Continuous production method of isooctyl nitrate

Abstract

The invention discloses a continuous production method of isooctyl nitrate, which comprises the following steps: by taking mixed acid and isooctyl alcohol as raw materials, carrying out continuous nitration reaction at 10-30 DEG C by adopting a spiral microchannel reactor; the mixed acid is a mixture of concentrated nitric acid and fuming sulfuric acid. The spiral micro-channel reactor is adopted to be matched with specific raw material types and dosage, the internal mass and heat transfer process can be enhanced so as to ensure the temperature uniformity, materials flow in a threaded flow channel, and the mass transfer effect is good through continuous mixing, separation, remixing, repeated shearing and cross flow, and the chemical reaction efficiency is improved; the use amount of raw material acid is effectively reduced, and the raw material input cost is reduced; the wastewater generation amount is greatly reduced, and the wastewater treatment cost is controlled; the device can be matched with post-treatment equipment for continuous acid distribution and continuous water washing and alkali washing, complete continuous post-treatment is achieved, intermittent operation is reduced, and the automatic whole process is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of continuous production and relates to a production method of isooctyl nitrate, in particular to a continuous production method of isooctyl nitrate. Background Art

[0002] Isooctyl nitrate, also known as 2-ethylhexyl nitrate, is an important additive to improve the cetane number (CN) of diesel. Higher CN lowers the flash point, accelerates ignition, improves engine power and reduces fuel consumption. Therefore, it is necessary to produce isooctyl nitrate efficiently, safely and environmentally friendly.

[0003] The synthesis of isooctyl nitrate is a nitration reaction using isooctyl alcohol as raw material, nitric acid as nitrating agent, and sulfuric acid as catalyst. The reaction equation is as follows: .

[0004] The Chinese invention patent with publication number CN101698646A discloses a method for continuously producing isooctyl nitrate to overcome the major safety hazards and low production efficiency problems of the prior art; the existing technical solution is: a continuous production process of isooctyl nitrate, comprising the following steps in sequence: (1) a mixed acid and alcohol formed by mixing industrial fuming nitric acid and concentrated sulfuric acid are fed into a microtubular reactor for reaction; (2) the product flows continuously from the outlet of the microtubular reactor into an alcohol-acid separation tank, and enters a crude product tank after removing the acid layer; (3) the crude product is washed with water, washed with alkali, and then washed with water until neutral, and a trace amount of water is removed by a drying unit to obtain the final product. However, the mass ratio of the mixed acid in the application is: 10-40% industrial fuming nitric acid, 60-90% concentrated sulfuric acid, and the reaction temperature is 40-70°C. The disadvantages of this process are that the amount of sulfuric acid is still too large, and the reaction temperature is high, which has a greater risk of potential side reactions. Summary of the invention

[0005] The invention aims to overcome the deficiencies of the prior art and to provide a continuous production method for isooctyl nitrate, so as to effectively reduce the amount of acid used, reduce unit consumption and cost under the condition of ensuring high purity and high yield.

[0006] To achieve the above object, the technical scheme adopted by the present invention is: a continuous production method of isooctyl nitrate, using mixed acid and isooctyl alcohol as raw materials, adopting a spiral microchannel reactor, and carrying out continuous nitration reaction at 10-30°C; the mixed acid is a mixture of concentrated nitric acid and fuming sulfuric acid.

[0007] Optimally, the concentration of the oleum is 102-110%, and the mass concentration of the concentrated nitric acid is 90-98%.

[0008] Furthermore, the molar ratio of concentrated nitric acid to oleum in the mixed acid is 1:0.8-0.98.

[0009] Optimally, the molar ratio of the isooctyl alcohol to the concentrated nitric acid is 1:1.05-1.2.

[0010] Optimally, the following steps are included: The mixed acid and isooctyl alcohol are introduced into the spiral microchannel reactor respectively to mix and contact and perform nitration reaction; the residence time of the mixed acid and isooctyl alcohol in the spiral microchannel reactor is 1-15 s, and the reaction pressure is 0-0.5 MPa; The reaction liquid after nitration is separated into two phases, and the organic phase is taken and successively washed with water, washed with alkali, washed with water, and then dried.

[0011] Optimally, the spiral microchannel reactor comprises: A reaction inner sleeve, wherein the outer surface of the reaction inner sleeve is formed with an external thread; A reaction outer sleeve, wherein the inner surface of the reaction outer sleeve is formed with an internal thread matching the external thread; a micro-reaction channel is formed between the internal thread and the external thread; an isooctyl alcohol feed port, wherein the isooctyl alcohol feed port is connected to the bottom of the micro-reaction channel; A mixed acid feed inlet, the mixed acid feed inlet is connected to the bottom of the micro-reaction channel; A reaction liquid outlet is communicated with the top of the micro-reaction channel.

