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Decomposition of organic hydroperoxides on cation exchangers
Applied Catalysis A: General 185 (1999) 165–169
Decomposition of organic hydroperoxides on cation exchangers VIII. The kinetics of the decomposition process of 1,3-diisopropylbenzene dihydroperoxide on a catalyst of montmorillonite type 夽
János Vodnár a,∗ , János Farkas b , Sándor Békássy b a
b
University Babes-Bolyai, Department of Technology and Merchandizing, 3400 Cluj-Napoca, Romania Technical University of Budapest, Department of Organic Chemical Technology, H-1521 Budapest, Hungary Received 21 October 1998; received in revised form 5 May 1999; accepted 5 May 1999
Abstract The experimental results of this paper refer to the kinetics of the decomposition process of 1,3-diisopropylbenzene dihydroperoxide (HPO) on a catalyst of montmorillonite type containing Cu2+ ions. Between 22 and 56 ◦ C the kinetic studies show a process having the rate equation to be characteristic of first order reactions. The activation energy (Ea = 50.7 kJ/mol), the enthalpy of activation (1H# = 43.5 kJ/mol), the entropy as well as the Gibbs free energy of activation were calculated for the temperature region in which the kinetics of the process was studied. Resorcinol and acetone were yielded by this chemical decomposition. Both compounds are important intermediates of the chemical industry. The catalyst has high activity and is really useful for such chemical purposes. It has high stability as a result of its mineral nature. Application of this catalyst can avoid using aqueous acids which are strong pollutants of the environment. ©1999 Elsevier Science B.V. All rights reserved. Keywords: Montmorillonite type catalyst; Organic hydroperoxide decomposition
1. Introduction This paper presents and discusses the experimental results obtained by studying the kinetics of the decomposition process of 1,3-diisopropylbenzene dihydroperoxide (HPO) on strongly acidic catalyst of montmorillonite type [1] (K10 from Süd Chemie, Germany). In this field of investigations strong acidic organic cation exchangers are used, too [2–8], but their thermal and chemical stability are not sufficiently high. Namely, the oxidizing effect of the reaction mixture 夽
For details of part VII, see ref. [9] Corresponding author. Tel.: +36-1-463-1497; fax: +36-1-4633648. ∗
causes their chemical degradation. In a previous paper [9], it was demonstrated that the activity of the montmorillonite type catalyst used by us and by other authors [10,11] is a few times higher than that of the organic cation exchangers. By the use of some mineral acids as catalyst (sulfuric acid, hydrochloric acid etc.) and some gaseous anhydrides with acid character (e.g. sulfur dioxide), a part of the hydroperoxides decomposes in different resinous substances, causing a low yield of the useful products, pollution of the environment and high trouble of the industrial process. Consequently, the catalyst used by us has a prominent property because it eliminates these inconveniences.
0926-860X/99/$ – see front matter ©1999 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 6 - 8 6 0 X ( 9 9 ) 0 0 1 3 3 - 7
166
J. Vodn´ar et al. / Applied Catalysis A: General 185 (1999) 165–169
The catalytic liquid phase conversion of hydroperoxides in the presence of metal ions has been studied as early as the end of the last century [12,13]. Most of the work was reported after 1945 but in those studies the solid catalysts did not include metal cations. The main products of the investigated decomposition process are resorcinol and acetone, important raw materials of the organic chemical industry. The former (world production is about 35,000 t/year) is used for the production of adhesives of rubber, starch tires, wood and for drugs, dyestuffs and special macromolecular products. The latter is generally used as solvent and as raw material for the production of methyl methacrylate and poly(methyl methacrylate) utilized in large quantities in the industry. The decomposition of 1,3-diisopropylbenzene dihydroperoxide is exploited at industrial level in Japan, producing 17,000 t/year resorcinol by conventional liquid acid catalysis [14]. The use of solid acid catalysts in organic synthesis is steadily gaining in importance [15].
