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Kinetics and Products Distribution of Selective Catalytic Hydration of Ethylene­ and Propylene Oxides in Concentrated Aqueous Solutions

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Kinetics and Products Distribution of Selective Catalytic Hydration of Ethylene­ and Propylene Oxides in Concentrated Aqueous Solutions Organic Process Research & Development 2002, 6, 660-664 Kinetics and Products Distribution of Selective Catalytic Hydration of Ethylene­ and Propylene Oxides in Concentrated Aqueous Solutions I. A. Kozlovsky, R. A. Kozlovsky,* A. V. Koustov, M. G. Makarov, J. P. Suchkov, and V. F. Shvets D.I.Mendeleev University of Chemical Technology of Russia, Chair of Basic Organic and Petrochemical Synthesis, 9 Miusskaya Square, Moscow 125047, Russia Abstract: and metalate anions.I" The kinetics and reaction mechanism The kinetics of selective hydration of ethylene- and propylene of the hydration of a-oxides using homogeneous catalysis oxides in concentrated aqueous solutions is studied during by salts have been explicitly studied.3,IO,1l The kinetic data homogeneous catalysis by sodium bicarbonate. The mathemati­ obtained have shown that at a concentration of some salts cal model of the process with determined parameters adequately of about 0.5 molJL the distribution factor b = klko is reduced describing the rate of the reaction and products distribution is lO-fold more (to 0.1-0.2). This enables the production of developed. monoglycol with high selectivity at water/oxide molar ratios close to 1. We have used hereinafter homogeneous nucleo­ philic catalysts with the above-mentioned properties for the Introduction creation of industrial heterogeneous catalysts of a selective The reaction of ethylene- and propylene oxides hydration hydration of ethylene- and propylene oxides by means of is an industrial way of obtaining of glycols, in particular an immobilization of anions of salts on heterogeneous ethylene glycol-one of the most-produced large-scale carriers. 12-17 The largest ethylene glycol producers Shell, 18-24 products of industrial organic synthesis, with the world (4) Masuda, T. Production of polygydric alcohol. (Mitsui Toatsu Chem Inc.). annual production in 2000 of about 15.3 million t/year.' The JP 61-271229. 1986. (5) Masuda, T. Production of polygydric alcohol. (Mitsui Toatsu Chem Inc.). oxide hydration reaction proceeds on a serial-to-parallel route IP 61-271230, 1986. with a formation of homologues of glycol: (6) Masuda, T.; Asano, K. H.; Naomi, A. S. Method for preparing ethylene glycol andlor propylene glycol. (Mitsui Toatsu Chem Inc.). EP 0226799, 1992; V.S. Patent 4,937,393, 1990. (7) Keen, B. T. Carbon dioxide-enhanced monoalkylene glycol production. (Union Carbide Corp.). V.S. Patent 4,578,524, 1985. (8) Keen, B. T.; Robson, J. H. Continuous process for the production of alkylene C glycol in the presence of organometalate. (Union Carbide Corp.). U.S. Patent 2H40 4,571,440, 1986. HO(CH 0 ) 2H k 'etc. (I) 2CH2 (9) Odanaka H.; Yamamoto T.; Kumazawa T. Preoparation of high-purity 2 alcylene glycol. (Nippon Shokubai Kagaku Kogyo Co. Ltd.). JP Patent 56-090029, 1981. where ko, ki. k2 are the rate constants of the series stages. (10) Lebedev N. N.; Shvets V. F.; Romashkina L. L. Kinetics Catal. (Russ.) Presently, all ethylene- and propylene glycol is produced 1976, 17(3), 583. (11) Lebedev N. N.; Shvets V. F.; Romashkina L. L. Kinetics Catal. (Russ.) in industry by a noncatalyzed reaction. Product distribution 1976, 17(4), 888. in the reaction I is regulated by the oxide-to-water ratio in (12) Shvets V. F.; Makarov M. G.; Suchkov J. P.; et al. Method for obtaining alkylene glycols. (Vega Chemical Co. Ltd.). RV Patent 2001901, 1993. the initial reaction mixture. The ratio of rate constants for (13) Shvets V. F.; Makarov M. G.; Suchkov J. P.; et al. Method for obtaining the stages of reaction I is unfavorable for monoglycol alkylene glycols. (Vega Chemical Co. Ltd.). RV Patent 2002726, 1993. = (14) Shvets V. F.; Makarov M. G.; Koustov A. V.; Kozlovsky, 1. A.; Kozlovsky, formation (the distribution factor b klh.J for a noncatalyzed RA.; Suchkov, J. P. Process for obtaining alkylene glycols. WO 9733850, reaction of ethylene oxide with water according to different 1997. data sources gives value 1.9-2.82) . For this reason consider­ (15) Shvets V. F.; Makarov M. G.; Koustov A. V.; Kozlovsky, 1. A.; Kozlovsky, R. A.; Suchkov, J. P. Method for obtaining alkylene glycols. RV Patent able excess of water (molarity up to 20x) is applied to 2122995, 1999. increase the monoglycol yield in industry. This results in a (16) Shvets V. F.; Makarov M. G.; Koustov A. V.; Kozlovsky, 1. A.; Kozlovsky, RA.; Suchkov, J. P. Method for producing alkylene glycols. WO 9912876, considerable power cost at the final stage of product isolation 1999. from dilute aqueous solutions. (17) Shvets V. F.; Makarov M. G.; Koustov A. V.; Kozlovsky, 1. A.; Kozlovsky, One of the ways of increasing the monoglycol selectivity R. A.; Suchkov, J. P. Method for obtaining alkylene glycols. RV