[0012] Furthermore, the spiral microchannel reactor also includes: An inner jacket, the inner jacket being formed on the inner wall of the reaction inner sleeve; An outer jacket is formed on the outer wall of the reaction jacket.

[0013] Furthermore, the spiral microchannel reactor also includes: An outer shell, the outer shell covering the outer surface of the outer jacket; Baffles are alternately formed on the outer surface of the reaction jacket and the inner surface of the outer jacket.

[0014] Furthermore, the spiral microchannel reactor also includes: An isooctyl alcohol feed pump, wherein the isooctyl alcohol feed pump is connected to the isooctyl alcohol feed port through a pipeline; A mixed acid feed pump, the mixed acid feed pump is connected to the mixed acid feed port through a pipeline; A multi-stage centrifugal extractor, wherein the multi-stage centrifugal extractors are sequentially connected in series and connected to the reaction liquid outlet, and are used to sequentially perform two-phase separation, water washing, alkali washing and water washing treatment on the reaction liquid.

[0015] Furthermore, the gap between the internal thread and the external thread is 0.2-4 mm.

[0016] Due to the application of the above technical scheme, the present invention has the following advantages compared with the prior art: the continuous production method of isooctyl nitrate of the present invention can strengthen the internal mass transfer and heat transfer process to ensure temperature uniformity by adopting a spiral microchannel reactor in combination with specific raw material types and amounts, and the material flows in the threaded flow channel, is continuously mixed, separated, and remixed, and is repeatedly sheared and cross-flowed, with good mass transfer effect, thereby improving the efficiency of the chemical reaction; the amount of raw acid used is effectively reduced, thereby reducing the raw material input cost; the amount of wastewater generated is greatly reduced, thereby controlling the wastewater treatment cost; and the post-treatment equipment can be used for continuous acid separation and continuous water washing, alkali washing, and water washing, thereby completely continuous post-treatment, reducing intermittent operation, and realizing full automation of the entire process. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the spiral microchannel reactor of the present invention; Figure 2 The present invention is a process flow chart of the continuous production method of isooctyl nitrate. DETAILED DESCRIPTION

[0018] The preferred embodiments of the present invention will be described in detail below. Example 1

[0019] This embodiment provides a spiral microchannel reactor, such as Figure 1 As shown, it mainly includes structures such as isooctyl alcohol feed port 1, mixed acid feed port 3, reaction liquid outlet 5, reaction outer sleeve 7 and reaction inner sleeve 8; the size of the spiral microchannel reactor can be any size as long as it can ensure that the residence time of the reaction raw materials and the reaction pressure are within a suitable range, and is usually coordinated with the specific raw material dosage.

[0020] Among them, the outer surface of the reaction inner sleeve 8 is formed with an external thread, and the inner surface of the reaction outer sleeve 7 is formed with an internal thread matching the external thread; the internal thread of the reaction outer sleeve 7 and the external thread of the reaction inner sleeve 8 are spaced and arranged correspondingly, so that a micro reaction channel 9 is formed therebetween, and at this time, the gap between the internal thread and the external thread is 0.2~4mm (that is, the width of the micro reaction channel 9 is 0.2~4mm).

[0021] The isooctyl alcohol feed port 1 can be provided on the reaction outer sleeve 7, or on the reaction inner sleeve 8, or between the reaction outer sleeve 7 and the reaction inner sleeve 8, as long as the isooctyl alcohol feed port 1 can be connected to the bottom of the micro-reaction channel 9, so that the isooctyl alcohol can be input into the micro-reaction channel 9 through the isooctyl alcohol feed port 1; the isooctyl alcohol feed port 1 is connected to the advection pump (i.e., the isooctyl alcohol feed pump) through a pipeline, so that the flow rate of the isooctyl alcohol can be controlled by the advection pump. Similarly, the mixed acid feed port 3 can be provided on the reaction outer sleeve 7, or on the reaction inner sleeve 8, or between the reaction outer sleeve 7 and the reaction inner sleeve 8, as long as the mixed acid feed port 3 can be connected to the bottom of the micro-reaction channel 9, so that the mixed acid can be input into the micro-reaction channel 9 through the mixed acid feed port 3; the mixed acid feed port 3 is also connected to another advection pump (i.e., the mixed acid feed pump) through a pipeline, so that the flow rate of the mixed acid can be controlled by the advection pump. The reaction liquid outlet 5 is connected to the top of the micro-reaction channel 9. The reaction liquid outlet 5 can be opened on the reaction outer sleeve 7, or on the reaction inner sleeve 8, or between the reaction outer sleeve 7 and the reaction inner sleeve 8, as long as the reaction liquid can be connected to the top of the micro-reaction channel 9, so that the reaction liquid after the nitration reaction can be discharged through the reaction liquid outlet 5.

