CN112457194A - Dechlorination refining process for preparing crude dimethyl carbonate by gas-phase carbonyl method - Google Patents
Dechlorination refining process for preparing crude dimethyl carbonate by gas-phase carbonyl method Download PDFInfo
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- CN112457194A CN112457194A CN202011329818.XA CN202011329818A CN112457194A CN 112457194 A CN112457194 A CN 112457194A CN 202011329818 A CN202011329818 A CN 202011329818A CN 112457194 A CN112457194 A CN 112457194A
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- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 title claims abstract description 69
- 238000000034 method Methods 0.000 title claims abstract description 64
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 title claims abstract description 16
- 238000006298 dechlorination reaction Methods 0.000 title claims abstract description 13
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 9
- 238000007670 refining Methods 0.000 title claims abstract description 8
- 239000003463 adsorbent Substances 0.000 claims abstract description 80
- 239000012043 crude product Substances 0.000 claims abstract description 62
- 239000000463 material Substances 0.000 claims abstract description 28
- 239000007788 liquid Substances 0.000 claims abstract description 27
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims abstract description 22
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims abstract description 7
- 239000000460 chlorine Substances 0.000 claims abstract description 7
- 229910052801 chlorine Inorganic materials 0.000 claims abstract description 7
- 238000001914 filtration Methods 0.000 claims abstract description 7
- 238000005303 weighing Methods 0.000 claims abstract description 6
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 94
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 31
- 238000005406 washing Methods 0.000 claims description 30
- 230000008569 process Effects 0.000 claims description 28
- 239000003513 alkali Substances 0.000 claims description 24
- 239000002351 wastewater Substances 0.000 claims description 22
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 21
- 230000008929 regeneration Effects 0.000 claims description 13
- 238000011069 regeneration method Methods 0.000 claims description 13
- 230000018044 dehydration Effects 0.000 claims description 12
- 238000006297 dehydration reaction Methods 0.000 claims description 12
- 238000006386 neutralization reaction Methods 0.000 claims description 11
- 239000002585 base Substances 0.000 claims description 10
- 229910052757 nitrogen Inorganic materials 0.000 claims description 10
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 claims description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 6
- 239000003456 ion exchange resin Substances 0.000 claims description 6
- 229920003303 ion-exchange polymer Polymers 0.000 claims description 6
- 230000001172 regenerating effect Effects 0.000 claims description 6
- 230000009471 action Effects 0.000 claims description 4
- 239000003054 catalyst Substances 0.000 claims description 4
- 229910003480 inorganic solid Inorganic materials 0.000 claims description 3
- 239000002808 molecular sieve Substances 0.000 claims description 3
- 229920006395 saturated elastomer Polymers 0.000 claims description 3
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 claims description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 2
- 230000000382 dechlorinating effect Effects 0.000 abstract description 4
- 238000001311 chemical methods and process Methods 0.000 abstract description 2
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 14
- 239000011347 resin Substances 0.000 description 11
- 229920005989 resin Polymers 0.000 description 11
- 230000006315 carbonylation Effects 0.000 description 10
- 238000005810 carbonylation reaction Methods 0.000 description 10
- 239000000047 product Substances 0.000 description 10
- 238000010276 construction Methods 0.000 description 8
- 239000012535 impurity Substances 0.000 description 6
- 239000002245 particle Substances 0.000 description 6
- 239000007787 solid Substances 0.000 description 6
- LOMVENUNSWAXEN-UHFFFAOYSA-N Methyl oxalate Chemical compound COC(=O)C(=O)OC LOMVENUNSWAXEN-UHFFFAOYSA-N 0.000 description 5
- 238000011001 backwashing Methods 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 229910001220 stainless steel Inorganic materials 0.000 description 3
- 239000010935 stainless steel Substances 0.000 description 3
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 2
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- 229910002091 carbon monoxide Inorganic materials 0.000 description 2
- TZIHFWKZFHZASV-UHFFFAOYSA-N methyl formate Chemical compound COC=O TZIHFWKZFHZASV-UHFFFAOYSA-N 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 238000005201 scrubbing Methods 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- NKDDWNXOKDWJAK-UHFFFAOYSA-N dimethoxymethane Chemical compound COCOC NKDDWNXOKDWJAK-UHFFFAOYSA-N 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 229910000856 hastalloy Inorganic materials 0.000 description 1
