CN1807381A - Crotonaldehyde production process - Google Patents
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- CN1807381A CN1807381A CN 200610001278 CN200610001278A CN1807381A CN 1807381 A CN1807381 A CN 1807381A CN 200610001278 CN200610001278 CN 200610001278 CN 200610001278 A CN200610001278 A CN 200610001278A CN 1807381 A CN1807381 A CN 1807381A
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Abstract
The related improved preparation technique for crotonaldehyde comprises: condensing the acetaldehyde catalyzed by organic amine to produce 2-hydroxybutyraldehyde; in acid environment, dewatering the former product to obtain the final compound. This invention needs mild reaction condition for control, reduces byproduct, improves yield, and decreases sewage greatly.
Description
Technical Field
The invention relates to a crotonaldehyde production process, in particular to an improved process capable of reducing reaction byproducts and wastewater discharge.
Background
Crotonaldehyde (2-Butenal), commonly known as Crotonaldehyde, is used industrially mainly for the production of sorbic acid, butyraldehyde, butanol, 2-ethylhexanol, crotonic acid, maleic anhydride and other chemicals, and is an important chemical raw material.
The aldol condensation reaction of acetaldehyde under the action of an alkaline catalyst is utilized to generate 2-hydroxybutyraldehyde, and the 2-hydroxybutyraldehyde is heated and dehydrated in an acidic solution to generate butenal, which is known and is also a synthetic route which is currently industrialized, and the chemical reaction process can be represented by the following reaction formula:
the pure butenal is colorless or light yellow liquid, the industrial grade butenal contains over 95% of trans-isomer, and the others are cis-isomer. In the traditional crotonaldehyde production process, inorganic base such as sodium hydroxide or anion exchange resin is mainly used as a catalyst, and aldol condensation reaction is violent and is difficult to control; meanwhile, the byproducts are more, so that the acetaldehyde conversion rate is low; and the high polymer in the by-product is easy to block the tubular heater, so the requirement on equipment is high, and the operation control is complicated. In addition, due to the limitation of equipment structure and process conditions, the energy consumption is high, and the amount of the generated three wastes is also large.
In the current research on the crotonaldehyde production process, the main emphasis is on the improvement of production process parameters and equipment structures. For example, CN1394840A discloses an improved crotonaldehyde production process, which mainly controls acetaldehyde to generate 2-hydroxybutyraldehyde through aldol condensation in a bubble-cap condensation tower, and makes the dehydration of 2-hydroxybutyraldehyde and the initial distillation of unreacted acetaldehyde take place in the dehydration tower at the same time, so as to simplify the structure and shorten the operation process, and the condensation reaction is carried out at 45 ± 3 ℃ and 0.05MPa, the operation is easier to control, and the conversion rate of acetaldehyde can be increased to 65% by using the method. However, in the production process of the butenal, strong alkali sodium hydroxide is still used as a catalyst, in order to avoid severe reaction and increase of byproducts, and in order to reduce the alkaline influence of the sodium hydroxide on a condensation system, water needs to be supplemented simultaneously in the process, and the side reaction is stopped by quickly neutralizing with acetic acid, so that the conversion rate of acetaldehyde in the production is improved to a certain extent, but the cost is that more waste water is generated, and the treatment cost is increased.
Acetaldehyde is used as a main raw material of a condensation reaction, an oxidation product of ethylene is mostly used in production, another factor influencing the production cost of crotonaldehyde is the thickening process of acetaldehyde after oxidation, the existing process is to absorb the acetaldehyde in the oxidation product at normal pressure, the concentration of the obtained acetaldehyde is about8-10%, and the energy consumption of a system is very high while a large amount of wastewater is discharged by rectifying low-concentration acetaldehyde.
The acetaldehyde is prepared by oxidizing ethylene, because ethylene is a downstream product of petroleum, the ethylene is very economical in the period of relatively rich petroleum resources and low price, but with the increasing shortage of global petroleum resources and the great increase of petroleum price, the cost for producing the acetaldehyde by the ethylene is also greatly increased due to the rising of the ethylene price. The utilization of other cheap raw materials, such as ethanol, and the development of a more reasonable and efficient production process have very significant significance in many aspects.
Disclosure of Invention
The invention mainly aims to provide an improved process for producing butenal, which is easy to control reaction conditions in industrial production, and can improve the conversion rate of acetaldehyde and reduce the amount of three wastes.
The invention also provides an optimized process for industrially producing high-purity crotonaldehyde by using ethanol as a raw material.
In order to achieve the purpose, the production process of the crotonaldehyde provided by the invention comprises the steps of condensing acetaldehyde under the catalysis of organic amine to generate 2-hydroxybutyraldehyde, and dehydrating the obtained 2-hydroxybutyraldehyde under an acidic condition to generate the crotonaldehyde.
