DE2151546B2 - Process for utilizing the heavy residues resulting from the production of C deep 1 and / or C deep 2 chlorohydrocarbons - Google Patents

Description

2. The method according to claim 1, characterized in that the liquid-phase chlorination executes so that the iron (IH) chloride in situ by the action of chlorine in the reaction medium introduced iron particles or on ordinary steel.

3. The method according to claim 1 and 2, characterized in that: in step (5 b) as Crackzone uses a distillation zone.

4. The method according to claim 1 to 3, characterized

The invention relates to a technical process for the utilization of heavy residues, which are a complex mixture rich in C _r chlorinated hydrocarbons with relatively less C ₃ -

Chlorinated hydrocarbons and very little C _e -chlorinated hydrocarbons.

These heavy residues are formed in the industrial production of C ₁ - and / or C ₂ chlorohydrocarbons, ie in the production of chlorinated solvents such as trichlorethylene, perchlorethylene, 1,1,1-trichloroethane, carbon tetrachloride and 1,2-dichloroethylene as well in the production of vinyl chloride and vinylidene chloride, which are well-known important monomers.

In the present description, “heavy residues” refers to a complex chlorohydrocarbon mixture whose boiling point is 80 to 350 ° C and which mainly contains C ₃ and 3 products as well as 0.1 to 3 percent by weight of chlorinated benzene hydrocarbons.

Qualitatively, this complex mixture can be defined as the totality of the components, contained in one or more ^{fractions labeled D 3} , D ² , D ¹ , L ¹ , L ² and / or L ³ , which are collected in the course of the distillation of the residues can be.

The D ³ fraction consists of at least one saturated and / or unsaturated C ₃ - and / or C ₄ chlorocarbon, which at atmospheric pressure of 87 ° C, the boiling point of trichlorethylene, to 113.5 ⁰ C, the boiling point of 1,1 , 2-trichloroethane. This fraction mainly contains isomers of dichlorobutane, dichlorobutadiene, trichloropropane and dichlorobutane.

The fraction D ² consists of at least one saturated and / or unsaturated C ₃ - and / or C ₄ -chlorohydrocarbon, which under atmospheric pressure between 113.5 ° C and 130.5 ° C, the boiling point of 1,1,1,2 -Tetrachloroethane. This fraction contains in particular isomers of dichloro- and trichlorobutenes as well as isomers of trichloropropene and trichloropropane.

Fraction D ¹ consists of at least one saturated and / or unsaturated C ₃ - and / or C ₄ -

Chlorinated hydrocarbon or a benzene chlorinated hydrocarbon that is at atmospheric pressure from 130.5 to 146.3 ° C, the boiling point of 1,1,2,2-Tetrachlorälhan, transforms. This group contains

also predominantly the isomers of dichloro- and trichlorobutenes and the isomers of dichloroeutadiene, Trichloropropene and trichloropropane as well as monochlorobenzene.

Fraction L ¹ consists of at least one saturated and / or unsaturated C ₃ and / or C ₄ chlorohydrocarbon, which passes under atmospheric pressure of 146.3 to 160.5 ° C., the boiling point of pentachloroethane. This fraction contains the isomers of dichloro-, trichloro- and tetrachlorobutene, of trichloro- and tetrachlorobutadiene, of tetrachiorpropene and of tetrachloropropane.

The fraction L ² consists of at least one saturated and / or unsaturated C ₃ and / or C ₄ hydrocarbon or a benzene (C ₆ ) chlorinated hydrocarbon, which is below atmospheric pressure of 160.5 to 186 ° C, the sublimation point of hexachloroethane, transforms. This fraction also contains the isomers of trichlorobutene and tetrachlorobutene, of trichlorobutadiene and tetrachlorobutadiene, of tetrachloropropene, of pentachloropropane as well as the looser isomers of tetrachlorobutane and dichlorobenzene.

The fraction L ³ consists of at least one saturated and / or unsaturated, strongly chlorinated C ₃ - and / or ^ -hydrocarbon and the chlorobenzenes, which pass over under atmospheric pressure of 186 to 350 ° C. This fraction contains the isomers of pentachlorobutadiene, hexachlorobutadiene, hexachloropropene, octachloropropane, of pentachlorobutane and hexachlorobutane, of octachloro-ethylene, and the isomers of tetrachlorobutene, pentachlorobutene and Hcxachlorobut and of trichlorobenzene and tetrachlorobenzene.

The composition of the mixture, ie the ratio of the various fractions D ³ to D ¹ and L ¹ to L ^s, fluctuates quantitatively very strongly and depends on the process conditions in the preparation of the chlorinated C ₁ and / or C ₂ solvents in which the heavy residues in question arise.

These heavy residues always also contain chlorinated C ₁ and / or C ₂ hydrocarbons, the boiling points of which are very close to those of certain C ₄ and / or C ₃ hydrocarbons of the heavy residues. For this reason, the complete separation of the C ₁ - and / or ^ -chlorohydrocarbons from these heavy residues is extremely difficult to achieve technically, if not impossible. The proportion of C ₁ and / or C ₂ chlorohydrocarbons varies depending on the manufacturing process used.

As an example it should be mentioned that in the process for the preparation of chlorine derivatives of ethylene according to French patents 14 03 743 and 15 52 849 the chlorinated solvents 5 to 70 percent by weight which can make heavy residues.

The economic importance of utilizing these residues in the industrial production of chlorinated solvents is obvious when one takes into account that for every ton of chlorinated C ₁ and / or C ₂ solvents obtained, by-products weighing 5 to 150 kg can be formed As stated above, entrain non-separable C ₂ - and / or Cg-chlorinated hydrocarbons with them.

It is impossible for this residue to be drained into water courses or the sea because of this serious pollution problems would arise; the residues are burned also out of the question because it is not profitable.

It is known that a product such as hexachlorobutadiene can be converted _{into C 2 chlorohydrocarbons by chlorination in the liquid phase.} According to the publication by A. Roedig in "Liebigs Annalen der Chemie", 1951, vol. 574, p. 122 bk 130, the chlorination of hexachlorobutadiene in the presence of light with gaseous chlorine or liquid chlorine at room temperature or in heat and, if necessary, carry out in the presence of iron powder or ferric chloride. In the reaction with gaseous chlorine at 200 ° C. for 2 hours in the presence of iron powder, the conversion of hexachlorobutadiene to hexachloroethane, the only reaction product described, is only 27 mol percent, based on theory. With liquid chlorine, the reaction is carried out in the fused tube, i.e. under pressure, at room temperature for 1 to 3 days. It is clear that no technical process can be based on such experiments, in particular on the experiments in a sealed tube.

Recently, Japanese Patent Nos. 4,321/68 and 4,326/68 have disclosed a method for Chlorination of hexachlorobutadiene described, also under pressure and at temperatures above 60 ° C is carried out. However, this working under pressure does not only set a special one adapted device ahead, but also raises numerous technical problems, in particular Problems with the corrosion that is accelerated when working under pressure and problems with the sealing losses. In addition, it is difficult to follow the course of the reactions that take place in the autoclave run under pressure to control.

It is also known to use tetrachlorobutadiene and / or pentachlorobutadiene in a two-stage process with vapor phase chlorination and liquid phase chlorination in carbon tetrachloride and tetrachlorethylene to convert (US-PS 34 54 660).

It has now been found that heavy residues which contain very little hexachlorobutadiene cannot be converted into C ₂ - and / or ^ -chlorohydrocarbons by chlorination in the heat in the liquid phase.

The object of the invention is to make the C ₄ - and / or ^ -chlorocarbons of the heavy residues _{usable by converting them into C 2} - and / or Cj-chlorohydrocarbons and at the same time to use the C ₁ - and / or to recover C-chlorohydrocarbons with the aid of a continuous process that is technically easy to carry out.

The invention thus relates to the method indicated in the preceding claims.

According to a preferred embodiment, the heavy residues are evaporated and with Chlorine is mixed in a mixing zone before the reactants enter the vapor phase chlorination zone be fed in. The residence time of the reactants in the mixing zone is 0.01 to 0.5 s, the temperature is 80 to 300 ° C. The mixture, containing the heavy products, can also be used immediately are fed in in the form of small liquid particles.

