CN114292188A - Production method of dimethyl carbonate - Google Patents
Production method of dimethyl carbonate Download PDFInfo
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- CN114292188A CN114292188A CN202111558342.1A CN202111558342A CN114292188A CN 114292188 A CN114292188 A CN 114292188A CN 202111558342 A CN202111558342 A CN 202111558342A CN 114292188 A CN114292188 A CN 114292188A
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- dimethyl carbonate
- urea
- sodium methoxide
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- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 title claims abstract description 104
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 56
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims abstract description 375
- WQDUMFSSJAZKTM-UHFFFAOYSA-N Sodium methoxide Chemical compound [Na+].[O-]C WQDUMFSSJAZKTM-UHFFFAOYSA-N 0.000 claims abstract description 128
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims abstract description 70
- 239000004202 carbamide Substances 0.000 claims abstract description 70
- 238000000034 method Methods 0.000 claims abstract description 27
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 15
- 238000006243 chemical reaction Methods 0.000 claims description 122
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 72
- DNIAPMSPPWPWGF-UHFFFAOYSA-N Propylene glycol Chemical compound CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 claims description 62
- 239000007788 liquid Substances 0.000 claims description 55
- 239000000126 substance Substances 0.000 claims description 43
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 42
- 238000010992 reflux Methods 0.000 claims description 41
- 239000003054 catalyst Substances 0.000 claims description 36
- 229960004063 propylene glycol Drugs 0.000 claims description 33
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 claims description 29
- 238000001035 drying Methods 0.000 claims description 28
- 239000012074 organic phase Substances 0.000 claims description 26
- 239000012071 phase Substances 0.000 claims description 26
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 19
- 238000003756 stirring Methods 0.000 claims description 18
- 239000012295 chemical reaction liquid Substances 0.000 claims description 17
- 239000012752 auxiliary agent Substances 0.000 claims description 16
- 238000005406 washing Methods 0.000 claims description 15
- 229910021529 ammonia Inorganic materials 0.000 claims description 12
- 230000008569 process Effects 0.000 claims description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 6
- -1 dodecyl dimethyl tertiary amine Chemical class 0.000 claims description 6
- 239000000395 magnesium oxide Substances 0.000 claims description 6
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 6
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims description 6
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 claims description 5
- 150000002009 diols Chemical class 0.000 claims description 4
- SNRUBQQJIBEYMU-UHFFFAOYSA-N Dodecane Natural products CCCCCCCCCCCC SNRUBQQJIBEYMU-UHFFFAOYSA-N 0.000 claims description 3
- 239000000377 silicon dioxide Substances 0.000 claims description 3
- 239000012876 carrier material Substances 0.000 claims description 2
- 235000012239 silicon dioxide Nutrition 0.000 claims description 2
- 238000009833 condensation Methods 0.000 claims 1
- 230000005494 condensation Effects 0.000 claims 1
- 238000006136 alcoholysis reaction Methods 0.000 abstract description 25
- 238000010924 continuous production Methods 0.000 abstract description 10
- 239000000463 material Substances 0.000 abstract description 9
- 238000007599 discharging Methods 0.000 abstract description 5
- 238000012824 chemical production Methods 0.000 abstract description 2
- 239000012847 fine chemical Substances 0.000 abstract description 2
- 239000000243 solution Substances 0.000 description 60
- 238000010438 heat treatment Methods 0.000 description 25
- 239000006227 byproduct Substances 0.000 description 24
- 238000003860 storage Methods 0.000 description 12
- GBMDVOWEEQVZKZ-UHFFFAOYSA-N methanol;hydrate Chemical compound O.OC GBMDVOWEEQVZKZ-UHFFFAOYSA-N 0.000 description 11
- 239000000047 product Substances 0.000 description 11
- 238000004817 gas chromatography Methods 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 8
- 239000002994 raw material Substances 0.000 description 6
- DNIAPMSPPWPWGF-GSVOUGTGSA-N (R)-(-)-Propylene glycol Chemical compound C[C@@H](O)CO DNIAPMSPPWPWGF-GSVOUGTGSA-N 0.000 description 4
- 235000013772 propylene glycol Nutrition 0.000 description 4
- 238000003786 synthesis reaction Methods 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- 238000001308 synthesis method Methods 0.000 description 3
- 230000002194 synthesizing effect Effects 0.000 description 3
- IZXIZTKNFFYFOF-UHFFFAOYSA-N 2-Oxazolidone Chemical compound O=C1NCCO1 IZXIZTKNFFYFOF-UHFFFAOYSA-N 0.000 description 2
- YGYAWVDWMABLBF-UHFFFAOYSA-N Phosgene Chemical compound ClC(Cl)=O YGYAWVDWMABLBF-UHFFFAOYSA-N 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000006315 carbonylation Effects 0.000 description 2
- 238000005810 carbonylation reaction Methods 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 150000005676 cyclic carbonates Chemical class 0.000 description 2
- 239000013067 intermediate product Substances 0.000 description 2
- 239000002608 ionic liquid Substances 0.000 description 2
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 231100000956 nontoxicity Toxicity 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 2
- 239000004575 stone Substances 0.000 description 2
- 230000004913 activation Effects 0.000 description 1
- 238000007259 addition reaction Methods 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- 150000001342 alkaline earth metals Chemical class 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 239000002274 desiccant Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000032050 esterification Effects 0.000 description 1
- 238000005886 esterification reaction Methods 0.000 description 1
- 150000002148 esters Chemical group 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000009533 lab test Methods 0.000 description 1
- 231100000053 low toxicity Toxicity 0.000 description 1
- 230000011987 methylation Effects 0.000 description 1
- 238000007069 methylation reaction Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000002808 molecular sieve Substances 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Landscapes
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
The invention relates to the technical field of fine chemical production, in particular to a production method of dimethyl carbonate. Aiming at solving the technical problem of low production efficiency of the method for preparing the dimethyl carbonate by two-step alcoholysis; the invention provides a method for producing dimethyl carbonate, which can realize continuous production; continuously adding urea, adding dihydric alcohol for a certain time, adding methanol solution of sodium methoxide, and continuously adding methanol after adding the methanol solution of sodium methoxide for a certain time; by controlling the production factors such as the material adding flow, the adding amount of the dihydric alcohol and the like, the continuous production mode of continuous feeding and continuous discharging is realized, and the production efficiency is high.