As described above, the traditional process realizes the aldol condensation reaction under the catalysis of strong base, the invention adopts organic amine to replace the strong base as the catalyst of the aldol condensation, so thatthe condensation reaction process becomes mild and easy to control, and byproducts, particularly high polymers, in the reaction are few, thereby greatly solving the problem of blocking the tubular heater. On the other hand, since the aqueous solution of the organic amine is weak in alkalinity, a large amount of water is not required for dilution in the condensation reaction, thereby reducing the amount of wastewater generated in the condensation reaction. By adopting the process, the yield of the final product, namely the butenal, is also improved by about 3 percent, the conversion rate of the acetaldehyde is actually improved, and the aim of reducing the production cost is fulfilled.
Among the organic amines, trimethylamine or triethylamine is preferable.
According to the process, the condensation reaction can be carried out under the protection of inert gas (such as nitrogen), the reaction temperature is 37-47 ℃, and the pressure in the production process is easy to control, and all parameters are easy to keep stable.
According to the process, the condensation product 2-hydroxy butyraldehyde is dehydrated under an acidic condition to obtain a crotonaldehyde crude product, the dehydration procedure is completed in a dehydration tower, and the 2-hydroxy butyraldehyde and an organic acid can be simultaneously fed into the dehydration tower to enable the 2-hydroxy butyraldehyde solution to be acidic. Preferably, the temperature of the top of the tower is controlled to be 105-112 ℃ and the pressure in the tower is controlled to be 0.20-0.25 MPa.
More preferably, the dehydration reaction of the 2-hydroxybutyraldehyde is controlled and completed by adopting a mode of jointly heating indirect steam and direct steam, which is not only beneficial to adjusting the amount of water in a tower kettle to be kept unchanged, but also can solve the problem of overlarge wastewater discharge caused by direct heating.
Rectifying the crude crotonaldehyde product obtained by the dehydration reaction into a finished product. The rectification process of the process preferably comprises pressure rectification, the pressure rectification product is subjected to normal pressure rectification after being subjected to water separation, and the specific rectification conditions and the control of the rectification tower can be finished according to a conventional method.
Acetaldehyde, which is the main raw material of the reaction, is required to have a purity of not less than 99%, particularly higher than 99.5% in production, and can be obtained from professional production enterprises or synthesized by using appropriate raw materials. As a complete system of industrial production, the production process of the invention can also comprise the steps of taking ethanol or ethylene as a raw material, synthesizing acetaldehyde gas through oxidation reaction, preparing a dilute acetaldehyde solution by reversely spraying and absorbing the generated acetaldehyde gas with water at 5-10 ℃ under the pressure condition of 0.13-0.17 MPa, and enabling the dilute acetaldehyde solution to enter a rectifying tower to be concentrated into the acetaldehyde solution with the purity higher than 99%.
Ethylene is mainly from petroleum processing products, crotonaldehyde is produced by using an ethylene oxidation process, and the production cost of the crotonaldehyde is influenced in the petroleum shortage period, so that ethanol can be used as a raw material in the production process of the invention, the ethylene and hot air react in an oxidation furnace to generate acetaldehyde gas, the reaction temperature in the oxidation furnace is 540-560 ℃, and the oxidation reaction is completed under the catalytic action of a silver catalyst.
One specific embodiment of the presentinvention may be described as follows:
preheating ethanol and air to form mixed gas, sending the mixed gas into an oxidation furnace, carrying out oxidative dehydrogenation reaction when the mixed gas passes through a silver catalyst layer, cooling acetaldehyde gas (high-temperature furnace gas) generated by the reaction, and then absorbing the cooled acetaldehyde gas (high-temperature furnace gas) by reverse spraying with water at the temperature of 5-10 ℃ under the pressure condition of 0.13-0.17 MPa to prepare a dilute acetaldehyde solution, wherein the acetaldehyde concentration can reach 17-20%;
the dilute acetaldehyde solution enters an acetaldehyde rectifying tower, and the finished product acetaldehyde with the purity of 99 percent, particularly more than 99.5 percent is obtained by rectifying by controlling the proper tower internal pressure (such as 0.15-0.25 MPa) and reflux ratio according to the tower plate number of the rectifying tower;
trimethylamine or triethylamine is used as a catalyst, and the trimethylamine or triethylamine and the finished product acetaldehyde are respectively input into a condensation tower (the mass ratio of the catalyst to the acetaldehyde is not less than 0.1 percent, and preferably 0.2 to 0.5 percent), and are indirectly heated by adopting steam under the protection of nitrogen to carry out condensation reaction to generate 2-hydroxybutyraldehyde, the condensation reaction temperature is generally controlled at 37 to 47 ℃, and the pressure of introduced nitrogen is about 0.02MPa (gauge pressure);
2-hydroxy butyraldehyde discharged from the bottom of the condensation tower enters a dehydration tower, organic acid is added at the same time, and the dehydration is carried out under an acidic condition to generate a crotonaldehyde crude product, wherein the temperature of the top of the tower is controlled to be 105-112 ℃, the temperature of a tower kettle is controlled to be 132-137 ℃, and the pressure in the tower is controlled to be 0.20-0.25 MPa in the reaction process;
the butenal crude product is further refined through secondary rectification to obtain a butenal finished product with high purity, preferably, the primary rectification adopts pressurized rectification, the secondary rectification adopts normal-pressure rectification, corrugated plate packing is filled in a rectification tower of the secondary rectification, the separation coefficient is large, the void ratio is high, the filling can be structured, compared with randomly stacked pall ring packing, the packing height can be reduced to 5m from 8-10 m under the same condition, a uniformly distributed groove type distributor is matched and adopted in the rectification tower, and under the premise that the separation effect is obviously improved, the tower height is effectively reduced, the equipment investment is reduced, and the consumption of heating steam is further reduced.
In the above process, the high temperature furnace gas formed after ethanol oxidation can be used for heating water to generate low pressure water vapor, the water vapor can be used for preheating the raw material ethanol and gasifying the ethanol, and the high temperature furnace gas is cooled for the first time, thereby realizing the recycling of heat sources and generating remarkable energy-saving effect, for example, compared with the traditional method that the mixed gas is directly cooled by circulating water and brine ice, the method can save 0.9 ton of externally supplied steam per ton of acetaldehyde produced, and reduce the amount of circulating cooling water by 108m3And the electricity is saved by 18 KWH.
The cooled acetaldehyde mixed gas (furnace gas) is subjected to reverse spray absorption under a pressurized condition, so that the concentration of the diluted acetaldehyde after absorption can be increased (the concentration of the acetaldehyde is 8-10% in normal pressure absorption); the concentration of the dilute acetaldehyde is improved, so that the amount of wastewater generated in the process is greatly reduced, the concentration of the dilute acetaldehyde is improved, the rectification of the acetaldehyde is facilitated, the steam consumption of a subsequent acetaldehyde distillation system is greatly reduced, and the energy-saving effect is achieved.
The production apparatus involved in the process of the present invention, such as an oxidation furnace, an absorption column with a spray mechanism, a condensation column, a rectification column and the like, are conventional in the art, and for example, a bubble column, a packed column, a plate column and the like can be suitably used as described in, for example, Chinese patent applications 02109587.6 and 01121787.1.
In conclusion, the invention provides an improved process for producing butenal, improves the yield of the butenal while improving the production efficiency, reducing the energy consumption and the production cost and reducing the discharge of production wastewater through scientific arrangement of various links and working procedures, and particularly provides an industrial production process for finally obtaining high-purity butenal from an ethanol raw material.
The whole production process operation parameters of the invention can all adopt a DCS automatic control system, thereby enhancing the stability of production operation, improving the working efficiency and reducing the labor intensity.
Drawings
FIG. 1 is a schematic diagram of the process flow for the production of crotonaldehyde from an ethanol feedstock according to the present invention.
In the figure: the method comprises the following steps of 1-an ethanol evaporation pot, 2-a filter, 3-an ethanol oxidation furnace, 4-a steam generator, 5-a pressure fan, 6-an absorption tower, 7-an acetaldehyde rectifying tower, 8-an ethanol recovery tower, 9-a condensation tower, a 10-2-hydroxybutyraldehyde charging pump, 11-a dehydration tower, 12-a dehydration tower reboiler, 13-a primary rectifying tower, 14-a primary rectifying tower layering device, 15-a secondary rectifying tower, 16-a secondary rectifying tower reboiler and 17-a secondary rectifying tower layering device.
Detailed Description
The present invention will now be further described with reference to the accompanying drawings and by reference to preferred embodiments thereof, in order to assist the reader in better understanding the true spirit of the invention.
Example 1:
the acetaldehyde solution with concentration higher than 99.5% can be from the oxidation reaction product of ethylene or ethanol or directly purchased, please refer to fig. 1 (the flow only includes the process from the condensation tower 9 to the back, for example, the part inside the dashed line box), the trimethylamine solution flow rate is controlled to be 36L/h (the concentration is 97.6g/L) and is added into the condensation tower 9 from the 8 th tower plate, meanwhile, the acetaldehyde flow rate is controlled to be 2000L/h and is added into the condensation tower 9 from the 9 th tower plate, the steam heating speed is continuously adjusted, the condensation reaction temperature is controlled to be 43 +/-1 ℃, nitrogen is introduced for protection (the pressure is about 0.02MPa), the 2-hydroxy butyraldehyde aqueous solution (containing part of acetaldehyde) generated bythe reaction is quantitatively discharged from the bottom of the tower, and the unreacted acetaldehyde is evaporated from the top of the tower and is condensed by the condenser of the top of the tower and.
The aqueous 2-hydroxybutyraldehyde solution discharged from the bottom of the condensation column 9 was pumped into a dehydration column 11 by a feed pump 10, and an acetic acid solution having a concentration of 401.3 g/l was added to make the aqueous 2-hydroxybutyraldehyde solution acidic to perform a dehydration reaction. Indirect and direct steam (through a dehydrating tower reboiler 12) is adopted to heat materials simultaneously, the temperature of a gas phase outlet at the top of the tower is controlled at 106 ℃, the pressure in the tower is 0.21MPa, the distilled crotonaldehyde, acetaldehyde and steam enter a condenser, the condensed liquid partially flows back, and part of the liquid and uncondensed gas are extracted and enter a crotonaldehyde primary rectifying tower 13.
The top temperature of the crotonaldehyde primary rectifying tower 13 is controlled to be 52 ℃, the bottom (tower bottom) temperature is controlled to be 135 ℃, and the pressure in the tower is controlled to be 0.20 MPa. The acetaldehyde gas distilled from the tower top enters an acetaldehyde condenser, a part of the condensed acetaldehyde liquid flows back to the primary rectifying tower, a part of the condensed acetaldehyde liquid is extracted (with the concentration of 99.5 percent) and returns to the condensation tower 9 for recycling, and the extraction amount of the acetaldehyde is controlled in the process to keep the outlet temperature of the crotonaldehyde aqueous solution extracted from the middle part of the tower at 120 ℃. The extracted mixture of the crotonaldehyde and the water enters a primary rectifying tower delayer 14 for layering after being condensed and cooled to 29 ℃, the lower layer water returns to a packing section of the primary rectifying tower to recover the crotonaldehyde in the water, and the crotonaldehyde (the content of 90.2 percent) on the upper part of the delayer 14 comes out from the upper part and enters a crotonaldehyde secondary rectifying tower 15 (the wastewater at the bottom of the tower 13 is discharged into a sewage treatment plant for centralized treatment after being cooled).
The crotonaldehyde solution with the concentration of 90.2 percent directly enters the atmospheric secondary rectification from the top of the secondary rectification tower 15 from the delayer 14. The secondary rectifying tower 15 adopts corrugated plate packing with the height of 5 meters and a groove type distributor, and the temperature of the top of the tower is controlled to be 84 ℃ and the temperature of the bottom of the tower is controlled to be 106 ℃ by controlling the amount of the materials fed and extracted and the speed of indirect heating steam (through a reboiler 16 of the secondary rectifying tower). During the distillation process, the concentrated crotonaldehyde product (crotonaldehyde content 99.6%, water content 0.10%) is extracted from the lower liquid phase of the tower, cooled and then enters a crotonaldehyde product tank (not shown).
The azeotrope of crotonaldehyde and water is evaporated from the top of the tower, cooled and condensed by a condenser at the top of the tower, and then enters a delayer 17 of a secondary rectifying tower, the oil phase after delamination returns to the secondary rectifying tower 15, and the water phase returns to a dehydrating tower 11 to recover the crotonaldehyde.
In the process, the conversion rate of acetaldehyde is 67.2%, and the yield of crotonaldehyde is 94.3%.
The crotonaldehyde obtained is a colorless transparent liquid with the specific gravity of 0.853(20 ℃) and the boiling point of 102.1 ℃.
The whole set of production device is controlled by adopting a DCS automatic control system.
Example 2: preparation of acetaldehyde using ethanol as raw material
Mixing 90.3% (V) ethanol water solution prepared from fresh ethanol and recovered ethanol at a ratio of 4.3m3The flow rate of the mixture is added into an ethanol evaporation pot 1, and the flow rate is 3000Nm3The air of/h is heated and evaporated by steam in the ethanol evaporation pot 1, the formed mixed gas with the temperature of 67.0 ℃ is filtered by a filter 2 and then enters an ethanol oxidation furnace 3, the mixed gas generates oxidative dehydrogenation reaction when passing through a silver catalyst layer (not shown in the figure) arranged in the oxidation furnace, and the acetaldehyde gas (furnace gas) generated by the reaction firstly exchanges heat with soft water from a steam generator 4 and then generates low-pressure water steam for the ethanol evaporation pot 1 to evaporate ethanolCooling with water and brine, pressurizing the cooled 8.1 deg.C furnace gas to 0.16MPa with pressurizing fan 5, feeding into acetaldehyde absorption tower 6 from the lower part, introducing absorption water (cold water at 8.2 deg.C) from the upper part of absorption tower 6 to form spray, absorbing acetaldehyde gas in reverse contact with absorption water under pressurizing condition to obtain 18.1% dilute acetaldehyde solution, and unabsorbed CO and CO gas2、O2、N2And the like is discharged from the top of the absorption column 6.
