CA1122227A - Production of allyl chloride by use of molten salts - Google Patents
Production of allyl chloride by use of molten saltsInfo
- Publication number
- CA1122227A CA1122227A CA000341492A CA341492A CA1122227A CA 1122227 A CA1122227 A CA 1122227A CA 000341492 A CA000341492 A CA 000341492A CA 341492 A CA341492 A CA 341492A CA 1122227 A CA1122227 A CA 1122227A
- Authority
- CA
- Canada
- Prior art keywords
- molten salt
- chlorine
- chloride
- zone
- hydrogen chloride
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J10/00—Chemical processes in general for reacting liquid with gaseous media other than in the presence of solid particles, or apparatus specially adapted therefor
- B01J10/005—Chemical processes in general for reacting liquid with gaseous media other than in the presence of solid particles, or apparatus specially adapted therefor carried out at high temperatures in the presence of a molten material
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C17/00—Preparation of halogenated hydrocarbons
- C07C17/093—Preparation of halogenated hydrocarbons by replacement by halogens
- C07C17/10—Preparation of halogenated hydrocarbons by replacement by halogens of hydrogen atoms
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
PRODUCTION OF ALLYL CHLORIDE BY USE OF
MOLTEN SALTS
Abstract of the Disclosure Propylene is chlorinated with chlorine to produce allyl chloride and hydrogen chloride byproduct. Recovered hydrogen chloride by-product is contacted with oxygen and a molten salt mixture containing a higher and lower valent chlorides of a multivalent metal, such as cuprous and cupric chloride, to effect recovery of the hydrogen chloride by enriching the molten salt content of the higher valent chloride. The molten salt, enriched in higher valent chloride, is then dechlorinated by use of a stripping gas, preferably hydrogen chloride, to produce a gaseous effluent containing stripped chlorine and the stripping gas which is then recycled to the chlorination step.
-i-
MOLTEN SALTS
Abstract of the Disclosure Propylene is chlorinated with chlorine to produce allyl chloride and hydrogen chloride byproduct. Recovered hydrogen chloride by-product is contacted with oxygen and a molten salt mixture containing a higher and lower valent chlorides of a multivalent metal, such as cuprous and cupric chloride, to effect recovery of the hydrogen chloride by enriching the molten salt content of the higher valent chloride. The molten salt, enriched in higher valent chloride, is then dechlorinated by use of a stripping gas, preferably hydrogen chloride, to produce a gaseous effluent containing stripped chlorine and the stripping gas which is then recycled to the chlorination step.
-i-
Description
~122227 This invention relates to the production of allyl chloride and more particularly to the production of allyl chloride by the use of molten salts.
Molten salt mixtures, containing the higher and lower valent chlorides of a multivalent metal have been previously employed for the production of chlorinated hydrocarbons. Thus, for example, U.S. Patent No. 3,879,4~2 describes a process for produc-ing vinyl chloride wherein ethane and/or ethylene is contacted with a molten salt mixture containing the higher and lower valent chlorides of a multivalent metal, such as cuprous and cupric chloride, and hydrogen chloride and/or chlorine to produce an effluent containing vinyl chloride.
Similarly, U.S. Patent No. 3,865,886 describes a process for the production of allyl chloride employing a molten salt mixture containing the higher and lower valent chlorides of a multivalent metal. In this process, propane is contacted with hydrogen chloride and/or chlorine and the molten salt mixture to produce an effluent containing allyl chloride.
The present invention is directed to the production of chlorinated compounds by the use of molten salts, without direct contact between the fresh feed and the molten salt.
In accordance with the present invention, there is provided a process for producing allyl chloride wherein propylene is contacted with chlorine to produce an effluent containing allyl chloride and hydrogen chloride~ ~he allyl chloride and hydrogen chloride are recovered from the effluent, with at least a portion of the recovered hydrogen chloride being contacted in an oxidation zone with gaseous oxygen and a molten salt mixture containing the higher and lower valent chlorides of a multivalent metal to effect recovery of hydrogen chloride by enriching the higher valent chloride content of the molten salt. The molten salt, now enriched in higher valent metal chloride, is then passed to a dechlorination zone wherein the molten salt is dechlorinated with the use of a stripping gas to effect stripping of chlorine from the molten salt. Chlorine, recovered from the dechlorination, is then passed to the chlorination step. In this manner, allyl chloride is produced by chlorination of propylene, with hydrogen chloride byproduct being ultimately recovered and reconverted to chlorine for use in the chlorination, whereby fresh chlorine feed is effectively utilized for the production of allyl chloride.
The molten salts employed in the present invention include the higher and lower valent forms of a chloride of a multivalent metal; i.e., a metal having more than one positive valent state, such as manganese, iron, copper, cobalt and chromium, preferably copper. In the case of higher melting multivalent metal chlorides, such as copper chlorides, a metal salt melting point depressant, which iB non-volatile and resistent to the action of oxygen at the processing conditions, such as a chloride ofaunivalent metal;
i.e., a metal having only one positive valent state, is added to the multivalent metal chloride to form a molten salt mixture having a reduced melting point. The metal chlorides employed as melting point depressants are preferably alkali metal chlorides, such as potassium and lithium chloride, in particular, but it is to be understood that other metal chlorides and mixtures thereof, such as the heavy metal chlorides; i.e., heavier than copper, of groups I, II, and III and IV of the Periodic Table; e.g., zinc, silver and thallium chloride, may also be employed. The metal chloride melting point depressant is added in an amount sufficient to maintain the salt mixture as a melt at the reaction temperatures, and is generally added in an amount sufficient to adjust the 1122Z~7 melting point of the molten salt mixture to a temperature of below about 650F. In the case of the salt mixture of copper chlorides and potassium chloride, the composition of the melt generally ranges from about 15% to about 40%, preferably about 20% to 25~, by weight, potassium chloride with the remainder being copper chlorides. It is to be understood, however, that in some cases the molten salt mixture may have a melting point higher than 650F, provided that the mixture remains in the form of the melt throughout the processing steps. It is further to be understood that the melt may contain a mixture of multi-valent metal chlorides or other reaction promoters.
