A method and device for recovering caustic pot residue for ethylene carbonate production of ethylene glycol

Abstract

In order to overcome the problems of high recovery price, high energy consumption and low utilization rate of the existing kettle residue for the production of ethylene glycol by ethylene carbonate alcoholysis method, the application provides a kettle residue recovery method and device for the production of ethylene glycol by ethylene carbonate alcoholysis method, and the application provides a kettle residue recovery method for the production of ethylene glycol by ethylene carbonate, which comprises the following steps: under the conditions of temperature 150-250 DEG C and pressure 0.6-2 MPa, the ethylene glycol in the kettle residue produced by the preparation of ethylene glycol by ethylene carbonate alcoholysis method is converted into diethylene glycol under the catalysis of alkali metal salt catalyst, and after the reaction is completed, the kettle residue is a mixture of ethylene glycol, diethylene glycol, triethylene glycol and salt, the mixture is purified, and ethylene glycol and diethylene glycol are recovered; the economic benefit is improved, the rectification separation operation is simplified, the equipment investment and the overall energy consumption are reduced, and the utilization rate of ethylene glycol kettle residue is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ethylene carbonate preparing ethylene glycol, and particularly relates to a kettle residue recovery method and device for preparing ethylene glycol from ethylene carbonate. BACKGROUND

[0002] Ethylene glycol is widely used in the fields of synthetic polyester, explosives, resins, refrigerants and the like, and is an important chemical raw material. The industrial preparation of ethylene glycol is usually performed by METEOR process (direct pressurized water and method), OMEGA process (ethylene carbonate hydrolysis method) and ethylene carbonate alcoholysis process. The ethylene carbonate alcoholysis process has the following three advantages over the METEOR and OMEGA processes: 1. The water consumption is greatly reduced, avoiding the consumption of a large amount of water from the absorption of gaseous ethylene oxide (EO) and the separation of ethylene glycol (EG), thereby reducing energy consumption; 2. The material consumption and energy consumption are low, the equipment investment is low, and the discharge of "three wastes" is small; 3. Ethylene glycol is produced while a high-value-added product DMC that is widely used in lithium ion electrolyte is also produced, and the atomic utilization is 100%. The reaction principle is as follows:

[0003]

[0004] Due to the high ethylene oxide (EO) conversion rate, clean production process, high ethylene glycol (EG) selectivity, widely available raw materials of carbon dioxide and methanol, and the product dimethyl carbonate (DMC) being a new type of environmentally friendly green basic chemical raw material with very wide application, the ethylene carbonate alcoholysis method is a production process route with great development potential, and the ethylene carbonate alcoholysis method has been increasingly applied to the industrial synthesis of ethylene glycol.

[0005] In the production of ethylene glycol by the ethylene carbonate alcoholysis method, the kettle residue contains polyols such as ethylene glycol, diethylene glycol and triethylene glycol, and various organic and inorganic salts and other impurities that continuously enrich, increasing the difficulty of the post-treatment of the kettle residue. Ethylene glycol is the target product of production, and diethylene glycol can be used as a solvent for nitric acid fiber, rubber, resin, paint and the like. Both of these two substances have great added value.

[0006] Until now, most of the ethylene glycol production stillage is burned as fuel, and a small amount of stillage is landfilled as waste, which not only wastes resources, but also pollutes the environment. A small number of manufacturers recover ethylene glycol stillage and mix it with other chemicals to form high-value additives such as water-reducing agents, solvents, rubber softeners, scale inhibitors, corrosion inhibitors, etc. The price of stillage recovery is low, and the economic benefit is poor. In order to maximize the economic benefit of recovering ethylene glycol, diethylene glycol, etc. from stillage, some distillation devices are also developed for single material recovery, such as Chinese patent CN102010294A which uses a four-stage distillation column to obtain commercial ethylene glycol, diethylene glycol, triethylene glycol, etc. The overall process of this invention is simple, and the utilization rate of ethylene glycol stillage is improved, but the equipment is more, the land occupation is large, the one-time investment is large, the overall energy consumption is high, and the economic benefit is poor. SUMMARY

[0007] In view of the problems of high recovery price, high recovery energy consumption and low utilization rate of stillage in the production of ethylene glycol by ethylene carbonate alcoholysis method, the present application provides a stillage recovery method and device for preparing ethylene glycol by ethylene carbonate alcoholysis method, which uses the alkaline substances contained in the stillage itself as catalyst to convert most of the ethylene glycol in the stillage into diethylene glycol, simplifies the distillation separation operation, reduces the equipment investment and overall energy consumption, and improves the utilization rate and economic benefit of ethylene glycol stillage.

[0008] The technical solution adopted by the present application to solve the above technical problems is as follows:

[0009] On the one hand, the present application provides a stillage recovery method for preparing ethylene glycol from ethylene carbonate, which comprises the following steps:

[0010] Under the conditions of temperature 150℃-250℃ and pressure 0.6MPa-2MPa, the ethylene glycol in the stillage produced by the preparation of ethylene glycol from ethylene carbonate alcoholysis is converted into diethylene glycol under the catalysis of alkali metal salt catalyst. After the reaction is completed, the stillage is a mixture of ethylene glycol, diethylene glycol, triethylene glycol and salt. The mixture is purified to recover ethylene glycol and diethylene glycol.

[0011] Preferably, in the step of purifying the mixture to recover ethylene glycol and diethylene glycol, the following steps are further included:

[0012] The mixture is introduced into a distillation column from a high-pressure reaction kettle, the distillation pressure is 10KPa-50KPa, the column top temperature is 145℃-185℃, the column bottom temperature is 185℃-220℃, and the front fraction material is collected at the column top;

[0013] After the top of the column to collect the front-end fraction material ends, adjust the pressure in the rectifying column to 0-10KPa, the top temperature 165-195℃, the bottom temperature 200-260℃, collect the transition fraction material; after the transition fraction material collection is completed, control the bottom temperature 210-270℃, the top temperature 165-220℃, the pressure unchanged, collect the rear-end fraction material.

[0014] Preferably, in the step of collecting the front-end fraction material, the top discharge flow rate is 20-100kg / h,

[0015] The top discharge flow rate is less than 20kg / h, and the collecting the front-end fraction material ends.