Then, the 18.1% dilute acetaldehyde solution can be pumped into an acetaldehyde rectifying tower 7, and is rectified under the conditions that the pressure in the tower is 0.17MPa, the temperature at the top of the tower is 49.6 ℃, and the reflux ratio is 2.5, and 99.6% acetaldehyde finished products obtained at the top of the tower can be used asraw materials for producing butenal. The ethanol water solution in the tower bottom enters an ethanol recovery tower 8 for normal pressure rectification, the 79.3 percent ethanol water solution obtained from the tower top returns to the ethanol evaporation pot 1 for reuse, and the wastewater containing trace ethanol in the tower bottom is discharged into a sewage treatment plant for centralized treatment.
The ethanol conversion in this process was 75.6% and the acetaldehyde yield was 90.3%.
Crotonaldehyde is further prepared from the resulting acetaldehyde solution according to the method of example 1.
Example 3:
still referring to FIG. 1, this example includes the entire process of first preparing acetaldehyde and then preparing crotonaldehyde from ethanol. The specific process comprises the following steps:
mixing 89.2% (V) ethanol water solution prepared from fresh ethanol and recovered ethanol at a ratio of 4.3m3The flow rate of the mixture is added into an ethanol evaporation pot 1, and the flow rate is 3000Nm3The air of/h is heated and evaporated by steam in an ethanol evaporation pot 1, the formed mixed gas at 68.3 ℃ is filtered by a filter 2 and then enters an ethanol oxidation furnace 3, the mixed gas generates oxidative dehydrogenation reaction when passing through a silver catalyst layer in the oxidation furnace, the acetaldehyde gas (furnace gas) generated by the reaction firstly exchanges heat with soft water from a steam generator 4 to generate low-pressure water vapor for the ethanol evaporation pot 1 to evaporate ethanol, then water and brine are used for cooling, the cooled furnace gas at 8.3 ℃ is pressurized to 0.17MPa by a pressurizing fan 5 and then is sent to an acetaldehyde absorption tower 6 from the lower part, absorbed water (cold water at the temperature of 8.0 ℃) enters from the upper part of the absorption tower 6 to form spraying, the acetaldehyde gas is reversely contacted with the absorbed water under the pressurizing condition to be absorbed to obtain 18.8 percent of dilute acetaldehyde solution, and unabsorbed gases such as CO, CO and CO2、O2、N2And the like is discharged from the top of the absorption column 6.
Pumping 18.8% dilute acetaldehyde solution into acetaldehyde rectifying tower 7, rectifying at tower top temperature of 52.9 deg.c and reflux ratio of 2.5 and pressure of 0.20MPa, and sending 99.7% acetaldehyde product to crotonaldehyde step. The ethanol water solution in the tower bottom enters an ethanol recovery tower 8 for normal pressure rectification, 80.1 percent ethanol water solution obtained from the tower top is returned to an ethanol evaporation pot 1 for reuse, and the wastewater containing trace ethanol in the tower bottom is discharged into a sewage treatment plant for centralized treatment.
The ethanol conversion was 75.3% and the acetaldehyde yield was 90.4%.
Controlling triethylamine solution flow rate to be 40L/h (concentration is 98.2g/L), adding triethylamine solution flow rate to be 9 from the 8 th tower plate, controlling acetaldehyde flow rate to be 2000L/h, adding acetaldehyde flow rate to be 9 from the 9 th tower plate, continuously adjusting steam heating speed, controlling condensation reaction temperature to be 44 +/-1 ℃, introducing nitrogen to protect (pressure is about 0.02MPa), quantitatively discharging 2-hydroxybutyraldehyde aqueous solution (containing partial acetaldehyde) generated by reaction from the bottom of the tower, evaporating unreacted acetaldehyde from the top of the tower, condensing by a condenser at the top of the tower, and refluxing to enter the condensation tower 9 for reaction.
The aqueous 2-hydroxybutyraldehyde solution discharged from the bottom of the condensation column 9 was pumped into a dehydration column 11 by a feed pump 10, and an acetic acid solution having a concentration of 401.5 g/l was added to make the aqueous 2-hydroxybutyraldehyde solution acidic to perform a dehydration reaction. Indirect and direct steam (through a dehydrating tower reboiler 12) is adopted to heat materials simultaneously, the temperature of a gas phase outlet at the top of the tower is controlled at 108 ℃, the pressure in the tower is 0.22MPa, the distilled crotonaldehyde, acetaldehyde, steam and the like enter a condenser, the condensed liquid partially flows back, and part of the liquid and uncondensed gas are extracted and enter a crotonaldehyde primary rectifying tower 13.
The top temperature of the crotonaldehyde primary rectifying tower 13 is controlled to be 56 ℃, the bottom temperature of the crotonaldehyde primary rectifying tower is controlled to be 137 ℃, and the pressure in the tower is controlled to be 0.23 MPa. The acetaldehyde gas distilled from the tower top enters an acetaldehyde condenser, a part of the condensed acetaldehyde liquid reflows to the primary rectifying tower, and a part of the condensed acetaldehyde liquid is extracted (with the concentration of 99.6 percent) and returns to the condensation tower 9 for recycling, and the extraction amount of the acetaldehyde is controlled in the process to keep the outlet temperature of the crotonaldehyde aqueous solution extracted from the middle part of the tower at 122 ℃. The extracted mixture of the crotonaldehyde and the water enters a primary rectifying tower delayer 14 for layering after being condensed and cooled to the temperature of 30 ℃, the lower layer water returns to a filling section of a primary rectifying tower 13 to recover the crotonaldehyde in the water, and the crotonaldehyde (with the content of 89.3%) on the upper part of the delayer 14 comes out from the upper part and enters a crotonaldehyde secondary rectifying tower 15 (the wastewater at the bottom of the tower 13 is discharged into a sewage treatment plant for centralized treatment after being cooled).
The crotonaldehyde solution with the concentration of 89.3 percent directly enters the top of the secondary rectifying tower 15 from the delayer 14 for normal-pressure secondary rectification. The secondary rectifying tower 15 adopts corrugated plate packing with the height of 5 meters and a groove type distributor, and the tower top temperature is controlled to be 83 ℃ and the tower kettle temperature is controlled to be 106 ℃ by controlling the amount of the materials fed and extracted and the speed of indirect heating steam (through a secondary rectifying tower reboiler 16). In the distillation process, the concentrated crotonaldehyde finished product (the crotonaldehyde content is 99.5 percent, and the water content is 0.15 percent) is extracted from the liquid phase at the lower part of the tower, cooled and then enters a crotonaldehyde finished product tank.
The azeotrope of crotonaldehyde and water is evaporated from the top of the tower, cooled and condensed by a condenser at the top of the tower, and then enters a delayer 17 of a secondary rectifying tower, the oil phase after delamination returns to the secondary rectifying tower 15, and the water phase returns to a dehydrating tower 11 to recover the crotonaldehyde.
The acetaldehyde conversion was 67.0% and the crotonaldehyde yield was 94.2%.
The crotonaldehyde obtained is a colorless transparent liquid with the specific gravity of 0.854(20 ℃) and the boiling point of 102.1 ℃.
The whole set of production device is controlled by a DCS automatic control system.
Example 4:
still referring to FIG. 1, an 89.5% (V) ethanol aqueous solution prepared from fresh feed ethanol and recovered ethanol was prepared at 3.6m3The flow rate of the mixture is added into an ethanol evaporation pot 1, and meanwhile, the flow rate is 2510Nm3The air of/h is heated and evaporated by steam in an ethanol evaporation pot 1, the formed mixed gas at 67.8 ℃ is filtered by a filter 2 and then enters an ethanol oxidation furnace 3, the mixed gas generates oxidative dehydrogenation reaction when passing through a silver catalyst layer in the oxidation furnace 3, the acetaldehyde gas (furnace gas) generated by the reaction firstly exchanges heat with soft water from a steam generator 4 to generate low-pressure water vapor for the ethanol evaporation pot 1 to evaporate ethanol, then water and saline water are used for cooling, the cooled furnace gas at 7.8 ℃ is pressurized to 0.14MPa by a pressurizing fan 5 and then is sent to an acetaldehyde absorption tower 6 from the lower part, absorbed water (cold water at 7.5 ℃ enters from the upper part of the absorption tower 6 to form spray, the acetaldehyde gas is reversely contacted with the absorbed water under the pressurizing condition to be absorbed to obtain a dilute acetaldehyde solution with 17.4 percent, and unabsorbed gases such as CO and CO2、O2、N2And the like is discharged from the top of the absorption column 6.
Pumping 17.4% dilute acetaldehyde solution into acetaldehyde rectifying tower 7, rectifying at tower top temperature of 51.7 deg.c and reflux ratio of 2.5 under the pressure of 0.19MPa, and sending 99.6% acetaldehyde product to crotonaldehyde step. The ethanol water solution in the tower bottom enters an ethanol recovery tower 8 for normal pressure rectification, 78.9 percent ethanol water solution obtained at the tower top is returned to the ethanol evaporation pot 1 for reuse, and the wastewater containing trace ethanol in the tower bottom is discharged into a sewage treatment plant for centralizedtreatment.
The ethanol conversion was 75.1% and the acetaldehyde yield was 90.1%.