[0022] In this embodiment, the spiral microchannel reactor also includes an inner jacket 11 and an outer jacket 10, the inner jacket 11 is formed on the inner wall of the inner reaction sleeve 8 (the formation method is usually a conventional method such as welding, the same below), and the outer jacket 10 is formed on the outer wall of the outer reaction sleeve 7, so that the mass transfer and heat transfer process of the outer reaction sleeve 7 and the inner reaction sleeve 8 can be strengthened to ensure the uniformity of temperature, thereby ensuring the stability of the reaction. The outer shell 6 is coated on the outer surface of the outer jacket 10 to protect its internal structure. The baffles 12 are alternately formed on the outer surface of the outer reaction sleeve 7 and the inner surface of the outer jacket 10 to further improve the heat transfer effect of the outer reaction sleeve 7.

[0023] In this embodiment, the spiral microchannel reactor also includes a multi-stage centrifugal extractor. In this embodiment, the centrifugal extractor has four stages (i.e., the first stage, the second stage, the third stage, and the fourth stage), which are respectively used for two-phase separation (the first stage), water washing (the second stage), alkali washing (the third stage), and water washing treatment (the fourth stage). The first-stage centrifugal extractor is connected to the reaction liquid outlet 5 through a pipeline, and is used to receive the reaction liquid and perform two-phase separation on it. After obtaining the upper organic phase, it is washed with water, washed with alkali, washed with water, etc. in sequence and finally output as a product (such as Figure 2 as shown). Example 2

[0024] This embodiment provides a continuous production method of isooctyl nitrate, using the spiral microchannel reactor in Example 1 (in this embodiment, the inner diameter of the micro-reaction channel 8 is 50 mm, the height is 50 mm, the height of the internal thread and the external thread are both 1 mm, the gap between the internal thread and the external thread is 1 mm, and the spacing between two adjacent internal threads is 5 mm), specifically as follows: Heat exchange medium is input into the inner jacket 11 and the outer jacket 10 to control the temperature of the micro-reaction channel 9 in the spiral micro-channel reactor to be 20° C. Add isooctyl alcohol to one container, and then add mixed acid (a mixture of concentrated nitric acid and fuming sulfuric acid, the mass concentration of concentrated nitric acid is 98%, the concentration of fuming sulfuric acid is 105%, and the molar ratio is 1:0.9 (the fuming sulfuric acid is calculated by converting all of it into sulfuric acid, the same below) to another container, and make the molar ratio of isooctyl alcohol to nitric acid in concentrated nitric acid be 1:1.1; Isooctyl alcohol and mixed acid are fed into the micro-reaction channel 9 through the isooctyl alcohol feed port 1 and the mixed acid feed port 3 by means of a horizontal flow pump for mixed contact to cause a nitration reaction; the flow rate of isooctyl alcohol is 3-8 g / min, the flow rate of mixed acid is 4-9 g / min (the flow rate of mixed acid is greater than that of isooctyl alcohol), the residence time is 10 s, and the reaction pressure is 0.05 MPa; The reaction liquid in the micro-reaction channel 9 is output through the reaction liquid outlet 5, and the two phases are separated in the first-stage centrifugal extractor to take the upper organic phase; the upper organic phase is then continuously washed with water (second-stage centrifugal extractor), alkali washed (third-stage centrifugal extractor), and washed with water (fourth-stage centrifugal extractor) and then dried to remove trace water to obtain the final product. After testing, the isooctyl alcohol conversion rate is 99.9%, the isooctyl nitrate content is 99.5%, and the yield is 99.01%. Example 3

[0025] This embodiment provides a continuous production method of isooctyl nitrate, which is basically the same as that disclosed in Example 2, except that the ratio of the components in the mixed acid is adjusted, and the molar ratio of nitric acid to fuming sulfuric acid is 1:0.8. The purity of the obtained isooctyl nitrate is 99.1%, and the conversion rate is 99.5%. Example 4

[0026] This embodiment provides a continuous production method of isooctyl nitrate, which is basically the same as that disclosed in Example 2, except that the temperature of the micro-reaction channel 9 in the spiral microchannel reactor is controlled to be 10° C., and the purity of isooctyl nitrate obtained is 98.8%, and its conversion rate is 99.0%.