[0016] Preferably, the transition fraction material collection time is 1-2h.

[0017] Preferably, the ethylene glycol in the kettle residue produced by the ethylene carbonate alcoholysis method under the conditions of temperature 200-250℃ and pressure 1.0-2.0MPa is converted into diethylene glycol under the catalysis of an alkali metal salt catalyst.

[0018] Preferably, the reaction time of the ethylene glycol converted into diethylene glycol under the catalysis of the alkali metal salt catalyst is 2-5h.

[0019] Preferably, the alkali metal salt catalyst comprises one or more of an organic alkali metal salt or an inorganic alkali metal salt, the inorganic alkali metal salt comprises at least one of an alkali metal carbonate and an alkali metal bicarbonate, and the organic alkali metal salt comprises an alkali metal salt of an alcohol.

[0020] Preferably, when the conversion rate of the ethylene glycol converted into diethylene glycol under the catalysis of the alkali metal salt catalyst is >70%, the mixture is purified.

[0021] In the second aspect, the application provides a kettle residue recovery device for preparing ethylene glycol from ethylene carbonate, comprising a high-pressure reaction kettle and a rectifying device, the rectifying device comprising a rectifying column, a front-end fraction tank, a transition fraction tank, a rear-end fraction tank and a kettle residue receiving tank, one end of the rectifying column being connected with the reaction kettle, the top of the rectifying column being connected with the front-end fraction tank, the transition fraction tank and the rear-end fraction tank respectively, and the bottom of the rectifying column being connected with the kettle residue receiving tank.

[0022] Preferably, the device further comprises a kettle residue receiving tank, and the bottom of the rectifying column is connected with the kettle residue receiving tank.

[0023] The application provides a recovery method of ethylene carbonate preparation ethylene glycol still residue, which utilizes alkali metal salt contained in the ethylene glycol still residue as a catalyst to convert most of the ethylene glycol in the still residue into diethylene glycol under the conditions of a temperature of 150-250 DEG C and a pressure of 0.6-2 MPa, and then purifies a mixture containing ethylene glycol, diethylene glycol, triethylene glycol and salt by distillation to recover ethylene glycol and diethylene glycol. Compared with the prior art, the recovery method provided by the application does not need to add a catalyst, utilizes a chemical reaction to convert most of the ethylene glycol in the still residue into diethylene glycol with a higher selling price, greatly increases the amount of diethylene glycol in the recovered product, and the total recovery rate of ethylene glycol and diethylene glycol reaches more than 80%, thereby improving the economic benefits of the application; meanwhile, the recovery method simplifies the distillation separation operation, reduces the equipment investment and overall energy consumption, and improves the utilization rate of the ethylene glycol still residue. DETAILED DESCRIPTION

[0024] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, the present application will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0025] The present application provides a recovery method of ethylene carbonate preparation ethylene glycol still residue, which comprises the following steps:

[0026] Under the conditions of a temperature of 150-250 DEG C and a pressure of 0.6-2 MPa, the ethylene glycol in the still residue produced by the ethylene carbonate alcoholysis method for preparing ethylene glycol is converted into diethylene glycol under the catalysis of an alkali metal salt catalyst, and a mixture of ethylene glycol, diethylene glycol, triethylene glycol and salt is obtained after the reaction is completed, and then the mixture is purified to recover ethylene glycol and diethylene glycol.

[0027] The recovery method of ethylene carbonate preparation ethylene glycol still residue provided by the application utilizes alkali metal salt contained in the still residue as a catalyst to convert most of the ethylene glycol in the still residue into diethylene glycol under the conditions of a temperature of 150-250 DEG C and a pressure of 0.6-2 MPa, and then purifies a mixture containing ethylene glycol, diethylene glycol, triethylene glycol and salt by distillation to recover ethylene glycol and diethylene glycol. Compared with the prior art, the recovery method provided by the application does not need to add a catalyst, utilizes a chemical reaction to convert most of the ethylene glycol in the still residue into diethylene glycol with a higher selling price, greatly increases the amount of diethylene glycol in the recovered product, and the total recovery rate of ethylene glycol and diethylene glycol reaches more than 80%, thereby improving the economic benefits of the application (according to the market price in April 2023, the market price of ethylene glycol is 4080-4200 yuan / ton, and the market price of diethylene glycol is 7600-7900 yuan / ton); meanwhile, the recovery method simplifies the distillation separation operation, reduces the equipment investment and overall energy consumption, and improves the utilization rate of the ethylene glycol still residue.

[0028] Specifically, the ethylene glycol in the still residue generated in the preparation of ethylene glycol by ethylene carbonate alcoholysis is converted into diethylene glycol under the catalysis of an alkali metal salt catalyst, at a temperature of 150-250°C and a pressure of 0.6-2 MPa. If the reaction temperature is lower than 150°C, the ethylene glycol does not react or the conversion rate of the ethylene glycol is low; if the temperature is too high, the volatilization rate of the ethylene glycol is high and the conversion rate of the ethylene glycol is low. If the reaction pressure is lower than 0.6 MPa, the conversion rate of the ethylene glycol is low; if the reaction pressure is higher than 2 MPa, the pressure is too high, the energy consumption increases, the catalysis of the catalyst is reduced, and the reaction rate is reduced. The reaction temperature may be, for example, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, or the like, as long as the reaction temperature is within the range of 150-250°C. The pressure may be, for example, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1.0 MPa, 1.1 MPa, 1.2 MPa, 1.5 MPa, 1.6 MPa, 1.8 MPa, 1.9 MPa, 2.0 MPa, or the like, as long as the pressure is within the range of 0.6-2 MPa.

[0029] In some preferred embodiments, the ethylene glycol in the still residue generated in the preparation of ethylene glycol by ethylene carbonate alcoholysis is converted into diethylene glycol under the catalysis of an alkali metal salt catalyst, at a temperature of 200-250°C and a pressure of 1.0-2.0 MPa.

[0030] Within the above temperature and pressure ranges, a large amount of ethylene glycol in the still residue can be converted into diethylene glycol under low energy consumption.

[0031] In some embodiments, the reaction time for the conversion of the ethylene glycol into diethylene glycol under the catalysis of the alkali metal salt catalyst is 2-5 h.