Controlling the flow rate of trimethylamine solution 36L/h (the concentration is 95.3g/L) and adding the trimethylamine solution into the condensation tower 9 from the 8 th tower plate, controlling the flow rate of acetaldehyde 1700L/h and adding the trimethylamine solution into the condensation tower 9 from the 9 th tower plate, continuously adjusting the heating speed of steam, controlling the condensation reaction temperature to be 42 +/-1 ℃, introducing nitrogen gas for protection (the pressure is about 0.02MPa), quantitatively discharging the 2-hydroxybutyraldehyde aqueous solution (containing part of acetaldehyde) generated by the reaction from the bottom of the tower, evaporating the unreacted acetaldehyde from the top of the tower, condensing the unreacted acetaldehyde by a condenser at the top of the tower, and then refluxing the unreacted acetaldehyde into the condensation tower 9 for reaction.
The aqueous 2-hydroxybutyraldehyde solution discharged from the bottom of the condensation column 9 was pumped into a dehydration column 11 by a feed pump 10, and an acetic acid solution having a concentration of 399.4 g/l was added to make the aqueous 2-hydroxybutyraldehyde solution acidic to perform a dehydration reaction. Indirect and direct steam (through a dehydrating tower reboiler 12) is adopted to heat materials simultaneously, the temperature of a gas phase outlet at the top of the tower is controlled to be 107 ℃, the pressure in the tower is 0.22MPa, the distilled crotonaldehyde, acetaldehyde, steam and the like enter a condenser, the condensed liquid partially flows back, and part of the liquid and uncondensed gas are extracted to enter a crotonaldehyde primary rectifying tower 13.
The top temperature of the crotonaldehyde primary rectifying tower 13 is controlled to be 51 ℃, the bottom temperature of the crotonaldehyde primary rectifying tower is controlled to be 136 ℃, and meanwhile, the pressure in the tower is controlled to be 0.21 MPa. The acetaldehyde gas distilled from the tower top enters an acetaldehyde condenser, a part of the condensed acetaldehyde liquid flows back to the primary rectifying tower, a part of the condensed acetaldehyde liquid is extracted (with the concentration of 99.6 percent) and returns to the condensation tower 9 for recycling, and the extraction amount of the acetaldehyde is controlled in the process to keep the outlet temperature of the crotonaldehyde aqueous solution extracted from the middle part of the tower at 120 ℃. The extracted mixture of the crotonaldehyde and the water is condensed and cooled to 28 ℃, then enters a primary rectifying tower delayer 14 for layering, the lower layer water returns to a filling section of a primary rectifying tower 13 to recover the crotonaldehyde in the water, and the crotonaldehyde (the content of 90.5 percent) on the upper part of the delayer 14 comes out and enters a crotonaldehyde secondary rectifying tower 15 (the wastewater at the bottom of the tower 13 is cooled and then discharged into a sewage treatment plant for centralized treatment).
The crotonaldehyde solution with the concentration of 90.5 percent enters a secondary rectifying tower 15 for secondary rectification under normal pressure. The secondary rectifying tower 15 adopts corrugated plate packing and a groove type distributor with the height of 5 meters, and controls the tower top temperature of 82 ℃ and the tower kettle temperature of 105 ℃ by controlling the amount of the materials fed and extracted and the speed of indirect heating steam (through a secondary rectifying tower reboiler 16). In the distillation process, the concentrated crotonaldehyde finished product (the crotonaldehyde content is 99.5 percent, and the water content is 0.17 percent) is extracted from the liquid phase at the lower part of the tower, cooled and then enters a crotonaldehyde finished product tank.
The azeotropic mixture of the crotonaldehyde and the water is evaporated from the tower top, cooled and condensed by a tower top condenser, enters a secondary rectifying tower delayer 17, oil phase reflux is carried out after delamination, and the water phase returns to the dehydration tower 11 to recover the crotonaldehyde.
The acetaldehyde conversion was 67.5% and the crotonaldehyde yield was 94.5%.
The crotonaldehyde obtained is a colorless transparent liquid with the specific gravity of 0.854(20 ℃) and the boiling point of 102.0 ℃.
The whole set of production device is controlled by a DCS automatic control system.
Claims (10)
1. The production process of butenal includes the condensation of acetaldehyde under the catalysis of organic amine to produce 2-hydroxy butyraldehyde and the dewatering of the obtained 2-hydroxy butyraldehyde to produce butenal under acidic condition.
2. The production process according to claim 1, wherein the organic amine is trimethylamine or triethylamine.
3. The production process according to claim 1 or 2, wherein the condensation reaction is carried out at a temperature of 37 to 47 ℃ under an inert gas atmosphere.
4. The production process of claim 1, wherein the 2-hydroxybutyraldehyde is dehydrated in the presence of an organic acid to produce a crude crotonaldehyde product, which is then rectified to produce the crotonaldehyde product.
