AU2021102463A4 - A Method of Extracting Tetramethylbenzene from Light C10 Aromatic Solvent Oil - Google Patents

Abstract

The present invention discloses a method of extracting Tetramethylbenzene from light Cio aromatic solvent oil, including a continuous drive belt crystallization device, which includes a housing at an angle to the horizontal, a cooling medium tube, a drive belt set inside the housing, and a charging port and a crystal discharge port set on the surface of the housing, the cooling medium tube being close to the lower surface of the upper side belt of the drive belt, and the charging port being located above the upper side belt of the drive belt, including adding raw materials to the upper side belt surface of the drive belt through the charging port and controlling the feed rate, by controlling the temperature of the drive belt through the cooling medium tube and controlling the residence time of the raw materials on the belt at the same time. When the crystals on the drive belt reach the upper end, the crystals are taken from the crystal outlet to obtain the Tetramethylbenzene. The method of the invention can be operated continuously, and the device used facilitates the control of crystallization temperature and the separation of crystallization and mother liquor, and after the separation under optimized conditions, the Tetramethylbenzene crystals can be obtained up to 99.18% at one time, and the yield can be as high as 90.95%.

Description

A Method of Extracting Tetramethylbenzene from Light C1 0 Aromatic Solvent Oil

TECHNICAL FIELD The present invention discloses a method for extracting Tetramethylbenzene from light Cio aromatic solvent oil, which belongs to the field of chemical raw material extraction technology. BACKGROUND Tetramethylbenzene is an important raw material for the current production of Tetramethylbenzene dianhydride, which is the most economical and ideal raw material for the production. At present, there are mainly adsorption and crystallization methods for Tetramethylbenzene refining, adsorption method is to absorb Tetramethylbenzene on the zeolite of file exchange X, remove other non-adsorbed aromatic hydrocarbons, and then use low boiling point hydrocarbons (>5°C) to desorb the adsorbed material, and then use flash steam to remove low boiling point hydrocarbons to get Tetramethylbenzene, In the adsorption and desorption process, the product purity is not stable and continuous operation is difficult; crystallization generally has kettle crystallization, column and Crystallization generally has kettle crystallization, column and tube crystallization and falling film crystallization, etc. Kettle crystallization is simple, but the product purity and yield is low, but the operation is simple and intermittent; column and tube crystallization device has a simple structure,after the material is added to the inside of the crystallizer, the hot and cold medium is passed into the jacket for temperature control until crystallize components are completely crystallized, which can generally meet the design requirements, but the crystallization time is long, the contact area of the hot and cold medium is small, and the temperature is difference inside, especially the crystallization process is not uniform, and the purity and yield of the crystallized products are low; the tube crystallization device is a crystallization method in which the cooling medium is passed in the tube process and the raw material is passed in the shell process to increase the contact area of hot and cold medium, which requires two steps of crystallization and melting, and the crystals are easy to stick to the outer wall when dealing with the material with larger grains, which is easy to cause the blockage of the crystal slurry and cannot realize long time Continuous operation. SUMMARY Objective of the invention: In order to make up for the existing production deficiency, the invention provides a method of extracting Tetramethylbenzene from light Cio aromatic solvent oil by continuous drive crystallization, which uses a continuous drive steel belt as the crystallization carrier and controls the temperature and rotation speed during the drive of the belt to achieve the purpose of extracting Tetramethylbenzene from light Cio aromatic solvent oil. The process realizes continuous crystallization and separation as a whole and operates at the same temperature, and after separation, homotetraphenyl crystals of up to 99.18% can be obtained at one time, and the yield can be as high as 90.95%. Technical solution: The present invention provides a method for extracting Tetramethylbenzenes from light Cio aromatic solvent oil, the method includes a continuous drive belt crystallization device, the device includes a housing at an angle to the horizontal, a cooling medium tube and a drive belt set inside the housing, and a charging port and a crystal discharge port set on the surface of the housing, the cooling medium tube is close to the lower surface of the side belt on the drive belt, and the charging port is located above the side belt on the drive belt. The cooling medium tube is close to the lower surface of the upper side steel belt of the drive steel belt, and the charging port is located above the upper side steel belt of the drive steel belt. The method includes adding raw materials to the upper side steel belt surface of the drive steel belt through the charge port, controlling the charge speed, controlling the temperature of the drive steel belt through the cooling medium tube, and also controlling the residence time of the raw materials on the steel belt, and taking the crystals from the crystal discharge port when the crystals on the drive steel belt reach the upper end, which results in the Tetramethylbenzenes. In the method, the charge rate is 40-80 ml/h, preferably 60 ml/h; the drive steel belt temperature is -10-0°C, preferably -5 to -6°C, and the residence time is 3-5h, preferably 4 hours. In the continuous drive steel belt crystallization device, the shell surface is also provided with a mother liquor outlet, the drive steel belt rotates clockwise upward, the crystal outlet is located near the upper end of the drive steel belt, and there is a scraper blade in contact with the steel belt of the drive steel belt, which can make the solid material on the steel belt fall into the crystal outlet, and the mother liquor outlet is located near the lower end of the drive steel belt. The housing is at a certain angle to the horizontal direction, wherein the angle is 15 0. The cooling medium tube is a serpentine cooling tube, which is provided with a refrigerating medium inlet at the low horizontal position end and a refrigerating medium outlet at the high horizontal position end. The drive steel belt is provided with a rotation shaft and a speed control motor at the high end of the horizontal position, and a drive shaft at the low end of the horizontal position. The charge ports include a first charge port, a second charge port and a third charge port. The crystal collection tank is also provided below the crystal outlet. The shell surface, near the location of the cooling medium tube is also provided with a first temperature measurement point and a second temperature measurement point Technical effect: Compared with the prior art, the method of the invention can be operated continuously and the device used is easy to control the crystallization temperature After the separation of the crystals and the mother liquor, the Tetramethylbenzene based crystals can be obtained up to 99.18% at one time and the yield can be up to 90.95% after the optimized conditions. BRIEF DESCRIPTION OF THE FIGURES Figure 1 shows the process flow diagram of the method of the present invention, which includes: drive shaft 2, first charge port 4, second charge port 5, third charge port 6, drive steel belt 7, rotation shaft 8, scraper blade 10, crystal discharge port 11, crystal collection tank 12, housing 13, mother liquor discharge port 14, freezing medium inlet 15, freezing medium outlet 16, first temperature measurement point 17, second temperature measurement point 18 and low temperature circulation freezer 19.