Description
Technical Field
The invention relates to the technical field of fine chemical production, in particular to a production method of dimethyl carbonate.
Background
The molecular structure of the dimethyl carbonate contains organic chemical functional groups such as methyl, methoxy, carbonyl and the like, has active chemical properties, and can react with various organic compounds such as methylation, carbonylation, methyl esterification, ester exchange and the like. Meanwhile, the stone has low toxicity and safe use, meets the requirements of clean production and environmental protection, and becomes a new stone for modern organic synthesis.
At the end of the last century, countries around the world have come to recognize the prospects and markets for the industrial application of dimethyl carbonate and have developed relevant research efforts. Among them, the research on the synthetic route of dimethyl carbonate is first conducted in the united states and japan, and the synthetic technical route of dimethyl carbonate is developed in the direction of simplification, non-toxicity and non-pollution, and a great breakthrough is made. At present, the synthesis process of dimethyl carbonate is gradually mature after being replaced by several generations. The traditional phosgene synthesis method is eliminated due to pollution and danger, the methanol oxidation carbonylation method is gradually abandoned due to the fact that the traditional phosgene synthesis method cannot follow the development step of the market, and a new synthesis technology, namely a urea alcoholysis method, is gradually accepted by the market due to the advantages of no toxicity, low pollution, high production condition safety coefficient and the like exhibited by the urea alcoholysis method.
The urea alcoholysis method is also the key direction for researching the synthesis of the dimethyl carbonate in various countries at the present stage. Chinese patent CN1280254C discloses a method for synthesizing dimethyl carbonate by alcoholysis of methanol and urea, which uses methanol and urea as raw materials and amine salt type ionic liquid as a catalyst, and adopts an intermittent reaction to synthesize the dimethyl carbonate. Chinese patent CN1903828A discloses a process for producing dimethyl carbonate by urea alcoholysis, which further optimizes the reaction and separation conditions. Chinese patents CN100395019C and CN113385207A both propose supported catalysts for synthesizing dimethyl carbonate from urea and methanol, and achieve better catalytic performance through the combination of alkali metals, alkaline earth metals, auxiliaries and molecular sieves. Chinese patent CN103980124B optimizes the method for synthesizing dimethyl carbonate by using ionic liquid to catalyze propylene carbonate. The method for preparing the dimethyl carbonate adopts a one-step synthesis method, mainly focuses on the updating preparation of the catalyst used in the reaction process, and the production mode is intermittent production, so that the technical problems of low yield, low production efficiency and the like exist, and the further expansion of the production scale and the efficiency are restricted.
Chinese patent CN106083585B discloses a method for preparing dimethyl carbonate by indirect alcoholysis; and (3) carrying out alcoholysis by adopting a two-step method, separating the intermediate product propylene carbonate after the first-stage alcoholysis, and carrying out second-stage alcoholysis on the intermediate product and methanol. In the preparation method, the catalysts, reaction equipment and reaction conditions required by the two-step alcoholysis are different; and the first-stage alcoholysis needs to be carried out under the vacuum condition, the production condition is harsh, the required production equipment is complex, the continuous production cannot be realized, and the production efficiency is low.
Disclosure of Invention
Aiming at solving the technical problem of low production efficiency of the method for preparing the dimethyl carbonate by two-step alcoholysis; the invention provides a method for producing dimethyl carbonate, which can realize continuous production; the production method uses a urea two-step alcoholysis method, produces the dimethyl carbonate by a continuous feeding and continuous discharging mode, and has high production efficiency. The production efficiency refers to the amount of the target product (dimethyl carbonate) produced in unit time.
In order to solve the technical problems, the invention adopts the following technical scheme:
a method for producing dimethyl carbonate comprises the following steps:
(1) in the presence of a catalyst, into a reaction vessel:
continuously adding urea; the mass flow rate of urea and the volume ratio of the reaction container are as follows: 200-300 kg/h: 2m3；
Adding dihydric alcohol, stirring, and performing reflux reaction; the flow rate of the dihydric alcohol is 1.4 to 1.6 times of the mass flow rate of the urea, and the adding time of the dihydric alcohol is 1 hour 20 minutes to 1 hour 40 minutes;
after the addition of the dihydric alcohol is stopped, adding methanol solution of sodium methoxide, stirring, and carrying out reflux reaction; when the mass of the sodium methoxide in the reaction liquid is 1-2% of the mass of the urea, stopping adding the methanol liquid of the sodium methoxide and stopping the reflux reaction; the mass content of sodium methoxide in the methanol solution of sodium methoxide is 1-3%, and the flow rate of the methanol solution of sodium methoxide is 1-1.2 times of the mass flow rate of urea;
after the addition of the methanol solution of sodium methoxide is stopped, continuously adding methanol, stirring and collecting steam; the flow rate of the methanol is 1 to 1.2 times of the mass flow rate of the urea;
controlling the temperature of the reaction liquid in the reaction container to be 130-150 ℃ in the whole process of the step (1);
(2) separating ammonia gas and methanol in the steam to obtain the dimethyl carbonate.