The from the vapor phase chlorination zone

5 6

emerging gas mixture is removed according to the invention. The following examples serve to frighten the invention in more detail with the aid of water or a chlorinated purification.
Solvents such as carbon tetrachloride, perchloric acid

ethylene, hexachlorobutadiene and optionally tri Example 1
chlorethylene. In the case of deterrence with 5

Water accruing hydrochloric acid or *. The plant for reprocessing the heavy quenching with chlorinated solvent for usable products comprised a leeward-dry hydrogen chloride is recovered and reactor A is used as a vapor-phase chlorination zone as required, in particular for production and a reactor B made of nickel as a liquid-phase volume Chlorine after the Deacon process in the chlorination zone. Reactor A was fed in or, for the oxychlorination of aliphatic, fed:
otherwise partially chlorinated C ₁ to C ₄ hydrocarbons 1600 ke / h chlorine
and / or of aliphatic unsaturated, " _{6 k} % 2D'i
optionally chlorinated C ₂ - to Q-hydrocarbons ffg gj ^

^StO vr ^en u AU ^ α c ι ■■ uj ^ u, ¹⁵ 170 kg / h circulating perchlorethylene,

After removal of the hydrochloric acid or ^ of chlorine _{295 k} |} _{h Reaktio} nsprodukt from the reactor B hydrogen, the excess chlorine in the ^B _{(of which} is ₇₀ \ ^ hexachlorobutadiene and Darnpfphasen-Chlonerungszone zurucVgefuhrt, WAN _{225 k} ^ _Pr * _{domestic product containing n5kg / h} rend the condensate a DesbUauon subjected hexachloroethane and 110 kg / h mixture ΐ ¹ * '? Π J? ^{6 S1} "" pD ^ Uat consisting of * o ctachlorbuten _{from O} and separated Deka chlorine-carbon tetrachloride and perchlorethylene _{butane rich m Oc} tachlorbuten ).
leave the 2641Cg ^ i residue made usable according to the invention, containing tetrachloroethane bonds which are used as chlorinated solvents in the * _{{m k} ^ _{h) and heavy products} .
Trade to be brought. The distillation residue ^{v &}

contains hexachlorobutadiene and is cooled to room temperature in order to ^{precipitate the small parts of the above-defined fractions D 2} , D ¹ , L ¹ , amounts of hexachlorobenzene contained in these heavy products; the solubility L ² and L ³ 2, 6, 28, 50 and 10 kg / h,
of hexachlorobenzene in 100 g of hexachlorobutadiene. All chlorinated compounds were fed into the reactor in a steam-laden state of 0.6 g at 20 ° C.

For hexachlorobutadiene itself there are currently not 30 temperatures inside the reactor were at 500 sufficiently important sales opportunities, and it up to 560 ⁰ C; the mean residence time of the reaction must therefore, in agreement with that of the inventor, be about 4 s.

The gas mixture flowing out was converted to CQ ₄

be delt. deterred and assigned the following weight

After the hexachlorobene has been separated off, the result is:

zols by filtering spin-off or centrifugal carbon tetrachloride 1232 kg

the hexachlorobutadiene yaw in the liquid phase perchlorethylene 767 kg

Chlorination zone fed and the amount ge ^ q _{584 k} |

dissolved chlorine to a value of 0.5 to 2 g / l reac chlorine 520 ke

tion liquid set. 40 Hexachlorobutadiene ""'.'.'.'.'.'.'.'.'. 200 kg

According to one embodiment, the hexachlorobenzene drain is 6 kg

the liquid phase chlorination zone into the steam hexachloroethane ............... traces

phase chlorination fed, either directly or after separation of the ferric The net performance or yield of ₄ was CQ chloride by distillation with flash vaporization. 45 462 kg / h, that of perchlorethylene 597 kg / h and

According to another embodiment, that of hexachlorobutadiene passes through 130 kg / h,

the discharge of the liquid phase chlorination zone one that was not absorbed by carbon tetrachloride