Figure 2 shows a side view of the continuous drive steel belt crystallization device in the method of the present invention: which includes: cooling medium tube 3, speed control motor 9, the rest as in Figure 1. FIG. 3 is a top perspective view of the continuous drive steel belt crystallizer in the method of the present invention, wherein the accompanying markings are the same as in FIGS. l and 2. Figure 4 shows the effect of temperature on purity and yield in the method of the present invention. Figure 5 shows the effect of residence time on purity and yield in the method of the present invention. Figure 6 shows the effect of charge rate on purity and yield in the method of the present invention,

DESCRIPTION OF THE INVENTION The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments described are helpful in the understanding and implementation of the invention and do not constitute a limitation of the invention, and the implementation of the invention, in addition to the materials and distillation operating conditions covered in the specific embodiments, can be equivalently or equivalently transformed by those skilled in the art for different separation purposes. Unless otherwise stated, the percentages in the present invention are mass percentages. Example 1 The continuous drive steel belt crystallization device in the method of the present invention, as shown in FIGS. 1 and 2, includes a housing 13 at an angle to the horizontal, a cooling medium tube 3 and a drive steel belt 7 set inside the housing 13, and a charging port, a crystal outlet 11 and a mother liquor outlet 14 set on the surface of the housing 13; the cooling medium tube 3 is close to the lower surface of the upper side steel belt of the drive steel belt 7. The charging port is located above the upper side steel belt of the drive steel belt 7, the drive steel belt 7 rotates clockwise upward, the crystal outlet 11 is located near the upper end of the drive steel belt 7 and is provided with a scraper blade 10 in contact with the steel belt of the drive steel belt 7 to enable the solid material on the steel belt to fall into the crystal outlet 11, and the mother liquor outlet 14 is located near the lower end of the drive steel belt 7. The housing 13 at an angle to the horizontal, wherein the angle is 15-450 The cooling medium tube 3 is a serpentine cooling tube with a refrigerated medium inlet 15 at the low horizontal position end and a refrigerated medium outlet 16 at the high horizontal position end. The horizontal position of the drive steel belt 7 is equipped with a rotation shaft 8 and a speed control motor 9 at the high end, and a drive shaft 2 at the low end. The charge ports include a first charge port 4, a second charge port 5 and a third charge port 6. A crystal collection tank 12 is also provided below the crystal outlet 11 The surface of the housing 13 near the cooling medium tube 3 is also provided with a first temperature measurement point 17 and a second temperature measurement point 18. The basic working principle and method of the device are as follows (1)The cooling serpentine tube 3 controls the temperature of the cooling medium, which enters from the lower end of the serpentine cooling tube 3 and exits from the upper end of the drive crystallizer, and then returns to the low temperature circulation freezer 19. (2) Three charge ports are designed above the drive belt crystallization device, including the first charge port 4, the second charge port 5 and the third charge port 6, and different charging positions are selected according to the composition of raw materials. The design of the drive steel belt size is 150mm x 1000mm,through the serpentine condensation tube 3 to control the temperature of the drive steel belt 7 and the crystallization temperature, through the speed control motor 9 to control the drive speed of the steel belt, to control the time of the raw material on the steel belt. (3) When the temperature and drive speed are stable, control the charging speed of raw materials, and when the crystals on the drive steel belt reach the upper end, take the crystals from the crystal outlet 11 and the mother liquor from the mother liquor outlet 14 at the lower end for analysis. The charging volume is adjusted in equal proportion to the drive steel belt 7 specification. Example 2