The production method adopts a two-step alcoholysis method, urea and methanol are used as raw materials, and dihydric alcohol is used as a reaction participant; alcoholysis in the first step: reacting urea with dihydric alcohol to generate cyclic carbonate, and performing alcoholysis in the second step: the cyclic carbonate reacts with methanol to produce dimethyl carbonate and diol. The reaction formula takes 1, 2-propylene glycol as an example of a reaction participant, and comprises the following steps:
the catalyst can adopt any one catalyst disclosed in the prior art for preparing dimethyl carbonate by a two-step alcoholysis method; for example, the supported catalyst of magnesium oxide, the carrier material is silicon dioxide, and the mass content of magnesium oxide in the catalyst is 10-15%; the amount of the catalyst is 0.1 time of the mass of the added urea per hour.
The urea mass flow, i.e. the mass of urea added per hour, was determined by the inventors through several laboratory experiments and production tests; the specific urea mass flow is a necessary condition for realizing continuous feeding, continuous production and high production efficiency. The urea mass flow provided by the invention can realize continuous feeding and continuous production, and can obtain high production efficiency. The volume of the reaction kettle is 2m3For example, the mass flow rate of the urea is controlled to be about 200-300kg/h, and high production efficiency can be obtained.
The specific addition of the reaction participant diol is also a necessary condition for realizing continuous feeding, continuous production and high production efficiency. The present invention limits the amount of glycol added by limiting the duration of glycol addition. Experimental research proves that the problems of incapability of continuous feeding (further incapability of continuous production) and/or reduction of production efficiency can be caused by excessive or insufficient addition of the dihydric alcohol. Possible reasons are: the production method of the invention needs the whole reaction system to be in dynamic balance, and the change of the dosage of any raw material (concentration in the reaction solution) can cause the change of the dynamic balance, so that the balance is continuously shifted to the right or to the left, which causes the incapability of continuously feeding or continuously discharging, and the incapability of realizing continuous production, thereby affecting the production efficiency. Preferably, the flow rate of the dihydric alcohol is 1.5 to 1.52 times of the mass flow rate of the urea; the addition time of the glycol was 1.5 h. Under the condition, the production efficiency is higher.
The glycol may be ethylene glycol or 1, 2-propylene glycol. 1, 2-propylene glycol is preferred because the ethylene glycol can generate 2-oxazolidinone as an impurity in the actual production process, the 2-oxazolidinone is enriched in a reaction kettle, and the cyclic utilization of dihydric alcohol is not utilized.
The sodium methoxide acts as a catalyst for the second alcoholysis step. The amount of the catalyst needs to be strictly limited, and on one hand, the amount needs to achieve the catalytic activation; on the other hand, due to the activity and chemical danger of sodium methoxide itself, too high a content may result in locally violent reactions, which may be dangerous. Therefore, through repeated experimental studies, the amount of sodium methoxide in the reaction system is limited to 1-2% of the mass of urea.
In order to further increase the reaction rate to obtain high production efficiency, it is preferable to use an auxiliary in combination with the catalyst. The auxiliary agent is dodecyl dimethyl tertiary amine, and the dosage of the auxiliary agent is 0.1 time of that of the catalyst.
The temperature of the reaction solution is preferably 130-134 ℃; under the temperature condition, high production efficiency can be obtained, and energy waste can not be caused.
In the step (2), the steam is a mixture of ammonia gas, gaseous methanol and gaseous dimethyl carbonate. The following separation methods may be employed: condensing the steam to 0-5 ℃, and respectively collecting gaseous substances and liquid substances; washing the liquid substance with water, separating to obtain an organic phase and a water phase, drying the organic phase with anhydrous calcium chloride to obtain dimethyl carbonate, and rectifying the water phase and drying the anhydrous calcium chloride to obtain methanol.
In addition, it should be noted that the absence of water in the reaction vessel should be ensured throughout step (1).
The invention has the beneficial effects that:
the invention provides a method for producing dimethyl carbonate, which uses a urea two-step alcoholysis method, takes urea and methanol as raw materials, takes 1, 2-propylene glycol as a reactant of the first-step alcoholysis of urea, and produces the dimethyl carbonate by a continuous feeding and continuous discharging mode. According to the method, the dynamic balance of the whole reaction system can be maintained under the condition of keeping continuous feeding by controlling the material feeding speed, the feeding amount ratio and the reaction time of the reaction participants and the urea, so that continuous feeding production is realized; on the other hand, the method promotes the equilibrium of the alcoholysis reaction of the first step to the right by continuously adding methanol into the reaction liquid after the alcoholysis of the first step and separating the alcoholysis product of the second step, so that the next reaction can be carried out completely without the alcoholysis of the first step, the working hours are shortened, the cost is reduced, and the production efficiency is greatly improved. The invention realizes continuous production, has high equipment utilization rate and reduced cost compared with the traditional batch kettle type production, and is beneficial to industrial popularization.
Detailed Description
The present invention will be further described with reference to the following examples.
In the present specification, the terms "upper", "lower", "left", "right", "middle" and "one" are used for clarity of description, and are not intended to limit the scope of the present invention, and changes or modifications in the relative relationship may be made without substantial technical changes.
The following examples, comparative examples, and some of the raw material specifications used:
the reaction kettle is a 2-cubic kettle (the capacity is 2 m)3) All pipelines and kettles are dried at 50 ℃ in advance;
the catalyst is a silica supported catalyst of magnesium oxide, the mass content of the magnesium oxide is 15%, the appearance is spherical, and the diameter is about 3 cm;
the auxiliary agent is dodecyl dimethyl tertiary amine, and is analytically pure; the drying agent is anhydrous calcium chloride;
the raw materials are all industrial pure, and methanol and 1, 2-propylene glycol are dried and dewatered in advance.
In the examples, the reaction operation was continuous feeding and discharging, and for better comparison, 12 hours was selected as a reaction period, and the time for calculating the yield and efficiency was 10.5 hours in total from the start of the dropwise addition of methanol.
