Production of Allyl Chloride

Europaisches Patentamt European Patent Office © Publication number: 0 455 644 B1 Office europeen des brevets

@ Date of filing: 27.11.89

&) PRODUCTION OF ALLYL CHLORIDE.

© Priority: 27.01.89 US 303498 © Proprietor: Stauffer, John E. 6 Pecksland Road © Date of publication of application: Greenwich, CT 06831 (US) 13.11.91 Bulletin 91/46 © Inventor: Stauffer, John E. © Publication of the grant of the patent: 6 Pecksland Road 05.10.94 Bulletin 94/40 Greenwich, CT 06831 (US)

@ Designated Contracting States: BE DE ES FR GB IT NL © Representative: Kugele, Bernhard et al NOVAPAT-CABINET CHEREAU, © References cited: 9, Rue du Valais GB-A- 1 175 952 CH-1202 Geneve (CH) US-A- 2 447 410 US-A- 3 449 450

Note: Within nine months from the publication of the mention of the grant of the European patent, any person ® may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition CL shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee LU has been paid (Art. 99(1) European patent convention). Rank Xerox (UK) Business Services (3. 10/3.09/3.3.3) EP 0 455 644 B1

Description

This invention relates to a method for the production of allyl chloride using hydrogen chloride and optionally chlorine as a source of chlorine. 5 Description of the Prior Art

Historically, allyl chloride has been made by the addition chlorination of propylene with chlorine followed by the pyrolysis of 1 ,2 - dichloropropane at high temperatures. The resulting product mix from the io dehydrochlorination reaction consists of about 55 to 70 percent allyl chloride and approximately 30 to 40 percent 1-chloropropene. Because of the relatively low yield of allyl chloride this process is not used industrially at the present time. The new method of producing allyl chloride involves the high-temperature substitution chlorination of propylene with chlorine to produce the product directly in one step. High yields of allyl chloride, up to 96 75 percent, have been reported for the reaction. Minor quantities of 2 - chloropropene - 1 and 1 - chloropropene -1 are obtained. The above method of making allyl chloride commercially has several disadvantages. First, it requires chlorine as the chlorinating agent. This raw raterial, which is produced by an electrochemical process, has been vulnerable to the escalating cost of electric power. Second, less than half of the chlorine consumed is 20 used to produce allyl chloride. The rest of the chlorine is wasted, mostly as byproduct hydrogen chloride. The object of the present invention, therefore, is to be able to produce allyl chloride by substituting hydrogen chloride for all or part of the chlorine requirements. Thereby dependence on an expensive raw material, which on occasion has been in short supply, is avoided. GB-A-1 175 952 discloses a method for the production of allyl chloride by reacting propylene and 25 hydrogen chloride. A further object of the present invention is the production of allyl chloride without producing byproduct hydrogen chloride. Added flexibility and improved economics thus can be realized. Still another object is to manufacture allyl chloride in high yields from propane and/or propylene. Several benefits accrue from this result. The consumption of hydrocarbon is minimized. Processing costs of 30 purifying the product are reduced. Finally, the disposal of unwanted and environmentally-damaging byproduct chlorohydrocarbons can be simplified.

Brief Description of the Drawing

35 The Figure is a diagrammatic representation of a preferred means for operating the present chlorination method. A shell and tube catalytic reactor is illustrated in series with a thermal reactor with means for separating allyl chloride and for isolating and recycling hydrogen chloride and perchloroethylene to the catalytic reactor.

40 Summary of the Detailed Description

The above objects are met by a process as mentioned above, which is characterized by the following steps : first, subjecting perchloroethylene to oxychlorination with hydrogen chloride and oxygen in the presence of an oxychlorination catalyst to give reaction products consisting essentially of hexachloroethane 45 and water; second, isolating and reacting said hexachloroethane with propylene and optionally added chlorine in the vapor phase to produce products comprising allyl chloride, perchloroethylene and hydrogen chloride; and third, isolating said products of the second step and repeating the first step using as starting materials the perchloroethylene and hydrogen chloride thus isolated whereby chlorination using regenerated hexachloroethane is accomplished; the process being operated with total utilization of hydrogen chloride 50 and net production of hydrogen chloride and hexachloroethane is avoided. Problems encountered by the conventional methods are circumvented by the method of the present invention. In the present method, according to a preferred embodiment, two separate reactions are carried out in tandem, as indicated. First, perchloroethylene is reacted with hydrogen chloride and air or oxygen to produce hexachloroethane and water. In the second reaction the hexachloroethane is reacted with a 55 hydrocarbon containing three carbon atoms, i.e. propane, propylene or any proportion of these compounds, to give the desired allyl chloride plus hydrogen chloride. The latter is recycled to the first reaction so that there is no net production of hydrogen chloride.