[0027] Comparative Example 1 This example provides a continuous production method of isooctyl nitrate, which is basically the same as that disclosed in Example 2, except that concentrated sulfuric acid with a concentration of 98% is used instead of fuming sulfuric acid, and the purity of isooctyl nitrate obtained is 81.3%, and its conversion rate is 83.6%.

[0028] Comparative Example 2 This example provides a continuous production method of isooctyl nitrate, which is basically the same as that disclosed in Example 2, except that the molar ratio of isooctyl alcohol, nitric acid and fuming sulfuric acid is 1:1.3:2.6; the purity of isooctyl nitrate obtained is 97.0%, and the conversion rate is 97.5%.

[0029] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the contents of the present invention and implement them accordingly. They cannot be used to limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A continuous production method of isooctyl nitrate, characterized in that: The method uses mixed acid and isooctyl alcohol as raw materials and adopts a spiral microchannel reactor to carry out continuous nitration reaction at 10-30°C; the mixed acid is a mixture of concentrated nitric acid and fuming sulfuric acid.

2. The continuous production method of isooctyl nitrate according to claim 1, wherein: The concentration of the oleum is 102-110%, and the mass concentration of the concentrated nitric acid is 90-98%.

3. The continuous production method of isooctyl nitrate according to claim 2, wherein: The molar ratio of concentrated nitric acid to fuming sulfuric acid in the mixed acid is 1:0.8-0.

99.

4. The continuous production method of isooctyl nitrate according to claim 1, wherein: The molar ratio of the isooctyl alcohol to the concentrated nitric acid is 1:1.05-1.

2.

5. The continuous production method of isooctyl nitrate according to claim 1, characterized in that: The following steps are involved: The mixed acid and isooctyl alcohol are introduced into the spiral microchannel reactor respectively to mix and contact and perform nitration reaction; the residence time of the mixed acid and isooctyl alcohol in the spiral microchannel reactor is 1-15 s, and the reaction pressure is 0-0.5 MPa; The reaction liquid after nitration is separated into two phases, and the organic phase is taken and successively washed with water, washed with alkali, washed with water, and then dried.

6. The continuous production method of isooctyl nitrate according to claim 1, characterized in that: The spiral microchannel reactor comprises: A reaction inner sleeve (8), wherein an outer surface of the reaction inner sleeve (8) is formed with an external thread; A reaction outer sleeve (7), wherein the inner surface of the reaction outer sleeve (7) is formed with an internal thread matching the external thread; a micro-reaction channel (9) is formed between the internal thread and the external thread; An isooctyl alcohol feed port (1), wherein the isooctyl alcohol feed port (1) is connected to the bottom of the micro-reaction channel (9); A mixed acid feed inlet (3), the mixed acid feed inlet (3) being connected to the bottom of the micro-reaction channel (9); A reaction liquid outlet (5), wherein the reaction liquid outlet (5) is connected to the top of the micro-reaction channel (9).

7. The continuous production method of isooctyl nitrate according to claim 6, characterized in that: The spiral microchannel reactor also includes: An inner jacket (11), the inner jacket (11) being formed on the inner wall of the reaction inner sleeve (8); An outer jacket (10), wherein the outer jacket (10) is formed on the outer wall of the reaction jacket tube (7).

8. The continuous production method of isooctyl nitrate according to claim 7, characterized in that: The spiral microchannel reactor also includes: An outer shell (6), the outer shell (6) covering the outer surface of the outer jacket (10); Baffles (12), wherein the baffles (12) are alternately formed on the outer surface of the reaction jacket (7) and the inner surface of the outer jacket (10).

9. The continuous production method of isooctyl nitrate according to claim 7 or 8, characterized in that: The spiral microchannel reactor also includes: an isooctyl alcohol feed pump, the isooctyl alcohol feed pump being connected to the isooctyl alcohol feed port (1) via a pipeline; A mixed acid feed pump, the mixed acid feed pump being connected to the mixed acid feed port (3) via a pipeline; A multi-stage centrifugal extractor, wherein the multi-stage centrifugal extractors are sequentially connected in series and connected to the reaction liquid outlet (5), and are used to sequentially perform two-phase separation, water washing, alkali washing and water washing treatment on the reaction liquid.

10. The continuous production method of isooctyl nitrate according to claim 6, characterized in that: The gap between the internal thread and the external thread is 0.2-4 mm.

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