Method of extracting Tetramethylbenzenes from light Cio aromatic solvent oil using the continuous drive steel belt crystallization unit described above. According to the operation method of the above device, the raw material Cio aromatic solvent oil (about 36% mass content of Tetramethylbenzene, see Table 1 for details) is added to the upper side of the steel belt surface of the drive steel belt through the charging port to control the charging speed, to control the temperature of the drive steel belt through the cooling medium tube, and also to control the residence time of the raw material on the steel belt, and when the crystals on the drive steel belt reach the upper end, the crystals are taken from the crystal discharge port, and the the Tetramethylbenzene is obtained. In the described method, the charge rate is 40-80 ml/h, the temperature of the drive steel belt is -1O-0°C, and the residence time is 3-5h. Specifically as follows. 1. light Cio aromatics containing 36.87% Tetramethylbenzene as raw material, C1O aromatic solvent oil was added from the upper part of the drive steel belt crystallizer, controlling the feed rate of 60 ml/h, maintaining the residence time of the raw material on the belt for 4h, and investigating the changes of the control temperature on the content and yield of Tetramethylbenzene. The relationship between crystallization temperature and paraxylene content and yield is shown in Figure 4, which shows that the crystallization temperature is controlled from 0 to -6 °C, the content and yield of paraxylene is on the rise, when the crystallization temperature reaches -5 to -6 °C, the content and yield of paraxylene reaches the maximum, continue to reduce the crystallization temperature paraxylene content has decreased, the yield does not change significantly, so the temperature of -5 to -6 °C is the best crystallization temperature. 2. under the condition of the crystallization temperature of -5- -6 °C, the amount of ml / h, to investigate the effect of residence time on the content and yield of Tetramethylbenzene, respectively, considering the residence time of 3, 3 .5, 4, 4 .5, 5h for Tetramethylbenzene content and yield changes is the adequate response. The results are shown in Fig.5. The content and yield of Tetramethylbenzene reached the maximum value when the residence time was controlled at 4 h. After the residence time was extended, the content of Tetramethylbenzene decreased and the yield did not change much, so the residence time of 4 h was better.

3. the changes of charge rate on the content and yield of Tetramethylbenzenes were investigated by controlling the -5 to -6°C and residence time 4h. The results are shown in Fig. 6, which shows that when the charge rate increased to 60 ml/h, the content of Tetramethylbenzenes reached 99.18% and decreases when the charge rate increases to 60 ml/h, but the yield does not change much. Therefore, it is more appropriate to control the charge rate at 60 ml/h.

4. for the crystallizer with 150 mmx1000 mm drive belt, it is more appropriate to control the charge rate of 60 ml/h, the temperature of the drive belt -5--6°C and the

residence time of 4h. Under the optimized conditions, the separation results are shown in Table 1, and the purity and yield of Tetramethylbenzene reached 99.18% and 90.95%, respectively. Table 1 Results of a continuous drive crystallization for the extraction of Tetramethylbenzene from light Cio aromatic solvent oil

composition Material volume (g/h) component (wt%) 1-Ethyl-2,4- 0.2561 dimethylbenzene Tetramethylbenzene 0.3687 light Cio 1,2,3,5- 0.1684 aromatic 48 Tetramethylbenzene solvent 1,2,3,4- 0.1217 oil Tetramethylbenzene 1,3-Diisopropylbenzene 0.0753 1,3,5-Triethylbenzene 0.0011 naphthalene 0.0087 1-Ethyl-2,4- 0.0024 dimethylbenzene Tetramethylbenzene 0.9918 Crystal 1,2,3,5- 0.0017 Tetramet 16.22 Tetramethylbenzene hylbenze 1 1,2,3,4- 0.0009 ne Tetramethylbenzene 1,3-Diisopropylbenzene 0.0002 1,3,5-Triethylbenzene 0.0000 naphthalene 0.0030 1-Ethyl-2,4- 0.3856 Mother 31.78 dimethylbenzene liquid Tetramethylbenzene 0.0507 1,2,3,5- 0.2535

Tetramethylbenzene 1,2,3,4- 0.1833 Tetramethylbenzene 1,3-Diisopropylbenzene 0.1136 1,3,5-Triethylbenzene 0.0017 naphthalene 0.0116

Example 3 The apparatus and method are the same as in Examples 1 and 2, differing only in the following. Charge rate of 40 ml/h, drive belt temperature of -10 - 9 °C and residence time of 5 h. The final purity and yield of Tetramethylbenzene reached 98.67% and 89.34%, respectively. Example 4 The apparatus and method are the same as in Examples 1 and 2, differing only in the following. Charge rate of 80 ml/h, drive belt temperature of -1-0°C and residence time of 3h. The final purity and yield of Tetramethylbenzene reached 98.72% and 89.45%, respectively.

Claims (9)

1. THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1 . A method for extracting Tetramethylbenzene from a light Cio aromatic solvent oil characterizes in that a continuous drive belt crystallization device, which includes a housing at an angle to the horizontal, a cooling medium tube, a drive belt set inside the housing, and a charging port and a crystal discharge port set on the surface of the housing, the cooling medium tube being close to the lower surface of the upper side belt of the drive belt, and the charging port being located above the upper side belt of the drive belt. The method includes adding raw materials to the upper side steel belt surface of the drive steel belt through the feeding port, controlling the feeding speed, controlling the temperature of the drive steel belt through the cooling medium tube, and also controlling the residence time of the raw materials on the steel belt, and taking the crystals from the crystal discharge port when the crystals on the drive steel belt reach the upper end, which results in the Tetramethylbenzene.
2. 2 . The method for extracting Tetramethylbenzene from light Cio aromatic solvent oil according to claim 1 characterizes in that the method has a feed rate of 40-80 ml/h, a drive steel belt temperature of -10-0°C and a residence time of 3-5h.
3. 3 . The method for extracting Tetramethylbenzene from light Cio aromatic solvent oil according to claim 1 characterizes in that in the continuous drive steel belt crystallization device, the housing surface is also provided with a mother liquor outlet, the drive steel belt rotates clockwise upward, the crystal outlet is located near the upper end of the drive steel belt, and a scraper blade is provided to contact with the steel belt of the drive steel belt to enable the solid material on the steel belt to fall into the crystal outlet The mother liquor outlet is located near the lower end of the drive steel belt.
4. 4 . The method for extracting Tetramethylbenzene from a light Cio aromatic solvent oil according to claim 1, the housing at an angle to the horizontal, wherein the angle is 15 0.
5. 5 . The method for extracting Tetramethylbenzene from light Cio aromatic solvent oil according to claim 1 characterizes in that the cooling medium tube is a serpentine cooling tube with a refrigerated medium inlet at the low horizontal position end and a refrigerated medium outlet at the high horizontal position end.
6. 6 . The method of extracting Tetramethylbenzene from light Cio aromatic solvent oil according to claim 1 characterizes in that the drive steel belt is provided with a rotating shaft and a speed control motor at the horizontally positioned high end, and a drive shaft at the horizontally positioned low end.
7. 7 . the method for extracting Tetramethylbenzene from a light Cio aromatic solvent oil according to claim 1 characterizes in that the dosing ports comprise a first dosing port, a second dosing port and a third dosing port.
8. 8 . The method for extracting Tetramethylbenzene from light Cio aromatic solvent oil according to claim 1 characterizes in that the crystal discharge port is further provided with a crystal collection tank below the crystal discharge port.
9. 9 . The method for extracting Tetramethylbenzene from light Cio aromatic solvent oil according to claim 1 characterizes in that the housing surface, near the cooling medium tube is further provided with a first temperature measurement point and a second temperature measurement point.