 was used. 111. Experimental Results The chemical reactions of the sulfonation of PDB are given below, where R1 and R, represent alkil groups having more than 16 C atoms. In order to choose a suitable
?2
I
S03H h
11. Experimental Section Materials. PDB and oleum are obtained from PETKIM, Petrochemical Corp., Izmir, Turkey. Spindle oil (a low-viscosity lubricating oil) is obtained from Aliaga Refinery Corp., Izmir, Turkey. Equipment. Sulfonation reactions were carried out in a three-necked, 4-L round flask which was equipped with a powerful stirrer. The temperature of the reactor was controlled by using a water bath. A Beckman researchtype potentiometer with Calomel and glass electrodes was used for titrations. Preparation of the Samples. The samples were prepared by the sulfonation of PDB using two different processes (William and Le Suer, 1956). After each sulfonation reaction, the mixture was transferred to a separatory funnel, and the organic and inorganic phases were separated. According to process I, PDB was placed in a sulfonation reactor, and oleum was added slowly from a separatory funnel for about 1h. Then spindle oil was added. During the sulfonation reaction (about 2 h), the contents of the reactor was stirred continuously, and the temperature of the reactor did not exceed 50 "C.
S03H
sulfonation process, to find the best sulfonation composition, and to obtain an optimum phase separation temperature and time, two different processes described in the Experimental Section were studied at various conditions. The results are presented in two sections. The effect of the quantity of oleum used in the sulfonation reaction on the products is reported in the first section. The affect of the phase separation conditions of the products from acid sludge and the related parameters are given in the second section. A. Quantity of Oleum. The results of seven sulfonation reactions which were carried out according to processes I and I1 are given in Table I. Organic and acid sludge phases are separated after the reaction mixture stood for a week at ambient temperature. Each organic phase is weighed and then analyzed (Holtzman and Mildwidsky, 1965). The sulfonation yields in the last column are calculated based on the obtained amount of the organic phases and 100% sulfonation of PDB used assuming the average molecular weight of sulfonic acid is 470 and of PDB is 370.
0888-5885/90/2629-0661$02.50/0 0 1990 American Chemical Society
668 Ind. Eng. Chem. Res., Vol. 29, No. 4, 1990 25
Table I. Sulfonation Reactions: Compositions, MWAV, and Sulfonation Yields of Products4 oleum, g/100 g PDB a , 9i
1 2 3 4 5 6 7
56 82 110 123 148 167 175
65.2 50.0 40.0 35.8 34.1 34.1 33.9
b, % c, 9i Process I 33.0 1.95 46.1 4.27 55.2 5.27 58.7 6.00 60.2 6.17 59.2 7.20 89.6 7.00
1 2 3 4 5 6 7
56 82 110 123 148 167 175
76.8 66.2 54.5 49.0 42.3 30.0 40.0
Process I1 22.3 1.01 31.9 2.06 43.9 1.75 47.9 3.39 52.8 5.32 56.5 4.85 55.5 4.83
run
(I
MWAv
yield, %
474 494 466 470 465 464 473
43.1 59.8 77.5 86.9 88.2 86.3 85.0
494 483 465 462 466 468 470
27.1 39.4 58.9 62.0 76.7 75.3 74.0
20
0
a, unsulfonated oil; b, pure sulfonic acid; c, inorganic acid.
U
:
'5
i\
4 U
C
P -c tc
5 I
I
I
I
1
2
3
4 Time, hrs
's-
-
5
6
Figure 2. Effects of phase seperation temperature and time on the amounts of inorganic acid in organic phases.
50
103 Olcum.g/lOOg PC0
-
150
203
Figure 1. Effects of the amount of oleum on sulfonation yields according to processes I and 11.
The following results can be obtained from analysis of the data given in Table I. 1. The sulfonation yield of PDB, which is calculated from the amount of sulfonic acid ( b ) ,is increased by increasing the amount of oleum used in the sulfonation process. However, after a certain concentration, an increase in oleum will cause a decrease in the yield. This indicates the decomposition of the sulfonic acid formed due to severe sulfonation conditions. 2. As the amount of sulfonic acid increases, the amount of inorganic acids ( c ) , adsorbed and suspended in the organic phase also increases, due to the dispersant properties of sulfonic acids. 3. The average molecular weight (MWAV)of the sulfonic acid remains approximately constant over the range of oleum used. The sulfonation percent yield of PDB is plotted against the amount of oleum used in Figure 1. It will be seed that the efficiency is greater in process I. The maximum yield obtained is 88.2% when 148 g of oleum is used per 100 g of PDB. When runs 4 and 5 are compared, it is seen that the yield of run 4 is 1.3% lower. However, when the amount of oleum consumed is taken into account, it is seen that at run 5 148 g is consumed, while for run 4 123 g of oleum
is consumed. This, in turn, means that 19% more oleum is consumed for run 5 . Therefore, due to the economic considerations, despite 1.3% lower sulfonic acid yield, run 4 is preferred. B. Phase Separation Conditions. The affect of temperature on phase separation is studied by repeating the experiment reported for run 4 (the most economic sulfonation) according to process I. Phase separation temperatures were 25, 50, and 70 "C for each experiment. During these experiments, samples from the organic phase of the mixtures in the separatory funnels which are kept at the above separation temperatures are withdrawn at intervals of 0.50, 0.75,2,4, and 5 h. The inorganic acid values (c), which are calculated by assuming a + b = 100, are plotted against time in Figure 2 for the three phase separation temperatures. It will be seen that temperature is an effective parameter for phase separation. After 6 h of separation, about 8, 6, and 4 g of inorganic acids remained at 25,50, and 70 "C respectively. That means that at higher temperatures the inorganic acids in the organic phase migrate faster to the acid sludge. To study the affect of sulfonic acid concentration on phase separation, samples of varying sulfonic acid concentrations were prepared, by using the formulations of runs 4-7. Reaction mixtures were subjected to phase separation experiments at 50 "C. Samples were withdrawn from the organic phases at the same intervals of time for run 4 as given above. The inorganic acid values are plotted against time for various amounts of sulfonic acid in Figure 3. It will be seen that phase separation is very fast during the first hour interval. In addition, phase separation will be slow if the sulfonic acid content is high. IV. Conclusions 1. Process I is preferred to process I1 since a higher yield of sulfonation is obtained.