[0032] The reaction time is controlled within the range of 2-5 h, which is beneficial to the conversion of a large amount of ethylene glycol in the still residue into diethylene glycol and improves the conversion rate of the ethylene glycol. Specifically, the reaction time may be, for example, 2 h, 2.5 h, 3.0 h, 3.5 h, 4.0 h, 4.5 h, 5.0 h, or the like, as long as the reaction time is controlled within the range of 2-5 h. It can be understood that the reaction for the conversion of the ethylene glycol in the still residue generated in the preparation of ethylene glycol by ethylene carbonate alcoholysis into diethylene glycol under the catalysis of the alkali metal salt catalyst can be performed in a high-pressure reaction kettle or in other reactors.

[0033] The purification of the mixture can be performed by, for example, rectification, distillation, or the like, and the present application preferably uses rectification.

[0034] In some embodiments, the step of purifying the mixture to recover the ethylene glycol and diethylene glycol specifically comprises the following steps:

[0035] The mixture is transferred from the high-pressure reactor into the rectification tower, the rectification pressure is 10-50 KPa, the tower top temperature is 145-185℃, the tower bottom temperature is 185-220℃, and the front fraction material is collected at the tower top;

[0036] After the front fraction material is collected, the rectification tower pressure is adjusted to 0-10 KPa, the tower top temperature is 165-195℃, the tower bottom temperature is 200-260℃, and the transition fraction material is collected; after the transition fraction material is collected, the tower bottom temperature is controlled to 210-270℃, the tower top temperature is 165-220℃, the pressure is unchanged, and the rear fraction material is collected.

[0037] The mixture is transferred into the rectification tower, the rectification tower pressure is controlled to 10-50 KPa, the tower top temperature is controlled to 145-185℃, and the tower bottom temperature is controlled to 185-220℃, the ethylene glycol is volatilized, and the front fraction material containing a large amount of ethylene glycol is collected at the tower top, so as to realize the purification and separation of ethylene glycol; if the tower bottom temperature is lower than 185℃, the ethylene glycol volatilization rate is low, and the ethylene glycol recovery rate is low; if the tower bottom temperature is higher than 220℃, the diethylene glycol is volatilized, and the ethylene glycol purity of the front fraction material is reduced; if the tower top temperature is lower than 145℃, the ethylene glycol volatilization rate is low, and the ethylene glycol yield collected at the tower top is reduced; if the tower top temperature is higher than 185℃, the diethylene glycol is volatilized, the diethylene glycol content in the front fraction material collected at the tower top is high, and the ethylene glycol purity is reduced.

[0038] The ethylene glycol and diethylene glycol mixture contained in the transition fraction material is volatilized, the tower top and tower bottom temperature and pressure are adjusted, the diethylene glycol is volatilized, and the rear fraction material containing a large amount of diethylene glycol is collected, so as to realize the purification and separation of diethylene glycol; after the front fraction material is collected at the tower top, if the tower bottom temperature is lower than 200℃, the ethylene glycol cannot be completely volatilized; if the tower bottom temperature is higher than 260℃, the diethylene glycol is volatilized, and the diethylene glycol recovery rate is reduced.

[0039] After the transition fraction material is collected, if the tower bottom temperature is too low, the diethylene glycol volatilization rate is low, and the diethylene glycol yield is reduced; if the tower bottom temperature is too high, the triethylene glycol is volatilized, and the diethylene glycol purity in the rear fraction material collected is reduced.

[0040] In the rear fraction material collection step, after the comprehensive yield of ethylene glycol and diethylene glycol is 80-90%, the heating is stopped, or the diethylene glycol product is collected, and the rectification is stopped when the discharge flow rate is less than 10 kg / h; at the same time, the material at the tower bottom is discharged and discarded while being hot.

[0041] The ethylene glycol is converted into diethylene glycol, the ethylene glycol is separated and purified first, the diethylene glycol is separated last, and the comprehensive yield of ethylene glycol and diethylene glycol is improved.

[0042] In some embodiments, the top collecting the forefraction material step, the top discharge flow rate is 20-100 kg / h; the forefraction material flow is less than 20 kg / h, and the top collecting the forefraction material ends. When the top discharge flow rate is in this range, the material flow rate is high, and the separation and extraction efficiency is improved.

[0043] In order to improve the purity of the collected ethylene glycol, the top discharge flow rate is reduced to less than 20 kg / h, and the collection of the forefraction material is stopped.

[0044] In some embodiments, the transition fraction material collection time is 1-2 h, and the transition fraction material discharge rate is controlled in the range of 10-20 kg / h. The purpose of controlling the transition fraction material collection time is to realize the complete discharge of ethylene glycol and improve the purity of recovered diethylene glycol.

[0045] In some embodiments, the mass content of ethylene glycol in the forefraction material is 99.5-99.9%, and the mass content of diethylene glycol is 0.01-0.5%.

[0046] In the forefraction material, the mass content of ethylene glycol is more than 99.5%, and the purity of ethylene glycol is high.

[0047] In some embodiments, after the collection of the forefraction material ends, in the bottom, the mass content of diethylene glycol is 5-10%, the mass content of triethylene glycol is 1-5%, and the mass content of salt is 85-90%.

[0048] There is no ethylene glycol in the bottom, and the content of diethylene glycol is between 5% and 10%, indicating that the recovery rate of ethylene glycol and diethylene glycol in the kettle residue for preparing ethylene carbonate is high. The salt contains an alkali metal salt catalyst.

[0049] In some embodiments, in the kettle residue generated in the ethylene carbonate alcoholysis method for preparing ethylene glycol, the mass content of ethylene glycol is 40-65%, the mass content of diethylene glycol is 25-45%, the mass content of triethylene glycol is 0.1-0.5%, and the mass content of salt is 5-10%.

[0050] In some embodiments, the alkali metal salt catalyst includes one or more of an organic alkali metal salt or an inorganic alkali metal salt, the inorganic alkali metal salt includes at least one of an alkali metal carbonate and an alkali metal bicarbonate, and the organic alkali metal salt includes an alkali metal salt of an alcohol.

