CA1312882C - Process for removing organochlorine compounds from the offgas from the oxidation of ethylene - Google Patents
Process for removing organochlorine compounds from the offgas from the oxidation of ethyleneInfo
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- CA1312882C CA1312882C CA000579729A CA579729A CA1312882C CA 1312882 C CA1312882 C CA 1312882C CA 000579729 A CA000579729 A CA 000579729A CA 579729 A CA579729 A CA 579729A CA 1312882 C CA1312882 C CA 1312882C
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- offgas
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- ethylene
- organochlorine compounds
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
- C07C45/78—Separation; Purification; Stabilisation; Use of additives
- C07C45/81—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
- C07C45/27—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation
- C07C45/32—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen
- C07C45/33—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen of CHx-moieties
- C07C45/34—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen of CHx-moieties in unsaturated compounds
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
- C07C45/78—Separation; Purification; Stabilisation; Use of additives
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- Organic Chemistry (AREA)
- Crystallography & Structural Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Treating Waste Gases (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
- Catalysts (AREA)
Abstract
Process for removing organochlorine compounds from the offgas from the oxidation of ethylene Abstract of the disclosure:
In the process for removing organochlorine compounds from the offgas produced on reaction of ethylene with oxygen to form acetaldehyde in the presence of a catalyst system com-prising palladium and copper or compounds thereof in aqueous hydrochloric acid solution, the offgas channeled off after isolation of the reaction products is washed at temperatures from 233 K to 323 K and pressures from 1 to 10 bar in countercurrent with polar organic solvents.
In the process for removing organochlorine compounds from the offgas produced on reaction of ethylene with oxygen to form acetaldehyde in the presence of a catalyst system com-prising palladium and copper or compounds thereof in aqueous hydrochloric acid solution, the offgas channeled off after isolation of the reaction products is washed at temperatures from 233 K to 323 K and pressures from 1 to 10 bar in countercurrent with polar organic solvents.
Description
1 3 1 2~2 The invention relates to a process for removing organo-chlorine compounds from the offgas produced on reaction of ethylene with oxygen to form acetaldehyde in the presence o-f a catalyst system compris;ng palladium and copper or compounds thereof in aqueous hydrochloric acid solution (K. Weissermel/H.J. Arpe, Industr;elle org.
Chem;e ~Industr;al Organic Chemistry], Verlag Chemie, 1976, pages 137-139).
The products of the oxidation of ethylene are withdrawn from the reactor together with the gaseous products. After isolation of the acetaldehyde by washing with water, the gas stream, comprising primarily of ethylene, is recycled in-to the reaction. In order to prevent accumulation of un-desired by-products such as C02, methane, ethane and organochlorine compounds, and of inert gases such as nitro-gen and argon in the circulatlng gas, a sub-stream is channeled off as offgas. This offgas stream contains the organochlorine compounds, which are present in the gas phase in accordance with their partial pressure. The organochlo-rine compounds of the withdrawn gas stream have a disadvan-tageous effect on the further use of the components con-tained therein, in particular the ethylene. Removal of the organochlorine compounds from the offgas stream is therefore ; essential so that the ethylene present can be fed to subsequent reactions and, on the other hand, a cleaned offgas can be discharged into the environment via a flare.
'~
The organochlorine compounds in the gas stream exist predominantly as methyl chloride and ethyl chloride.
The present invention allows virtually quantitative rem~val of the organochLorine compounds from the offgases produced during oxidation of ethylene to form acetaldehyde by means of countercurrent extraction using polar organic solvents.
The process of the invention comprises washing the offgas channeled off after isolation of the reaction products, at temperatures from 233 K to 323 K and pressures from 1-10 bar in countercurrent w;th polar organ;c solvents.
In addition, the process of the invention may preferably and optionally comprise -a) using, as polar organic solvent, N-methylpyrrolidone, dimethyl sulfoxide, dimethyl~ormamide~ diethylene gly-col dimethyl ether or triethylene glycol dimethyl ether;
b) the volume ratio between the offgas and the solvent in the countercurrent wash being (10 to 300) : 1, prefer-ably (50 to 200) : 1;
c) carrying out the countercurrent wash at temperatures ; from 253 K to 303 K and pressures from 1-5 bar;
d) the offgas containing ethylene, carbon dioxide, oxygen, argon, nitrogen, methane, ethane and at least one organochlorine compound from the group comprising 0ethyl chloride and ethyl chloride;
S e) feeding the solvent charged with organochlorine com-pounds during the countercurrent wash to a separation step, removing the or~anochlorine compounds in vapor form and re-employing in the countercurrent wash the solvent freed from or~anochLorine compounds in this manner; and f) freeing the solvent from organochlorine compounds by stripping with nitrogen~
The organochlorine compounds are removed virtually quanti-tatively from the offgas stream by means of the process of the invention. The cleaned offgas stream contains predo-- minantly ethylene besides carbon dioxide, methane and ethane, inert gases and oxygen. It can be employed for subsequent reactions.