Example 1
Step (1): adding 20kg of catalyst and 2kg of auxiliary agent into a reaction kettle, then continuously adding urea and 1, 2-propylene glycol into the reaction kettle at the speed of 200kg/h and 304kg/h respectively to carry out reflux reaction, starting stirring after 30min, heating the reaction solution in the kettle to 132 +/-2 ℃ through a heating sleeve, and keeping the temperature to continuously dropwise add for reaction for 1 h.
Step (2): keeping the adding amount of urea (200kg/h) unchanged, and carrying out the following operations under the condition of keeping the temperature of reaction liquid in the kettle at 132 +/-2 ℃; stopping dropwise adding 1, 2-propylene glycol, starting adding a methanol solution of sodium methoxide (the mass content of sodium methoxide in the methanol solution of sodium methoxide is 1%) at a speed of 220kg/h under the liquid level for reflux reaction, stopping adding the methanol solution of sodium methoxide after 2h, and closing reflux; methanol was then added continuously at a rate of 220kg/h below the liquid level and the vapors were collected.
And (3): condensing the steam to 0-5 ℃, wherein the gaseous substance is the by-product ammonia; the liquid substances are dimethyl carbonate and methanol. And drying the ammonia gas as a byproduct and feeding the ammonia gas into an ammonia gas temporary storage tank. Washing the liquid substance with water, separating to obtain an organic phase (dimethyl carbonate) and a water phase (methanol water solution), drying the organic phase with anhydrous calcium chloride to obtain dimethyl carbonate, and rectifying the water phase with anhydrous calcium chloride to obtain methanol. The methanol can be recycled.
And (3) counting the mass of each product after being processed in the step (3) when the step (2) lasts for 10.5 hours: 1244kg of ammonia gas, 3266kg of dimethyl carbonate and 270kg of methanol.
Detecting and analyzing by high performance gas chromatography to obtain: the purity of dimethyl carbonate was 99.54%, the yield of dimethyl carbonate was 91.13% (based on urea), and the production efficiency of dimethyl carbonate was 311 kg/h.
Example 2 (comparison with example 1, the urea flow rate is 300kg/h, and the other material flow rates are adjusted accordingly)
Step (1): adding 30kg of catalyst and 3kg of auxiliary agent into a reaction kettle, then continuously adding urea and 1, 2-propylene glycol into the reaction kettle respectively at the speed of 300kg/h and 456kg/h for reflux reaction, starting stirring after 30min, heating the reaction solution in the kettle to 138 +/-2 ℃ through a heating sleeve, and keeping the temperature for continuous dropwise addition reaction for 1 h.
Step (2): keeping the adding amount of urea (300kg/h) unchanged, and carrying out the following operations under the condition of keeping the temperature of the reaction liquid in the kettle at 132 +/-2 ℃; stopping adding 1, 2-propylene glycol, starting adding liquid methanol of sodium methoxide (the mass content of sodium methoxide in the liquid methanol of sodium methoxide is 1%) at the speed of 330kg/h, carrying out reflux reaction, stopping adding the liquid methanol of sodium methoxide after 2h, and closing reflux; methanol was added under the liquid surface at a rate of 330kg/h, and the vapor was collected.
And (3): condensing the steam to 0-5 ℃, wherein the gaseous substance is the by-product ammonia; the liquid substances are dimethyl carbonate and methanol. And drying the ammonia gas as a byproduct and feeding the ammonia gas into an ammonia gas temporary storage tank. Washing the liquid substance with water, separating to obtain an organic phase (dimethyl carbonate) and a water phase (methanol water solution), drying the organic phase with anhydrous calcium chloride to obtain dimethyl carbonate, and rectifying the water phase with anhydrous calcium chloride to obtain methanol. The methanol can be recycled.
And (3) counting the mass of each product after being processed in the step (3) when the step (2) lasts for 10.5 hours: 1865kg of ammonia gas, 4907kg of dimethyl carbonate and 400kg of methanol.
Detecting and analyzing by high performance gas chromatography to obtain: the purity of dimethyl carbonate was 99.55%, the yield of dimethyl carbonate (based on urea) was 91.28%, and the production efficiency of dimethyl carbonate was 467 kg/h.
Example 3 (1, 2-propanediol addition time is shortened by 10min compared to example 1)
Step (1): adding 20kg of catalyst and 2kg of auxiliary agent into a reaction kettle, then continuously adding urea and 1, 2-propylene glycol into the reaction kettle at the speed of 200kg/h and 304kg/h respectively to carry out reflux reaction, starting stirring after 30min, heating the reaction solution in the kettle to 132 +/-2 ℃ through a heating sleeve, and keeping the temperature to continuously dropwise add for reaction for 50 min.
Step (2): keeping the adding amount of urea (200kg/h) unchanged, and carrying out the following operations under the condition of keeping the temperature of reaction liquid in the kettle at 132 +/-2 ℃; stopping dropwise adding 1, 2-propylene glycol, starting adding a methanol solution of sodium methoxide (the mass content of sodium methoxide in the methanol solution of sodium methoxide is 1%) at a speed of 220kg/h under the liquid level for reflux reaction, stopping adding the methanol solution of sodium methoxide after 2h, and closing reflux; methanol was then added continuously at a rate of 220kg/h below the liquid level and the vapors were collected.
And (3): condensing the steam to 0-5 ℃, wherein the gaseous substance is the by-product ammonia; the liquid substances are dimethyl carbonate and methanol. And drying the ammonia gas as a byproduct and feeding the ammonia gas into an ammonia gas temporary storage tank. Washing the liquid substance with water, separating to obtain an organic phase (dimethyl carbonate) and a water phase (methanol water solution), drying the organic phase with anhydrous calcium chloride to obtain dimethyl carbonate, and rectifying the water phase with anhydrous calcium chloride to obtain methanol. The methanol can be recycled.