Ind. Eng. Chem. Res. 1990,29,669-675
\
669
peratures, further shortening of separation times are expected. However, in this case, darkening of the sulfonated products might be a considerable drawback. Separation times higher than 6 h may be undesirable from the industrial point of view. The sulfonation product produced under the conditions described in this work has the following composition and properties: sulfonic acid, 60.8%; spindle oil, 32.9%; p dialkylbenzene, 2.6%; inorganic acid, 4.2%; MWAv= 470, and yield, 86.9%.
\
Registry No. Oleum, 8014-95-7.
Literature Cited
1
2
3
4 Time,hrs
-
5
6
Figure 3. Effects of the amounts of sulfonic acids and the phase separation time on the amount of inorganic acids (I, 49.2%; 11, 49.4%; 111, 56.2%;IV, 63.8%).
2. In process I, the recipe (formulation) of run 4 is preferred due to the low oleum consumption and high sulfonation yield. 3. For phase separation, 6-h reaction time at 70 "C is preferred. If reactions were carried out at higher tem-
Besergil, B.; Baysal, B. M. Determination of the Composition of Post Dodecyl Benzene by IR Spectroscopy. J . Appl. Polym. Sci. 1989, in press. Gilbert, E.; Veldhius, B. Sulfation with Sulfur Trioxide. Znd. Eng. Chen. 1958,50,997-1000. Holtzman, S.; Mildwidsky, B. M. SOs Sulphonation of Heavy Alkylates. Soap Chem. Spec. 1965, 4 1 , 64-67. Kirk, J. C.; Shadan, A. Chemicals from Petrol. Prepr., Am. Chem. SOC.Diu. Pet. Chem. 1956, 2, 49-55. Lavigne, J. B.; Huges, M. F. (to Chevron Research Co.) U.S. Patent 3470097, 1969. Sweeney, W. J.; Hudson, B. E. Sulphonation of Petroleum Products. Sci. pet. 1955, 5 , 329. William, M.; Le Suer, T. (to the Lubrizol Co.) U.S. Patent 2760970, 1956. Received for review January 27, 1989 Accepted October 12, 1989
Radiative Heat-Transfer Model in the Interior of a Pulverized Coal Furnace L. Cafiadas,* L. Salvador, and P. Ollero Departamento de Zngenieria Quimica y Ambiental, Escuela Superior de Zngenieros Industriales, 41012 Sevilla, Spain
A practical mathematical model simulating radiative heat transfer in the furnace of a pulverized coal boiler is presented. The model is based on an adaptation of the zone method, and it has been originally developed as an essential part of an overall pulverized coal combustion model. The model includes calculation of the internal exchanges between coal particles and also the exchanges between the two phases, gas and solid particles, and furnace walls, for which the gas-phase participating character is taken into account. The inclusion of this model in a pulverized coal combustion model allows for testing its validity and its sensitivity to furnace walls and particle emissivity values, by comparison with measurements in a 550-MW power plant boiler. One of the greatest difficulties in constructing a model that simulates pulverized coal combustion in the furnace of an industrial boiler lies in determining the radiative heat exchanges established in the interior of the coal cloud and between the cloud and the bounding walls. This is a complex problem because of the consequence of the great heterogeneity of this system, since the coal cloud is a biphasic medium, composed of a particle suspension at different temperatures and size distributions in each furnace point and a gas phase with important contents of C 0 2 and water vapor, where strong temperature and composition gradients exist. This medium is confined in a prismatic enclosure with a rectangular base and walls covered by a layer of slag with radiative properties that are difficult to determine. From a global perspective, the solution techniques for a radiation problem with complex geometry like the one approached here can be grouped into two large categories,
flux methods and zone methods (Heap et al., 1986), apart from the radiation diffusion methods applicable to optically dense systems. Without entering into a detailed discussion of these, the flux methods, based on evaluating the radiant intensity in a determined direction (usually coinciding with the coordinate's axis) from the integration of the corresponding intensity flux equations, are designed to be solved with finite difference techniques, with special application to coupled models where the radiative exchange is solved simultaneously with the momentum, matter, and energy balances. These types of techniques are only approximate, and the results obtained with different versions of these models differ considerably from each other (Richter and Bauersfeld, 1974). An example of these would be the Richter (1978) two-flux model and the Lockwood and Shah (1976) six-flux model. Zone methods allow for a more accurate simulation of
0888-5885190f 2629-0669$02.50/0 0 1990 American Chemical Society