As hereinabove indicated, hydrogen chloride byproduct pro-duced during the chlorination reaction is converted to chlorine for recycle to the chlorination step by the use of the molten salt, with such conversion being effected in two reaction zones.
In particular, the hydrogen chloride byproduct is contacted with gaseous oxygen and the molten salt containing the higher and lower valent chlorides of the multivalent metal in an oxidation reaction zone to effect conversion and recovery of hydrogen chloride by enriching the higher valent metal chloride content of the molten salt.
The oxidation reaction zone is generally operated at a pressure of from about 1 atm to about 20 atm, and preferably at a pressure of from about 3 atm to about 6 atm. The salt in~et temperature to the oxidation reaction zone is generally from about 750F to about 950F and preferably from about 770F to about 840F.
The oxidation reaction zone is provided with gaseous oxygen (either as oxygen alone, or in admixture with another gas, for example, preferably air), in an amount sufficient to effect oxidation of the hydrogen chloride to effect recovery thereof by llZ2Z~7 enriching the higher valent chloride content of the salt. The precise amount of oxygen required for effecting such conversion can be readily determined by those skilled in the art from the teachings herein. The oxygen is preferably employed in an amount S whereby the molten salt withdrawn from the oxidation reaction zone is free of oxychloride. The oxidation reaction for effect-ing recovery of hydrogen chloride, employing copper chloride as a representative multivalent metal chloride, is represented by the following equations:
(1) 2 CuCl + 1/2 2- > CuC12.CuO
Molten salt mixtures, containing the higher and lower valent chlorides of a multivalent metal have been previously employed for the production of chlorinated hydrocarbons. Thus, for example, U.S. Patent No. 3,879,4~2 describes a process for produc-ing vinyl chloride wherein ethane and/or ethylene is contacted with a molten salt mixture containing the higher and lower valent chlorides of a multivalent metal, such as cuprous and cupric chloride, and hydrogen chloride and/or chlorine to produce an effluent containing vinyl chloride.
Similarly, U.S. Patent No. 3,865,886 describes a process for the production of allyl chloride employing a molten salt mixture containing the higher and lower valent chlorides of a multivalent metal. In this process, propane is contacted with hydrogen chloride and/or chlorine and the molten salt mixture to produce an effluent containing allyl chloride.
The present invention is directed to the production of chlorinated compounds by the use of molten salts, without direct contact between the fresh feed and the molten salt.
In accordance with the present invention, there is provided a process for producing allyl chloride wherein propylene is contacted with chlorine to produce an effluent containing allyl chloride and hydrogen chloride~ ~he allyl chloride and hydrogen chloride are recovered from the effluent, with at least a portion of the recovered hydrogen chloride being contacted in an oxidation zone with gaseous oxygen and a molten salt mixture containing the higher and lower valent chlorides of a multivalent metal to effect recovery of hydrogen chloride by enriching the higher valent chloride content of the molten salt. The molten salt, now enriched in higher valent metal chloride, is then passed to a dechlorination zone wherein the molten salt is dechlorinated with the use of a stripping gas to effect stripping of chlorine from the molten salt. Chlorine, recovered from the dechlorination, is then passed to the chlorination step. In this manner, allyl chloride is produced by chlorination of propylene, with hydrogen chloride byproduct being ultimately recovered and reconverted to chlorine for use in the chlorination, whereby fresh chlorine feed is effectively utilized for the production of allyl chloride.
The molten salts employed in the present invention include the higher and lower valent forms of a chloride of a multivalent metal; i.e., a metal having more than one positive valent state, such as manganese, iron, copper, cobalt and chromium, preferably copper. In the case of higher melting multivalent metal chlorides, such as copper chlorides, a metal salt melting point depressant, which iB non-volatile and resistent to the action of oxygen at the processing conditions, such as a chloride ofaunivalent metal;
i.e., a metal having only one positive valent state, is added to the multivalent metal chloride to form a molten salt mixture having a reduced melting point. The metal chlorides employed as melting point depressants are preferably alkali metal chlorides, such as potassium and lithium chloride, in particular, but it is to be understood that other metal chlorides and mixtures thereof, such as the heavy metal chlorides; i.e., heavier than copper, of groups I, II, and III and IV of the Periodic Table; e.g., zinc, silver and thallium chloride, may also be employed. The metal chloride melting point depressant is added in an amount sufficient to maintain the salt mixture as a melt at the reaction temperatures, and is generally added in an amount sufficient to adjust the 1122Z~7 melting point of the molten salt mixture to a temperature of below about 650F. In the case of the salt mixture of copper chlorides and potassium chloride, the composition of the melt generally ranges from about 15% to about 40%, preferably about 20% to 25~, by weight, potassium chloride with the remainder being copper chlorides. It is to be understood, however, that in some cases the molten salt mixture may have a melting point higher than 650F, provided that the mixture remains in the form of the melt throughout the processing steps. It is further to be understood that the melt may contain a mixture of multi-valent metal chlorides or other reaction promoters.
As hereinabove indicated, hydrogen chloride byproduct pro-duced during the chlorination reaction is converted to chlorine for recycle to the chlorination step by the use of the molten salt, with such conversion being effected in two reaction zones.
In particular, the hydrogen chloride byproduct is contacted with gaseous oxygen and the molten salt containing the higher and lower valent chlorides of the multivalent metal in an oxidation reaction zone to effect conversion and recovery of hydrogen chloride by enriching the higher valent metal chloride content of the molten salt.
The oxidation reaction zone is generally operated at a pressure of from about 1 atm to about 20 atm, and preferably at a pressure of from about 3 atm to about 6 atm. The salt in~et temperature to the oxidation reaction zone is generally from about 750F to about 950F and preferably from about 770F to about 840F.