Liquid phase cracking zone before going into the steam- anhydrous hydrogen chloride was separated and

phase chlorination zone is fed. The temperature for oxychlorination of aliphatic C ₁ - to C ₄ -

temperature of the cracking zone is 200 to 300 ° C and 50 hydrocarbons, such as ethylene or propylene,

the dwell time of the process in this zone is used for 30 minutes.

up to 7 h. The cracking zone is preferably a de- The condensate obtained during quenching

Stillation column, the top product of which is the chlorine absorbed by carbon tetrachloride,

nes distillate mainly perchlorethylene and hexa-perchlorethylene and hexachlorobutadiene. The chlorine

contains chloroethane and in the vapor phase chlorine- 55 was separated by heating and in the reac-

tion zone is fed, while the residue is fed back to gate A; CCl ₄ and perchlorethylene were

or the bottom product of this column in the rivers as the process made usable pro-

sig-phase chlorination zone is returned. products by fractional distillation from one another

According to an advantageous embodiment of the separately.

Chlorination in vapor phase is additionally carried out in this 60 After filtering off the hexachlorobenzene

Zone 1,2-dichloropropane, propane and / or propene hexachlorobutadiene (200 kg / h), containing traces

fed in. In this way, at the same time, the hexachloroethane, in the liquid phase Chiorie-

Perchlorination of the heavy residues and the anchoring zone at around 150 ° C together with 8 g / h of water

known perchlorination of dichloropropane, serfree FeCl ₃ (40 ppm, based on weight)

Propane and / or propene carried out; this measure as well as chlorine in an amount corresponding to 1 g of dissolved

would be economically very advantageous because chlorine would then be introduced into 1 reaction liquid. The mid-

no special reaction zone for the more perchloric dwell time of the reactants in the homo-

heavy residues is required. The corresponding reactor B took about 12 hours.

7 8

The flow of reactor B corresponded to the following. In a nickel reactor were continuous

Composition by weight per h: 1 kg / h heavy residues of the following

Hexachlorobutadiene 70 kg ^set2UnB fed in:

Hexachloroethane 115 kg 1,1,2-trichloroethane ... 5.03 percent by weight

Mixture of 1,1,2,2-tetrachloroethane ⁵ Octachlorbuten and 14.36 percent by weight

Dekachlorobutane rich in 1,1,2,2-tetrachloroethane 22.40 percent by weight

Octachlorobutene 110 kg fraction D ² 0.48 percent by weight

_ .. ...,, · "tu · j τ» ι fraction Di 3.66 percent by weight

This process was immediately in the reac fraction L «17.36 percent by weight

tor A, ie m the vapor phase i described above. _{Fraction L} 2 27.18 percent by weight

Chlorination zone, fed in and there in perchlorine fraction U 9.53 percent by weight

converted to ethylene and carbon tetrachloride.

In one of the previous working methods of the case, 0.2 g / h FeCl ₃ (200 ppm)

game 1 clearly different operation to and chlorine under atmospheric pressure accordingly

Proof of the origin of the product that has been made usable, with a constant content of 1 g of dissolved chlorine / 1

fed products from the outlet of reactor B and the BiI reaction liquid.

formation of hexachlorobutadiene from the heavy The temperature of this chlorination zone in liquid

Residues were fed into reactor A: the lower phase was 110 ° C. and the mean residence time

Q 1245 kg / h of the reactants for 7 h. The analysis of the process

!, iDidilorpropane "'!'.! '.!'. !!! I '.! 226 kg / h" showed that only about 5 percent by weight of the

Tetrachloroethanes. ... residues weighing 168 kg / h had been converted,

QQj 770 Wh with the exception of 1,1,1,2-tetrachloroethane, which is fully

Perchlorethylene ............... 170 kg / h was constantly converted into pentachloroethane.