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 1
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 1
- XMJHPCRAQCTCFT-UHFFFAOYSA-N methyl chloroformate Chemical compound COC(Cl)=O XMJHPCRAQCTCFT-UHFFFAOYSA-N 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
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Classifications
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C68/00—Preparation of esters of carbonic or haloformic acids
- C07C68/08—Purification; Separation; Stabilisation
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a dechlorination refining process for preparing a dimethyl carbonate crude product by a gas-phase carbonyl method, and relates to the field of chemical processes. The method comprises the following steps: weighing a preset number of adsorbents, and filling the adsorbents into fixed bed equipment; and filtering the crude dimethyl carbonate prepared by the gas-phase carbonyl method through a fixed bed at a preset temperature and a preset pressure according to a preset liquid hourly space velocity. The residual trace chloride ions in the dimethyl carbonate crude product prepared by the gas-phase carbonyl method are adsorbed by the adsorbent in the fixed bed, and the concentration of the chloride ions in the adsorbed crude product is reduced to be below 2.0ppm, so that the aim of dechlorinating the crude product is fulfilled, the chlorine corrosivity of the crude product is effectively reduced, and the material requirement of a subsequent treatment working section is reduced.
Description
Technical Field
The invention belongs to the field of chemical processes, and particularly relates to a dechlorination refining process for preparing a dimethyl carbonate crude product by a gas-phase carbonyl method.
Background
The main raw materials for producing the dimethyl carbonate by the gas-phase carbonylation method are carbon monoxide (CO) and methanol, the main reaction product is the dimethyl carbonate, and the byproducts are methyl formate, methylal, dimethyl oxalate (DMO) and the like.
In order to maintain the reactivity of the palladium catalyst synthesized during the production process, a small amount of hydrogen chloride or methyl chloroformate needs to be supplemented to the inlet of the reactor. Part of the supplemented chlorine is washed in a dimethyl carbonate product washing tower and enters a subsequent treatment system along with a dimethyl carbonate crude product.
At present, a large amount of anticorrosive materials such as glass lining, ceramics, hastelloy, graphite and the like are adopted for the subsequent alkali treatment process and the rectification process of the crude dimethyl carbonate product. However, not only is the construction cost of the project greatly increased, but also the construction period of the project is prolonged, higher requirements are put on daily equipment management, and the daily operation needs to be more careful.
If the crude dimethyl carbonate product is dechlorinated, the chloride ion concentration in the crude dimethyl carbonate product is greatly reduced, and the subsequent alkali treatment process and the rectification process can adopt common stainless steel materials such as S304, S316 and the like, so that the construction cost of the project is greatly saved, the construction period of the project is shortened, and the daily equipment management and the daily operation are more convenient and efficient.
Through the search of the existing published patent documents, the published patent documents of similar technologies are not searched.
Disclosure of Invention
The invention provides a dechlorination refining process for preparing a dimethyl carbonate crude product by a gas-phase carbonyl method, which solves the problems.
In order to solve the technical problems, the invention is realized by the following technical scheme:
the invention relates to a dechlorination refining process for preparing a dimethyl carbonate crude product by a gas-phase carbonyl method, which comprises the following steps:
s01, weighing a preset amount of adsorbent, and filling the adsorbent into fixed bed equipment;
s02, filtering the crude product of dimethyl carbonate to be dechlorinated, which is prepared by the gas-phase carbonyl method, through a fixed bed at a preset liquid hourly space velocity under a preset temperature and a preset pressure; adsorbing trace chloride ions remained in the crude product of the dimethyl carbonate to be dechlorinated, which is prepared by a gas-phase carbonyl method, under the action of an adsorbent in a fixed bed, reducing the concentration of the chloride ions in the crude product to be below 2.0ppm, and feeding the dechlorinated crude product of the dimethyl carbonate reaching the standard into a subsequent rectification working section;
s03, after the chlorine adsorbent in the fixed bed is adsorbed and saturated, regenerating the adsorbent by adopting a certain regeneration step; the regenerated adsorbent can be used for dechlorination continuously.