And (3) counting the mass of each product after being processed in the step (3) when the step (2) lasts for 10.5 hours: 1240kg of ammonia gas, 3260kg of dimethyl carbonate and 276kg of methanol.
Detecting and analyzing by high performance gas chromatography to obtain: the purity of dimethyl carbonate was 99.52%, the yield of dimethyl carbonate (based on urea) was 90.96%, and the production efficiency of dimethyl carbonate was 310 kg/h.
Example 4 (1, 2-propanediol addition time is extended by 10min compared to example 1)
Step (1): adding 20kg of catalyst and 2kg of auxiliary agent into a reaction kettle, then continuously adding urea and 1, 2-propylene glycol into the reaction kettle at the speed of 200kg/h and 304kg/h respectively to carry out reflux reaction, starting stirring after 30min, heating the reaction solution in the kettle to 132 +/-2 ℃ through a heating sleeve, and keeping the temperature to continuously dropwise add for reaction for 50 min.
Step (2): keeping the adding amount of urea (200kg/h) unchanged, and carrying out the following operations under the condition of keeping the temperature of reaction liquid in the kettle at 132 +/-2 ℃; stopping dropwise adding 1, 2-propylene glycol, starting adding a methanol solution of sodium methoxide (the mass content of sodium methoxide in the methanol solution of sodium methoxide is 1%) at a speed of 220kg/h under the liquid level for reflux reaction, stopping adding the methanol solution of sodium methoxide after 2h, and closing reflux; methanol was then added continuously at a rate of 220kg/h below the liquid level and the vapors were collected.
And (3): condensing the steam to 0-5 ℃, wherein the gaseous substance is the by-product ammonia; the liquid substances are dimethyl carbonate and methanol. And drying the ammonia gas as a byproduct and feeding the ammonia gas into an ammonia gas temporary storage tank. Washing the liquid substance with water, separating to obtain an organic phase (dimethyl carbonate) and a water phase (methanol water solution), drying the organic phase with anhydrous calcium chloride to obtain dimethyl carbonate, and rectifying the water phase with anhydrous calcium chloride to obtain methanol. The methanol can be recycled.
And (3) counting the mass of each product after being processed in the step (3) when the step (2) lasts for 10.5 hours: 1251kg of ammonia gas, 3264kg of dimethyl carbonate and 273kg of methanol.
Detecting and analyzing by high performance gas chromatography to obtain: the purity of dimethyl carbonate was 99.54%, the yield of dimethyl carbonate (based on urea) was 91.07%, and the production efficiency of dimethyl carbonate was 311 kg/h.
Example 5 (reaction temperature 150 ℃ C., other conditions were the same as in example 1)
Step (1): adding 20kg of catalyst and 2kg of auxiliary agent into a reaction kettle, then continuously adding urea and 1, 2-propylene glycol into the reaction kettle at the speed of 200kg/h and 304kg/h respectively to carry out reflux reaction, starting stirring after 30min, heating the reaction solution in the kettle to 150 +/-2 ℃ through a heating sleeve, and keeping the temperature to continuously dropwise add for reaction for 1 h.
Step (2): keeping the adding amount of urea (200kg/h) unchanged, and carrying out the following operations under the condition of keeping the temperature of the reaction liquid in the kettle at 150 +/-2 ℃; stopping dropwise adding 1, 2-propylene glycol, starting adding a methanol solution of sodium methoxide (the mass content of sodium methoxide in the methanol solution of sodium methoxide is 1%) at a speed of 220kg/h under the liquid level for reflux reaction, stopping adding the methanol solution of sodium methoxide after 2h, and closing reflux; methanol was then added continuously at a rate of 220kg/h below the liquid level and the vapors were collected.
And (3): condensing the steam to 0-5 ℃, wherein the gaseous substance is the by-product ammonia; the liquid substances are dimethyl carbonate and methanol. And drying the ammonia gas as a byproduct and feeding the ammonia gas into an ammonia gas temporary storage tank. Washing the liquid substance with water, separating to obtain an organic phase (dimethyl carbonate) and a water phase (methanol water solution), drying the organic phase with anhydrous calcium chloride to obtain dimethyl carbonate, and rectifying the water phase with anhydrous calcium chloride to obtain methanol. The methanol can be recycled.
And (3) counting the mass of each product after being processed in the step (3) when the step (2) lasts for 10.5 hours: 1254kg of ammonia gas, 3263kg of dimethyl carbonate and 274kg of methanol.
Detecting and analyzing by high performance gas chromatography to obtain: the purity of dimethyl carbonate was 99.55%, the yield of dimethyl carbonate (based on urea) was 91.05%, and the production efficiency of dimethyl carbonate was 311 kg/h.
Comparative example 1 (reaction temperature 120 ℃ C., other conditions were the same as in example 1)
Step (1): adding 20kg of catalyst and 2kg of auxiliary agent into a reaction kettle, then continuously adding urea and 1, 2-propylene glycol into the reaction kettle at the speed of 200kg/h and 304kg/h respectively to carry out reflux reaction, starting stirring after 30min, heating the reaction solution in the kettle to 120 +/-2 ℃ through a heating sleeve, and keeping the temperature to continuously dropwise add for reaction for 1 h.
Step (2): keeping the adding amount of urea (200kg/h) unchanged, and carrying out the following operations under the condition of keeping the temperature of the reaction liquid in the kettle at 120 +/-2 ℃; stopping dropwise adding 1, 2-propylene glycol, starting adding a methanol solution of sodium methoxide (the mass content of sodium methoxide in the methanol solution of sodium methoxide is 1%) at a speed of 220kg/h under the liquid level for reflux reaction, stopping adding the methanol solution of sodium methoxide after 2h, and closing reflux; methanol was then added continuously at a rate of 220kg/h below the liquid level and the vapors were collected.