2. Experimental 2.1. Preparation and properties of the catalyst The montmorillonite type K10 acidic catalyst was obtained from clay containing predominantly montmorillonite. During preparation this clay was treated with strong mineral acid and with water at high temperature. Copper ion exchange [16] was performed by adding K10 to a stirred CuCl2 solution at room temperature and stirring the suspension for 24 h. After filtration
and washing with deionised water the resulted solid was dried at 120◦ C and ground. The most important properties of the catalyst used in these experiments are as follows:
Cu2+ content 1.24% m/m (measured by plasma emission spectroscopy) (calculated by the specific sur- 236 m2 /g BET equation from N2 face area isotherms determined at 77 K) average pore 56 Å (calculated from N2 adsorption-desorption diameter by the BJH method) Before its actual use the catalyst must be treated at 250◦ C for 5 h. The number of acid sites of this heat treated catalyst is 0.57 mmol/g (measured by NH3 thermodesorption) and its acidity is predominantly Lewis acidity. 2.2. Reaction conditions Experiments have been carried out in static conditions, using 0.03–0.3 g of catalyst and 20 cm3 acetone solution of HPO (0.46 mol/dm3 as active oxygen). The elaborated reaction technique [17]: the catalyst was introduced at once in the thermostated liquid and the mixture was stirred vigorously. Tests for determination of HPO content are periodically taken from the reaction mixture. The applied analytical method was described in ref. [3]. The resorcinol content of the resulted product mixtures was monitored by HPLC (C18 reversed phase column, methanol-water as eluent, UV detector at 254 nm). 3. Results and discussion As a result of the decomposition process of 1,3diisopropylbenzene dihydroperoxide, resorcinol and acetone are obtained:
Kinetic curves of the decomposition process are determined at five temperatures, between 22.8 and 56 ◦ C. The curves of Fig. 1 illustrate the results obtained in the decomposition of HPO in function of the
J. Vodn´ar et al. / Applied Catalysis A: General 185 (1999) 165–169
167
Fig. 1. Decomposition of 1,3-diisopropylbenzene dihydroperoxide (HPO, as active oxygen) at different temperatures.
Fig. 3. Unified decomposition curve of HPO in function of [reaction time × catalyst amount] product.
Fig. 2. Variation of HPO content (as active oxygen) in function of the reaction time, using different amounts of catalyst.
Fig. 4. The accumulation of resorcinol by the decomposition of HPO.
reaction time, at different temperatures and using the same amount of catalyst. Over 50◦ C the reaction rate is high enough to permit a practically complete decomposition of dihydroperoxide even in half an hour. In practical use one must know the quantity of the catalyst which offers a sufficiently high rate of decomposition. That is why we studied the decomposition varying the quantities of catalyst, at 56◦ C where the reaction rate is appropriate from technological point of view. These results are illustrated in Fig. 2. When the reaction sample is equal to 20 cm3 and its HPO content is 0.46 mol/dm3 , the decomposition takes place very well if the quantity of the catalyst is at least 0.1 g and the temperature is 56◦ C. Above 0.1 g of catalyst the reaction rate practically does not de-
pend on further increasing the quantity of the catalyst. In the interval of 0.1–0.3 g catalyst the conversion depends on the [reaction time × catalyst amount] product (Fig. 3), so the mass transfer has no influence on the reaction. In a specially selected experiment (Fig. 4) we pursued the increase of the resorcinol as chief product of the decomposition process. It can be stated that after 45 min the decomposition is finished and the quantity of resorcinol is on the top (6.11 g/dm3 ). Temperature was 41.1◦ C and the catalyst quantity was equal to 0.1 g. On the basis of the experimental results obtained, the activation energy (Ea ), the enthalpy of activation (1H# ), the entropy of activation (1S# ) and the Gibbs free energy of activation (1G# ) were calculated for the temperature region mentioned above.
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J. Vodn´ar et al. / Applied Catalysis A: General 185 (1999) 165–169
particles is considerably restricted, in accordance with the negative, but not too high 1S# value. Further investigations are necessary to clear the mode of action of the montmorillonite type acid catalysts and we are continuing these studies also on catalysts ion-exchanged with other suitable metals.
4. Conclusions
Fig. 5. Dependence of lg(a/a-x) on the reaction time.