The oxidation reaction zone is provided with gaseous oxygen (either as oxygen alone, or in admixture with another gas, for example, preferably air), in an amount sufficient to effect oxidation of the hydrogen chloride to effect recovery thereof by llZ2Z~7 enriching the higher valent chloride content of the salt. The precise amount of oxygen required for effecting such conversion can be readily determined by those skilled in the art from the teachings herein. The oxygen is preferably employed in an amount S whereby the molten salt withdrawn from the oxidation reaction zone is free of oxychloride. The oxidation reaction for effect-ing recovery of hydrogen chloride, employing copper chloride as a representative multivalent metal chloride, is represented by the following equations:
(1) 2 CuCl + 1/2 2- > CuC12.CuO
(2) CuC12.CuO + 2HC1 ~ 2 CuC12 + H2O
(3) 2 CuCl + 1/2 2 + 2HCl > 2 CuC12 + H2O
The molten salt mixture from the oxidation reaction zone, which is now enriched in the higher valent metal chloride, lS preferably cupric chloride, and which is also preferably free of oxychloride, is then intorduced into the dechlorination reaction zone wherein chlorine is stripped from the salt employ-ing a stripping gas to facilitate such chlorine stripping. The dechlorination reaction zone is generally operated at a pressure of from about 0.1 atm to about 3 atm, and preferably a pressure of from about 1 atm to about 2 atm. The molten salt inlet temperature to the dechlorination reaction zone is generally from about 850F to about 1000~, and preferably from about 900F to about 950~F. The dechlorination reaction zone is further provided with a stripping gas in an amount sufficient to facilitate stripping of chlorine from the molten salt. The amount of stripping gas employed is determined by the amount of chlorine d~sired in the dechlorination reactor effluent. Thus, the chlorine vapor pressure is determined by the temperature and the cupric chloride concentration, and for such a chlorine vapor 1~222~7 pressure the total pressure is selected to provide the desired chlorine mole fraction. The moles of stripping gas per mole of chlorine is then:
Total Pressure less Chlorine Partial Pressure Chlorine Partial Pressure The conditions of the dechlorination and the amount of stripping gas provided are generally coordinated to provide a dechlorination effluent containing from 5 to 40 mole percent of chlorine.
The stripping gas employed for stripping chlorine from the molten salt is one which is inert with respect to the molten salt, and which is also preferably inert with respect to the subsequent chlorination reaction in that in accordance with the preferred embodiment, chlorine produced in the dechlorination is not separated from the stripping gas and is employed directly for the chlorination operation. As representative examples of suitable stripping gases, there may be mentioned: hydrogen, chloride, nitrogen, helium, carbon dioxide, etc. The preferred stripping gas is hydrogen chloride in that hydrogen chloride is readily a~ailable in the process. The stripping of chlorine from the molten salt, employing copper chlorides as representative multivalent metal chlorides, is represented by the following equation:
The molten salt mixture from the oxidation reaction zone, which is now enriched in the higher valent metal chloride, lS preferably cupric chloride, and which is also preferably free of oxychloride, is then intorduced into the dechlorination reaction zone wherein chlorine is stripped from the salt employ-ing a stripping gas to facilitate such chlorine stripping. The dechlorination reaction zone is generally operated at a pressure of from about 0.1 atm to about 3 atm, and preferably a pressure of from about 1 atm to about 2 atm. The molten salt inlet temperature to the dechlorination reaction zone is generally from about 850F to about 1000~, and preferably from about 900F to about 950~F. The dechlorination reaction zone is further provided with a stripping gas in an amount sufficient to facilitate stripping of chlorine from the molten salt. The amount of stripping gas employed is determined by the amount of chlorine d~sired in the dechlorination reactor effluent. Thus, the chlorine vapor pressure is determined by the temperature and the cupric chloride concentration, and for such a chlorine vapor 1~222~7 pressure the total pressure is selected to provide the desired chlorine mole fraction. The moles of stripping gas per mole of chlorine is then:
Total Pressure less Chlorine Partial Pressure Chlorine Partial Pressure The conditions of the dechlorination and the amount of stripping gas provided are generally coordinated to provide a dechlorination effluent containing from 5 to 40 mole percent of chlorine.
The stripping gas employed for stripping chlorine from the molten salt is one which is inert with respect to the molten salt, and which is also preferably inert with respect to the subsequent chlorination reaction in that in accordance with the preferred embodiment, chlorine produced in the dechlorination is not separated from the stripping gas and is employed directly for the chlorination operation. As representative examples of suitable stripping gases, there may be mentioned: hydrogen, chloride, nitrogen, helium, carbon dioxide, etc. The preferred stripping gas is hydrogen chloride in that hydrogen chloride is readily a~ailable in the process. The stripping of chlorine from the molten salt, employing copper chlorides as representative multivalent metal chlorides, is represented by the following equation:
(4) 2 ~uC12 ~ 2 CuCl + C12 In accordance with a preferred embodiment of the present invention, the operating pressure of the oxidation reaction zone is at least 0.5 atm. greater than the operating pressure of the dechlorination reaction zone, with the pressure of the oxidation reaction zone generally being in the order of from about 1 atm.
to about 10 atm. greater than the pressure in the dechlorination reaction zone. In addition, the salt inlet temperature to the 1~22227 oxidation reactor is generally at least 50F less than the inlet temperature to the dechlorination reactor, with the salt inlet temperature to the oxidation reactor generally being from 80F
to 150F less than the salt inlet temperature to the dechlorina-tion reactor. The change in conditions between the oxidationreaction zone and the dechlorination reaction zone increases chlorine yields based on hydrogen chloride introduced into the oxidation reaction zone. The temperature change and change in the higher valent chloride concentration between the oxidation and dechlorination reaction zones can be achieved, without the use of heat exchange apparatus, by controlling the salt circula-tion rate. In general, the salt circulation rate is in the order of from about 20 to about 300 moles salt/mole C12 stripped and preferably from about 40 to about 90 moles salt/mole C12 stripped.
In accordance with a preferred embodimentl the dechlorination reactlon zone is maintained dry in order to provide a dechlorina-tion effluent which avoids the presence of aqueous hydrogen chloride, and the necessity to separate large amounts of water from the chlorination effluent. The dechlorination reaction zone may be maintained in a dry state by introducing a dry stripping gas, and by preventing water from being present in the molten salt withdrawn from the oxidation reaction zone. The molten salt withdrawn from the oxidation reaction zone may be maintained in a dry state by contacting the salt, immediately prior to withdrawal thereof from the oxidation reaction zone with hdyrogen chloride feed to strip water therefrom~ The hydrogen chloride also converts any copper oxide present in the salt whereby the salt introduced into the dechlorination zone is free of both water and copper oxide.