And (3): condensing the steam to 0-5 ℃, wherein the gaseous substance is the by-product ammonia; the liquid substances are dimethyl carbonate and methanol. And drying the ammonia gas as a byproduct and feeding the ammonia gas into an ammonia gas temporary storage tank. Washing the liquid substance with water, separating to obtain an organic phase (dimethyl carbonate) and a water phase (methanol water solution), drying the organic phase with anhydrous calcium chloride to obtain dimethyl carbonate, and rectifying the water phase with anhydrous calcium chloride to obtain methanol. The methanol can be recycled.
And (3) counting the mass of each product after being processed in the step (3) when the step (2) lasts for 10.5 hours: 921kg of ammonia gas, 2718kg of dimethyl carbonate and 612kg of methanol.
Detecting and analyzing by high performance gas chromatography to obtain: the purity of dimethyl carbonate was 99.54%, the yield of dimethyl carbonate (based on urea) was 75.84%, and the production efficiency of dimethyl carbonate was 259 kg/h.
Comparative example 2 (reaction temperature 160 ℃ C., other conditions were the same as in example 1)
Step (1): adding 20kg of catalyst and 2kg of auxiliary agent into a reaction kettle, then continuously adding urea and 1, 2-propylene glycol into the reaction kettle at the speed of 200kg/h and 304kg/h respectively to carry out reflux reaction, starting stirring after 30min, heating the reaction solution in the kettle to 160 +/-2 ℃ through a heating sleeve, and keeping the temperature to continuously dropwise add for reaction for 1 h.
Step (2): keeping the adding amount of urea (200kg/h) unchanged, and carrying out the following operations under the condition of keeping the temperature of the reaction liquid in the kettle at 160 +/-2 ℃; stopping dropwise adding 1, 2-propylene glycol, starting adding a methanol solution of sodium methoxide (the mass content of sodium methoxide in the methanol solution of sodium methoxide is 1%) at a speed of 220kg/h under the liquid level for reflux reaction, stopping adding the methanol solution of sodium methoxide after 2h, and closing reflux; methanol was then added continuously at a rate of 220kg/h below the liquid level and the vapors were collected.
And (3): condensing the steam to 0-5 ℃, wherein the gaseous substance is the by-product ammonia; the liquid substances are dimethyl carbonate and methanol. And drying the ammonia gas as a byproduct and feeding the ammonia gas into an ammonia gas temporary storage tank. Washing the liquid substance with water, separating to obtain an organic phase (dimethyl carbonate) and a water phase (methanol water solution), drying the organic phase with anhydrous calcium chloride to obtain dimethyl carbonate, and rectifying the water phase with anhydrous calcium chloride to obtain methanol. The methanol can be recycled.
And (3) counting the mass of each product after being processed in the step (3) when the step (2) lasts for 10.5 hours: 1252kg of ammonia gas, 3227kg of dimethyl carbonate and 297kg of methanol.
Detecting and analyzing by high performance gas chromatography to obtain: the purity of dimethyl carbonate was 99.55%, the yield of dimethyl carbonate (based on urea) was 90.04%, and the production efficiency of dimethyl carbonate was 307 kg/h.
Comparative example 3 (comparison with example 1, the urea flow is 400kg/h, the other material flows are adjusted accordingly)
Step (1): adding 40kg of catalyst and 4kg of auxiliary agent into a reaction kettle, then continuously adding urea and 1, 2-propylene glycol into the reaction kettle at the speed of 400kg/h and 608kg/h respectively to carry out reflux reaction, starting stirring after 30min, heating the reaction solution in the kettle to 138 +/-2 ℃ through a heating sleeve, and keeping the temperature to continuously dropwise add for reaction for 1 h.
Step (2): keeping the adding amount of urea (400kg/h) unchanged, and carrying out the following operations under the condition of keeping the temperature of reaction liquid in the kettle at 132 +/-2 ℃; stopping adding 1, 2-propylene glycol, starting adding a methanol solution of sodium methoxide (the mass content of sodium methoxide in the methanol solution of sodium methoxide is 1%) at the speed of 440kg/h under the liquid level for reflux reaction, stopping adding the methanol solution of sodium methoxide after 2h, and closing reflux; methanol was added under the liquid surface at a rate of 440kg/h and the vapors were collected.
And (3): condensing the steam to 0-5 ℃, wherein the gaseous substance is the by-product ammonia; the liquid substances are dimethyl carbonate and methanol. And drying the ammonia gas as a byproduct and feeding the ammonia gas into an ammonia gas temporary storage tank. Washing the liquid substance with water, separating to obtain an organic phase (dimethyl carbonate) and a water phase (methanol water solution), drying the organic phase with anhydrous calcium chloride to obtain dimethyl carbonate, and rectifying the water phase with anhydrous calcium chloride to obtain methanol. The methanol can be recycled.
And (3) counting that the volume of the materials in the reaction kettle is 4/5 when the step (2) lasts for 5.5 hours, and stopping feeding when the reaction cannot be continued.
Comparative example 4 (catalyst only, no auxiliary, other conditions the same as in example 1)
Step (1): adding 20kg of catalyst into a reaction kettle, then continuously adding urea and 1, 2-propylene glycol into the reaction kettle at the speed of 200kg/h and 304kg/h respectively to carry out reflux reaction, starting stirring after 30min, heating the reaction solution in the kettle to 132 +/-2 ℃ through a heating sleeve, and keeping the temperature to continuously dropwise add for reaction for 1 h.