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The reactions in the present invention may be illustrated by the following equations using propylene as the hydrocarbon feedstock:

cat' 5 1. CC12 = CC12 + 2 KC1 + | 02 >CCl3CCl3 4- H20

2a. CCI3CCI3 + C3HG - CCb = CCb + CH2 = CHCH2CI + HCI

10 Therefore the net reaction is:

+ 3. C3K6 + HCI + I 02_A_>CH2 = CKCH2C1 H20

15 If, in a preferred embodiment, chlorine is added in the second step, the following reaction will occur:

2b. Cl2 + C3HG - CH2 = CHCH2CI + HCI

20 The first reaction, in which perchloroethylene is oxychlorinated to hexachloroethane employing an oxychlorination catalyst, may typically be carried out in a molten salt reactor, fluidized bed reactor, or in a shell and tube reactor. Such reactor designs assist in the control of the reaction temperature. This temperature is maintained preferably in the range from 200 0 C. to 375 0 C. The catalyst of choice is copper chloride which may be deposited on an inert support. This is the well-known Deacon catalyst which has 25 been used in experimental processes to produce chlorine from hydrogen chloride and air. Various salts may be mixed with the copper chloride in order to promote its effectiveness, e.g., potassium chloride, ferric chloride, and lead chloride. The second reaction is conducted in the vapor phase of an elevated temperature preferably in the range from 400 °C. to 700 °C. The probable mechanism by which propylene is chlorinated in this 30 temperature range is a series of free radical reactions. In the event that insufficient hydrogen chloride is available to produce the required hexachloroethane, chlorine can be added to supplement the hexachloroethane. Thus, various predetermined proportions of hydrogen chloride and chlorine, depending on requirements, can be used in the overall process. As a feature of the invention, temperature control of the second reaction is facilitated when using 35 hexachloroethane instead of chlorine as the chlorinating agent. Substitution chlorination, such as the formation of allyl chloride from propylene and chlorine, releases considerable heat. By contrast, dissociation reactions, such as the instant decomposition of hexachloroethane to perchloroethylene and chlorine, absorb a substantial quantity of heat. Thus, according to the present invention, when these two reactions, substitution chlorination and dissociation, are conducted in an intimate manner, the heat requirements can 40 be closely balanced. Operation of the process is illustrated in the attached drawing. Air, hydrogen chloride and perchloroethylene are fed to the shell and tube reactor which contains the copper chloride catalyst. The effluent is cooled sufficiently to condense the liquids. The inert gases are vented to a scrubber while a separator decants the water from the chlorinated organics. After being dried, hexachloroethane dissolved in unreacted 45 perchloroethylene is pumped to the thermal reactor where it chlorinates propylene. The hot vapors from the reactor are quenched, and the hydrogen chloride is separated for recycle to the catalytic reactor. Unreacted hydrocarbon is recycled to the thermal reactor. The chlorinated organic compounds are fractionated in a distillation column. Allyl chloride is removed overhead and the higher boiling perchloroethylene is recovered in the still bottoms and returned to the oxychlorination step. 50 Although the process seems rather straightforward, successful operation depends on the strict adher- ence to the following rules: 1 . Hexachloroethane produced via oxychlorination must be isolated from all impurities with the exception of perchloroethylene before being fed to the thermal reactor. This separation is necessary to avoid the formation of byproducts and the loss of hydrogen chloride efficiency. The thermal reactor must be kept 55 anhydrous or above the dew point to prevent severe corrosion problems. All oxygen has to be excluded from the thermal reactor to avoid burning and the formation of water. 2. Hydrogen chloride, before being recycled to the oxychlorination reactor, must be freed of all hydrocarbons to prevent combustion reactions and to avoid pollution problems caused by their escape in

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the vent gases. 3. Perchloroethylene that is reformed in the thermal reactor must be isolated from the product stream before being recycled to the oxychlorination reactor. Any saturated hydrocarbons which are fed to the oxychlorination reactor will partially burn. Unsaturated hydrocarbons, other than perchloroethylene, will 5 be chlorinated in the oxychlorination reactor and eventually lead to unwanted byproducts. The allyl chloride produced by the method of the present invention is a valuable item of commerce. It is an intermediate in the production of allyl alcohol, epichlorohydrin, and synthetic glycerol. End use markets include pharmaceuticals, resins, plastics and food products. Recent market research data indicate that epichlorohydrin accounts for 5.7 percent of chlorine consumption in the United States and is the second io fastest growing outlet for chlorine. The embodiments of the invention in which exclusive property or privilege is claimed are defined as follows:

Claims 15 1. A process for the production of allyl chloride using hydrogen chloride and optionally chlorine as a source of chlorine, said process including reaction steps operated in first, subjecting perchloroethylene to oxychlorination with hydrogen chloride and oxygen in the presence of an oxychlorination catalyst to give reaction products consisting essentially of hexach- 20 loroethane and water; second, isolating and reacting said hexachloroethane with propylene and optionally added chlorine in the vapor phase to produce products comprising allyl chloride, perchloroethylene and hydrogen chloride, and third, isolating said products of the second step and repeating the first step using as starting 25 materials the perchloroethylene and hydrogen chloride thus isolated whereby chlorination using regenerated hexachloroethane is accomplished, the process being operated with total utilization of hydrogen chloride and net production of hydrogen chloride and hexachloroethane is avoided.