The temperature of the reactor was 500 to 25 Example 2

Maintained 560 ° C. The emerging gas mixture continued

consists of: In reactor A of the vapor-phase chlorination

£ Q 1120 ke / h ^zone 8 ^e according to Example 1 were continuous

Perchloräthyien "'.'.'.'.'.'.'.'.'.'.'.'.'.'.'. 638 k | / h ⁹⁸⁰ ^ ™ °'« previously fed in a mixed -

Q 305 ke / h ^{3o zone m} ' ^s an evaporated pro-

TTQ 5J2 ke / h product of the composition:

Hexachlorobutadiene 3 kg / h CQ ₄ 300 kg / h

Hexachlorobenzene 2 kg / h C ₂ Cl ₄ 294 kg / h

. . __ CH ₂ Cl-CHCl-CH ₃ 226 kg / h

The net output or yield of CCl ₄ and 35

Perchlorethylene was 350 kg / h and 468 kg / h, respectively. had been mixed; then were 534 kg / h

A comparison with the procedure according to the liquid mixture of the following composition in game 1 showed that the performance or yield of the sprayed reactor A: hexachlorobutadiene was only 3 kg / h. As a result, after the working 40 C ₂ H ₂ Cl ₄ according to the invention, 31.4 percent by weight

wise 130-3 = 127 kg / h hexachlorobutadiene from C ₂ Cl ₆ 29.4 percent by weight

96 kg / h heavy products obtained. Fraction D ² 0.8 percent by weight

The performance or yield of CCI ₄ and perchlorine fraction D »2.3 percent by weight

ethylene from 225 kg / h chlorinated products from the fraction Li 11.6 percent by weight

Reactor B was 462-350 = 112 kg / h or 45 fraction L ^{2 was} 19.4 percent by weight

597-469 = 129 kg / h; these values are therefore the fraction U 5.1 percent by weight

Amounts of CCl ₄ and perchlorethylene, which with the help of the

Process according to the invention from the heavy The temperature of the reaction zone was about

Residues have been made usable. 520 ° C (maximum temperature 535 ° C); the middle

For comparison, example 1 was repeated, with a residence time of 5 ° being about 5.7 s.

the modification that the liquid-phase chlorine- The outflowing gas mixture was composed

zone was not fed with ferric chloride. It men from:

it was found that the flow of reactor B from rrj 700 kg / h

Hexachlorobutadiene existed, which did not convert _c Cl 845 ke / h

tes dissolved chlorine contained. In the absence of 55 rf * 47 kg / h

Ferrichloride therefore does not find any reaction between Λ gj g Wh

Hexachlorobutadiene and chlorine instead. 5, ri 1 ke / h

In a second comparative experiment, At- ^ Vi ⁶ 200 ke / h

game 1 repeats with the modification that the fluids ^{4 β}

sig-phase chlorination zone with chlorine under a 60 It was treated as in Example 1 and dai

Pressure of 5 bar and a glass or isolated hexachlorobutadiene in the reactor B au

Enamel-lined homogeneous reactor uses nickel fed along with 7 g / h anhydrous

became. The discharge of this reactor consisted of hexa-FeCl ₃ and chlorine under atmospheric pressure corre

chlorobutadiene, which only contained traces of chlorine. accordingly a constant content of about 1 g / l Re

To prove that working in two 65 action liquid. The temperature in reactor B be

Chlorination zones is necessary for the practical carried about 150 ° C and the mean residence time de

Implementation of the method according to the invention, reactants 10 h.

the following experiment was carried out: To carry out the cracking reaction, de

The discharge from reactor B is fed into the cooker of a distillation column, which is heated to 210 ° C., and a residence time under atmospheric pressure of about 5 hours is maintained here. At the top of the column was a mixture of 144 kg; C ₂ Cl ₄ and 156 kg of C ₂ Cl ₆ withdrawn, which contained traces of hexachlorobutadiene and carbon tetrachloride. This mixture was returned to reactor A for the vapor phase chlorination reaction where the Cl ₂ Cl _{6 was converted} to perchlorethylene and CCl ₄₁ . The bottom product of the column was returned to reactor B, the liquid phase chlorination zone for hexachlorobutadiene.

The use of the cracking zone thus allows the heavy residues to be worked up without Hexachlorobutadiene remains.

The net outputs or yields of CCl ₄ and C ₂ Cl ₄ from the heavy residues were 49 kg / h and 228 kg / h, respectively. These values were determined with the aid of a comparative test in which a starting product without heavy residues was chlorinated under otherwise identical working conditions.