The organochlorine compounds removed from the offgas by extraction are removed from the solvent in a separation step together with dissolved components of ~he offgas.
They can be purified by distillation or, if desired~ used ZS as fuel in a combustion plant.
The invention is illustrated in greater detail below with reference to the drawing:
', , :
The reaction product obtained during the oxidation of ethy-lene us;ng oxygen in the presence of a catalyst system comprising palladium and copper or compounds thereof in aqueous hydrochloric acid solution is removed from the reactor together with the circulat;ng gas and fed to a wash column 2 via line 1. The wash column 2 is kept at a prPssure of 1-5 bar. The product stream fed through the line 1 is washed in the wash column 2 with water in counter-current and separated into a liquid component, which is removed via line 3, and a gaseous component. The gas stream arriving at the head of the wash co~umn 2, prefer-ably at a temperature of 288-303 K, is removed via line 4 and circulated back to the reactor. A sub-stream is chan-neled off as offgas and fed via line 5 to the bottom tray of the wash column 6, which contains bubble-cap trays or packing elements in order to increase the contact between gas and liquid. In addition to the reaction products car-bon dioxide, methane, ethane and organochlorine compounds, the offgas predominantly contains unreacted ethylene and inert gases (nitrogen and argon). The polar organic sol-vent is transferred at a temperature of 233-323 K via line 7 to the head of the wash column 6, and the upward-flowing offgas is washed in countercurrent. The ratio between the volumes of gas and wash liquid (polar organic solvent) is ~; 25 10-300 : 1, preferably 50-200 : 1. The wash liquid charged w;th organo chlorine compounds is removed via line 8 and fed to the separation step 9. The cleaned offgas can be removed via line 10 and used for subsequent reactions. The organochlorine compounds and the d;ssolved components of the offgas are removed from the polar organ;c solvent in the separation step 9 via line 11. They can be purified in a further separation step or, if desired, used as fuels in a combustion plant. The solvent is subsequently fed back to the wash column 6 via line 7.
In the examples below, the liters indicated relate to standard conditions of temperature and pressure (273.16 K
and 1.013 bar)~
Example 1 In order to maintain a constant gas circulation, an offgas stream having the composition: 77.2 % by volume of ethy-lene, 0.5 % by volume of methane and ethane-, 10.5 % by volume of carbon dioxide, 7.3 % by volume of nitrogen and argon, 4.2 % by volume of oxygen and 0.3 % by volume of methyl chloride is removed from the reaction gas from the oxidation of ethylene after recovering the liquid products.
In order to remove the methyl chloride, 300 l/h of this offgas are passed from line 5 at a temperature of 298 K and a pressure of 4 bar to the base of a wash column 6 packed with 4 mm Berl saddles (packing level: 2 m, diameter: 25 mm) and brought into contact in countercurrent with 1.5 l/h of N-methylpyrrolidone fed in above the packing bed via line 7. 289 l of cleaned offgas having the composit;on:
77.4 % by volume of ethylene, 0.5 % by volume of methane and ethane, 10.6 ~ by volume of carbon d;ox;de, 7.3 ~ by volume Gf nitrogen and argon, 4.2 % by volume of oxygen and < 0.01 ~ by volume of methyl chloride are produced per hour at the head of the ~ash column 6. The N-methylpyr-rolidone flowing out at the base and charged w;th methyl chloride and further offgas components reaches the separa-t;on step 9 (desorption column: depth of the 6 mm Berl saddle bed: 1.5 m, d;ameter: 25 mm) v;a l;ne 8 after pres-sure equal;zation. For desorpt;on of the gaseous compo-nents, the N-methylpyrrol;done metered in above the pack;ng bed at a pressure of 1 bar is str;pped at a temperature of 47S K using 2 l/h of nitrogen passed into the bottom of the separation step 9~ At the same time, 13 l of gas having the composition: o.9 % by volume of methyl chloride, ~û.0 % by volume of ethylene, û.5 % by volume of ethane and methane, 8~5 % by volume of carbon dioxide, 21.0 % by volume of nitrogen and argon and 3.1 % by volume of oxygen are removed per hour at the condenser of the column head.
They are fed to a combustion plant or processed further ;n order to recover the methyl chloride~ Due to the ex-tract;on, the CH3Cl in the offgas is concent.r.ated by a factor of Z3. The N-methylpyrrolidone flo~ing out at the base of the separation step 9 contains no detectable gase-ous components. After cooling, it is fed back to the headof the wash column 6.
