Gas-liquid-solid three-phase bubbling bed reactive distillation device and application thereof in preparation of diisoamyl oxalate
By designing a gas-liquid-solid three-phase bubbling bed reactive distillation device, the problem of catalyst loading method was solved, achieving efficient catalytic reaction and separation, reducing equipment investment and operating costs, and improving conversion rate and separation effect.
Patent Information
- Application Number
- CN202511924673.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-19
- Publication Date
- 2026-02-17
AI Technical Summary
In the existing technology, the catalyst loading method of reactive distillation unit is difficult to simultaneously meet the requirements of providing sufficient surface area and good gas-liquid mass transfer conditions, resulting in problems such as large pressure drop, easy blockage, small loading amount, and difficult processing. In addition, the catalyst is easy to break, which affects the conversion rate and separation effect.
A gas-liquid-solid three-phase bubbling bed reactive distillation unit was adopted. Through multi-stage layered sieve plate design and silica-modified NKC-9 catalyst, the multi-stage layered sieve plate design (Figure 1) was used to optimize the catalyst design. One gas-liquid design and another multi-stage layered sieve plate design were designed. The catalyst was silica-modified NKC-9 resin catalyst. The design achieved uniform distribution and fine and uniform bubble flow, avoided channeling and short-circuiting, provided smooth flow channels and mass and heat transfer conditions, and improved conversion rate and separation effect.
This technology enables efficient catalyst loading, improves the conversion rate and separation effect of catalytic reactions, reduces equipment costs, extends catalyst lifespan, and promotes economic and social benefits.
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Figure CN121534401A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of chemical engineering, specifically relating to a gas-liquid-solid three-phase bubbling bed reactive distillation apparatus and its application in the preparation of diisoamyl oxalate. Background Technology
[0002] Diisoamyl oxalate is an ester-based diesel cetane number improver. Because it does not contain nitrogen, it does not emit NO after combustion. x It offers clean combustion and could potentially replace existing cetane number improvers such as isoamyl nitrate and isooctyl nitrate, effectively reducing NO in vehicle exhaust. x This leads to environmental pollution. Therefore, researching cetane number improvers such as diisoamyl oxalate, which do not contain nitrogen, is of great significance for promoting the implementation of new emission standards and future environmental protection.
[0003] Reactive distillation technology, as an important means of chemical process intensification, couples chemical reactions and product separation into the same device. By breaking the reversible reaction equilibrium through real-time product separation, it enables the reaction to overcome the limitations of equilibrium conversion rate, achieving deep conversion, improving conversion rate, simplifying process flow, and reducing equipment costs. However, the successful implementation of this technology is highly dependent on the design of the catalyst loading method. An ideal loading structure must simultaneously meet two basic requirements: first, to provide sufficient surface area for the catalytic reaction; and second, to create good vapor-liquid mass transfer conditions and unobstructed flow channels for distillation separation. This invention designs a silica-modified NKC-9 resin catalyst and a reactive distillation device, and successfully applies it to the preparation of diisoamyl oxalate. Summary of the Invention
[0004] This invention provides a preparation process for diisoamyl oxalate, characterized in that the preparation process is carried out in a gas-liquid-solid three-phase bubbling bed reactive distillation apparatus.
[0005] Another embodiment of the present invention provides the above-mentioned preparation process, characterized in that the gas-liquid-solid three-phase bubbling bed reactive distillation device includes a rectification section, a stripping section, and a bubbling bed reaction section, wherein the rectification section and the stripping section are composed of a plate column or a packed column, and the bubbling bed reaction section is composed of a catalyst and a column plate.
[0006] The preparation process is preferably carried out under the following conditions: the system vacuum degree is 80-90 kPa, the molar ratio of oxalic acid to isoamyl alcohol in the upper part of the reaction section is 1:1.2, the solution feeding temperature is 90-100 ℃; the isoamyl alcohol feeding amount in the lower part of the reaction section is 1.8 times (molar ratio) of the oxalic acid feeding amount in the upper part, the product A amount is 2% of the oxalic acid mass, the feeding temperature is normal temperature; the reflux ratio is 1-2, the overhead temperature is 40-65 ℃, the reaction section temperature is 100-115 ℃, the bottom temperature is 180-220 ℃, and the external circulation device is optionally opened, and the circulation amount is 0.25-0.5 times of the upper part feeding amount of the reaction section.
[0007] Another embodiment of the present application provides the above preparation process, characterized in that the catalyst is a silica-modified NKC-9 resin. The preparation method of the catalyst comprises the following steps: adding an ethanol solution of tetraethyl orthosilicate into NKC-9 cation exchange resin, heating to 70-80 ℃, stirring for 8-12 h, and then naturally cooling, filtering and drying to obtain the silica-modified NKC-9 resin. The ethanol solution is preferably a 70%-95% ethanol solution, and the amount of tetraethyl orthosilicate is preferably 6%-10% (preferably 8%) of the mass of NKC-9 cation exchange resin. The amount of ethanol solution can be reasonably selected by those skilled in the art, and it is appropriate to fully immerse the NKC-9 cation exchange resin, and the amount can be appropriately increased or decreased.
[0008] Another embodiment of the present application provides a preparation method of diisopentyl oxalate, characterized by comprising the following steps:
[0009] The isoamyl alcohol and oxalic acid are mixed, heated under stirring, and then the silica-modified NKC-9 resin is added, and the temperature is continuously increased to 108-110 ℃ to obtain diisopentyl oxalate.
[0010] In the above preparation method, the molar ratio of isoamyl alcohol to oxalic acid is preferably 3:1, and further preferably 2.5:1; the amount of silica-modified NKC-9 resin is preferably 1.0%-3.0% of the mass of oxalic acid, and further preferably 1.5%-2.0%; the heating under stirring is preferably heated to 70-90 ℃, and further preferably heated to 80-85 ℃; preferably, the water produced during the reaction is separated out in time, and a water separation device is preferably used. After the reaction is completed, the silica-modified NKC-9 resin is preferably recovered, and the number of times of recycling is preferably 10.
[0011] The above preparation process provided by the present application is carried out in a gas-liquid-solid three-phase bubble column reaction rectification device, such as Figure 1As shown, L1 is a heavy component raw material inlet, L2 is a light component raw material inlet, the light and heavy components are reacted in a reaction section, the light component in the reaction product enters a rectification section upward for rectification and purification, the overhead gas phase G1 enters a condenser E2 at the top for condensation, the condensate L3 enters a separator V1 for separation (or enters a storage tank), an appropriate reflux ratio is controlled, L5 is refluxed, and L4 is produced; the heavy component in the reaction product enters a stripping section downward for purification, part of the material in the column sump enters a reboiler E1 to be heated to form steam and then returns to the column, and the other part is produced as the column sump L6 to go to a refining process; an external circulation device is connected to the bubbling bed reaction section of the reaction rectification column as a standby facility, when the residence time of the liquid phase in the reaction section is insufficient, part of the liquid phase at the bottom of the last tray in the reaction section is produced as L7, cooled to an appropriate temperature by a cooler E3, and then sent to the top of the first tray in the reaction section, so as to increase the residence time of the liquid phase in the reaction section, promote the reaction to be complete, and at the same time, effectively control the column height.
[0012] To solve the problems of large pressure drop, easy plugging, small loading capacity, difficult processing, and easy swelling and breaking in the reaction rectification, a multi-stage layered sieve plate is used to modularly design the bubbling bed reaction section, and the composition of a single module is: tray→bubble breaking zone→catalyst bottom net→gas-liquid-solid three-phase bubbling reaction zone→catalyst top net→gas-liquid two-phase zone→gas phase rising zone. As shown in the figure. Figure 2 The reaction section is formed by stacking a plurality of gas-liquid-solid three-phase bubbling reaction zones.
[0013] The bubble breaking zone has a bubble breaking net to avoid the formation of surging, channeling or short circuiting; the catalyst bottom net not only supports the catalyst, but also re-distributes the bubbles to make the bubbles rise more uniformly; the catalyst layer not only catalyzes the reaction, but also improves the separation of the gas-liquid two-phase mass transfer and heat transfer rate; when the device is normally operated, the gas-liquid-solid three-phase bubbling reaction zone (including the catalyst layer) is a gas-liquid-solid mass transfer and heat transfer reaction zone, the gas-liquid two-phase zone is a gas-liquid mass transfer and heat transfer zone, and the gas phase rising zone is a rising area for gas to leave the foam section and a gas-liquid separation space, and the gas rises into the upper tray after rising.
[0014] The height of the bubble breaking zone is 10-20 mm, the height of the gas-liquid-solid three-phase bubbling reaction zone is 60-200 mm, the height of the liquid layer of the gas-liquid two-phase zone is 20-100 mm, and the height of the separation space of the gas phase rising zone is 200-400 mm.