[0051] The alkali metal includes at least one of lithium, sodium, potassium, rubidium, cesium, and francium. The preferred alkali metal in the present application is sodium.

[0052] In some embodiments, the alkali metal salt catalyst includes one or more of sodium oxide, sodium hydroxide, a carbonate, sodium methoxide, and sodium ethoxide.

[0053] In some embodiments, when the conversion rate of ethylene glycol is greater than 70% during the conversion of ethylene glycol into diethylene glycol under the catalysis of the alkali metal salt catalyst, the mixture is purified

[0054] The present application controls the conversion rate of ethylene glycol to be greater than 70%, so that most of the ethylene glycol is converted into diethylene glycol, the conversion rate of ethylene glycol is high, and more diethylene glycol is recovered, thereby increasing the recovery benefit.

[0055] In some embodiments, in the mixture, the mass content of ethylene glycol is 5-15%, the mass content of diethylene glycol is 55-75%, the mass content of triethylene glycol is 0.2-1%, and the mass content of salt is 5-10%.

[0056] Specifically, the still residue generated during the preparation of ethylene glycol by alcoholysis of vinyl carbonate is subjected to a reaction under the catalysis of an alkali metal salt catalyst at a temperature of 150-250°C and a pressure of 0.6-2 MPa, so that ethylene glycol is converted into diethylene glycol, and the reaction is ended when the conversion rate of ethylene glycol is controlled to be greater than 70%. Then, the mixture of ethylene glycol, diethylene glycol, triethylene glycol and salt is subjected to rectification and purification.

[0057] In the mixture, the mass content of ethylene glycol is 5-15%, and the content of diethylene glycol is 55-75%, which indicates that most of the ethylene glycol has been converted into diethylene glycol.

[0058] In the second aspect, the present application provides a still residue recovery device for preparing ethylene glycol from vinyl carbonate, which comprises a high-pressure reaction kettle and a rectification device. The rectification device comprises a rectification tower, a front fraction tank, a transition fraction tank, a rear fraction tank and a still residue receiving tank. One end of the rectification tower is connected with the reaction kettle, and the top of the rectification tower is connected with the front fraction tank, the transition fraction tank and the rear fraction tank, respectively. The bottom of the rectification tower is connected with the still residue receiving tank.

[0059] Specifically, the reaction of ethylene glycol into diethylene glycol under the catalysis of an alkali metal salt catalyst is carried out in a high-pressure reaction kettle. The high-pressure reaction kettle is connected with the rectification tower, so that the mixture containing ethylene glycol, diethylene glycol, triethylene glycol and salt can enter the rectification tower in the rectification device after the reaction of ethylene glycol is ended, and then be subjected to rectification and purification to recover ethylene glycol and diethylene glycol. The top of the rectification tower is connected with the front fraction tank, the transition fraction tank and the rear fraction tank, respectively. The front fraction tank is used to collect front fraction materials, the transition fraction tank is used to collect transition fraction materials, and the rear fraction tank is used to collect rear fraction materials.

[0060] The still residue recovery device for preparing ethylene glycol from vinyl carbonate provided by the present application only needs one high-pressure reaction kettle, one rectification kettle and three fraction collecting tanks, and the reaction process is simple and effective, the equipment investment is small, and the land occupation is small.

[0061] In some embodiments, the device further comprises a pressure pump, and the high-pressure reactor is connected with the rectifying tower through the pressure pump.

[0062] The pressure pump is mainly used for pumping the mixture in the reactor into the rectifying tower.

[0063] The rectifying tower is 15 meters high, and the tower is filled with ceramic structured packing.

[0064] It can be understood that the device can further comprise a plurality of flow rate detectors, at least one flow rate detector is arranged on the pipeline connecting the front fraction tank with the rectifying tower, at least one flow rate detector is arranged on the pipeline connecting the transition fraction tank with the rectifying tower, and at least one flow rate detector is arranged on the pipeline connecting the rear fraction tank with the rectifying tower. At least one flow rate detector is arranged on the pipeline connected with the tower top outlet of the rectifying tower. The flow rate detector can be used to test the flow rate of the material.

[0065] It can be understood that the device can further comprise a control valve, and the control valve is arranged on the pipeline connecting the front fraction tank, the transition fraction tank, and the rear fraction tank with the rectifying tower, so as to realize the separate connection of the rectifying tower with the front fraction tank, or the separate connection of the rectifying tower with the transition fraction tank, or the separate connection of the rectifying tower with the rear fraction tank.

[0066] In some embodiments, the device further comprises a residue receiving tank, and the bottom of the rectifying tower is connected with the residue receiving tank.

[0067] The specific use method of the residue recovery device for preparing ethylene glycol from ethylene carbonate includes the following steps:

[0068] (1) Pump the residue generated in the preparation of ethylene glycol by alcoholysis of ethylene carbonate into a high-pressure reactor, control the temperature at 150-250℃, the pressure at 0.6-2MPa, and convert ethylene glycol into diethylene glycol under the catalysis of alkali metal salt catalyst, and the reaction time is 2-5h.

[0069] (2) After the conversion rate of ethylene glycol in the reaction liquid in step (1) is greater than 70%, the reaction gradually reaches equilibrium, and after the reaction is completed, a mixture of ethylene glycol, diethylene glycol, triethylene glycol, and salt is obtained. Pump the mixture into a rectifying tower for vacuum rectification, the rectification operation pressure is 10-50KPa, the tower top temperature is 145-185℃, the tower bottom temperature is 185-220℃, the tower top discharge flow rate is controlled at 20-100kg / h, and the front fraction ethylene glycol is collected, so that the main component in the reactor liquid becomes diethylene glycol with higher economic value;

[0070] (3) After the tower top material discharge flow rate is less than 20kg / h, the tower bottom temperature is increased to 200-260℃, the operation pressure is 0-10KPa, the tower top temperature is 165-195℃, and the discharge speed is maintained at 10-20kg / h, and the transition fraction is collected.

[0071] (4) After 1-2h of the transition fraction collection, cut the post-fraction tank, control the tower bottom temperature 210-270℃, the tower top temperature 165-220℃, the pressure unchanged, collect the post-fraction material diethylene glycol.

