(12) United States Patent (10) Patent No.: US 6,765,110 B2 Warner Et Al

USOO676511 OB2 (12) United States Patent (10) Patent No.: US 6,765,110 B2 Warner et al. (45) Date of Patent: Jul. 20, 2004 (54) PROCESS FOR THE SIMULTANEOUS (56) References Cited COPRODUCTION AND PURIFICATION OF U.S. PATENT DOCUMENTS ETHYLACETATE AND SOPROPYL a ACETATE 3,898.291 A 8/1975 Darsi et al. ............. 260/643 D 4,710,274. A 12/1987 Berg et al. .................... 203/51 (75) Inventors: R. Jay Warner, Corpus Christi, TX 4,826,576 A * 5/1989 Berg et al. .................... 203/56 (US); Carl David Murphy, Corpus FOREIGN PATENT DOCUMENTS Christi, TX (US); Gustavo Angel WO WO 98/25876 6/1998 RobeloFrancisco Grajales, Javier SanchezVeracruz Santiago,(MX). WO WO 98/426952 10/1998 Veracruz (MX); Fernando Alejo OTHER PUBLICATIONS Solorzano, Veracruz (MX); Jose Simons, R. M., “Esterification” in Encyclopedia of Chemi Alfonso Torres, Corpus Christi, TX cal Process and Design vol. 19, J. J. McKetta (ed.), p. 384, (US) Marcel Dekker, Inc., 1983. (73) Assignee: Celanese International Corporation, * cited by examiner Dallas, TX (US) Primary Examiner Peter O'Sullivan - (74) Attorney, Agent, or Firm M. Susan Spiering (*) Notice: Subject to any disclaimer, the term of this (57) ABSTRACT patent is extended or adjusted under 35 U.S.C. 154(b) by 587 days. This invention relates to a process for the Simultaneous coproduction of ethyl acetate and isopropyl acetate. The (21) Appl. No.: 09/740,224 esterification reaction comprises contacting acetic acid with a mixed alcohol Stream of ethanol and isopropanol. Exem (22) Filed: Dec. 19, 2000 plified is a purified, Fischer Tropsch derived mixture of (65) Prior Publication Data ethanol and isopropanol. The esterification reaction occurs in the presence of an acidic catalyst in a liquid phase reaction US 2003/0166964 A1 Sep. 4, 2003 System. The resultant crude reaction Step product is sepa (51) Int. Cl. .......................... co7c67.03. Co7C 67/54 rated and purified by distillation to produce acetate ester (52) 560/265; 560/248 products having greater than 99.5 wt % purity. (58) Field of Search .................................. 560/248, 265 9 Claims, 1 Drawing Sheet U.S. Patent Jul. 20, 2004 US 6,765,110 B2 uo!onpoud-okoIA??E.Jopue|Adoudos!s??e?eov ZZZZZZ NNNNN pov peov US 6,765,110 B2 1 2 PROCESS FOR THE SIMULTANEOUS acetate, comprising reacting an alcohol mixture of ethanol COPRODUCTION AND PURIFICATION OF and isopropanol with acetic acid, in the liquid phase, in the ETHYLACETATE AND SOPROPYL presence of an acidic catalyst wherein the reaction is carried ACETATE out at elevated temperature and at a preSSure Sufficient to effect esterification of the reactant. An example of an alcohol mixture is that which is derived from the purification of a FIELD OF THE INVENTION Fischer Tropsch alcohol mixture. Fischer Tropsch alcohol This invention relates to the production of organic car mixtures contain impurities. In the present invention, impu boxylic acid esters and in particular to a proceSS for Simul rities of primary concern are the heavy components, or the taneously coproducing ethyl acetate and isopropyl acetate in 1O C or C alcohol components of the Fischer TropSch mix a reaction mixture comprising a mixed alcohol Stream of ture. The Fischer Tropsch mixture may or may not be ethanol and isopropanol, with acetic acid, in the liquid phase purified, prior to use. Purification of the Fischer TropSch in the presence of an acidic catalyst. The invention further mixture can occur employing distillation or alternatively relates to the Subsequent Separation of ethyl acetate and employing extractive distillation with water. If the Fischer isopropyl acetate from the crude acetate ester mixture, and 15 TropSch mixture is used without prior purification, high to the removal of impurities which may be present. boiling ester byproducts are produced during the esterifica tion reaction and removed from the reaction product during BACKGROUND the purification process of the respective ethyl and isopropyl It is well known to produce esterS Such as ethyl acetate or acetate products. The crude mixed ester product is separated isopropyl acetate by reaction of an ethanol or isopropanol into purified ethyl and isopropyl acetate products via a Series respectively with acetic acid in the presence of an acidic of distillation towers. catalyst. However, in the coproduction of esters, difficulty is Examples of percent alcohol mixtures to employ include encountered in driving the esterification reactions to alcohol mixtures containing between about 90% etha completion, especially with mixtures of alcohols with dis nol:10% isopropanol to between about 10% ethanol:90% Similar reactivity, thereby resulting in acetate product con 25 isopropanol, or alternatively the mixture is between about taminated with unreacted alcohols. It is also known to 80% ethanol:20% isopropanol to between about 60% etha coproduce these esters in a Single reactor by operating the nol:40% isopropanol. reactor Sequentially, i.e., by first producing one ester by Employing the current process, both ethyl acetate and reaction of the acid with the first alcohol, and then in a Swing isopropyl acetate are recovered at greater than about 99.5% operation changing over to a Second alcohol to produce the purity and up to or greater than about 99.7%. Presently the Second ester. In all of these reactions involving the use of a industry accepts Specification grade ethyl acetate and Speci mixture of alcohols for esterification, it is important to use fication grade isopropyl acetate as being a minimum purity relatively pure reactants for reaction with acetic acid. This is of 99.5%. especially important if the esters are coproduced in a proceSS BRIEF DESCRIPTION OF THE DRAWINGS for the Simultaneous rather than the Sequential production of 35 both esters. The use of reactants of high purity may not be FIG. 1 is a Schematic of the ethyl and isopropyl acetate economic commercially for it would add significantly to the coproduction process. cost of producing both esters. It has been relatively difficult DETAILED DESCRIPTION OF THE to coproduce Simultaneously a mixture of these esters from INVENTION a relatively impure Set of reactants, primarily because if the 40 alcohol is contaminated with impurities, for example, A continuous coproduction process is illustrated in FIG. 1. “heavy” or C or greater alcohols, it is difficult to separate A homogeneous or heterogeneous catalyst may be employed the eventual ester product from the impurities. in the present esterification reaction. The acid catalyst WO 98/42652 (BP Chem.) describes ester coproduction should be temperature stable at the temperature which the for the coproduction of ethyl acetate and n-butyl acetate. The 45 reaction is effected, i.e., does not deteriorate to an appre reference describes use of impure crude industrial ethanol ciable extent at the temperature at which the reaction is and “oxo' based n-butanol in a liquid phase esterification effected. The acid catalyst may comprise any conventional reaction System. The process is capable of using relatively esterification catalyst. It is preferred that Sulfonic acids or impure reactants and provides for removing Some of the ion exchange resins with Strongly acidic functionalities be aldehyde type impurities of the alcohols by the use of resin 50 employed. guard beds. The temperature at which the reaction is effected is WO 98/25876 (Sasol Chem.) describes production of determined by the Steady State composition and operating organic carboxylic acid esters employing Fischer TropSch preSSure of the liquid phase catalyzed reaction Zone, being derived alcohols or carboxylic acids, Said esterfication reac typically in the range of 90 to 150 C. tion occurring in the vapor phase. Among other esters, 55 Suitable pressure for the present invention is from about WO’876 exemplifies the production of ethyl acetate and/or 1 to 3 atmospheres. Present binary and tertiary azeotropes butyl acetate. It is Stated that due to the complexity of are slightly pressure Sensitive So reaction pressure is Selected Fischer TropSch product Streams, it is normally uneconomic based primarily on operating parameterS Such as throughput, to purify the alcohols obtained to a purity in excess of 99%. energy consumption, and corrosion. WO 876 describes use of the Fischer Tropsch alcohol 60 It is preferred that an exceSS concentration of acid be without purification prior to use. The alcohol, or Fischer present in the liquid phase catalyzed reaction Zone to pref TropSch carboxylic acid, if used, is employed as is and erentially drive the esterification, and to minimize hydroly blended with acetic acid in the reaction System. sis of etherification reactions, thus increasing conversion and Selectivity towards the desired products. In general, the SUMMARY 65 acetic acid concentration in the reaction Zone ranges from The present invention is directed to a proceSS for the about 50 to 80 wt %, most preferably between about 60 and Simultaneous coproduction of ethyl acetate and isopropyl 70 wt %. US 6,765,110 B2 3 4 Although the present description is directed to Separation Overhead 32 containing a crude mixture of ethyl/ of acetate esters, there is a body of information dealing with isopropyl acetate reaction product plus water produced by separation of alcohols, for example U.S. Pat. No. 4,710,274, the esterification reaction, and Small amount of unreacted U.S. Pat. No. 3,898,291. It was found that for producing the alcohols, is condensed and directed to decanter 6 which desired acetate esters (ethyl acetate/isopropyl acetate), the Serves to Separate the organic and aqueous layers of the preferred route was to coproduce the acetate esters and reaction product mixture. The composition of Stream 32 is Separate them at the end of the production process, as dictated by the ratio of ethanol/isopropanol fed to the opposed to Separating the alcohols at the beginning of the reactor, alcohol conversion, and the binary and tertiary proceSS and producing the acetate esters individually.

Load more