Step (2): keeping the adding amount of urea (200kg/h) unchanged, and carrying out the following operations under the condition of keeping the temperature of reaction liquid in the kettle at 132 +/-2 ℃; stopping dropwise adding 1, 2-propylene glycol, starting adding a methanol solution of sodium methoxide (the mass content of sodium methoxide in the methanol solution of sodium methoxide is 1%) at a speed of 220kg/h under the liquid level for reflux reaction, stopping adding the methanol solution of sodium methoxide after 2h, and closing reflux; methanol was then added continuously at a rate of 220kg/h below the liquid level and the vapors were collected.
And (3): condensing the steam to 0-5 ℃, wherein the gaseous substance is the by-product ammonia; the liquid substances are dimethyl carbonate and methanol. And drying the ammonia gas as a byproduct and feeding the ammonia gas into an ammonia gas temporary storage tank. Washing the liquid substance with water, separating to obtain an organic phase (dimethyl carbonate) and a water phase (methanol water solution), drying the organic phase with anhydrous calcium chloride to obtain dimethyl carbonate, and rectifying the water phase with anhydrous calcium chloride to obtain methanol. The methanol can be recycled.
And (3) counting the mass of each product after being processed in the step (3) when the step (2) lasts for 10.5 hours: 1158kg of ammonia gas, 2965kg of dimethyl carbonate and 456kg of methanol.
Detecting and analyzing by high performance gas chromatography to obtain: the purity of dimethyl carbonate was 99.53%, the yield of dimethyl carbonate (based on urea) was 82.75%, and the production efficiency of dimethyl carbonate was 282 kg/h.
Comparative example 5 (batch kettle type production)
Step (1): adding 20kg of catalyst and 2kg of auxiliary agent into a reaction kettle, then continuously adding urea and 1, 2-propylene glycol into the reaction kettle at the speed of 200kg/h and 304kg/h respectively, starting stirring after 30min, heating the reaction solution in the kettle to 132 +/-2 ℃ through a heating sleeve, keeping the temperature, continuously dropwise adding for reaction for 2h, stopping dropwise adding, and continuously preserving the temperature for 30min, wherein the byproduct ammonia gas is not generated any more.
Step (2): and (2) dropwise adding methanol solution of sodium methoxide at the speed of 220kg/h below the liquid level for reflux reaction, stopping dropwise adding after 2h, closing reflux, starting steam external extraction, dropwise adding methanol at the temperature of 132 +/-2 ℃ at the speed of 220kg/h below the liquid level for 1h, and stopping heating and dropwise adding.
And (3): 279kg of condensed and dried ammonia gas as a byproduct is put into an ammonia gas temporary storage tank, steam methanol and dimethyl carbonate are cooled into liquid, dimethyl carbonate and methanol aqueous solution are obtained by water washing and separation, 778kg of dimethyl carbonate is obtained by drying anhydrous calcium chloride, and 170kg of methanol is obtained by rectifying the methanol aqueous solution and drying the anhydrous calcium chloride and can be recycled.
Detecting and analyzing by high performance gas chromatography to obtain: the content of dimethyl carbonate in the product is 99.55 percent, the yield of dimethyl carbonate is 91.14 percent, and the production efficiency is 141 kg/h.
Comparative example 6 (1 h total time of 1, 2-propanediol to autoclave, other steps same as example 1) step (1): adding 20kg of catalyst and 2kg of auxiliary agent into a reaction kettle, then continuously adding urea and 1, 2-propylene glycol into the reaction kettle at the speed of 200kg/h and 304kg/h respectively to carry out reflux reaction, starting stirring after 30min, heating the reaction solution in the kettle to 132 +/-2 ℃ through a heating sleeve, and keeping the temperature to continuously dropwise add for reaction for 0.5 h.
Step (2): keeping the adding amount of urea (200kg/h) unchanged, and carrying out the following operations under the condition of keeping the temperature of reaction liquid in the kettle at 132 +/-2 ℃; stopping dropwise adding 1, 2-propylene glycol, starting adding a methanol solution of sodium methoxide (the mass content of sodium methoxide in the methanol solution of sodium methoxide is 1%) at a speed of 220kg/h under the liquid level for reflux reaction, stopping adding the methanol solution of sodium methoxide after 2h, and closing reflux; methanol was then added continuously at a rate of 220kg/h below the liquid level and the vapors were collected.
And (3): condensing the steam to 0-5 ℃, wherein the gaseous substance is the by-product ammonia; the liquid substances are dimethyl carbonate and methanol. And drying the ammonia gas as a byproduct and feeding the ammonia gas into an ammonia gas temporary storage tank. Washing the liquid substance with water, separating to obtain an organic phase (dimethyl carbonate) and a water phase (methanol water solution), drying the organic phase with anhydrous calcium chloride to obtain dimethyl carbonate, and rectifying the water phase with anhydrous calcium chloride to obtain methanol. The methanol can be recycled.
After the reaction is carried out for 6 hours, the volume of the materials in the reaction kettle is increased to 0.7 time from the initial 0.5 times, the reaction can not be continued along with the continuous accumulation of the materials in the reaction kettle, and the feeding reaction is stopped.
Comparative example 7 (1, 2-propanediol added to the autoclave for a total time of 2h, other steps being the same as in example 1) step (1): adding 20kg of catalyst and 2kg of auxiliary agent into a reaction kettle, then continuously adding urea and 1, 2-propylene glycol into the reaction kettle at the speed of 200kg/h and 304kg/h respectively to carry out reflux reaction, starting stirring after 30min, heating the reaction solution in the kettle to 132 +/-2 ℃ through a heating sleeve, and keeping the temperature to continuously dropwise add for reaction for 1.5 h.