[0072] After the comprehensive yield of ethylene glycol and diethylene glycol is 80%-90%, stop heating, collect the material obtained from the tower bottom of the rectifying tower into the still residue receiving tank while hot, and then perform barrel filling and scrap.

[0073] The application is further described below through examples.

[0074] Example 1

[0075] This example is used to illustrate the still residue recovery method and device for preparing ethylene glycol from ethylene carbonate disclosed by the application.

[0076] The still residue recovery device for preparing ethylene glycol from ethylene carbonate by alcoholysis method includes a high-pressure reaction kettle, a rectifying tower, a pre-fraction tank, a transition fraction tank, and a post-fraction tank. First, 1000kg of still residue generated by preparing ethylene glycol from ethylene carbonate by alcoholysis method is input into the high-pressure reaction kettle, then heating starts to 200℃, nitrogen is introduced to pressurize the pressure in the kettle to 0.8MPa, reaction is performed for 3h, sampling tests the conversion rate of ethylene glycol in the raw material to be 78.93%, the reaction liquid is pumped into the rectifying tower by a pressure pump for vacuum rectification, the rectification operation pressure is 20KPa, the tower top temperature is 165℃, the tower bottom temperature is 200℃, the discharge flow rate is controlled to be 80kg / h, the rectifying tower top is connected with the pre-fraction tank, and the pre-fraction material ethylene glycol product is collected into the pre-fraction tank.

[0077] After the pre-fraction material flow rate decreases to 20kg / h, the tower bottom temperature is increased to 220℃, the operation pressure is controlled to be 10KPa, the discharge flow rate is controlled to be 20kg / h, the rectifying tower top is connected with the transition fraction tank, the transition fraction tank is cut, and the transition fraction material is collected into the transition fraction tank. After 1h, the tower top temperature is increased to 180℃, the rectifying tower top is connected with the post-fraction tank, the fraction is switched to the post-fraction tank, the post-fraction material diethylene glycol product is collected, and the rectification can be stopped when the discharge flow rate is <10kg / h. Stop heating, when the temperature in the kettle decreases to 100℃, the tower bottom material is discharged into the still residue receiving tank, and the remaining still residue is barrelled while hot.

[0078] The component proportion of each material in Example 1 is as follows:

[0079] The components of the still residue generated by preparing ethylene glycol from ethylene carbonate by alcoholysis method are as follows: the mass content of ethylene glycol is 51.03%, the mass content of diethylene glycol is 38.96%, the mass content of triethylene glycol is 0.31%, and the mass content of salt is 9.7%.

[0080] The components of the mixture are: ethylene glycol mass content 10.75%, diethylene glycol mass content 78.96%, triethylene glycol mass content 0.72%, salt mass content 9.57%;

[0081] The main content of the front fraction material ethylene glycol product is 99.78%, and the mass is 105.2 kg,

[0082] The main content of the front fraction material ethylene glycol product is 99.78%, and the mass is 105.2 kg,

[0083] The total recovery rate of ethylene glycol and diethylene glycol is 84.5%.

[0084] Example 2

[0085] The difference between Example 2 and Example 1 is that the reaction time is different, the conversion rate of ethylene glycol is different, and the rest is the same as Example 1. Specifically, the reaction time in Example 2 is 5h; the conversion rate of ethylene glycol in the sample test raw material is 78.40%.

[0086] The component proportions of each material in Example 2 are as follows:

[0087] The components of the mixture are: ethylene glycol mass content 10.75%, diethylene glycol mass content 78.96%, triethylene glycol mass content 0.72%, salt mass content 9.57%;

[0088] The components of the mixture are: ethylene glycol mass content 10.75%, diethylene glycol mass content 78.96%, triethylene glycol mass content 0.72%, salt mass content 9.57%;

[0089] The main content of the front fraction material ethylene glycol product is 99.66%, and the mass is 108.4 kg,

[0090] The main content of the front fraction material ethylene glycol product is 99.66%, and the mass is 108.4 kg,

[0091] The total recovery rate of ethylene glycol and diethylene glycol is 83.6%.

[0092] Example 3

[0093] The difference between Example 3 and Example 1 is that the reaction temperature in the reaction kettle is different, the conversion rate of ethylene glycol is different, and the rest is the same as Example 1. Specifically, the reaction temperature in Example 3 is 160℃; the conversion rate of ethylene glycol in the sample test raw material is 73.01%.

[0094] The component proportions of each material in Example 3 are as follows:

[0095] The components of the kettle residue produced by the above-mentioned ethylene carbonate alcoholysis method for preparing ethylene glycol are: ethylene glycol mass content 51.03%, diethylene glycol mass content 38.96%, triethylene glycol mass content 0.31%, and salt mass content 9.7%.

[0096] The components of the mixture are: ethylene glycol mass content 13.77%, diethylene glycol mass content 75.46%, triethylene glycol mass content 0.84%, and salt mass content 9.93%;

[0097] The main content of the front fraction material ethylene glycol product is: 99.55%, and the mass is 137 kg,

[0098] The main content of the front fraction material ethylene glycol product is: 99.55%, and the mass is 137 kg,

[0099] The total recovery rate of ethylene glycol and diethylene glycol is 82.2%.

[0100] Example 4

[0101] The difference between Example 4 and Example 1 is that the reaction temperature in the reaction kettle is different, the conversion rate of ethylene glycol is different, and the rest is the same as Example 1. Specifically, the reaction temperature in Example 4 is 180°C; the conversion rate of ethylene glycol in the sample test raw material is 76.11%.

[0102] The components of each material in Example 4 are as follows:

[0103] The components of the kettle residue produced by the above-mentioned ethylene carbonate alcoholysis method for preparing ethylene glycol are: ethylene glycol mass content 51.03%, diethylene glycol mass content 38.96%, triethylene glycol mass content 0.31%, and salt mass content 9.7%.

[0104] The components of the mixture are: ethylene glycol mass content 12.19%, diethylene glycol mass content 76.33%, triethylene glycol mass content 1.56%, and salt mass content 9.92%;

[0105] The main content of the front fraction material ethylene glycol product is: 99.65%, and the mass is 122.4 kg,

[0106] The main content of the front fraction material ethylene glycol product is: 99.65%, and the mass is 122.4 kg,

[0107] The total recovery rate of ethylene glycol and diethylene glycol is 83.0%.