Example 2 In order to maintain a contast gas circulation, an offgas stream having the composition: 78 5 % by volume of ethy-lene, 9.7 X by volume of carbon dioxide, 7.3 % by volume of nitrogen and argon, 3.8 % by volume of oxygen Jnd 0.7 %
by volume of methyl chlor;de is removed from the reaction gas from the ox;dation of ethylene after recovering the liquid products. In order to remove the methyl chloride, Z00 l/h of this offgas are passed from line 5 at a tempera-ture of 253 K and a pressure of 1 bar to the base of awash column 6 (diameter: 50 mm), fitted with 22 bubble-cap trays and brought into contact in countercurrent ~ith 2 l/h of N-methylpyrrolidone fed to the uppermost tray of the column via line 7. 192 l of cleaned offgas having the composition: 79.1 % by volume of ethylene, 9.7 % by vol-ume of carbon dioxide, 7.3 % by volume of nitrogen and argon, 3.8 % by volume of oxygen and < 0.01 X by volume of methyl chloride are obtained per hour at the head of the wash column 6. The N-me~hylpyrrolidone flowing out at the base and charged with methyl chlor;de and further offgas components is fed to the separation step 9 {clesorption column) via line 8. For desorption of the gaseous compo-nents, the N-methylpyrrolidone metered in above the pack-ing bed is stripped at a temperature of 475 K and a pres-; 25 sure of 1 bar using 0.5 l/h of nitrogen passed into the bottom of the separat;ng step 9. At the same time, 8.5 l of gas having the composition: 16.5 % by volume of methyl-chloride, 61.2 % by volume of ethylene, 8.2 % by volume ' of carbon dioxide, 11.8 % by volume of nitrogen and argon, and Z~3 % by volume of oxygen are withdrawn per hour v;a the column condenser. They are passed to a combust;on plant or are processed further in order to recover the methyl chloride. Under these conditions, the methyl chlo-ride ;n the offgas is concentrated by the extraction by a factor of 23.6.
The N-methylpyrrolidone flowing out at the bas~ of the separating step 9 does not contain any detectable gaseous components~ After,cooling, it is re-employed for extrac-tion~
Example 3 In order to maintain a constant gas circulation, an offgas stream hav;ng the compositi~n: 76.1 ~ by volume of ethy-lene, 10.8 X by volume of carbon dioxide, 8.4 ~ by volume of nitrogen and argon, 3.5 % by volume of oxygen and 1.1 %
by volume of methyl chloride and 0.1 ~ by volume of ethyl chloride is removed from the reaction gas from the oxida-tion of ethylene after recover;ng the liquid products. In order to remove the methyl chloride, 200 l/h of th;s off-gas are passed from line S at a temperature of 273 K and a pressure of 2 bar to the base of a wash column 6 fitted with 22 bubble-cap trays and brought into contact in countercurrent with 3 l/h of triethylene glycol dimethyl ether (tr;glyme) which is fed to the uppermost tray of the column via line 7. 190.5 l of cleaned offgas having the composition: 77 0 % by volume of ethylene, 10 9 % by vol-ume of carbon dioxide, 8.5 X by volume of nitrogen and argon, 3.6 ~ by volume of oxygen and 0.01 % by volume of methyl chloride and 0.01 % by volume of ethyl chlor;de are produced per hour at the head of the wash column 6. The triglyme flowing out at the base and charged with methyl chloride, ethyl chlor;de and further offgas components passes into the separation step 9 (desorpt;on column) v;a line 8 after pressure equalizat;on.
For desorpt;on of the gaseous components, the triglyme metered in above the packing bed is stripped at a tempera-ture of 495 K and a pressure of 1 bar with 1 l/h of nitro-gen passed into the bottom of the separation step 9. Atthe same time, 10~5 l of gas having the composition: 21.0 by volume of methyl chlor;de, 1.9 % by volume of ethyl chloride, 51.4 % by volume of ethylene, 8.6 % by volume of carbon dioxide, 15 2 ~ by volume of nitrogen and argon, and 1.9 % by volume of oxygen are removed per hour at the condenser of the column head. They are either burnt in order to produce steam or processed further for recovery of the methyl chloride. The triglyme flowing out at the base of the separation step 9 does not contain any detect-able gaseous components. After cooling, it is re-circu-lated to the wash column 6 Example 4 In order to maintain a constant gas c;rculation, an off-gas stream having the composition: 77.7 % by volume of S ethylene, 10.5 % by volume of carbon clioxide, 7~3 % by volume of nitrogen and argon, 4.2 ~ by volume of oxygen and 0.3 % by volume of methyl chloride is removed from the reaction gas from the oxidation of ethylene after re-covery of the liquid products. In order to remove the methyl chloride, 3500 l/h of this offgas are passed from line 5 at a temperature of 298 K and a pressure of 4 bar to the base of a wash column 6 packed ~ith 6 mm ~erl saddles (packing depth 2.5 m, diameter 35 mm) and brought into contact in countercurrent with 20 l/h of dimethyl-formamide, which is passed in above the packing bed vialine 7. 3290 l of cleaned offgas having the composition:
78.0 % by volume of ethylene, 10.5 ~ by volume of carbon dioxide, 7.3 % by volume of nitrogen and argon, 4.2 % by volume of oxygen and c 0.01 % by volume of methyl chloride are produced per hour at the head of the wash column o.
The dimethylformamide flowing out at the base and charged with methyl chloride and further offgas components passes into the separation step 9 (desorption column) via line 8.
For desorption of the gaseous components, the dimethyl-formamide metered in above the packing bed is heated to a temperature of 450 K under a pressure of 1.8 bar in the evaporator of the separation step 9. At the same time~
210 l of gas having the composition: 5.0 X by volume of methyl chloride, 73.7 % by volume of ethylene, 10.0 X by volume of carbon diox;de, 7.1 % by volume of nitrogen and argon, and 4.2 X by volume of oxygen are removed per hour at the condenser of the column head. They are either burnt in order to produce steam or processed further for recovery of the methyl chloride.
The d;methylforma~;de flowing out at the base of the sepa-ration step 9 does not contain any detectable gaseous com-ponents. After cooling, it is re-circulated to the wash column 6.
Example S
In order to maintain a constant gas circulation, an off-gas stream having the composit;on: 77.8 % by volume of ethylene, 10.1 % by volume of carbon dioxide, 708 % by voL-ume of n;trogen and argon, 4.0 % by volume of o~ygen and 0.3 % by volume of methyl chloride is removed from the reaction gas from the oxidation of ethylene after recovery of the liquid products. In order to remove the methyl chlorideO 2500 l/h of this offgas are passed from line 5 at a temperature of 298 K and a pressure of 4 bar to the base of a wash column 6 (diameter 25 mm) fitted with 11 bubble-cap trays and brought ;nto contact ;n counter-current with Z0 l/h of d;methyl sulfox;de, which is fed in v;a l;ne 7. 2390 l of cleaned offgas having the t 31 2882 composition: 78.3 % by volume of ethylene, 9.6 % by volume of carbon dioxide, 8.0 % by volume of nitrogen and argon, 4.1 % by volume of oxygen and < 0.01 % by volume of methyl chloride are produced per hour at the head of the wash column 6. The dimethyl~sulfoxide flowing out at the base and charged with methyl chloride and further off-gas components passes into the separation step 9 (desorp-t;on column) via line 8. For desorption of the gaseous componentsJ the dimethyl sulfoxide metered in above the packing bed is heated to a temperature of 483 K under a pressure of 108 bar in the evaporator of the separation step 9. At the same time, 110 l of gas having the compo-sition: 6.a % by volume af methyl chLoride, 65.6 % by volume of ethylene, Z1.6 % by vol~me of carbon dioxide, 4.1 % by valume of nitrogen and àrgon, and 1~9 X by volume of axygen are removed per hour at the condenser of the column head. They are either burnt in order to produce steam or processed further for recovery of the methyl chloride.
The d;methyl sulfox;de flow;ng out at the base of the separat;on step 9 does not conta;n any detectable gaseous components. After cooling, it is re-circulated ts the wash colurnn 6.
Chem;e ~Industr;al Organic Chemistry], Verlag Chemie, 1976, pages 137-139).
The products of the oxidation of ethylene are withdrawn from the reactor together with the gaseous products. After isolation of the acetaldehyde by washing with water, the gas stream, comprising primarily of ethylene, is recycled in-to the reaction. In order to prevent accumulation of un-desired by-products such as C02, methane, ethane and organochlorine compounds, and of inert gases such as nitro-gen and argon in the circulatlng gas, a sub-stream is channeled off as offgas. This offgas stream contains the organochlorine compounds, which are present in the gas phase in accordance with their partial pressure. The organochlo-rine compounds of the withdrawn gas stream have a disadvan-tageous effect on the further use of the components con-tained therein, in particular the ethylene. Removal of the organochlorine compounds from the offgas stream is therefore ; essential so that the ethylene present can be fed to subsequent reactions and, on the other hand, a cleaned offgas can be discharged into the environment via a flare.
'~
The organochlorine compounds in the gas stream exist predominantly as methyl chloride and ethyl chloride.
The present invention allows virtually quantitative rem~val of the organochLorine compounds from the offgases produced during oxidation of ethylene to form acetaldehyde by means of countercurrent extraction using polar organic solvents.