2. A process according to claim 1 wherein the catalyst in step 1 comprises copper chloride. 30 3. A process according to claim 2 where the catalyst comprises an admixture of copper chloride with one or more salts selected from the group consisting of potassium chloride, ferric chloride, and lead chloride.

35 4. A process according to claim 1 in which the oxychlorination reaction with perchloroethylene is carried out at temperatures in the range from 200 ° C. to 375 ° C.

5. A process according to claim 1 in which the vapor phase reaction is carried out at temperatures in the range from 400 ° C. to 700 ° C. 40 Patentanspruche

1. Verfahren zur Herstellung von Allylchlorid unter Verwendung von Chlorwasserstoff und gegebenenfalls von Chlor als Quelle fur Chlor, welches Verfahren Reaktionsschritte aufweist, die wie folgt betrieben 45 werden: erstens, Unterwerfen von Perchlorathylen einer Oxychlorierung mit Chlorwasserstoff und Sauerstoff in Gegenwart eines Oxychlorierungskatalysators, urn Reaktionsprodukte zu ergeben, die im wesentli- chen aus Hexachlorathan und Wasser bestehen; zweitens, Isolieren und Umsetzen des Hexachlorathans mit Propylen und gegebenenfalls in der 50 Dampfphase hinzugefugtem Chlor, urn Produkte zu erzeugen, die Allylchlorid, Perchlorathylen und Chlorwasserstoff umfassen, und drittens, Isolieren der Produkte des zweiten Schrittes und Wiederholen des ersten Schrittes unter Verwendung des so isolierten Perchlorathylen und Chlorwasserstoffes als Ausgangsmaterialien, wo- durch die Chlorierung unter Verwendung regenerierten Hexachlorathans bewerkstelligt wird, wobei das 55 Verfahren unter totalem Aufbrauch des Chlorwasserstoffes betrieben wird und die Nettoproduktion von Chlorwasserstoff und Hexachlorathan vermieden wird.

2. Verfahren nach Anspruch 1 , bei dem der Katalysator im Schritt 1 Kupferchlorid aufweist.

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3. Verfahren nach Anspruch 2, bei dem der Katalysator eine Mischung von Kupferchlorid mit einem oder mehreren Salz(en) aufweist, die aus der aus Kaliumchlorid, Ferrichlorid und Bleichlorid bestehenden Gruppe gewahlt sind.

5 4. Verfahren nach Anspruch 1, bei dem die Oxychlorierungsreaktion mit Perchlorathylen bei Temperatu- ren im Bereiche von 200 °C bis 375 °C durchgefuhrt wird.

5. Verfahren nach Anspruch 1, bei dem die Dampfphasenreaktion bei Temperaturen im Bereiche von 400 ° C bis 700 ° C durchgefuhrt wird. 10 Revendicatlons

1. Procede pour la fabrication de chlorure allylique en utilisant de I'acide chlorhydrique et en option du chlore comme source de chlore, ledit procede comprenant les etapes reactionnelles effectuees : is - premierement, en soumettant du perchloroethylene a une oxychloration avec de I'acide chorhy- drique et de I'oxygene en presence d'un catalyseur d'oxychloration pour donner des produits reactionnels constitues essentiellement d'hexachloroethane et d'eau; - deuxiemement, en isolant et faisant reagir ledit hexachloroethane avec du propylene et en option avec du chlore ajoute dans la phase vapeur afin d'obtenir des produits constitues de chlorure 20 allylique, de perchloroethylene et d'acide chlorhydrique; et - troisiemement, en isolant lesdits produits de la seconde etape et en repetant la premiere etape en utilisant comme matieres de depart le perchloroethylene et I'acide chlorhydrique ainsi isoles, d'ou il resulte que la chloration en utilisant I'hexachloroethane regenere est effectuee; le procede etant conduit avec une utilisation totale de I'acide chlorhydrique, et la production nette d'acide 25 chlorhydrique et d'hexachloroethane est evitee.

2. Procede selon la revendication 1, dans lequel le catalyseur de I'etape 1 comprend du chlorure de cuivre.

30 3. Procede selon la revendication 2, ou le catalyseur comprend un melange de chlorure de cuivre avec un ou plusieurs sels choisis dans le groupe constitue du chlorure de potassium, du chlorure ferrique, et du chlorure de plomb.

4. Procede selon la revendication 1 , dans lequel la reaction d'oxychloration avec du perchloroethylene est 35 effectuee a des temperatures dans la gamme de 200 ° C a 375 ° C.

5. Procede selon la revendication 1, dans lequel la reaction en phase vapeur est executee a des temperatures dans la gamme de 400 ° C a 700 ° C.

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