In accordance with a preferred embodiment, the chlorine ~1~"227 containing effluent withdrawn from the dechlorination reactor is employed without further treatment in the chlorination, except in some cases for separating any entrained and vaporized salt.
The use of the dechlorination effluent, which includes chlorine and stripping gas, directly, offers the advantage that there is a savings in heat and processing equipment costs. In addition, the stripping gas present in the chlorine functions as a diluent in the chlorination reaction which aids in stabilizing and controlling the chlorination reaction temperature. It is also possible, however, if necessary to treat the dechlorination effluent to separate the stripping gas from the chlorine, whereby chlorine, in the essential absence of stripping gas, is recycled to the chlorination reaction. It is also possible to effect compression of the stream and/or heating or cooling thereof, as appropriate, for subsequent chlorination. The use of the stripping gas as a diluent for the chlorination is preferred in that it affords good temperature control to both improve yield and lncrease onstream time.
The propylene can be chlorinated to allyl chloride by procedures known in the art. In general, propylene is contacted with gaseous chlorine at a temperature of from 600F to 1100F
and preferably at 900F to 950F. The chlorination is generally effected at a pressure of from 1 atm to 5 atm. The chlorination does not require a catalyst, however, as should be apparent, a catalyst could be employed.
The chlorination reaction effluent generally contains,in addition to allyl chloride and hydrogen chloride, unreacted propylene, 1,2 dichloropropane, mono and dichloropropylene. The unreacted propylene can be recovered and recycled to the chlorination reaction zone. Chlorinated reaction intermediates, which are potentially convertible to allyl chloride, in X
particular 1,2 dichloropropane, may be introduced into a further reaction zone for conversion to allyl chloride, however, in general the quantity of 1,2 dichloropropane produced does not warrant such further conversion.
The invention will be further described with respect to an embodiment thereof illustrated in the accompanying drawing, wherein:
The drawing is a simplified schematic flow diagram of an embodiment of the present invention.
Referring now to the drawing, propylene to be chlorinated, in line 10, is combined with recycle unreacted feed organic compound in line 11 and the combined stream in line 12 is combined with fresh feed chlorine in line 13 and a dechlorination reaction effluent in line 14, containing chlorine and hydrogen chloride, and obtained as hereinafter described. The combined stream in line 15 is intro~uced into a chlorination reactor, schematically generally indicated as 16.
In chlorination reactor 16, the propylene is chlorinated by direct contact with chlorine to produce allyl chloride, hydrogen chloride byproduct, as well as other chlorinated C3 compounds. The hydrogen chloride introduced with the feed does not react in the chlorination reactor.
A chlorination reactor effluent, containing allyl chloride, hydrogen chloride by-product, as well as unreacted feed and other by-products is withdrawn from reactor 16 through line 17 and introduced into a hydrogen chloride recovery zone, schemati-cally indicated as 18, for recovering hydrogen chloride from the effluent. Thus, for example, hydrogen chloride may be recovered by the use of two columns operated at two different pressures, with the gaseous effluent being introduced into the X - g _ 1~222"7 low pressure column, along with aqueous hydrogen chloride bottoms from the high pressure column, with the low pressure column being designed and operated to recover a gas stream essentially free of hydrogen chloride and an aqueous hydrogen chloride bottoms essentially free of organics. The bottoms recovered from the low pressure column is introduced into the high pressure column, which is designed and operated to recover an essentially water free hydrogen chloride gas. The aqueous hydrogen chloride bottoms from the high pressure column (having a hydroden chloride concentration lower than the liquid bottoms from the low pressure column) is then introduced into the low pressure column.
The above procedure and others may be employed for effecting recovery of hydrogen chloride.
An organic product essentially free of hydrogen chloride and now containing water in line 19 is introduced into a separa-tion and recovery section sechematically generally indicated as 21 in order to effect drying thereof and recovery of reaction product, organic byproducts and recycle for the chlorination reaçtor. Thus, allyl chloride is recovered through line 22, and unreacted feed is recovexed through line 11 for recycle to the chlorination reactor 16.
Chlorinated hydrocarbon byproducts are recovered through line 24 for treatment as hereinafter described.
The hydrogen chloride recovered from zone 18 in line 31 is split into two portions, one portion of which is the net hydrogen chloride produced in the chlorination reactor 16, in line 32, and the other portion, in line 33, being the portion employed as stripping gas for the dechlorination reactor, which is ultimately introduced into the chlorination reactor 16. The net hydrogen chloride in line 32 is introduced into an oxidation reactor, schematically indicated as 34 for effecting reco~ery thereof.
/\
~.. ` -- 10 --~2~ 7 The oxidation reactor 34 is provided through line 35 with a molten salt mixture, containing the higher and lower valent chlorides of a multivaLent metal, and further including a melting point depressant, such as a mixture of cuprous chloride, cupric chloride and potassium chloride, and is further provided with an oxygen containing gas, such as air, through line 36, A chlorinated hydrocarbon combustion effluent, containing hydrogen chloride and some chlorine is also introduced into reactor 34 through line 37 Such effluent is obtained by burning the chlorinated byproducts in line 24 in a combustion zone 38 which is provided with air through line 39 As a result of the contact between the hydrogen chloride, air and molten salt, the hydrogen chloride is recovered by enriching the cupric chloride content of the molten salt In addition, any gaseous chlorine present in the effluent in line 37 is recovered by enriching the cupric chloride content of the molten salt A gaseous effluent is withdrawn from reactor 34 through line 43, and such gaseous effluent may include e~uilibrium amounts of hydrogen chloride, and chlorine, if any, as well as components intro-duced with the combustion effluent in line 37, such as carbon oxides, and with the air, such as nitrogen The effluent in line 43 may be further treated in a hydrogen chloride recovery zone 44, as known in the art, in order to recover aqueous hydrogen chloride in line 45 which is recycled to the oxidation reactor 34, ~hus, for example, such effluent in line 39 may be further treated as described in U S
Patent 3; 96 3, 2 00 .