5. The production process as claimed in claim 4, wherein the dehydration reaction is carried out in a dehydration column, and the temperature at the top of the column is controlled to 105 to 112 ℃ and the pressure in the column is controlled to 0.20 to 0.25 MPa.
6. The process according to claim 4 or 5, wherein the dehydration of 2-hydroxybutyraldehyde is controlled by indirect and direct steam heating.
7. The production process according to claim 4, wherein the rectification of the crude crotonaldehyde comprises pressure rectification, and the pressure rectification product is subjected to atmospheric rectification after water separation.
8. The production process as claimed in claim 1, further comprising synthesizing acetaldehyde gas by oxidation reaction using ethanol or ethylene as raw material, absorbing the generated acetaldehyde gas by reverse spray with water of 5-10 ℃ under the pressure of 0.13-0.17 MPa to prepare a dilute acetaldehyde solution, and feeding the dilute acetaldehyde solution into a rectifying tower to be concentrated into an acetaldehyde solution with purity higher than 99%.
9. The production process of claim 8, wherein ethanol is used as a raw material, the ethanol and hot air react in an oxidation furnace to generate an oxidation reaction to generate acetaldehyde gas, the reaction temperature in the oxidation furnace is 540-560 ℃, and the oxidation reaction is completed under the catalysis of a silver catalyst.
10. The process according to claim 7, wherein the crotonaldehyde is rectified at atmospheric pressure by a rectifying column equipped with corrugated plate packing and a trough distributor.
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105037119A (en) * | 2015-08-21 | 2015-11-11 | 吉林市凇泰化工有限责任公司 | Improvement of crotonaldehyde production technique |
| CN106349043A (en) * | 2016-08-30 | 2017-01-25 | 安徽金禾实业股份有限公司 | Attenuant acetaldehyde rectification residual liquor recycling method |
| CN106883112A (en) * | 2017-02-16 | 2017-06-23 | 福州福大双众化工科技有限公司 | A kind of improvement production technology of crotonaldehyde |
| CN109320406A (en) * | 2018-11-14 | 2019-02-12 | 常州大学 | A kind of big temperature difference thermal sensitivity system rectifier unit and method |
| CN109422635A (en) * | 2017-09-05 | 2019-03-05 | 东营市海科新源化工有限责任公司 | A kind of preparation method of 1,3 butylene glycol |
| CN112057946A (en) * | 2020-08-10 | 2020-12-11 | 金沂蒙集团有限公司 | Method and device for resource utilization of wastewater generated in synthesis of butenal from acetaldehyde |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB757812A (en) * | 1953-03-09 | 1956-09-26 | Union Carbide & Carbon Corp | Improvements in production of alpha, beta-unsaturated aldehydes |
| GB783458A (en) * | 1954-04-20 | 1957-09-25 | Celanese Corp | Aldehyde condensation reactions |
| JPS5718642A (en) * | 1980-07-08 | 1982-01-30 | Mitsubishi Gas Chem Co Inc | Preparation of unsaturated aldehyde |
| CN1394840A (en) * | 2001-07-09 | 2003-02-05 | 吉林化学工业股份有限公司电石厂 | Improvement of production process of butenal |
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2006
- 2006-01-12 CN CNB2006100012786A patent/CN100344598C/en active Active
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105037119A (en) * | 2015-08-21 | 2015-11-11 | 吉林市凇泰化工有限责任公司 | Improvement of crotonaldehyde production technique |
| CN106349043A (en) * | 2016-08-30 | 2017-01-25 | 安徽金禾实业股份有限公司 | Attenuant acetaldehyde rectification residual liquor recycling method |
| CN106349043B (en) * | 2016-08-30 | 2018-11-06 | 安徽金禾实业股份有限公司 | A kind of dilute acetaldehyde distillation residual liquid recycling application method |
| CN106883112A (en) * | 2017-02-16 | 2017-06-23 | 福州福大双众化工科技有限公司 | A kind of improvement production technology of crotonaldehyde |
| CN106883112B (en) * | 2017-02-16 | 2020-09-15 | 福州福大双众化工科技有限公司 | Improved production process of crotonaldehyde |
| CN109422635A (en) * | 2017-09-05 | 2019-03-05 | 东营市海科新源化工有限责任公司 | A kind of preparation method of 1,3 butylene glycol |
| CN109320406A (en) * | 2018-11-14 | 2019-02-12 | 常州大学 | A kind of big temperature difference thermal sensitivity system rectifier unit and method |
| CN112057946A (en) * | 2020-08-10 | 2020-12-11 | 金沂蒙集团有限公司 | Method and device for resource utilization of wastewater generated in synthesis of butenal from acetaldehyde |
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| CN100344598C (en) | 2007-10-24 |
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