[0108] Example 5

[0109] The difference between Example 5 and Example 1 is that the reaction temperature in the reaction kettle is different, the conversion rate of ethylene glycol is different, and the rest is the same as Example 1. Specifically, the reaction temperature in Example 5 is 240°C; the conversion rate of ethylene glycol in the sample test raw material is 86.03%.

[0110] The component proportions of each material in Example 5 are as follows:

[0111] The components of the still residue produced by the above-mentioned ethylene carbonate alcoholysis method for preparing ethylene glycol are: ethylene glycol mass content 51.03%, diethylene glycol mass content 38.96%, triethylene glycol mass content 0.31%, and salt mass content 9.7%.

[0112] The components of the mixture are: ethylene glycol mass content 7.13%, diethylene glycol mass content 82.20%, triethylene glycol mass content 0.89%, and salt mass content 9.78%;

[0113] The main content of the ethylene glycol product of the front fraction material is: 99.70%, mass 71.2 kg,

[0114] The main content of the diethylene glycol product of the rear fraction material is: 99.83%, mass 809.4 kg,

[0115] The total recovery rate of ethylene glycol and diethylene glycol is 87.9%.

[0116] Example 6

[0117] The difference between Example 6 and Example 1 is that the pressure conditions in the reaction kettle are different, and the conversion rate of ethylene glycol is different, and the rest is the same as Example 1. Specifically: in Example 6, the pressure in the kettle is increased to 1.2 MPa by passing nitrogen; the conversion rate of ethylene glycol in the raw material is 80.70% by sampling test.

[0118] The component proportions of each material in Example 6 are as follows:

[0119] The components of the still residue produced by the above-mentioned ethylene carbonate alcoholysis method for preparing ethylene glycol are: ethylene glycol mass content 51.03%, diethylene glycol mass content 38.96%, triethylene glycol mass content 0.31%, and salt mass content 9.7%.

[0120] The components of the mixture are: ethylene glycol mass content 9.85%, diethylene glycol mass content 80.11%, triethylene glycol mass content 0.54%, and salt mass content 9.50%;

[0121] The main content of the ethylene glycol product of the front fraction material is: 99.83%, mass 98.0 kg,

[0122] The main content of the diethylene glycol product of the rear fraction material is: 99.69%, mass 716.6 kg,

[0123] The total recovery rate of ethylene glycol and diethylene glycol is 85.7%.

[0124] Example 7

[0125] The difference between Example 7 and Example 1 is that the pressure condition in the reaction kettle is different, the conversion rate of ethylene glycol is different, and the rest is the same as Example 1. Specifically, in Example 7, the pressure in the kettle is pressurized to 2.0 MPa by passing nitrogen; the conversion rate of ethylene glycol in the raw material is 80.59%.

[0126] The component ratio of each material in Example 7 is as follows:

[0127] The kettle residue generated by the above ethylene carbonate alcoholysis method for preparing ethylene glycol is: ethylene glycol mass content 51.03%, diethylene glycol mass content 38.96%, triethylene glycol mass content 0.31%, salt mass content 9.7%.

[0128] The components of the mixture are: ethylene glycol mass content 9.90%, diethylene glycol mass content 79.21%, triethylene glycol mass content 0.77%, salt mass content 10.12%;

[0129] The main content of the front fraction material ethylene glycol product is: 99.58%, mass 99.4 kg,

[0130] The main content of the diethylene glycol product of the rear fraction material is: 99.70%, mass 766.3 kg,

[0131] The total recovery rate of ethylene glycol and diethylene glycol is 86.3%.

[0132] Example 8

[0133] The difference between Example 8 and Example 1 is that the reaction time is different, the conversion rate of ethylene glycol is different, and the rest is the same as Example 1. Specifically, the reaction time in Comparative Example 1 is 1.5 h; the conversion rate of ethylene glycol in the raw material is 40.82%.

[0134] The component ratio of each material in Example 8 is as follows:

[0135] The kettle residue generated by the above ethylene carbonate alcoholysis method for preparing ethylene glycol is: ethylene glycol mass content 51.03%, diethylene glycol mass content 38.96%, triethylene glycol mass content 0.31%, salt mass content 9.7%.

[0136] The components of the mixture are: ethylene glycol mass content 30.20%, diethylene glycol mass content 60.49%, triethylene glycol mass content 0.28%, salt mass content 9.03%;

[0137] The main content of the front fraction material ethylene glycol product is: 99.79%, mass 208.7 kg,

[0138] The main content of the diethylene glycol product of the rear fraction material is: 99.63%, mass 644.3 kg,

[0139] The total recovery rate of ethylene glycol and diethylene glycol is 85.0%.

[0140] Example 9

[0141] The difference between Example 9 and Example 1 is that the reaction time is different, the conversion rate of ethylene glycol is different, and the rest is the same as Example 1. Specifically, the reaction time in Comparative Example 1 is 5.5h; the conversion rate of ethylene glycol in the raw material is 76.8%.

[0142] The component proportions of each material in Example 9 are as follows:

[0143] The components of the still residue generated by the above ethylene carbonate alcoholysis method for preparing ethylene glycol are: ethylene glycol mass content 51.03%, diethylene glycol mass content 38.96%, triethylene glycol mass content 0.31%, and salt mass content 9.7%.

[0144] The components of the mixture are: ethylene glycol mass content 11.82%, diethylene glycol mass content 78.33%, triethylene glycol mass content 0.55%, and salt mass content 9.30%;

[0145] The main content of the front fraction material ethylene glycol product is: 99.58%, mass 118kg,

[0146] The main content of the front fraction material diethylene glycol product is: 99.66%, mass 696.9kg,

[0147] The total recovery rate of ethylene glycol and diethylene glycol is 81.3%.

[0148] Example 10

[0149] The difference between Example 10 and Example 1 is that the reaction time is different, the conversion rate of ethylene glycol is different, and the rest is the same as Example 1. Specifically, the reaction time in Example 10 is 2h; the conversion rate of ethylene glycol in the raw material is 74.7%.