[0015] The bubble breaking net adopts a wire mesh with a higher opening rate of 10 mesh (wire diameter 0.457 mm, aperture 2.083 mm, opening rate 67%) - 20 mesh (wire diameter 0.315 mm, aperture 0.955 mm, opening rate 0.57%). The top net and the bottom net of the catalyst adopt a wire mesh with a higher opening rate of 50 mesh (wire diameter 0.153 mm, aperture 0.355 mm, opening rate 49%) - 100 mesh (wire diameter 0.08 mm, aperture 0.174 mm, opening rate 47%). The wire mesh maintains a higher opening rate, so that the wire mesh does not form resistance to the gas-liquid phase flow, which is beneficial to reducing the tray pressure drop.
[0016] The gas-liquid-solid three-phase bubbling zone has a voidage of not less than 80%, and the upper limit of the gas phase flow rate is controlled to be not more than 1.5-2.5 m / s.
[0017] The single-layer reaction section tray is divided into a bubble breaking zone, a gas-liquid-solid three-phase bubbling reaction zone, a gas-liquid two-phase zone and a gas phase rising zone. The bubbling bed zone is located in the gas-liquid-solid three-phase zone, the gas phase flows from bottom to top, the liquid phase is in a horizontal flow state from the downcomer, and the solid phase is the catalyst particles. The liquid phase and the solid particles are in a bubbling state under the action of the gas bubbles, the flow direction is orthogonal contact, the disturbance is sufficient, and the bubbling state is good. As shown in FIG. 1. The volume of the gas-liquid-solid three-phase bubbling reaction zone is 1.5-3 times the volume of the catalyst. Figure 3
[0018] The NKC-9 cation exchange resin in the application is a pretreated NKC-9 hydrogen type cation exchange resin. The pretreatment method is a conventional method in the art, and the specific method is as follows: the NKC-9 hydrogen type cation exchange resin is placed in a glass or plastic beaker, washed with clean water until the water is clear, and the water is filtered as clean as possible. The NKC-9 resin is soaked in anhydrous ethanol for 3-5 hours, and the amount of anhydrous ethanol is based on completely immersing the resin. The anhydrous ethanol can be used to wash and remove some organic pigments and impurities in the resin. The NKC-9 resin after removing the impurities is washed with deionized water until it is neutral, dried at room temperature, placed in a constant temperature vacuum drying oven, dried at 80-100℃ for 5-7h, and sealed for use.
[0019] Compared with the prior art, the advantages of the present application are: 1, the structure design of the bubble bed reaction zone of the gas-liquid-solid three-phase bubble bed reaction rectification device in the present application adopts multi-section layered sieve plate to reduce pressure drop, and the catalyst loading capacity is improved, sufficient surface area and residence time are provided for the catalytic reaction, so that the solid catalyst can accelerate the chemical reaction in the rectification tower, promote the reaction to reach a higher conversion rate, and at the same time, the gas-liquid two-phase mass transfer and heat transfer surface area is increased, which plays the role of the filler, so that the reaction products can leave the reaction zone in time, which is beneficial to improve the conversion rate and separation effect; uniform catalyst distribution eliminates the influence of internal diffusion, and improves the reaction rate; the flow of small and uniform bubbles promotes the formation of uniform spatial distribution of the catalyst, avoiding channeling and short circuit; a smooth flow channel is provided for the gas-liquid two-phase, and the turbulence degree of the gas-liquid two-phase is increased, forming uniform distribution of the gas flow and the liquid flow, strengthening the mass transfer and heat transfer process, and improving the gas-liquid mass transfer and heat transfer efficiency; the low gas flow rate avoids liquid flooding caused by too high gas flow rate. The catalyst is only suspended in the gas-liquid phase, and does not contact with mechanical stirring paddle or fluid conveying equipment, so that the catalyst does not bear mechanical pressure and shear force, and the probability of mechanical wear and breakage is reduced; the volume of the gas-liquid-solid three-phase bubble zone is increased, and the bed porosity is improved, which can prevent extrusion and breakage during swelling; the upper limit of the gas flow rate is low, and the gas flow is mainly in the form of bubbling, without forming a fluidized state, avoiding the wear of the catalyst particles caused by high gas flow rate, and the liquid film on the surface of the catalyst reduces the probability of collision and contact between the catalyst particles, protecting the integrity of the catalyst particles and avoiding the breakage of the catalyst particles. Therefore, the reaction zone structure meets the dual requirements of reaction and separation, and effectively protects the catalyst. The implementation of the present application can greatly reduce equipment investment, reduce operating costs, improve economic and social benefits, and promote energy saving and emission reduction. 2, the present application can greatly improve the efficiency of the catalytic reaction by using the silica modified NKC-9 resin catalyst, and the catalyst can be recycled and reused, and the catalytic efficiency is basically unchanged after 10 times of reuse. BRIEF DESCRIPTION OF DRAWINGS
[0020] Figure 1 is a schematic diagram of the gas-liquid-solid three-phase bubble bed reaction rectification device of the present application.