Between 22.8 and 56 ◦ C the kinetics of the decomposition process can be expressed by the following relation: dx = k (a − x) dt
(1)
where a is the initial quantity of HPO (as active oxygen) in mol/dm3 g catalyst; x is the quantity of HPO (as active oxygen) decomposed up to time t in mol/dm3 g catalyst. This means that the decomposition has the rate equation of first order kinetics. The integrated form of the Eq. (1) a (2) kt = ln a−x made possible the linearization of the kinetic curves and the calculation of k values (Fig. 5) by representing the values of ln[a/(a – x)] versus the reaction time. Using the k values obtained at different temperatures, the activation energy of the decomposition (Ea ) was calculated, having a value of 50.7 kJ/mol. Applying the k values, some other kinetic data were calculated (by representing the pairs of lg(k0 /T) and 1/T), using the relation 0 k 1S # 1H # k = lg + − (3) lg T h 2.303R 2.303RT This way the following data were obtained:1H# = 43.5 kJ/mol; 1S# = –136.7 J/mol K; 1G# = 88.5 kJ/mol From these data it can be concluded that the rate of decomposition depends more on the Gibbs free energy of activation (1G# ) than on the activation energy (Ea ). In other words determinant is the state of the transition complex, in which the spatial motion of the
As a result of the decomposition process of 1,3diisopropylbenzene dihydroperoxide, resorcinol and aceton are obtained. The best yield of resorcinol was 87.9% which showed that the montmorillonite based material as strong acidic catalyst is really useful for such chemical purposes. By the application of the above mentioned catalyst one can avoid using aqueous acids which are strong environment pollutants. An other advantage of this method is the easy regeneration of the catalyst. A final remark is that the separation of the resulted products and the catalyst from the reaction mixture is free of trouble.
Acknowledgements J. Vodnár thanks the Foundation “Domus Hungarica Scientiarum et Artium” of the Hungarian Academy of Sciences for the financial support. J. Farkas thanks the Foundation Varga József of the Technical University of Budapest for a grant. The financial support of OTKA (T-015673) and the Ministry of Education and Culture (FKFP 0402/1997) is also gratefully acknowledged. References [1] S. Békássy, T. Cseri, M. Horváth, J. Farkas, F. Figueras, New J. Chem. 22 (1998) 339. [2] J. Vodnár, Rev. Chim. 22 (1971) 394. [3] T.H. Dickey, F.F. Rust, W.M. Vaughan, J. Am. Chem. Soc. 71 (1949) 1432. [4] J. Vodnár, Rev. Chim. 27 (1976) 11. [5] J. Vodnár, Rev. Roum. Chim. 18 (1973) 797. [6] J. Vodnár, React. Kinet. Catal. Lett. 10 (1979) 237. [7] J. Vodnár, Acta Chim. Hung. 128 (1991) 861. [8] J. Vodnár, P. Fejes, K. Varga, F. Berger, Appl. Catal. A: General 122 (1995) 33. [9] J. Vodnár, S. Békássy, M. Dragan, A. Chis, Múzeumi Füzetek (Cluj-Napoca RO) 7 (1998) 56.
J. Vodn´ar et al. / Applied Catalysis A: General 185 (1999) 165–169 [10] M. Stojanova, Chr. Karshalykov, V. Kanazirev, G.L. Price, Appl. Catal. A: General 143 (1996) 175. [11] L. Becker, Horst Förster, Appl. Catal A: General 153 (1997) 31. [12] H.J.H. Fenton, J. Chem. Soc. 65 (1894) 899. [13] G. Sosnovsky, D.J. Rawlinson, in: D. Swern (Ed.), Organic Peroxides, Vol. II., Wiley-Interscience, New York, 1971, p. 154
169
[14] K. Weissermel, H.-J. Arpe, Industrial Organic Chemistry, 3rd ed. VCH, Weinheim, 1997. [15] C.S. John, D.M. Clark, I.E. Maxwell, in: J.M. Thomas, K. Zamaraev (Eds.), Perspectives in Catalysis, Blackwell Science Publishers, London, 1992, p. 384 [16] T. Cseri, S. Békássy, F. Figueras, S. Rizner, J. Mol. Catal. A: Chemical 98 (1995) 101. [17] J. Vodnár, Rev. Roum. Chim. 15 (1970) 1947.
Decomposition of organic hydroperoxides on cation exchangers VIII. The kinetics of the decomposition process of 1,3-diisopropylbenzene dihydroperoxide on a catalyst of montmorillonite type 夽
János Vodnár a,∗ , János Farkas b , Sándor Békássy b a
b
University Babes-Bolyai, Department of Technology and Merchandizing, 3400 Cluj-Napoca, Romania Technical University of Budapest, Department of Organic Chemical Technology, H-1521 Budapest, Hungary Received 21 October 1998; received in revised form 5 May 1999; accepted 5 May 1999
Abstract The experimental results of this paper refer to the kinetics of the decomposition process of 1,3-diisopropylbenzene dihydroperoxide (HPO) on a catalyst of montmorillonite type containing Cu2+ ions. Between 22 and 56 ◦ C the kinetic studies show a process having the rate equation to be characteristic of first order reactions. The activation energy (Ea = 50.7 kJ/mol), the enthalpy of activation (1H# = 43.5 kJ/mol), the entropy as well as the Gibbs free energy of activation were calculated for the temperature region in which the kinetics of the process was studied. Resorcinol and acetone were yielded by this chemical decomposition. Both compounds are important intermediates of the chemical industry. The catalyst has high activity and is really useful for such chemical purposes. It has high stability as a result of its mineral nature. Application of this catalyst can avoid using aqueous acids which are strong pollutants of the environment. ©1999 Elsevier Science B.V. All rights reserved. Keywords: Montmorillonite type catalyst; Organic hydroperoxide decomposition
1. Introduction This paper presents and discusses the experimental results obtained by studying the kinetics of the decomposition process of 1,3-diisopropylbenzene dihydroperoxide (HPO) on strongly acidic catalyst of montmorillonite type [1] (K10 from Süd Chemie, Germany). In this field of investigations strong acidic organic cation exchangers are used, too [2–8], but their thermal and chemical stability are not sufficiently high. Namely, the oxidizing effect of the reaction mixture 夽
For details of part VII, see ref. [9] Corresponding author. Tel.: +36-1-463-1497; fax: +36-1-4633648. ∗
causes their chemical degradation. In a previous paper [9], it was demonstrated that the activity of the montmorillonite type catalyst used by us and by other authors [10,11] is a few times higher than that of the organic cation exchangers. By the use of some mineral acids as catalyst (sulfuric acid, hydrochloric acid etc.) and some gaseous anhydrides with acid character (e.g. sulfur dioxide), a part of the hydroperoxides decomposes in different resinous substances, causing a low yield of the useful products, pollution of the environment and high trouble of the industrial process. Consequently, the catalyst used by us has a prominent property because it eliminates these inconveniences.
0926-860X/99/$ – see front matter ©1999 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 6 - 8 6 0 X ( 9 9 ) 0 0 1 3 3 - 7
166
J. Vodn´ar et al. / Applied Catalysis A: General 185 (1999) 165–169
The catalytic liquid phase conversion of hydroperoxides in the presence of metal ions has been studied as early as the end of the last century [12,13]. Most of the work was reported after 1945 but in those studies the solid catalysts did not include metal cations. The main products of the investigated decomposition process are resorcinol and acetone, important raw materials of the organic chemical industry. The former (world production is about 35,000 t/year) is used for the production of adhesives of rubber, starch tires, wood and for drugs, dyestuffs and special macromolecular products. The latter is generally used as solvent and as raw material for the production of methyl methacrylate and poly(methyl methacrylate) utilized in large quantities in the industry. The decomposition of 1,3-diisopropylbenzene dihydroperoxide is exploited at industrial level in Japan, producing 17,000 t/year resorcinol by conventional liquid acid catalysis [14]. The use of solid acid catalysts in organic synthesis is steadily gaining in importance [15].
2. Experimental 2.1. Preparation and properties of the catalyst The montmorillonite type K10 acidic catalyst was obtained from clay containing predominantly montmorillonite. During preparation this clay was treated with strong mineral acid and with water at high temperature. Copper ion exchange [16] was performed by adding K10 to a stirred CuCl2 solution at room temperature and stirring the suspension for 24 h. After filtration
and washing with deionised water the resulted solid was dried at 120◦ C and ground. The most important properties of the catalyst used in these experiments are as follows:
Cu2+ content 1.24% m/m (measured by plasma emission spectroscopy) (calculated by the specific sur- 236 m2 /g BET equation from N2 face area isotherms determined at 77 K) average pore 56 Å (calculated from N2 adsorption-desorption diameter by the BJH method) Before its actual use the catalyst must be treated at 250◦ C for 5 h. The number of acid sites of this heat treated catalyst is 0.57 mmol/g (measured by NH3 thermodesorption) and its acidity is predominantly Lewis acidity. 2.2. Reaction conditions Experiments have been carried out in static conditions, using 0.03–0.3 g of catalyst and 20 cm3 acetone solution of HPO (0.46 mol/dm3 as active oxygen). The elaborated reaction technique [17]: the catalyst was introduced at once in the thermostated liquid and the mixture was stirred vigorously. Tests for determination of HPO content are periodically taken from the reaction mixture. The applied analytical method was described in ref. [3]. The resorcinol content of the resulted product mixtures was monitored by HPLC (C18 reversed phase column, methanol-water as eluent, UV detector at 254 nm). 3. Results and discussion As a result of the decomposition process of 1,3diisopropylbenzene dihydroperoxide, resorcinol and acetone are obtained:
Kinetic curves of the decomposition process are determined at five temperatures, between 22.8 and 56 ◦ C. The curves of Fig. 1 illustrate the results obtained in the decomposition of HPO in function of the
J. Vodn´ar et al. / Applied Catalysis A: General 185 (1999) 165–169
167
Fig. 1. Decomposition of 1,3-diisopropylbenzene dihydroperoxide (HPO, as active oxygen) at different temperatures.
Fig. 3. Unified decomposition curve of HPO in function of [reaction time × catalyst amount] product.
Fig. 2. Variation of HPO content (as active oxygen) in function of the reaction time, using different amounts of catalyst.
Fig. 4. The accumulation of resorcinol by the decomposition of HPO.
reaction time, at different temperatures and using the same amount of catalyst. Over 50◦ C the reaction rate is high enough to permit a practically complete decomposition of dihydroperoxide even in half an hour. In practical use one must know the quantity of the catalyst which offers a sufficiently high rate of decomposition. That is why we studied the decomposition varying the quantities of catalyst, at 56◦ C where the reaction rate is appropriate from technological point of view. These results are illustrated in Fig. 2. When the reaction sample is equal to 20 cm3 and its HPO content is 0.46 mol/dm3 , the decomposition takes place very well if the quantity of the catalyst is at least 0.1 g and the temperature is 56◦ C. Above 0.1 g of catalyst the reaction rate practically does not de-
pend on further increasing the quantity of the catalyst. In the interval of 0.1–0.3 g catalyst the conversion depends on the [reaction time × catalyst amount] product (Fig. 3), so the mass transfer has no influence on the reaction. In a specially selected experiment (Fig. 4) we pursued the increase of the resorcinol as chief product of the decomposition process. It can be stated that after 45 min the decomposition is finished and the quantity of resorcinol is on the top (6.11 g/dm3 ). Temperature was 41.1◦ C and the catalyst quantity was equal to 0.1 g. On the basis of the experimental results obtained, the activation energy (Ea ), the enthalpy of activation (1H# ), the entropy of activation (1S# ) and the Gibbs free energy of activation (1G# ) were calculated for the temperature region mentioned above.
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J. Vodn´ar et al. / Applied Catalysis A: General 185 (1999) 165–169
particles is considerably restricted, in accordance with the negative, but not too high 1S# value. Further investigations are necessary to clear the mode of action of the montmorillonite type acid catalysts and we are continuing these studies also on catalysts ion-exchanged with other suitable metals.
4. Conclusions
Fig. 5. Dependence of lg(a/a-x) on the reaction time.
Between 22.8 and 56 ◦ C the kinetics of the decomposition process can be expressed by the following relation: dx = k (a − x) dt
(1)
where a is the initial quantity of HPO (as active oxygen) in mol/dm3 g catalyst; x is the quantity of HPO (as active oxygen) decomposed up to time t in mol/dm3 g catalyst. This means that the decomposition has the rate equation of first order kinetics. The integrated form of the Eq. (1) a (2) kt = ln a−x made possible the linearization of the kinetic curves and the calculation of k values (Fig. 5) by representing the values of ln[a/(a – x)] versus the reaction time. Using the k values obtained at different temperatures, the activation energy of the decomposition (Ea ) was calculated, having a value of 50.7 kJ/mol. Applying the k values, some other kinetic data were calculated (by representing the pairs of lg(k0 /T) and 1/T), using the relation 0 k 1S # 1H # k = lg + − (3) lg T h 2.303R 2.303RT This way the following data were obtained:1H# = 43.5 kJ/mol; 1S# = –136.7 J/mol K; 1G# = 88.5 kJ/mol From these data it can be concluded that the rate of decomposition depends more on the Gibbs free energy of activation (1G# ) than on the activation energy (Ea ). In other words determinant is the state of the transition complex, in which the spatial motion of the
As a result of the decomposition process of 1,3diisopropylbenzene dihydroperoxide, resorcinol and aceton are obtained. The best yield of resorcinol was 87.9% which showed that the montmorillonite based material as strong acidic catalyst is really useful for such chemical purposes. By the application of the above mentioned catalyst one can avoid using aqueous acids which are strong environment pollutants. An other advantage of this method is the easy regeneration of the catalyst. A final remark is that the separation of the resulted products and the catalyst from the reaction mixture is free of trouble.
Acknowledgements J. Vodnár thanks the Foundation “Domus Hungarica Scientiarum et Artium” of the Hungarian Academy of Sciences for the financial support. J. Farkas thanks the Foundation Varga József of the Technical University of Budapest for a grant. The financial support of OTKA (T-015673) and the Ministry of Education and Culture (FKFP 0402/1997) is also gratefully acknowledged. References [1] S. Békássy, T. Cseri, M. Horváth, J. Farkas, F. Figueras, New J. Chem. 22 (1998) 339. [2] J. Vodnár, Rev. Chim. 22 (1971) 394. [3] T.H. Dickey, F.F. Rust, W.M. Vaughan, J. Am. Chem. Soc. 71 (1949) 1432. [4] J. Vodnár, Rev. Chim. 27 (1976) 11. [5] J. Vodnár, Rev. Roum. Chim. 18 (1973) 797. [6] J. Vodnár, React. Kinet. Catal. Lett. 10 (1979) 237. [7] J. Vodnár, Acta Chim. Hung. 128 (1991) 861. [8] J. Vodnár, P. Fejes, K. Varga, F. Berger, Appl. Catal. A: General 122 (1995) 33. [9] J. Vodnár, S. Békássy, M. Dragan, A. Chis, Múzeumi Füzetek (Cluj-Napoca RO) 7 (1998) 56.
J. Vodn´ar et al. / Applied Catalysis A: General 185 (1999) 165–169 [10] M. Stojanova, Chr. Karshalykov, V. Kanazirev, G.L. Price, Appl. Catal. A: General 143 (1996) 175. [11] L. Becker, Horst Förster, Appl. Catal A: General 153 (1997) 31. [12] H.J.H. Fenton, J. Chem. Soc. 65 (1894) 899. [13] G. Sosnovsky, D.J. Rawlinson, in: D. Swern (Ed.), Organic Peroxides, Vol. II., Wiley-Interscience, New York, 1971, p. 154
169
[14] K. Weissermel, H.-J. Arpe, Industrial Organic Chemistry, 3rd ed. VCH, Weinheim, 1997. [15] C.S. John, D.M. Clark, I.E. Maxwell, in: J.M. Thomas, K. Zamaraev (Eds.), Perspectives in Catalysis, Blackwell Science Publishers, London, 1992, p. 384 [16] T. Cseri, S. Békássy, F. Figueras, S. Rizner, J. Mol. Catal. A: Chemical 98 (1995) 101. [17] J. Vodnár, Rev. Roum. Chim. 15 (1970) 1947.