[0150] The component proportions of each material in Example 10 are as follows:

[0151] The components of the still residue generated by the above ethylene carbonate alcoholysis method for preparing ethylene glycol are: ethylene glycol mass content 51.03%, diethylene glycol mass content 38.96%, triethylene glycol mass content 0.31%, and salt mass content 9.7%.

[0152] The components of the mixture are: ethylene glycol mass content 12.8%, diethylene glycol mass content 76.8%, triethylene glycol mass content 0.78%, and salt mass content 9.62%;

[0153] The main content of the front fraction material ethylene glycol product is: 99.57%, mass 126.3kg,

[0154] The main content of the product of the second fraction material diethylene glycol is 99.72%, and the mass is 708.6 kg,

[0155] The total recovery rate of ethylene glycol and diethylene glycol is 83.2%.

[0156] Comparative Example 1

[0157] The difference between Comparative Example 1 and Example 1 is that the reaction temperature in the reaction kettle is different, and the conversion rate of ethylene glycol is different. The rest is the same as Example 1. Specifically, the reaction temperature in Comparative Example 1 is 130°C; the conversion rate of ethylene glycol in the sample test raw material is 25.04%.

[0158] The component proportions of each material in Comparative Example 1 are as follows:

[0159] The kettle residue components generated by the above ethylene carbonate alcoholysis method for preparing ethylene glycol are: ethylene glycol mass content 51.03%, diethylene glycol mass content 38.96%, triethylene glycol mass content 0.31%, and salt mass content 9.7%.

[0160] The components of the mixture are: ethylene glycol mass content 38.25%, diethylene glycol mass content 52.07%, triethylene glycol mass content 0.41%, and salt mass content 9.27%;

[0161] The main content of the product of the second fraction material diethylene glycol is 99.46%, and the mass is 502.7 kg,

[0162] The main content of the product of the second fraction material diethylene glycol is 99.46%, and the mass is 502.7 kg,

[0163] The total recovery rate of ethylene glycol and diethylene glycol is 85.60%.

[0164] Comparative Example 2

[0165] The difference between Comparative Example 2 and Example 1 is that the reaction temperature in the reaction kettle is different, and the conversion rate of ethylene glycol is different. The rest is the same as Example 1. Specifically, the reaction temperature in Comparative Example 2 is 280°C; the conversion rate of ethylene glycol in the sample test raw material is 75.97%.

[0166] The component proportions of each material in Comparative Example 2 are as follows:

[0167] The kettle residue components generated by the above ethylene carbonate alcoholysis method for preparing ethylene glycol are: ethylene glycol mass content 51.03%, diethylene glycol mass content 38.96%, triethylene glycol mass content 0.31%, and salt mass content 9.7%.

[0168] The components of the mixture are: ethylene glycol mass content 12.26%, diethylene glycol mass content 77.81%, triethylene glycol mass content 0.39%, and salt mass content 9.54%;

[0169] The main content of the front fraction material ethylene glycol product is 99.63%, and the mass is 123.5 kg,

[0170] The main content of the front fraction material ethylene glycol product is 99.63%, and the mass is 123.5 kg,

[0171] The total recovery rate of ethylene glycol and diethylene glycol is 79.9%.

[0172] Comparative Example 3

[0173] The difference between Comparative Example 3 and Example 1 is that the pressure conditions in the reaction kettle are different, and the conversion rate of ethylene glycol is different. The rest is the same as Example 1. Specifically, in Comparative Example 3, nitrogen is introduced to pressurize the kettle to 0.5 MPa; the conversion rate of ethylene glycol in the sample is 69.51%.

[0174] The composition of each material in Comparative Example 3 is as follows:

[0175] The kettle residue generated by the above ethylene carbonate alcoholysis method for preparing ethylene glycol is composed of ethylene glycol with a mass content of 51.03%, diethylene glycol with a mass content of 38.96%, triethylene glycol with a mass content of 0.31%, and salt with a mass content of 9.7%.

[0176] The composition of each material in Comparative Example 3 is as follows:

[0177] The main content of the front fraction material ethylene glycol product is 99.63%, and the mass is 123.5 kg,

[0178] The main content of the front fraction material ethylene glycol product is 99.63%, and the mass is 123.5 kg,

[0179] The total recovery rate of ethylene glycol and diethylene glycol is 79.9%.

[0180] Comparative Example 4

[0181] The difference between Comparative Example 4 and Example 1 is that the pressure conditions in the reaction kettle are different, and the conversion rate of ethylene glycol is different. The rest is the same as Example 1. Specifically, in Comparative Example 4, nitrogen is introduced to pressurize the kettle to 2.2 MPa; the conversion rate of ethylene glycol in the sample is 73.54%.

[0182] The composition of each material in Comparative Example 4 is as follows:

[0183] The kettle residue generated by the above ethylene carbonate alcoholysis method for preparing ethylene glycol is composed of ethylene glycol with a mass content of 51.03%, diethylene glycol with a mass content of 38.96%, triethylene glycol with a mass content of 0.31%, and salt with a mass content of 9.7%.

[0184] The components of the mixture were: ethylene glycol mass content 13.51%, diethylene glycol mass content 75.88%, triethylene glycol mass content 0.84%, salt mass content 9.77%;

[0185] The main content of the front fraction material ethylene glycol product was 99.73%, mass 135.4 kg,

[0186] The main content of the front fraction material ethylene glycol product was 99.73%, mass 135.4 kg,

[0187] The total recovery rate of ethylene glycol and diethylene glycol was 80.1%.

[0188] By comparing the above Example 1 and Comparative Examples 1, 2, the reaction temperature of the kettle residue produced by the ethylene carbonate alcoholysis method in Comparative Example 1 is lower than 150℃, the conversion rate of ethylene glycol is only about 25%, the mass content of diethylene glycol in the mixture is low, and the yield of recovered diethylene glycol is low; the reaction temperature in Comparative Example 2 is higher than 250℃, although the conversion rate of ethylene glycol is higher than 70%, the mass content of diethylene glycol in the mixture is low, and the yield of recovered diethylene glycol is low; it is shown that the reaction temperature of the kettle residue produced by the ethylene carbonate alcoholysis method in the presence of the alkali metal salt catalyst is in the range of 150℃-250℃, the conversion rate of ethylene glycol is high, the content of diethylene glycol in the mixture is high, the yield of recovered diethylene glycol is high, and the total recovery rate of ethylene glycol and diethylene glycol is higher than 80%. By comparing Example 1 with Comparative Examples 3-4, the reaction pressure in Comparative Example 3 is lower than 0.6MPa, the conversion rate of ethylene glycol is reduced, the content of diethylene glycol in the mixture is low, and the yield of recovered diethylene glycol is low; the reaction pressure in Comparative Example 4 is higher than 2.0MPa, the mass content of diethylene glycol in the mixture is low, and the content of recovered diethylene glycol is low; it is shown that the reaction pressure of the kettle residue produced by the ethylene carbonate alcoholysis method in the presence of the alkali metal salt catalyst is in the range of 0.6-2.0MPa, the conversion rate of ethylene glycol is high, the content of diethylene glycol in the mixture is high, and the yield of recovered diethylene glycol is high. By comparing Example 1 with Examples 8-9, the reaction time in Example 8 is lower than 2h, the conversion rate of ethylene glycol is low, and the yield of recovered diethylene glycol is low; the reaction time in Example 9 is higher than 5h, the conversion rate of ethylene glycol is slightly lower than that in Example 1; it is shown that the reaction time is in the range of 2-5h, the conversion rate of ethylene glycol is high, the yield of recovered diethylene glycol is high, and the economic benefit is improved. By comparing Examples 1, 2, 10, the reaction time is in the range of 2-5h, the conversion rate of ethylene glycol is relatively high, the yield of recovered diethylene glycol is high, and the economic benefit is improved. By comparing Examples 1, 3-5, the reaction time is in the range of 150-250℃, the higher the reaction temperature, the higher the conversion rate of ethylene glycol, the higher the yield of recovered diethylene glycol, the higher the total recovery rate of ethylene glycol and diethylene glycol, the higher the economic benefit, and the higher the recovery rate of the kettle residue. By comparing Examples 1, 6, 7, the reaction pressure is in the range of 0.6-2.0MPa, the higher the reaction pressure, the higher the conversion rate of ethylene glycol, the higher the yield of recovered diethylene glycol, the higher the total recovery rate of ethylene glycol and diethylene glycol, the higher the economic benefit, and the higher the recovery rate of the kettle residue.

[0189] By comparing the above examples and comparative examples, using the alkali metal salt contained in the kettle residue for preparing ethylene glycol as catalyst, under the conditions of temperature 150-250℃ and pressure 0.6-2MPa, most of the ethylene glycol in the kettle residue is first converted into diethylene glycol, then the mixture containing ethylene glycol, diethylene glycol, triethylene glycol and salt is purified by rectification, and ethylene glycol and diethylene glycol are recovered, more diethylene glycol with higher price can be recovered, the recovery benefit is improved, the rectification separation operation is simple, the energy consumption of the equipment and the whole is reduced, and the recovery cost is reduced.

[0190] The above merely describes preferred embodiments of the present application, but should not be used to restrict the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for recovering residue from the reactor during the preparation of ethylene glycol from ethylene carbonate, characterized in that, Includes the following steps: Under conditions of temperature 150℃~250℃ and pressure 0.6MPa~2MPa, the ethylene glycol in the reactor residue produced by the alcoholysis of ethylene carbonate to ethylene glycol is converted into diethylene glycol under the catalysis of an alkali metal salt catalyst. After the reaction, the reactor residue is a mixture of ethylene glycol, diethylene glycol, triethylene glycol and salt. The mixture is purified to recover ethylene glycol and diethylene glycol. The alkali metal salt catalyst comprises one or more of organic alkali metal salts or inorganic alkali metal salts, wherein the inorganic alkali metal salt comprises at least one of alkali metal carbonates and alkali metal bicarbonates, and the organic alkali metal salt comprises an alkali metal salt of an alcohol; the alkali metal catalyst is derived from reactor residue.

2. The method for recovering residue from the reactor used in the preparation of ethylene glycol from ethylene carbonate according to claim 1, characterized in that, The step of purifying the mixture to recover ethylene glycol and diethylene glycol specifically includes the following steps: The mixture is fed from the high-pressure reactor into a distillation column. The distillation pressure is 10 kPa to 50 kPa, the top temperature is 145°C to 185°C, and the bottom temperature is 185°C to 220°C. The fore-distillate is collected at the top of the column. After the initial distillate is collected at the top of the column, adjust the pressure inside the distillation column to 0~10 kPa, the top temperature to 165℃~195℃, and the bottom temperature to 200℃~260℃, and collect the transition distillate. After the transition distillate is collected, control the bottom temperature to 210~270℃, the top temperature to 165~220℃, and keep the pressure constant, and collect the final distillate.

3. The method for recovering residue from the reactor during the preparation of ethylene glycol from ethylene carbonate according to claim 2, characterized in that, In the step of collecting the pre-distillate material at the top of the column, the top outlet flow rate is 20 kg / h to 100 kg / h. When the top discharge velocity of the tower is less than 20 kg / h, the collection of pre-distillate material ends.

4. The method for recovering residue from the reactor used in the preparation of ethylene glycol from ethylene carbonate according to claim 2, characterized in that, The transition fraction material is collected over a period of 1 to 2 hours.

5. The method for recovering residue from the reactor used in the preparation of ethylene glycol from ethylene carbonate according to claim 1, characterized in that, Ethylene glycol in the reactor residue produced by the alcoholysis of ethylene carbonate to ethylene glycol under the conditions of temperature 200℃~250℃ and pressure 1.0MPa~2.0MPa is converted into diethylene glycol under the catalysis of an alkali metal salt catalyst.

6. The method for recovering residue from the reactor used in the preparation of ethylene glycol from ethylene carbonate according to claim 1, characterized in that, The reaction time for ethylene glycol to be converted into diethylene glycol under the catalysis of alkali metal salt catalyst is 2h~5h.

7. The method for recovering residue from the reactor during the preparation of ethylene glycol from ethylene carbonate according to claim 1, characterized in that, Ethylene glycol is converted into diethylene glycol under the catalysis of an alkali metal salt catalyst. When the conversion rate of ethylene glycol is >70%, the mixture is purified.

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