~Z2Z~7 A molten salt, now enriched in cupric chloride, is withdrawn from reactor 34 through line 41 and introduced into the top of a dechlo-rination reactor, schematicalLy generally indicated as 42. The de-chlorination reactor 42 is operated as hereinabove described in order to strip chlorine from the salt. The dechlorination reactor is provided with hydrogen chloride stripping gas through line 33, and as a result of the conditions in reactor 42 and the stripping action of the hydrogen chloride, gaseous chlorine is stripped from the salt, with the cupric chloride being converted to cuprous chloride.
Molten salt withdrawn from reactor 42 is recycled to reactor 34 through line 35.
A dechlorination effluent, containing gaseous chlorine, as well as hydrogen chloride, introduced as stripping g~s, is withdrawn from reactor 42 through line 14, for introduction into the chlorination reactor 16 The chlorine stripped from the salt is that produced from the hydrogen chloride generated in reactor 16, as well as any chlorine values recovered from waste chlorinated product produced in the chlori-natlon reactor 16, As hereinabove described, the mixture of chlorine and hydrogen chloride stripping gas is preferably directly employed for the chlori-nation reaction; however, the effluent from the dechlorination reactor 42 may be treated to separately recover the chlorine for introduction into the chlorination reactor 16 In addition, although the addition of hydrogen chloride as the stripping gas is preferred, the stripping of chlorine from the molt~
salt may be effected by the use of a stripping gas other than hydrogen chloride; e. g, nitrogen It is also to be understood that all or a portion of the byproducts recovered in line 24 could be separately recovered as product and/or recycle for further production of allyl chloride.
~l~2~:~27 The invention will be further described with respect to the following example:
EXAMPLE
The following provides in Tabular form a flow scheme for producing allyl chloride in accordance with embodiment of the dra~ring.
Flow rates are in moles per hour, The organics produced in reactor 16 are primarily various chlorinated C3 hydrocarbons.
1~2~227 TA BLE
.
N2 0 2 4. 5 5.2 4.5 0. 7 H2O 0.4 0. 6 C12 83. 5 139. 4 C2 0 3 4.1 4.7 4.1 0.6 C3H6 200. 5 466. 8 0. 7 467. 8 1. 00.2 C3HsCl 165.2 163.4 1.8 Organics 1. 5 36.28 1.4533.33 HCl 4.7 1487.4 1713. 8 1487.4 221.7 pPsrieaS s ur e 20 20 20 20 18 25 80 5 ~) 85 Temp F 80 110 80 905 950 80 80 100 200 1.1~22~7 TABLE I, Cont.
l39 36 37 43 35 41 45 N2 1264 229 1264 1493.7 2 334 60 197.4 185,2 H2 O 55 11 116,6 3 6 224,1 C2 107,1 108,3 HCl 58,1 23,7 29,2 KCl 2407 2407 CuCl 2661 2382 CuCl2 2956 3235 pPsriessure 85 80 80 75 75 21 80 Temp F 80 80 770 775 910 310 l~ Z~7 The present invention is particularly advantageous in that it permits allyl chloride production with effective recovery of hydrogen chloride byproduct for use in such production. In addition, the use of recovered chlorine diluted with the stripping gas provides for improved ternperature control, which improves selectivity. In addition, chlorine does not have to be precisely metered to the chloristor to avoid chlorinolysis and the resultant production of carbon, tars and byproducts.
Thus, a more stable operation is achieved, Furthermore, the sensible heat of the dechlorination effluent can be recovered in the chlorir~a~or.
to about 10 atm. greater than the pressure in the dechlorination reaction zone. In addition, the salt inlet temperature to the 1~22227 oxidation reactor is generally at least 50F less than the inlet temperature to the dechlorination reactor, with the salt inlet temperature to the oxidation reactor generally being from 80F
to 150F less than the salt inlet temperature to the dechlorina-tion reactor. The change in conditions between the oxidationreaction zone and the dechlorination reaction zone increases chlorine yields based on hydrogen chloride introduced into the oxidation reaction zone. The temperature change and change in the higher valent chloride concentration between the oxidation and dechlorination reaction zones can be achieved, without the use of heat exchange apparatus, by controlling the salt circula-tion rate. In general, the salt circulation rate is in the order of from about 20 to about 300 moles salt/mole C12 stripped and preferably from about 40 to about 90 moles salt/mole C12 stripped.
In accordance with a preferred embodimentl the dechlorination reactlon zone is maintained dry in order to provide a dechlorina-tion effluent which avoids the presence of aqueous hydrogen chloride, and the necessity to separate large amounts of water from the chlorination effluent. The dechlorination reaction zone may be maintained in a dry state by introducing a dry stripping gas, and by preventing water from being present in the molten salt withdrawn from the oxidation reaction zone. The molten salt withdrawn from the oxidation reaction zone may be maintained in a dry state by contacting the salt, immediately prior to withdrawal thereof from the oxidation reaction zone with hdyrogen chloride feed to strip water therefrom~ The hydrogen chloride also converts any copper oxide present in the salt whereby the salt introduced into the dechlorination zone is free of both water and copper oxide.
In accordance with a preferred embodiment, the chlorine ~1~"227 containing effluent withdrawn from the dechlorination reactor is employed without further treatment in the chlorination, except in some cases for separating any entrained and vaporized salt.
The use of the dechlorination effluent, which includes chlorine and stripping gas, directly, offers the advantage that there is a savings in heat and processing equipment costs. In addition, the stripping gas present in the chlorine functions as a diluent in the chlorination reaction which aids in stabilizing and controlling the chlorination reaction temperature. It is also possible, however, if necessary to treat the dechlorination effluent to separate the stripping gas from the chlorine, whereby chlorine, in the essential absence of stripping gas, is recycled to the chlorination reaction. It is also possible to effect compression of the stream and/or heating or cooling thereof, as appropriate, for subsequent chlorination. The use of the stripping gas as a diluent for the chlorination is preferred in that it affords good temperature control to both improve yield and lncrease onstream time.