The process of the invention comprises washing the offgas channeled off after isolation of the reaction products, at temperatures from 233 K to 323 K and pressures from 1-10 bar in countercurrent w;th polar organ;c solvents.
In addition, the process of the invention may preferably and optionally comprise -a) using, as polar organic solvent, N-methylpyrrolidone, dimethyl sulfoxide, dimethyl~ormamide~ diethylene gly-col dimethyl ether or triethylene glycol dimethyl ether;
b) the volume ratio between the offgas and the solvent in the countercurrent wash being (10 to 300) : 1, prefer-ably (50 to 200) : 1;
c) carrying out the countercurrent wash at temperatures ; from 253 K to 303 K and pressures from 1-5 bar;
d) the offgas containing ethylene, carbon dioxide, oxygen, argon, nitrogen, methane, ethane and at least one organochlorine compound from the group comprising 0ethyl chloride and ethyl chloride;
S e) feeding the solvent charged with organochlorine com-pounds during the countercurrent wash to a separation step, removing the or~anochlorine compounds in vapor form and re-employing in the countercurrent wash the solvent freed from or~anochLorine compounds in this manner; and f) freeing the solvent from organochlorine compounds by stripping with nitrogen~
The organochlorine compounds are removed virtually quanti-tatively from the offgas stream by means of the process of the invention. The cleaned offgas stream contains predo-- minantly ethylene besides carbon dioxide, methane and ethane, inert gases and oxygen. It can be employed for subsequent reactions.
The organochlorine compounds removed from the offgas by extraction are removed from the solvent in a separation step together with dissolved components of ~he offgas.
They can be purified by distillation or, if desired~ used ZS as fuel in a combustion plant.
The invention is illustrated in greater detail below with reference to the drawing:
', , :
The reaction product obtained during the oxidation of ethy-lene us;ng oxygen in the presence of a catalyst system comprising palladium and copper or compounds thereof in aqueous hydrochloric acid solution is removed from the reactor together with the circulat;ng gas and fed to a wash column 2 via line 1. The wash column 2 is kept at a prPssure of 1-5 bar. The product stream fed through the line 1 is washed in the wash column 2 with water in counter-current and separated into a liquid component, which is removed via line 3, and a gaseous component. The gas stream arriving at the head of the wash co~umn 2, prefer-ably at a temperature of 288-303 K, is removed via line 4 and circulated back to the reactor. A sub-stream is chan-neled off as offgas and fed via line 5 to the bottom tray of the wash column 6, which contains bubble-cap trays or packing elements in order to increase the contact between gas and liquid. In addition to the reaction products car-bon dioxide, methane, ethane and organochlorine compounds, the offgas predominantly contains unreacted ethylene and inert gases (nitrogen and argon). The polar organic sol-vent is transferred at a temperature of 233-323 K via line 7 to the head of the wash column 6, and the upward-flowing offgas is washed in countercurrent. The ratio between the volumes of gas and wash liquid (polar organic solvent) is ~; 25 10-300 : 1, preferably 50-200 : 1. The wash liquid charged w;th organo chlorine compounds is removed via line 8 and fed to the separation step 9. The cleaned offgas can be removed via line 10 and used for subsequent reactions. The organochlorine compounds and the d;ssolved components of the offgas are removed from the polar organ;c solvent in the separation step 9 via line 11. They can be purified in a further separation step or, if desired, used as fuels in a combustion plant. The solvent is subsequently fed back to the wash column 6 via line 7.
In the examples below, the liters indicated relate to standard conditions of temperature and pressure (273.16 K
and 1.013 bar)~
Example 1 In order to maintain a constant gas circulation, an offgas stream having the composition: 77.2 % by volume of ethy-lene, 0.5 % by volume of methane and ethane-, 10.5 % by volume of carbon dioxide, 7.3 % by volume of nitrogen and argon, 4.2 % by volume of oxygen and 0.3 % by volume of methyl chloride is removed from the reaction gas from the oxidation of ethylene after recovering the liquid products.
In order to remove the methyl chloride, 300 l/h of this offgas are passed from line 5 at a temperature of 298 K and a pressure of 4 bar to the base of a wash column 6 packed with 4 mm Berl saddles (packing level: 2 m, diameter: 25 mm) and brought into contact in countercurrent with 1.5 l/h of N-methylpyrrolidone fed in above the packing bed via line 7. 289 l of cleaned offgas having the composit;on:
77.4 % by volume of ethylene, 0.5 % by volume of methane and ethane, 10.6 ~ by volume of carbon d;ox;de, 7.3 ~ by volume Gf nitrogen and argon, 4.2 % by volume of oxygen and < 0.01 ~ by volume of methyl chloride are produced per hour at the head of the ~ash column 6. The N-methylpyr-rolidone flowing out at the base and charged w;th methyl chloride and further offgas components reaches the separa-t;on step 9 (desorption column: depth of the 6 mm Berl saddle bed: 1.5 m, d;ameter: 25 mm) v;a l;ne 8 after pres-sure equal;zation. For desorpt;on of the gaseous compo-nents, the N-methylpyrrol;done metered in above the pack;ng bed at a pressure of 1 bar is str;pped at a temperature of 47S K using 2 l/h of nitrogen passed into the bottom of the separation step 9~ At the same time, 13 l of gas having the composition: o.9 % by volume of methyl chloride, ~û.0 % by volume of ethylene, û.5 % by volume of ethane and methane, 8~5 % by volume of carbon dioxide, 21.0 % by volume of nitrogen and argon and 3.1 % by volume of oxygen are removed per hour at the condenser of the column head.
They are fed to a combustion plant or processed further ;n order to recover the methyl chloride~ Due to the ex-tract;on, the CH3Cl in the offgas is concent.r.ated by a factor of Z3. The N-methylpyrrolidone flo~ing out at the base of the separation step 9 contains no detectable gase-ous components. After cooling, it is fed back to the headof the wash column 6.
Example 2 In order to maintain a contast gas circulation, an offgas stream having the composition: 78 5 % by volume of ethy-lene, 9.7 X by volume of carbon dioxide, 7.3 % by volume of nitrogen and argon, 3.8 % by volume of oxygen Jnd 0.7 %
by volume of methyl chlor;de is removed from the reaction gas from the ox;dation of ethylene after recovering the liquid products. In order to remove the methyl chloride, Z00 l/h of this offgas are passed from line 5 at a tempera-ture of 253 K and a pressure of 1 bar to the base of awash column 6 (diameter: 50 mm), fitted with 22 bubble-cap trays and brought into contact in countercurrent ~ith 2 l/h of N-methylpyrrolidone fed to the uppermost tray of the column via line 7. 192 l of cleaned offgas having the composition: 79.1 % by volume of ethylene, 9.7 % by vol-ume of carbon dioxide, 7.3 % by volume of nitrogen and argon, 3.8 % by volume of oxygen and < 0.01 X by volume of methyl chloride are obtained per hour at the head of the wash column 6. The N-me~hylpyrrolidone flowing out at the base and charged with methyl chlor;de and further offgas components is fed to the separation step 9 {clesorption column) via line 8. For desorption of the gaseous compo-nents, the N-methylpyrrolidone metered in above the pack-ing bed is stripped at a temperature of 475 K and a pres-; 25 sure of 1 bar using 0.5 l/h of nitrogen passed into the bottom of the separat;ng step 9. At the same time, 8.5 l of gas having the composition: 16.5 % by volume of methyl-chloride, 61.2 % by volume of ethylene, 8.2 % by volume ' of carbon dioxide, 11.8 % by volume of nitrogen and argon, and Z~3 % by volume of oxygen are withdrawn per hour v;a the column condenser. They are passed to a combust;on plant or are processed further in order to recover the methyl chloride. Under these conditions, the methyl chlo-ride ;n the offgas is concentrated by the extraction by a factor of 23.6.
The N-methylpyrrolidone flowing out at the bas~ of the separating step 9 does not contain any detectable gaseous components~ After,cooling, it is re-employed for extrac-tion~
Example 3 In order to maintain a constant gas circulation, an offgas stream hav;ng the compositi~n: 76.1 ~ by volume of ethy-lene, 10.8 X by volume of carbon dioxide, 8.4 ~ by volume of nitrogen and argon, 3.5 % by volume of oxygen and 1.1 %
by volume of methyl chloride and 0.1 ~ by volume of ethyl chloride is removed from the reaction gas from the oxida-tion of ethylene after recover;ng the liquid products. In order to remove the methyl chloride, 200 l/h of th;s off-gas are passed from line S at a temperature of 273 K and a pressure of 2 bar to the base of a wash column 6 fitted with 22 bubble-cap trays and brought into contact in countercurrent with 3 l/h of triethylene glycol dimethyl ether (tr;glyme) which is fed to the uppermost tray of the column via line 7. 190.5 l of cleaned offgas having the composition: 77 0 % by volume of ethylene, 10 9 % by vol-ume of carbon dioxide, 8.5 X by volume of nitrogen and argon, 3.6 ~ by volume of oxygen and 0.01 % by volume of methyl chloride and 0.01 % by volume of ethyl chlor;de are produced per hour at the head of the wash column 6. The triglyme flowing out at the base and charged with methyl chloride, ethyl chlor;de and further offgas components passes into the separation step 9 (desorpt;on column) v;a line 8 after pressure equalizat;on.
For desorpt;on of the gaseous components, the triglyme metered in above the packing bed is stripped at a tempera-ture of 495 K and a pressure of 1 bar with 1 l/h of nitro-gen passed into the bottom of the separation step 9. Atthe same time, 10~5 l of gas having the composition: 21.0 by volume of methyl chlor;de, 1.9 % by volume of ethyl chloride, 51.4 % by volume of ethylene, 8.6 % by volume of carbon dioxide, 15 2 ~ by volume of nitrogen and argon, and 1.9 % by volume of oxygen are removed per hour at the condenser of the column head. They are either burnt in order to produce steam or processed further for recovery of the methyl chloride. The triglyme flowing out at the base of the separation step 9 does not contain any detect-able gaseous components. After cooling, it is re-circu-lated to the wash column 6 Example 4 In order to maintain a constant gas c;rculation, an off-gas stream having the composition: 77.7 % by volume of S ethylene, 10.5 % by volume of carbon clioxide, 7~3 % by volume of nitrogen and argon, 4.2 ~ by volume of oxygen and 0.3 % by volume of methyl chloride is removed from the reaction gas from the oxidation of ethylene after re-covery of the liquid products. In order to remove the methyl chloride, 3500 l/h of this offgas are passed from line 5 at a temperature of 298 K and a pressure of 4 bar to the base of a wash column 6 packed ~ith 6 mm ~erl saddles (packing depth 2.5 m, diameter 35 mm) and brought into contact in countercurrent with 20 l/h of dimethyl-formamide, which is passed in above the packing bed vialine 7. 3290 l of cleaned offgas having the composition:
78.0 % by volume of ethylene, 10.5 ~ by volume of carbon dioxide, 7.3 % by volume of nitrogen and argon, 4.2 % by volume of oxygen and c 0.01 % by volume of methyl chloride are produced per hour at the head of the wash column o.
The dimethylformamide flowing out at the base and charged with methyl chloride and further offgas components passes into the separation step 9 (desorption column) via line 8.
For desorption of the gaseous components, the dimethyl-formamide metered in above the packing bed is heated to a temperature of 450 K under a pressure of 1.8 bar in the evaporator of the separation step 9. At the same time~
210 l of gas having the composition: 5.0 X by volume of methyl chloride, 73.7 % by volume of ethylene, 10.0 X by volume of carbon diox;de, 7.1 % by volume of nitrogen and argon, and 4.2 X by volume of oxygen are removed per hour at the condenser of the column head. They are either burnt in order to produce steam or processed further for recovery of the methyl chloride.
The d;methylforma~;de flowing out at the base of the sepa-ration step 9 does not contain any detectable gaseous com-ponents. After cooling, it is re-circulated to the wash column 6.
Example S
In order to maintain a constant gas circulation, an off-gas stream having the composit;on: 77.8 % by volume of ethylene, 10.1 % by volume of carbon dioxide, 708 % by voL-ume of n;trogen and argon, 4.0 % by volume of o~ygen and 0.3 % by volume of methyl chloride is removed from the reaction gas from the oxidation of ethylene after recovery of the liquid products. In order to remove the methyl chlorideO 2500 l/h of this offgas are passed from line 5 at a temperature of 298 K and a pressure of 4 bar to the base of a wash column 6 (diameter 25 mm) fitted with 11 bubble-cap trays and brought ;nto contact ;n counter-current with Z0 l/h of d;methyl sulfox;de, which is fed in v;a l;ne 7. 2390 l of cleaned offgas having the t 31 2882 composition: 78.3 % by volume of ethylene, 9.6 % by volume of carbon dioxide, 8.0 % by volume of nitrogen and argon, 4.1 % by volume of oxygen and < 0.01 % by volume of methyl chloride are produced per hour at the head of the wash column 6. The dimethyl~sulfoxide flowing out at the base and charged with methyl chloride and further off-gas components passes into the separation step 9 (desorp-t;on column) via line 8. For desorption of the gaseous componentsJ the dimethyl sulfoxide metered in above the packing bed is heated to a temperature of 483 K under a pressure of 108 bar in the evaporator of the separation step 9. At the same time, 110 l of gas having the compo-sition: 6.a % by volume af methyl chLoride, 65.6 % by volume of ethylene, Z1.6 % by vol~me of carbon dioxide, 4.1 % by valume of nitrogen and àrgon, and 1~9 X by volume of axygen are removed per hour at the condenser of the column head. They are either burnt in order to produce steam or processed further for recovery of the methyl chloride.
The d;methyl sulfox;de flow;ng out at the base of the separat;on step 9 does not conta;n any detectable gaseous components. After cooling, it is re-circulated ts the wash colurnn 6.