[0021] Figure 2 is a schematic diagram of the bubble bed reaction section tray structure.
[0022] Figure 3 is a schematic diagram of the reaction section gas-liquid flow direction. DETAILED DESCRIPTION
[0023] The NKC-9 cation exchange resin described in this invention is a pretreated NKC-9 hydrogen-form cation exchange resin. The pretreatment method is a conventional method in the art, specifically as follows: Place the NKC-9 hydrogen-form cation exchange resin in a glass or plastic beaker, wash with water until the water is clear, and filter the water as thoroughly as possible. Soak the NKC-9 resin in anhydrous ethanol for 3-5 hours, with the amount of anhydrous ethanol ensuring complete immersion of the resin. Anhydrous ethanol can wash away some organic pigments and impurities contained in the resin. After removing impurities, the NKC-9 resin is washed with deionized water until neutral, air-dried at room temperature, and then placed in a constant temperature vacuum drying oven and dried at 80-100℃ for 5-7 hours. It is then sealed for later use.
[0024] Example 1
[0025] Take 100g of pretreated NKC-9 hydrogen-type cation exchange resin, add an appropriate amount of ethanol solution of tetraethyl orthosilicate (preferably enough to fully immerse the resin, the ethanol solution is a 75% ethanol solution with a mass of 8g of tetraethyl orthosilicate), heat to 70℃, stir and react for 12h, then cool naturally, filter and vacuum dry to obtain the silica-modified NKC-9 resin (hereinafter referred to as Product A).
[0026] Example 2
[0027] Take 100g of pretreated NKC-9 hydrogen-type cation exchange resin, add an appropriate amount of ethanol solution of tetraethyl orthosilicate (preferably enough to fully immerse the resin, the ethanol solution is an 80% ethanol solution with a mass of 6g of tetraethyl orthosilicate), heat to 80℃, stir and react for 8h, then cool naturally, filter and vacuum dry to obtain the silica-modified NKC-9 resin (hereinafter referred to as Product B).
[0028] Example 3
[0029] Take 100g of pretreated NKC-9 hydrogen-form cation exchange resin, add an appropriate amount of ethanol solution of tetraethyl orthosilicate (preferably enough to fully immerse the resin, the ethanol solution is 85% ethanol solution by volume, containing 10g of tetraethyl orthosilicate), heat to 75℃, stir and react for 10h, then cool naturally, filter and vacuum dry to obtain the silica-modified NKC-9 resin (hereinafter referred to as product C).
[0030] Example 4
[0031] Isoamyl alcohol (0.25 mol) and oxalic acid (0.1 mol) were added to a reactor, and the mixture was heated to 80-85°C with stirring. Product A (135 mg, 1.5% of the mass of oxalic acid) was added, and the temperature was further increased to 108-110°C. During the reaction, the water layer in the separator was separated in time, and the upper organic matter was returned to the reactor. The entire reaction process took about 3 hours. After the reaction was completed, the catalyst (i.e., product A) was recovered by filtration, and diisoamyl oxalate (22.86 g, conversion rate of 99.25%) was obtained by vacuum distillation. The recovered catalyst was reused 10 times, and the catalytic efficiency remained basically unchanged. The conversion rate still reached 98.36% in the 10th reuse.
[0032] The following Examples 5-7 demonstrate large-scale production using the gas-liquid-solid three-phase bubbling bed reactive distillation apparatus of the present invention.
[0033] Example 5
[0034] The system vacuum was 80 kPa. In the upper feed of the reaction section, the molar ratio of oxalic acid to isoamyl alcohol was 1:1.2, and the solution feed temperature was 90-100℃. The isoamyl alcohol feed rate in the lower part of the reaction section was 1.8 times (molar ratio) of the oxalic acid feed rate in the upper part. The amount of product A was 2% of the oxalic acid mass, and the feed temperature was room temperature. The reflux ratio was 2. The top temperature of the column was 55-65℃, the reaction section temperature was 100-115℃, and the bottom temperature was 200-220℃. Without external circulation, the oxalic acid conversion rate obtained in the experiment was 93.1%.