Step (2): keeping the adding amount of urea (200kg/h) unchanged, and carrying out the following operations under the condition of keeping the temperature of reaction liquid in the kettle at 132 +/-2 ℃; stopping dropwise adding 1, 2-propylene glycol, starting adding a methanol solution of sodium methoxide (the mass content of sodium methoxide in the methanol solution of sodium methoxide is 1%) at a speed of 220kg/h under the liquid level for reflux reaction, stopping adding the methanol solution of sodium methoxide after 2h, and closing reflux; methanol was then added continuously at a rate of 220kg/h below the liquid level and the vapors were collected.
And (3): condensing the steam to 0-5 ℃, wherein the gaseous substance is the by-product ammonia; the liquid substances are dimethyl carbonate and methanol. And drying the ammonia gas as a byproduct and feeding the ammonia gas into an ammonia gas temporary storage tank. Washing the liquid substance with water, separating to obtain an organic phase (dimethyl carbonate) and a water phase (methanol water solution), drying the organic phase with anhydrous calcium chloride to obtain dimethyl carbonate, and rectifying the water phase with anhydrous calcium chloride to obtain methanol. The methanol can be recycled.
After the reaction is carried out for 10 hours, the volume of the materials in the reaction kettle is increased to 0.65 time from the initial 0.5 times, the reaction can not be continued along with the continuous accumulation of the materials in the reaction kettle, and the feeding reaction is stopped.
Although the present invention has been described with reference to the specific embodiments, it should be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.
Claims (10)
1. The method for producing the dimethyl carbonate is characterized by comprising the following steps of:
(1) in the presence of a catalyst, into a reaction vessel:
continuously adding urea; the mass flow rate of urea and the volume ratio of the reaction container are as follows: 200-300 kg/h: 2m3；
Adding dihydric alcohol, stirring, and performing reflux reaction; the flow rate of the dihydric alcohol is 1.4 to 1.6 times of the mass flow rate of the urea, and the adding time of the dihydric alcohol is 1 hour 20 minutes to 1 hour 40 minutes;
after the addition of the dihydric alcohol is stopped, adding methanol solution of sodium methoxide, stirring, and carrying out reflux reaction; when the mass of the sodium methoxide in the reaction liquid is 1-2% of the mass of the urea, stopping adding the methanol liquid of the sodium methoxide and stopping the reflux reaction; the mass content of sodium methoxide in the methanol solution of sodium methoxide is 1-3%, and the flow rate of the methanol solution of sodium methoxide is 1-1.2 times of the mass flow rate of urea;
after the addition of the methanol solution of sodium methoxide is stopped, continuously adding methanol, stirring and collecting steam; the flow rate of the methanol is 1 to 1.2 times of the mass flow rate of the urea;
controlling the temperature of the reaction liquid in the reaction container to be 130-150 ℃ in the whole process of the step (1);
(2) separating ammonia gas and methanol in the steam to obtain the dimethyl carbonate.
2. The process according to claim 1, wherein the flow rate of the glycol is 1.5 to 1.52 times the mass flow rate of the urea.
3. The process according to claim 1, wherein the diol is added for 1.5 hours.
4. The production method according to claim 1, wherein the diol is ethylene glycol or 1, 2-propylene glycol.
5. The production method as claimed in claim 1, wherein the temperature of the reaction liquid in the reaction vessel is 130-134 ℃.
6. The production method according to claim 1, wherein the catalyst is a supported catalyst of magnesium oxide, the carrier material is silicon dioxide, and the mass content of magnesium oxide in the catalyst is 10-15%.
7. The process according to claim 6, wherein the amount of catalyst is 0.1 times the mass of urea added per hour.
8. The production method according to claim 6, wherein an auxiliary is used in combination with the catalyst; the auxiliary agent is dodecyl dimethyl tertiary amine, and the dosage of the auxiliary agent is 0.1 time of that of the catalyst.
9. The process according to claim 1, wherein ammonia gas is separated from the steam by a condensation method and methanol is separated by a water washing method.
10. The production method according to claim 9, wherein the steam is condensed to 0 to 5 ℃, and the gaseous substance and the liquid substance are collected separately; the gaseous substance is ammonia; washing the liquid substance with water, separating to obtain an organic phase and a water phase, drying the organic phase with anhydrous calcium chloride to obtain dimethyl carbonate, and rectifying the water phase and drying the anhydrous calcium chloride to obtain methanol.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1036322A (en) * | 1996-07-19 | 1998-02-10 | Chiyoda Corp | Production of dimethyl carbonate |
| CN106083585A (en) * | 2016-06-21 | 2016-11-09 | 太仓市东明化工有限公司 | A kind of method that dimethyl carbonate is prepared in indirect alcoholysis |
| CN106478421A (en) * | 2015-08-31 | 2017-03-08 | 亚申科技研发中心（上海）有限公司 | DMC Processes |
| CN106866421A (en) * | 2017-01-17 | 2017-06-20 | 山东德普化工科技有限公司 | A kind of method of utilization producing dimethyl carbonate by alcoholysis of urea |
| CN107353207A (en) * | 2017-08-21 | 2017-11-17 | 中石化上海工程有限公司 | A kind of method and its system of urea two-step method production dimethyl carbonate |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1036322A (en) * | 1996-07-19 | 1998-02-10 | Chiyoda Corp | Production of dimethyl carbonate |
| CN106478421A (en) * | 2015-08-31 | 2017-03-08 | 亚申科技研发中心（上海）有限公司 | DMC Processes |
| CN106083585A (en) * | 2016-06-21 | 2016-11-09 | 太仓市东明化工有限公司 | A kind of method that dimethyl carbonate is prepared in indirect alcoholysis |
| CN106866421A (en) * | 2017-01-17 | 2017-06-20 | 山东德普化工科技有限公司 | A kind of method of utilization producing dimethyl carbonate by alcoholysis of urea |
| CN107353207A (en) * | 2017-08-21 | 2017-11-17 | 中石化上海工程有限公司 | A kind of method and its system of urea two-step method production dimethyl carbonate |
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