The propylene can be chlorinated to allyl chloride by procedures known in the art. In general, propylene is contacted with gaseous chlorine at a temperature of from 600F to 1100F
and preferably at 900F to 950F. The chlorination is generally effected at a pressure of from 1 atm to 5 atm. The chlorination does not require a catalyst, however, as should be apparent, a catalyst could be employed.
The chlorination reaction effluent generally contains,in addition to allyl chloride and hydrogen chloride, unreacted propylene, 1,2 dichloropropane, mono and dichloropropylene. The unreacted propylene can be recovered and recycled to the chlorination reaction zone. Chlorinated reaction intermediates, which are potentially convertible to allyl chloride, in X
particular 1,2 dichloropropane, may be introduced into a further reaction zone for conversion to allyl chloride, however, in general the quantity of 1,2 dichloropropane produced does not warrant such further conversion.
The invention will be further described with respect to an embodiment thereof illustrated in the accompanying drawing, wherein:
The drawing is a simplified schematic flow diagram of an embodiment of the present invention.
Referring now to the drawing, propylene to be chlorinated, in line 10, is combined with recycle unreacted feed organic compound in line 11 and the combined stream in line 12 is combined with fresh feed chlorine in line 13 and a dechlorination reaction effluent in line 14, containing chlorine and hydrogen chloride, and obtained as hereinafter described. The combined stream in line 15 is intro~uced into a chlorination reactor, schematically generally indicated as 16.
In chlorination reactor 16, the propylene is chlorinated by direct contact with chlorine to produce allyl chloride, hydrogen chloride byproduct, as well as other chlorinated C3 compounds. The hydrogen chloride introduced with the feed does not react in the chlorination reactor.
A chlorination reactor effluent, containing allyl chloride, hydrogen chloride by-product, as well as unreacted feed and other by-products is withdrawn from reactor 16 through line 17 and introduced into a hydrogen chloride recovery zone, schemati-cally indicated as 18, for recovering hydrogen chloride from the effluent. Thus, for example, hydrogen chloride may be recovered by the use of two columns operated at two different pressures, with the gaseous effluent being introduced into the X - g _ 1~222"7 low pressure column, along with aqueous hydrogen chloride bottoms from the high pressure column, with the low pressure column being designed and operated to recover a gas stream essentially free of hydrogen chloride and an aqueous hydrogen chloride bottoms essentially free of organics. The bottoms recovered from the low pressure column is introduced into the high pressure column, which is designed and operated to recover an essentially water free hydrogen chloride gas. The aqueous hydrogen chloride bottoms from the high pressure column (having a hydroden chloride concentration lower than the liquid bottoms from the low pressure column) is then introduced into the low pressure column.
The above procedure and others may be employed for effecting recovery of hydrogen chloride.
An organic product essentially free of hydrogen chloride and now containing water in line 19 is introduced into a separa-tion and recovery section sechematically generally indicated as 21 in order to effect drying thereof and recovery of reaction product, organic byproducts and recycle for the chlorination reaçtor. Thus, allyl chloride is recovered through line 22, and unreacted feed is recovexed through line 11 for recycle to the chlorination reactor 16.
Chlorinated hydrocarbon byproducts are recovered through line 24 for treatment as hereinafter described.
The hydrogen chloride recovered from zone 18 in line 31 is split into two portions, one portion of which is the net hydrogen chloride produced in the chlorination reactor 16, in line 32, and the other portion, in line 33, being the portion employed as stripping gas for the dechlorination reactor, which is ultimately introduced into the chlorination reactor 16. The net hydrogen chloride in line 32 is introduced into an oxidation reactor, schematically indicated as 34 for effecting reco~ery thereof.
/\
~.. ` -- 10 --~2~ 7 The oxidation reactor 34 is provided through line 35 with a molten salt mixture, containing the higher and lower valent chlorides of a multivaLent metal, and further including a melting point depressant, such as a mixture of cuprous chloride, cupric chloride and potassium chloride, and is further provided with an oxygen containing gas, such as air, through line 36, A chlorinated hydrocarbon combustion effluent, containing hydrogen chloride and some chlorine is also introduced into reactor 34 through line 37 Such effluent is obtained by burning the chlorinated byproducts in line 24 in a combustion zone 38 which is provided with air through line 39 As a result of the contact between the hydrogen chloride, air and molten salt, the hydrogen chloride is recovered by enriching the cupric chloride content of the molten salt In addition, any gaseous chlorine present in the effluent in line 37 is recovered by enriching the cupric chloride content of the molten salt A gaseous effluent is withdrawn from reactor 34 through line 43, and such gaseous effluent may include e~uilibrium amounts of hydrogen chloride, and chlorine, if any, as well as components intro-duced with the combustion effluent in line 37, such as carbon oxides, and with the air, such as nitrogen The effluent in line 43 may be further treated in a hydrogen chloride recovery zone 44, as known in the art, in order to recover aqueous hydrogen chloride in line 45 which is recycled to the oxidation reactor 34, ~hus, for example, such effluent in line 39 may be further treated as described in U S
Patent 3; 96 3, 2 00 .
~Z2Z~7 A molten salt, now enriched in cupric chloride, is withdrawn from reactor 34 through line 41 and introduced into the top of a dechlo-rination reactor, schematicalLy generally indicated as 42. The de-chlorination reactor 42 is operated as hereinabove described in order to strip chlorine from the salt. The dechlorination reactor is provided with hydrogen chloride stripping gas through line 33, and as a result of the conditions in reactor 42 and the stripping action of the hydrogen chloride, gaseous chlorine is stripped from the salt, with the cupric chloride being converted to cuprous chloride.
Molten salt withdrawn from reactor 42 is recycled to reactor 34 through line 35.