[0035] Example 6
[0036] The system vacuum was 80 kPa. In the upper feed of the reaction section, the molar ratio of oxalic acid to isoamyl alcohol was 1:1.2, and the solution feed temperature was 90-100℃. The isoamyl alcohol feed rate in the lower part of the reaction section was 1.8 times (molar ratio) of the oxalic acid feed rate in the upper part. The amount of product A was 2% of the oxalic acid mass, and the feed temperature was room temperature. The reflux ratio was 1. The top temperature of the column was 55-65℃, the reaction section temperature was 100-115℃, and the bottom temperature was 200-220℃. The external circulation device was turned on, and the circulation rate was 0.25 times the feed rate in the upper part of the reaction section. The experimental oxalic acid conversion rate was 95.3%.
[0037] Example 7
[0038] The system vacuum was 90 kPa. In the upper feed of the reaction section, the molar ratio of oxalic acid to isoamyl alcohol was 1:1.2, and the solution feed temperature was 90-100℃. The isoamyl alcohol feed rate in the lower part of the reaction section was 1.8 times (molar ratio) of the oxalic acid feed rate in the upper part. The amount of product A was 2% of the oxalic acid mass, and the feed temperature was room temperature. The reflux ratio was 1. The top temperature of the column was 40-50℃, the reaction section temperature was 100-115℃, and the bottom temperature was 180-190℃. The external circulation device was turned on, and the circulation rate was 0.5 times the feed rate in the upper part of the reaction section. The experimental oxalic acid conversion rate was 96.6%.
Claims
1. A process for the preparation of diisopentyl oxalate, characterized in that The preparation process is carried out in a gas-liquid-solid three-phase bubble bed reaction rectification device; the gas-liquid-solid three-phase bubble bed reaction rectification device comprises a rectification section, a stripping section and a bubble bed reaction section, wherein the rectification section and the stripping section are composed of a plate column or a packed column, and the bubble bed reaction section is composed of a catalyst and a tray.
2. The manufacturing process according to claim 1, characterized in that The catalyst is a silicon dioxide modified NKC-9 resin.
3. The manufacturing process of claim 2, wherein The preparation method of the catalyst comprises the following steps: adding an ethanol solution of tetraethyl orthosilicate into NKC-9 cation exchange resin, heating to 70-80 ℃, stirring for 8-12 h, and then naturally cooling, filtering and drying to obtain the silicon dioxide modified NKC-9 resin.
4. The manufacturing process of claim 3, wherein The ethanol solution is selected from an ethanol solution with a volume fraction of 70%-95%, and the amount of tetraethyl orthosilicate is 6%-10% of the mass of the NKC-9 cation exchange resin.
5. The production process according to any one of claims 1 to 4, characterized in that The process conditions are as follows: the system vacuum degree is 80-90 kPa, the molar ratio of oxalic acid to isoamyl alcohol in the upper part of the reaction section is 1:1.2, the solution feeding temperature is 90-100 ℃, the isoamyl alcohol feeding amount in the lower part of the reaction section is 1.8 times (molar ratio) of the oxalic acid feeding amount in the upper part, the product A amount is 2% of the mass of the oxalic acid, the feeding temperature is normal temperature, the reflux ratio is 1-2, the top temperature is 40-65 ℃, the reaction section temperature is 100-115 ℃, the bottom temperature is 180-220 ℃, and the external circulation device is optionally opened, and the circulation amount is 0.25-0.5 times of the feeding amount in the upper part of the reaction section.
6. A process for the preparation of diisopentyl oxalate, characterized in that The method comprises the following steps: The isoamyl alcohol and the oxalic acid are mixed, heated under stirring, and then the silicon dioxide modified NKC-9 resin involved in any one of claims 3-4 is added, and the reaction is continued by heating to 108-110 ℃ to obtain diisopentyl oxalate.
7. The method of claim 6, wherein The molar ratio of isoamyl alcohol to oxalic acid is preferably 3:1, and further preferably 2.5:
1.
8. The method of making according to any one of claims 6-7, wherein The amount of the silicon dioxide modified NKC-9 resin is preferably 1.0%-3.0% of the mass of the oxalic acid, and further preferably 1.5%-2.0%.
9. The method of any one of claims 6-8, wherein The heating under stirring is preferably heating to 70-90 ℃, and further preferably heating to 80-85 ℃; preferably, the water generated in the reaction is separated out in time during the reaction, and a water separation device is preferably used.
10. The silicon dioxide modified NKC-9 resin according to any one of claims 3-4 for use in catalyzing the reaction of isoamyl alcohol and oxalic acid to prepare diisopentyl oxalate.