Patent 2149864, 2000. and, therefore, of decreasing water excess is the application (18) Reman W. G.; Van Kruchten, E. M. G. Process for the preparation of of catalysts to accelerate only the first stage of the reaction alkylene glycols. (Shell Oil Co.). V.S. Patent 5,488,184, 1996. (19) Van Kruchten, E. M. G. Process for the preparation of alkylene glycols. I. Such catalysts are the anions of salts of some acidsv" (Shell Oil Co.). V.S. Patent 5,874,653, 1999. (20) Van Kruchten, E. M. G. Catalytic hydrolysis of alkylene oxides. (Shell * To whom correspondence should be addressed. E-mail: (RA.K.) Oil Co.). WO 9923053, 1999. [email protected]; (V.F.S.) [email protected]. (21) Van Kruchten, E. M. G. Quaternary phosphonium salt catalyst in catalytic (1) Noor-Drugan, N. Testing Times for Ethylene Glycol Makers. Chem. Week hydrolysis of alkylene oxides. (Shell Oil Co.). WO 0035840, 2000. 1999, March 3. 32. (22) Van Kruchten, E. M. G. Carboxylates in catalytic hydrolysis of alkylene (2) Dyment O. N.; Kazansky K. S.; Miroshnikov A. M. Glycols and Their oxides. (Shell Oil Co.). WO 0035842, 2000. Derivatives (Russ.) Moscow, 1976. (23) Kunin R.; Lernanski M. F.; Van Kruchten, E. M. G. Catalyst stabilising (3) Lebedev N. N.; Shvets V. F.; Romashkina L. L. Kinetics Catal. (Russ.) additive in the hydrolysis of alkylene oxides. (Shell Oil Co.). WO 0035841, 1976, 17(3), 576. 2000. 660 • Vol. 6, No. 5, 2002 1Organic Process Research & Development 10,1021/opOl0099+ CCC: $22,00 © 2002 American Chemical Society Published on Web 07/20/2002 Dow,2S,26 BASF,27 Union Carbide,n-30and Mitsubishi'" con­ duct researches on the elaboration of selective catalysts of ethylene oxide hydration in the same direction. The Kinetic Model. The mechanism of the catalysis of (Vl) a-oxides hydration by anions consists of the nucleophilic addition of anion (A-) of the catalyst to a solvated molecule In concentrated aqueous solutions of glycols it is necessary to take into account that the oxide is solvated in equilibrium of u-oxide.v JO H not only by water, but also by glycols." Having designated the effective concentration of proton donor materials activat­ ing an oxide cycle through a hydrogen bond formation by (11) [SH], we obtain: (2) where L[GlYi] is the sum of the concentrations of monoglycol and all polyglycols obtained by reaction I; p is the parameter describing the efficiency of a-oxide solvation by glycols relative to water. Supposing, that the equilibrium 11 is established quickly (Ill) and is shifted to the left, eq 1 for concentrated glycol solutions can be presented by the equation: and subsequent hydrolysis of an intermediate ester with the formation of glycol and regeneration of the catalyst: (3) Taking into account the parallel noncatalyzed reactions of a-oxide (reaction I) proceeding according to the mech­ The rate-determining stage in most cases is the formation anism (V, VI), we obtain a general kinetic equation of of an intermediate ester by reaction III, and in dilute aqueous a-oxide consumption in concentrated solutions at a nucleo­ solutions the rate of the reaction is described by the following philic catalysis: kinetic equation:" -d[C2H40]/dt = (ko([H20] + bL[GlYa) + kct[A -])([HzO] + (1) pL[GlYa)[C2H40] (4) In the derivation of eq 4 it was also assumed- that the The kinetic model of reaction III, suitable for the rate constants of series stages of the reaction I after the first quantitative description of the heterogeneous catalytic process (k ) are equal, that is in a wide range of concentrations of water and glycol is o indispensable for the implementation of the industrial b = k/ko = kz/ko = kiko = ... catalytic process of the hydration of concentrated water The determination of the parameters of the eq 4 was solutions of a-oxide. The kinetic experiments conducted by conducted for a homogeneous catalysis using a bicarbonate us have shown that the immobilization of anions on ion­ ion, one of the most active and accessible nucleophilic exchange resin does not change selectivity, the kinetic catalysts of a-oxide hydration. equation, or its parameters. It gives the basis to use the results of experiments on a homogeneous catalytic hydration for Experimental Section obtaining the demanded model. Let's deduce such a model Materials. NaHC03, ethylene glycol, diethylene glycol, on the basis of a trimolecular mechanism of an oxide ring­ triethylene glycol, and propylene glycol were purchased from opening (H, III), which is also valid for a noncatalyzed commercial suppliers and used without further purification. reaction of an a-oxide hydration: Ethylene oxide and propylene oxide were purified by distillation under solid NaOH. Water was purified by distillation. (V) (28) Soo, H.; Ream. B. c.;Robson, J. H. Monoalkylene glycol production using mixed metal framework compositions, (Union Carbide Chem. Plastic). U.S. Patent 4,967,018, 1990, and reaction of polyglycols formation.F (29) Soo H,; Ream B. C.; Robson J. H. Mixed metal framework compositions for monoalkylene glycol production.
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