Further, the adsorbent in the step S01 is one or more of conventional dechlorination adsorbents such as strong base ion exchange resin, weak base ion exchange resin, supported inorganic solid base catalyst using alumina/activated carbon/molecular sieve as a carrier, and the like.
Further, the fixed bed structure in the step S01 includes a cylinder, a liquid distributor connected to the feed inlet, a support plate provided with a water cap, a heat tracing pipe, and the like.
Further, the preset temperature range in the step S02 is 40.0 to 80.0 ℃.
Further, the preset pressure value range in the step S02 is 0.05-0.5mpa (g).
Further, the value range of the preset liquid hourly space velocity in the step S02 is 1.0-10.0h-1。
Further, a certain regeneration step in the step S03 is:
(1) the residual dimethyl carbonate crude product in the fixed bed is pressed out through the low-pressure nitrogen at the top and sent back to the dimethyl carbonate crude product tank;
(2) continuously introducing a certain amount of methanol, washing and taking out residual dimethyl carbonate crude products in the adsorbent, and returning the washed materials to a dimethyl carbonate crude product tank;
(3) continuously introducing a certain amount of desalted water, washing and taking out the methanol in the bed layer, and returning the washed material to the methanol dehydration process;
(4) allowing the alkali liquor to pass through an adsorbent of a fixed bed according to the preset alkali concentration, the preset liquid hourly space velocity and the preset regeneration time, regenerating the adsorbent, and performing waste water neutralization on the discharged alkali liquor wastewater;
(5) continuously introducing a certain amount of desalted water, washing the alkali liquor in the adsorbent bed layer and taking out until the pH value of the washing liquid is 7-8, and stopping washing; the discharged alkali liquor wastewater is subjected to a wastewater neutralization process;
(6) continuously introducing a certain amount of methanol to wash and take out the water in the adsorbent bed until the water content of the washing liquid is lower than 1000 ppm; the washed materials are returned to the methanol dehydration procedure.
Compared with the prior art, the invention has the following beneficial effects:
the method treats the dimethyl carbonate crude product prepared by the gas-phase carbonylation method by using the adsorbent, adsorbs trace chloride ions remained in the dimethyl carbonate crude product prepared by the gas-phase carbonylation method, and achieves the aim of dechlorinating the crude product by the purpose that the concentration of the chloride ions in the adsorbed dimethyl carbonate crude product is lower than 2.0ppm, thereby effectively reducing the chlorine corrosivity of the crude product and reducing the material requirement of a subsequent treatment working section; therefore, the subsequent alkali treatment process and the rectification process can adopt common stainless steel materials such as S304, S316 and the like, the construction cost of the project is saved, the construction period of the project is shortened, and the daily equipment management and the daily operation of the project are more convenient and efficient.
Of course, it is not necessary for any product in which the invention is practiced to achieve all of the above-described advantages at the same time.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a process flow diagram of the present invention;
in the drawings, the components represented by the respective reference numerals are listed below:
1-methanol, 2-alkali liquor, 3-crude dimethyl carbonate to be dechlorinated, 4-low-pressure nitrogen, 5-desalted water, 6-exhaust gas, 7-crude dechlorinated dimethyl carbonate, 8-recycle of materials in a dimethyl carbonate crude tank, 9-recycle of materials in a methanol dehydration process, 10-removal of materials for wastewater neutralization, A-adsorbent and B-fixed bed.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention will be further described in detail by the following specific examples in conjunction with the accompanying drawings, and the following examples are only illustrative, but not limiting, and should not be construed as limiting the scope of the invention.
As shown in fig. 1, a process for dechlorinating and refining crude dimethyl carbonate prepared by a gas-phase carbonylation method, which takes a production process of preparing dimethyl carbonate by a gas-phase carbonylation method of 5 ten thousand tons per year as an example, comprises the following steps:
s01, weighing 2.0-20.0m3The adsorbent A is filled into a fixed bed B device;
s02, filtering a crude product 3 of dimethyl carbonate to be dechlorinated, which is prepared by a gas-phase carbonylation method, at a preset temperature and a preset pressure, wherein the flow rate of the crude product is 175000.0-50000.0kg/h (wherein the concentration of dimethyl oxalate is 54.0-80.0%, the concentration of dimethyl carbonate is 14.0-40.0%, the concentration of methanol 1 is 2.0-6.0%, and the other concentration is 0.3-3.0%) through a fixed bed B according to a preset liquid hourly space velocity, and the concentration of chloride ions in the crude product before filtering is 4.0-100.0 ppm. And adsorbing trace chloride ions remained in the crude dimethyl carbonate product prepared by the gas-phase carbonyl method under the action of the adsorbent A in the fixed bed B, reducing the concentration of the chloride ions in the crude product to be below 2.0ppm, and feeding the dechlorinated crude dimethyl carbonate product 7 reaching the standard into a subsequent rectification working section.
S03, after the chlorine of the adsorbent A in the fixed bed B is adsorbed and saturated, the adsorbent A can be regenerated by adopting a certain regeneration step. The regenerated adsorbent A can be used for dechlorination continuously.
The adsorbent A is one or more of conventional dechlorination adsorbents such as strong base ion exchange resin, weak base ion exchange resin, supported inorganic solid base catalysts taking aluminum oxide/active carbon/molecular sieves as carriers and the like.
The structure of the fixed bed B comprises a cylinder body, a liquid distributor connected with a feed inlet, a supporting plate provided with a water cap, a heat tracing pipe and the like.
Wherein, the preset temperature value range in the step S01 is 40.0-80.0 ℃.
Wherein, the preset pressure value range in the step S02 is 0.05-0.5MPa (G).
Wherein the value range of the preset liquid hourly space velocity in the step S02 is 1.0-10.0h-1。
The certain regeneration step in step S03 is: the residual crude dimethyl carbonate in the fixed bed B is pressed out by the nitrogen gas 4 with low pressure at the top and is sent back to the crude dimethyl carbonate tank. And (3) continuously introducing a certain amount of methanol 1, washing and taking out the residual dimethyl carbonate crude product in the adsorbent A, and returning the washed material to the dimethyl carbonate crude product tank. And (3) continuously introducing a certain amount of desalted water 5, washing the methanol 1 in the bed layer and taking out, and returning the washed material to the methanol dehydration process. And (3) according to the preset alkali concentration, the preset liquid hourly space velocity and the preset regeneration time, enabling the alkali liquor 2 to pass through the adsorbent A of the fixed bed B, carrying out regeneration treatment on the adsorbent A, and carrying out a wastewater neutralization process on the discharged alkali liquor wastewater. And continuously introducing a certain amount of desalted water 5, washing the alkali liquor 2 in the adsorbent A bed layer, taking out until the PH of the washing liquid is 7-8, and stopping washing. The discharged alkali liquor wastewater goes to a wastewater neutralization process. And (3) continuously introducing a certain amount of methanol 1, and washing and taking out the water in the adsorbent A bed layer until the water content of the washing liquid is lower than 1000 ppm. The washed materials return to the methanol dehydration procedure; wherein 10 is a material for removing waste water and neutralizing; reference numeral 8 is a dimethyl carbonate crude product tank material; reference numeral 9 is a material for the methanol back dehydration step.
When the pressure drop of the adsorbent bed layer is increased, the adsorbent bed layer is uneven and the adsorbent bed layer has bias flow, nitrogen can be introduced to the bottom of the fixed bed B under the condition of a certain liquid level of the fixed bed B, the whole adsorbent bed layer is blown up, the adsorbent bed layer is loosened and leveled again, and the phenomena of overlarge pressure drop and bias flow are avoided; the top of the fixed bed B is provided with exhaust gas 6.
With the continuous use of the adsorbent A, part of the adsorbent A is crushed, and part of solid particle impurities are filtered in a bed layer, the desalted water 5 can be continuously introduced into the bottom of the fixed bed B under the condition of a certain liquid level of the fixed bed B, the finely crushed adsorbent A and the solid particle impurities are discharged from a backwashing outlet, and a certain amount of the adsorbent A is supplemented to maintain the height of the adsorbent bed layer unchanged.
Example 1
Weighing 10.0m3The strong alkaline resin is filled into a resin tower; the resin tower structure comprises a cylinder body, a liquid distributor connected with a feed inlet, a supporting plate provided with a water cap, a heat tracing pipe and the like. The crude product of dimethyl carbonate to be dechlorinated, which is prepared by a gas-phase carbonylation method, is filtered through a fixed bed B at a flow rate of 20000.0kg/h (wherein the concentration of dimethyl oxalate is 58.0%, the concentration of dimethyl carbonate is 35.0%, the concentration of methanol 1 is 6.0%, and the other 1.0%) under the conditions of a temperature of 60.0 ℃ and a pressure of 0.1MPa (G), and the concentration of chloride ions in the crude product before filtration is 16.0 ppm. The residual trace chloride ions in the crude dimethyl carbonate product prepared by the gas-phase carbonyl method are absorbed through the absorption action of strong-base resin, the concentration of the chloride ions in the filtered crude dimethyl carbonate product is 0.8ppm, and the dechlorinated crude dimethyl carbonate product reaching the standard can be sent to a subsequent rectification working section.
And when the concentration of chloride ions in the filtered crude product is more than 2.0ppm, regenerating the strong basic resin. The regeneration step is as follows:
introducing top low-pressure nitrogen 4 at the flow rate of 50.0Nm3/h for 1 hour, pressing out the residual dimethyl carbonate crude product in the fixed bed B, and sending the residual dimethyl carbonate crude product back to the dimethyl carbonate crude product tank. And (3) continuously introducing methanol 1 at the flow rate of 20000.0kg/h for 1 hour, washing and taking out residual dimethyl carbonate crude product in the adsorbent A, and returning the washed material to a dimethyl carbonate crude product tank. And (3) continuously introducing desalted water 5 at the flow rate of 20000.0kg/h for 1 hour, washing the methanol 1 in the bed layer and taking out, and returning the washed material to the methanol dehydration process.
Continuously introducing sodium hydroxide lye 2 with the concentration of 4.0 percent at the flow rate of 20000.0kg/h for 2 hours to carry out regeneration treatment on the resin, and leading the discharged lye wastewater to a wastewater neutralization procedure.
And continuously introducing desalted water 5 at the flow rate of 20000.0kg/h, washing the alkali liquor 2 in the adsorbent bed layer out until the pH value of the washing solution is 7-8, and stopping washing. The discharged alkali liquor wastewater goes to a wastewater neutralization process. Methanol 1 was continuously introduced at a flow rate of 20000.0kg/h to strip the water from the adsorbent bed until the water content of the scrubbing solution was below 1000 ppm. The washed materials are returned to the methanol dehydration procedure.
When the pressure drop of the adsorbent bed is increased, the adsorbent bed is not flat and the adsorbent bed has bias flow, nitrogen can be introduced to the bottom of the fixed bed B under the condition of a certain liquid level of the fixed bed B, the nitrogen flow is 50.0Nm3/h, the whole adsorbent bed is blown up, the adsorbent bed is loosened and flattened again, and the phenomena of overlarge pressure drop and bias flow are avoided.
With the continuous use of the adsorbent A, part of the adsorbent A is crushed, and part of solid particle impurities are filtered in the bed layer, the desalted water 5 can be continuously fed into the bottom of the fixed bed B under the condition of a certain liquid level of the fixed bed B, the flow rate of the desalted water 5 is 50000.0kg/h, the finely-crushed adsorbent A and the solid particle impurities are discharged from a backwashing outlet, and a certain amount of the adsorbent A is supplemented to maintain the height of the adsorbent bed layer unchanged.
Example 2
Weighing 20.0m3The strong alkaline resin is filled into a resin tower; the resin tower structure comprises a cylinder body, a liquid distributor connected with a feed inlet, a supporting plate provided with a water cap, a heat tracing pipe and the like. The crude product of dimethyl carbonate to be dechlorinated, which is prepared by a gas-phase carbonylation method, is filtered through a fixed bed B at a flow rate of 25000.0kg/h (wherein the concentration of dimethyl oxalate is 67.0%, the concentration of dimethyl carbonate is 28.0%, the concentration of methanol 1 is 4.0%, and the other 1.0%) under the conditions of a temperature of 70.0 ℃ and a pressure of 0.2MPa (G), and the concentration of chloride ions in the crude product before filtration is 40.0 ppm. The dimethyl carbonate prepared by the gas phase carbonyl method is absorbed by strong alkaline resinAnd adsorbing trace chloride ions remained in the ester crude product, wherein the concentration of the chloride ions in the filtered crude product is 1.2ppm, and the dechlorinated dimethyl carbonate crude product reaching the standard can be sent to a subsequent rectification working section.
And when the concentration of chloride ions in the filtered crude product is more than 2.0ppm, regenerating the strong basic resin. The regeneration step is as follows:
introducing top low-pressure nitrogen 4 at the flow rate of 100.0Nm3/h for 1 hour, pressing out the residual dimethyl carbonate crude product in the fixed bed B, and sending the residual dimethyl carbonate crude product back to the dimethyl carbonate crude product tank. And (3) continuously introducing methanol 1 at the flow rate of 40000.0kg/h for 1 hour, washing and taking out residual dimethyl carbonate crude product in the adsorbent A, and returning the washed material to a dimethyl carbonate crude product tank. And (3) continuously introducing desalted water 5 at the flow rate of 40000.0kg/h for 1 hour, washing and taking out the methanol in the bed layer, and returning the washed material to the methanol dehydration process.
Continuously introducing sodium hydroxide lye 2 with the concentration of 4.0 percent at the flow rate of 40000.0kg/h for 2 hours to carry out regeneration treatment on the resin, and leading the discharged lye wastewater to a wastewater neutralization procedure.
And continuously introducing desalted water 5 at the flow rate of 40000.0kg/h, washing the alkali liquor 2 in the adsorbent bed layer out until the pH value of the washing solution is 7-8, and stopping washing. The discharged alkali liquor wastewater goes to a wastewater neutralization process. Methanol 1 was continuously introduced at a flow rate of 40000.0kg/h to strip the water from the adsorbent bed until the water content of the scrubbing solution was below 1000 ppm. The washed materials are returned to the methanol dehydration procedure.
When the pressure drop of the adsorbent bed is increased, the adsorbent bed is not flat and the adsorbent bed has bias flow, nitrogen can be introduced to the bottom of the fixed bed B under the condition of a certain liquid level of the fixed bed B, the nitrogen flow is 100.0Nm3/h, the whole adsorbent bed is blown up, the adsorbent bed is loosened and flattened again, and the phenomena of overlarge pressure drop and bias flow are avoided.
With the continuous use of the adsorbent A, part of the adsorbent A is crushed, and part of solid particle impurities are filtered in the bed layer, the desalted water 5 can be continuously fed into the bottom of the fixed bed B under the condition of a certain liquid level of the fixed bed B, the flow rate of the desalted water 5 is 100000.0kg/h, the finely-crushed adsorbent A and the solid particle impurities are discharged from a backwashing outlet, and a certain amount of the adsorbent A is supplemented to maintain the height of the adsorbent bed layer unchanged.
Has the advantages that:
the method treats the dimethyl carbonate crude product prepared by the gas-phase carbonylation method by using the adsorbent, adsorbs trace chloride ions remained in the dimethyl carbonate crude product prepared by the gas-phase carbonylation method, and achieves the aim of dechlorinating the crude product by the purpose that the concentration of the chloride ions in the adsorbed dimethyl carbonate crude product is lower than 2.0ppm, thereby effectively reducing the chlorine corrosivity of the crude product and reducing the material requirement of a subsequent treatment working section; therefore, the subsequent alkali treatment process and the rectification process can adopt common stainless steel materials such as S304, S316 and the like, the construction cost of the project is saved, the construction period of the project is shortened, and the daily equipment management and the daily operation of the project are more convenient and efficient.
The preferred embodiments of the invention disclosed above are intended to be illustrative only. The preferred embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention. The invention is limited only by the claims and their full scope and equivalents.
Claims (7)
1. A dechlorination refining process for preparing a dimethyl carbonate crude product by a gas-phase carbonyl method is characterized by comprising the following steps:
s01, weighing a preset amount of adsorbent, and filling the adsorbent into fixed bed equipment;
s02, filtering the crude product of dimethyl carbonate to be dechlorinated, which is prepared by the gas-phase carbonyl method, through a fixed bed at a preset liquid hourly space velocity under a preset temperature and a preset pressure; adsorbing trace chloride ions remained in the crude product of the dimethyl carbonate to be dechlorinated, which is prepared by a gas-phase carbonyl method, under the action of an adsorbent in a fixed bed, reducing the concentration of the chloride ions in the crude product to be below 2.0ppm, and feeding the dechlorinated crude product of the dimethyl carbonate reaching the standard into a subsequent rectification working section;
s03, after the chlorine adsorbent in the fixed bed is adsorbed and saturated, regenerating the adsorbent by adopting a certain regeneration step; the regenerated adsorbent can be used for dechlorination continuously.
2. The process of claim 1, wherein the adsorbent used in step S01 is one or more of strong base ion exchange resin, weak base ion exchange resin, supported inorganic solid base catalyst with alumina/activated carbon/molecular sieve as carrier, and other conventional dechlorination adsorbents.
3. The process of claim 1, wherein the fixed bed structure of step S01 comprises a cylinder, a liquid distributor connected to the inlet, a support plate with a water cap, a heat tracing pipe, etc.
4. The process of claim 1, wherein the temperature in the step S02 is set to be in the range of 40.0-80.0 ℃.
5. The process of claim 1, wherein the pressure in the step S02 is set to be in the range of 0.05-0.5mpa (g).
6. The process of claim 1, wherein the liquid hourly space velocity in the step S02 is set within a range of 1.0-10.0h-1。
7. The process of claim 1, wherein the step S03 comprises the steps of:
(1) the residual dimethyl carbonate crude product in the fixed bed is pressed out through the low-pressure nitrogen at the top and sent back to the dimethyl carbonate crude product tank;
(2) continuously introducing a certain amount of methanol, washing and taking out residual dimethyl carbonate crude products in the adsorbent, and returning the washed materials to a dimethyl carbonate crude product tank;
(3) continuously introducing a certain amount of desalted water, washing and taking out the methanol in the bed layer, and returning the washed material to the methanol dehydration process;
(4) allowing the alkali liquor to pass through an adsorbent of a fixed bed according to the preset alkali concentration, the preset liquid hourly space velocity and the preset regeneration time, regenerating the adsorbent, and performing waste water neutralization on the discharged alkali liquor wastewater;
(5) continuously introducing a certain amount of desalted water, washing the alkali liquor in the adsorbent bed layer and taking out until the pH value of the washing liquid is 7-8, and stopping washing; the discharged alkali liquor wastewater is subjected to a wastewater neutralization process;
(6) continuously introducing a certain amount of methanol to wash and take out the water in the adsorbent bed until the water content of the washing liquid is lower than 1000 ppm; the washed materials are returned to the methanol dehydration procedure.
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| CN115228119A (en) * | 2022-08-10 | 2022-10-25 | 宁波中科远东催化工程技术有限公司 | Dimethyl carbonate purification system and method |
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