Example 3

A direct phase chlorination was carried out as in Example 1 with 1600 kg / h of chlorine and a mixture of chlorinated products of the following composition:

CCl ₄ 770 kg / h

CH ₂ Cl-CHCl-CH ₃ 226 kg / h

C ₂ CI ₄ 170 kg *

C ₂ H ₂ Cl ₄ 168 kg / h

Fraction D ² 2 kg / h

Group D ¹ 6 kg / h

Fraction L »28 kg / h

U 50 kg / h

L ^s 10 kg / h

Mixture from reactor B 300 kg / h, (of which 110 kg / h hexachloroethane, S 80 kg / h hexachlorobutadiene and

110 kg / h a mixture rich in octachlorobutene, Contains very little decachlorobutane and octachloropropane

The gas mixture emerging from the reactor composed of:

CCl ₄ 1232 kg / h

C ₂ Cl ₄ 767 kg / h

is Cl ₂ 520 kg / h

HCl 584 kg / h

C ₆ Cl ₈ 6 kg / h

C ₄ Cl ₆ 200 kg / h

C ₂ Cl ₆ lanes

The hexachlorobutadiene was separated off as in Example 1 and the chlorination was carried out in the liquid phase under atmospheric pressure at 150 ° C. in a reactor B made of ordinary steel. The _a5 residence time was about 11 hours, and the reaction liquid contained 1.5 g of dissolved excess chlorine per reaction liquid. The effluent from this reactor was freed of its iron content (about 500 ppm) by distillation with flash evaporation at 250 ° C. under partial vacuum.

The iron-free reaction product was composed of:

Hexachlorobutadiene 80 kg / h

Hexachloroethane 110 kg / h

Octachlorobutene, containing very little decachlorobutane and octachloropropane IiOkg / h

Claims (1)

21 2ί 546 Patent claims: 1. Process for utilizing the _{heavy residues resulting from the production of C 1} - and / or Q-chlorinated hydrocarbons (chlorinated hydrocarbon mixtures with a boiling point of 80 to 350 ° C, containing mainly C ₃ and C ₄ products as well as 0.1 up to 3 percent by weight of chlorinated benzene hydrocarbons) by reaction with molecular chlorine at elevated temperature, in a vapor phase chlorination zone at 400 to 600 ° C and in a liquid phase chlorination zone in the presence of ferric chloride at 100 to 200 ° C and with a residence time of the reactants works from 5 to 20 hours, characterized in that one (1) the heavy residues mentioned first in the vapor phase chlorination zone with an excess of chlorine corresponding to 5 to 150 g of molecular chlorine for every 100 g of chlorinated organic compounds in the exhaust gas converts and maintains an average dwell time of 2 to 8 seconds .; (2) the gas mixture exiting from (1) using water or a chlorinated solvent deterring the resulting hydrochloric acid or the resulting dry Separating off hydrogen chloride and returning the excess chlorine to (1); (3) from the condensate obtained in (2) by distillation Separating carbon tetrachloride and perchlorethylene as main products; (4) the hexachlorobenzene is separated off from the distillation residue obtained in (3) and the remaining residue containing hexachlorobutadiene into a liquid phase chlorination zone introduces and there at 100 to 200 ° C, atmospheric pressure, a content of dissolved molecular chlorine from 0.5 to 2 g / l of reaction liquid and in the presence from 15 to 1800 ppm iron (III) chloride, based on the weight of the residue used in this stage, is reacted; (5) the sequence from (4) either a) immediately or after the iron (III) chloride has been separated off, by distillation returns to stage (1) with rapid evaporation or b) introduces into a liquid base cracking zone and there at 200 to 300 ° C a residence time of 30 minutes to 7 hours, with the top product obtained here in stage (1) and recycling the residue to the liquid phase chlorination zone (4). characterized in that 1,2-dichloipropane, propane and / or propene are additionally used in stage (1) and perchlorination of these compounds at the same time as the heavy residues. 5. The method according to any one of the preceding claims 1 to 4, characterized in that the heavy residues are evaporated and placed in a mixing zone at a contact time of 0.01 to 0.5 seconds and at a temperature of 80 to 300 ° C mixed with chlorine before feeds it into the vapor phase chlorination zone.