A dechlorination effluent, containing gaseous chlorine, as well as hydrogen chloride, introduced as stripping g~s, is withdrawn from reactor 42 through line 14, for introduction into the chlorination reactor 16 The chlorine stripped from the salt is that produced from the hydrogen chloride generated in reactor 16, as well as any chlorine values recovered from waste chlorinated product produced in the chlori-natlon reactor 16, As hereinabove described, the mixture of chlorine and hydrogen chloride stripping gas is preferably directly employed for the chlori-nation reaction; however, the effluent from the dechlorination reactor 42 may be treated to separately recover the chlorine for introduction into the chlorination reactor 16 In addition, although the addition of hydrogen chloride as the stripping gas is preferred, the stripping of chlorine from the molt~
salt may be effected by the use of a stripping gas other than hydrogen chloride; e. g, nitrogen It is also to be understood that all or a portion of the byproducts recovered in line 24 could be separately recovered as product and/or recycle for further production of allyl chloride.
~l~2~:~27 The invention will be further described with respect to the following example:
EXAMPLE
The following provides in Tabular form a flow scheme for producing allyl chloride in accordance with embodiment of the dra~ring.
Flow rates are in moles per hour, The organics produced in reactor 16 are primarily various chlorinated C3 hydrocarbons.
1~2~227 TA BLE
.
N2 0 2 4. 5 5.2 4.5 0. 7 H2O 0.4 0. 6 C12 83. 5 139. 4 C2 0 3 4.1 4.7 4.1 0.6 C3H6 200. 5 466. 8 0. 7 467. 8 1. 00.2 C3HsCl 165.2 163.4 1.8 Organics 1. 5 36.28 1.4533.33 HCl 4.7 1487.4 1713. 8 1487.4 221.7 pPsrieaS s ur e 20 20 20 20 18 25 80 5 ~) 85 Temp F 80 110 80 905 950 80 80 100 200 1.1~22~7 TABLE I, Cont.
l39 36 37 43 35 41 45 N2 1264 229 1264 1493.7 2 334 60 197.4 185,2 H2 O 55 11 116,6 3 6 224,1 C2 107,1 108,3 HCl 58,1 23,7 29,2 KCl 2407 2407 CuCl 2661 2382 CuCl2 2956 3235 pPsriessure 85 80 80 75 75 21 80 Temp F 80 80 770 775 910 310 l~ Z~7 The present invention is particularly advantageous in that it permits allyl chloride production with effective recovery of hydrogen chloride byproduct for use in such production. In addition, the use of recovered chlorine diluted with the stripping gas provides for improved ternperature control, which improves selectivity. In addition, chlorine does not have to be precisely metered to the chloristor to avoid chlorinolysis and the resultant production of carbon, tars and byproducts.
Thus, a more stable operation is achieved, Furthermore, the sensible heat of the dechlorination effluent can be recovered in the chlorir~a~or.
Claims (12)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for producing allyl chloride, comprising (a) contacting in a chlorination zone propylene with chlorine to produce an effluent containing allyl chloride and hydrogen chloride;
(b) recovering allyl chloride and hydrogen chloride;
(c) introducing at least a portion of the recovered hydrogen chloride into an oxidation reaction zone wherein the hydrogen chloride is contacted with a molten salt mixture containing the higher and lower valent chlorides of a multivalent metal and oxygen to recover chlorine by enriching the higher valent metal chloride content of the molten salt;
(d) passing molten salt from the oxidation reaction zone to a dechlorination zone wherein the molten salt is contacted with a stripping gas to strip chlorine from the molten salt;
(e) recovering gaseous chlorine from the dechlorination zone; and (f) passing recovered gaseous chlorine to the chlorination zone.
(b) recovering allyl chloride and hydrogen chloride;
(c) introducing at least a portion of the recovered hydrogen chloride into an oxidation reaction zone wherein the hydrogen chloride is contacted with a molten salt mixture containing the higher and lower valent chlorides of a multivalent metal and oxygen to recover chlorine by enriching the higher valent metal chloride content of the molten salt;
(d) passing molten salt from the oxidation reaction zone to a dechlorination zone wherein the molten salt is contacted with a stripping gas to strip chlorine from the molten salt;
(e) recovering gaseous chlorine from the dechlorination zone; and (f) passing recovered gaseous chlorine to the chlorination zone.
2. The process of Claim 1 wherein the gaseous chlorine and stripping gas recovered from the dechlorination zone are introduced into the chlorination zone.
3. The process of Claim 2 wherein the gaseous chlorine and stripping gas withdrawn from the dechlorination zone are essentially free of water.
4. The process of Claim 3 wherein the stripping gas employed in the dechlorination zone is a portion of the hydrogen chloride recovered from the effluent from the chlorination zone.
5. The process of Claim 2 wherein the gaseous chlorine and stripping gas recovered from the dechlorination zone contains from 5 to 40 mole percent chlorine.
6. The process of Claim 5 wherein the molten salt mixture contains a mixture of cuprous and cupric chloride.
7. The process of Claim 5 wherein the oxidation reaction zone is operated at a pressure of from 1 to 20 atm and a molten salt inlet temperature of from 750°F to 950°F and the dechlorination zone is operated at a pressure of from 0.1 to 3.0 atm, and a molten salt inlet temperature of from 750°F to 1000°F.
8. The process of Claim 7 wherein the oxidation reaction zone pressure is at least 0.5 atm greater than the dechlorination zone pressure and the molten salt inlet temperature to the oxidation reaction zone is at least 50°F less than the molten salt inlet temperature to the dechlorination zone.
9. The process of Claim 5 wherein the molten salt introduced into the dechlorination zone is free of water and the oxide of the multi-valent metal.
10. The process of Claim 1 wherein the contacting of step (a) is effected at a temperature of from 600°F to 1100°F.
11. The process for producing allyl chloride claimed in Claim 1, comprising:
(a) contacting in a chlorination zone propylene with fresh feed chlorine and a recycle mixture containing chlorine and hydrogen chloride to produce an effluent containing allyl chloride and hydrogen chloride;
(b) recovering allyl chloride and hydrogen chloride;
(c) introducing a first portion of recovered hydrogen chloride into an oxidation reaction zone wherein the hydrogen chloride is contacted with a molten salt mixture containing the higher and lower valent chlorides of a multivalent metal and oxygen to recover chlorine by enriching the higher valent metal chloride content of the molten salt;
(d) passing molten salt from the oxidation reaction zone to a dechlorination zone wherein the molten salt is contacted with a second portion of recovered hydrogen chloride, as stripping gas, to strip chlorine from the molten salt; and (e) withdrawing from the dechlorination zone a mixture of chlorine and hydrogen chloride for introduction into the chlorination zone as said recycle mixture.