Claims (7)
1. A process for removing organochlorine compounds from the offgas produced on reaction of ethylene with oxygen to form ace-taldehyde in the presence of a catalyst system comprising palla-dium and copper or compounds thereof in aqueous hydrochloric acid solution, which comprises washing the offgas channeled off after isolation of the reaction products, at temperatures from 233 K to 323 K and pressures from 1-10 bar in countercurrent with polar organic solvents.
2. A process as claimed in claim 1, wherein the solvent used is N-methylpyrrolidone, dimethyl sulfoxide, dimethylforma-mide, diethylene glycol dimethyl ether or triethylene glycol dimethyl ether.
3. A process as claimed in claim 1, wherein the volume ratio between the offgas and the solvent in the countercurrent wash is (10 to 300) : 1.
4. A process as claimed in claim 1, wherein the counter-current wash is carried out at temperatures from 253 K to 303 K
and at pressures from 1-5 bar.
and at pressures from 1-5 bar.
5. A process as claimed in claim 1, wherein the offgas contains ethylene, carbon dioxide, oxygen, argon, nitrogen, methane, ethane and at least one organo-chlorine compound from the group comprising methyl chloride and ethyl chloride.
6. A process as claimed in claim 1, wherein the solvent charged with organochlorine compounds during the countercurrent wash is fed to a separation step, the organochlorine compounds are removed in vapor form, and the solvent freed from organochlorine compounds in this manner is re-employed in the countercurrent wash.
7. A process as claimed in claim 6, wherein the solvent is freed from the organochlorine compounds by stripping with nitrogen.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3736459.6 | 1987-10-28 | ||
| DE19873736459 DE3736459A1 (en) | 1987-10-28 | 1987-10-28 | METHOD FOR SEPARATING ORGANIC CHLORINE COMPOUNDS FROM THE EXHAUST GAS FROM ETHYLENE OXIDATION |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1312882C true CA1312882C (en) | 1993-01-19 |
Family
ID=6339235
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000579729A Expired - Fee Related CA1312882C (en) | 1987-10-28 | 1988-10-11 | Process for removing organochlorine compounds from the offgas from the oxidation of ethylene |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0313910B1 (en) |
| JP (1) | JP2761497B2 (en) |
| CN (1) | CN1014055B (en) |
| AU (1) | AU606225B2 (en) |
| CA (1) | CA1312882C (en) |
| DE (2) | DE3736459A1 (en) |
| ES (1) | ES2037787T3 (en) |
| MX (1) | MX169319B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102433154B (en) * | 2010-09-29 | 2014-10-01 | 中国石油化工股份有限公司 | Method for removing organic chlorine from hydrocarbon oil |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2827380A1 (en) * | 1978-06-22 | 1980-01-10 | Hoechst Ag | METHOD FOR PRODUCING ACETALDEHYDE |
| JPS5835969B2 (en) * | 1980-04-28 | 1983-08-05 | 三菱化学株式会社 | Process for treating waste gas from acetaldehyde production |
| DE3610706A1 (en) * | 1986-03-29 | 1987-10-08 | Bayer Ag | Purification of methyl chloride during continuous methylchlorosilane synthesis |
-
1987
- 1987-10-28 DE DE19873736459 patent/DE3736459A1/en not_active Withdrawn
-
1988
- 1988-10-11 CA CA000579729A patent/CA1312882C/en not_active Expired - Fee Related
- 1988-10-11 ES ES198888116822T patent/ES2037787T3/en not_active Expired - Lifetime
- 1988-10-11 DE DE8888116822T patent/DE3867798D1/en not_active Expired - Lifetime
- 1988-10-11 EP EP88116822A patent/EP0313910B1/en not_active Expired - Lifetime
- 1988-10-25 CN CN88106839A patent/CN1014055B/en not_active Expired
- 1988-10-26 JP JP63268375A patent/JP2761497B2/en not_active Expired - Lifetime
- 1988-10-27 AU AU24377/88A patent/AU606225B2/en not_active Ceased
- 1988-10-27 MX MX013586A patent/MX169319B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| JP2761497B2 (en) | 1998-06-04 |
| AU606225B2 (en) | 1991-01-31 |
| EP0313910A2 (en) | 1989-05-03 |
| ES2037787T3 (en) | 1993-07-01 |
| AU2437788A (en) | 1989-05-04 |
| CN1014055B (en) | 1991-09-25 |
| CN1032780A (en) | 1989-05-10 |
| JPH01157928A (en) | 1989-06-21 |
| MX169319B (en) | 1993-06-29 |
| EP0313910A3 (en) | 1989-10-11 |
| DE3736459A1 (en) | 1989-05-11 |
| DE3867798D1 (en) | 1992-02-27 |
| EP0313910B1 (en) | 1992-01-15 |
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