(a) contacting in a chlorination zone propylene with fresh feed chlorine and a recycle mixture containing chlorine and hydrogen chloride to produce an effluent containing allyl chloride and hydrogen chloride;
(b) recovering allyl chloride and hydrogen chloride;
(c) introducing a first portion of recovered hydrogen chloride into an oxidation reaction zone wherein the hydrogen chloride is contacted with a molten salt mixture containing the higher and lower valent chlorides of a multivalent metal and oxygen to recover chlorine by enriching the higher valent metal chloride content of the molten salt;
(d) passing molten salt from the oxidation reaction zone to a dechlorination zone wherein the molten salt is contacted with a second portion of recovered hydrogen chloride, as stripping gas, to strip chlorine from the molten salt; and (e) withdrawing from the dechlorination zone a mixture of chlorine and hydrogen chloride for introduction into the chlorination zone as said recycle mixture.
12. The process of Claim 11 wherein the gaseous chlorine and stripping gas recovered from the dechlorination zone contains from 5 to 40 mole percent chlorine.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US268779A | 1979-01-11 | 1979-01-11 | |
| US2,687 | 1979-01-11 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1122227A true CA1122227A (en) | 1982-04-20 |
Family
ID=21701982
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000341492A Expired CA1122227A (en) | 1979-01-11 | 1979-12-07 | Production of allyl chloride by use of molten salts |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS5594324A (en) |
| BE (1) | BE881083A (en) |
| CA (1) | CA1122227A (en) |
| DE (1) | DE3000277A1 (en) |
| FR (1) | FR2446268A1 (en) |
| GB (1) | GB2039905A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5981818A (en) | 1995-03-21 | 1999-11-09 | Stone & Webster Engineering Corp. | Integrated cracking and olefins derivative process utilizing dilute olefins |
| US6593506B1 (en) | 2000-10-12 | 2003-07-15 | Exxonmobil Chemical Patents Inc. | Olefin recovery in a polyolefin production process |
| US6495609B1 (en) | 2000-11-03 | 2002-12-17 | Exxonmobil Chemical Patents Inc. | Carbon dioxide recovery in an ethylene to ethylene oxide production process |
| JP2011105637A (en) * | 2009-11-17 | 2011-06-02 | Sumitomo Chemical Co Ltd | Method for producing allyl chloride and dichlorohydrin |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1960158A1 (en) * | 1969-12-01 | 1971-06-16 | Hoechst Ag | Allyl chloride by chlorination of propylene |
| US3865886A (en) * | 1973-06-20 | 1975-02-11 | Lummus Co | Production of allyl chloride |
| US4119705A (en) * | 1977-04-06 | 1978-10-10 | The Lummus Company | Production of chlorine |
-
1979
- 1979-12-07 CA CA000341492A patent/CA1122227A/en not_active Expired
- 1979-12-14 JP JP16343579A patent/JPS5594324A/en active Pending
-
1980
- 1980-01-03 GB GB8000166A patent/GB2039905A/en not_active Withdrawn
- 1980-01-05 DE DE19803000277 patent/DE3000277A1/en not_active Ceased
- 1980-01-09 FR FR8000415A patent/FR2446268A1/en active Granted
- 1980-01-10 BE BE0/198911A patent/BE881083A/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| BE881083A (en) | 1980-05-02 |
| FR2446268A1 (en) | 1980-08-08 |
| JPS5594324A (en) | 1980-07-17 |
| FR2446268B1 (en) | 1984-06-29 |
| GB2039905A (en) | 1980-08-20 |
| DE3000277A1 (en) | 1980-07-24 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4129604A (en) | Reactor effluent quench system | |
| US4899000A (en) | Production of allyl chloride | |
| US4329525A (en) | Production of chlorinated compounds by use of molten salts | |
| US3591646A (en) | Process for obtaining halogenated,fluorine containing organic compounds | |
| US4094915A (en) | Recovery of 12-dichloroethane from vinyl chloride production effluent | |
| CA1122227A (en) | Production of allyl chloride by use of molten salts | |
| CA1054777A (en) | Oxidation of molten salts and recovery of chlorine values | |
| US4046823A (en) | Process for producing 1,2-dichloroethane | |
| KR20180036915A (en) | Chlorination and dehydrogenation of ethane | |
| US4036776A (en) | Recovery of chlorine values from a melt oxidation gas | |
| KR790001615B1 (en) | Oxychlorination of methane | |
| CA1105675A (en) | Recovery of hydrogen chloride in carbochlorination of metal oxides | |
| US3949010A (en) | Production of chlorinated hydrocarbons | |
| GB1375329A (en) | ||
| CA1169885A (en) | Recovery of chlorine values in integrated process for oxychlorination and combustion of chlorinated hydrocarbons | |
| US4036897A (en) | Production of hexachlorocyclopentadiene | |
| CA1071238A (en) | Purging tars and carbon from chlorinated hydrocarbon effluent | |
| US3879482A (en) | Vinyl chloride process | |
| US3965202A (en) | Production of trichloro-ethylene from waste C2 chlorinated hydrocarbons | |
| CA1069943A (en) | Aqueous stream treatment in chlorinated hydrocarbon production | |
| US4115323A (en) | Catalyst and process for production of VCM | |
| CA1043359A (en) | Dehydrochlorination of 1,2-dichloroethane | |
| US4207267A (en) | Dehydrochlorination of 1,2-dichloroethane | |
| KR790001614B1 (en) | Oxychlororination of methane | |
| US3980723A (en) | Purging of inerts in chlorinated hydrocarbon production |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |