阅读说明：本技术 一种邻氯苯胺的制备方法 (Preparation method of o-chloroaniline ) 是由 奚雪荣 单迎梅 苏复 杨文兵 于 2018-06-29 设计创作，主要内容包括：本发明提供了一种邻氯苯胺的制备方法,本发明包括以下的原料：邻硝基氯化苯、催化剂、双氰胺、溶剂、氮气、氢气；本发明通过使用Ru/C作为催化剂,组分简单、活性稳定,选择性高,同时使用双氰胺作为脱氯抑制剂,有效地抑制了脱氯副反应,转化率高、选择性高；通过改善精馏塔的结构,改善了传热、传质方面汽液传质性能,利用辅助件,增加了气液相间的接触面积；通过台阶结构的进流堰以及湍流块,有效地增大了湍流程度,从而提高了气液相间的传质换热效率与速率；通过流通槽提高了液相的处理、流通能力,利用降液管的挡板设置及内径变化,有利于延长气液相间的接触时间,从而提高邻氯苯胺的产率的纯度。(The invention provides a preparation method of o-chloroaniline, which comprises the following raw materials: ortho-nitrochlorobenzene, a catalyst, dicyandiamide, a solvent, nitrogen and hydrogen; according to the invention, Ru/C is used as the catalyst, so that the catalyst is simple in component, stable in activity and high in selectivity, and meanwhile, dicyandiamide is used as a dechlorination inhibitor, so that the dechlorination side reaction is effectively inhibited, and the catalyst is high in conversion rate and selectivity; the structure of the rectifying tower is improved, the vapor-liquid mass transfer performance in the aspects of heat transfer and mass transfer is improved, and the contact area between gas and liquid is increased by using an auxiliary component; the turbulence degree is effectively increased through the inflow weir with the step structure and the turbulence block, so that the mass transfer and heat exchange efficiency and speed of gas-liquid interphase are improved; the liquid phase treatment and circulation capacity is improved through the circulation groove, and the gas-liquid interphase contact time is favorably prolonged by utilizing the baffle arrangement and the inner diameter change of the downcomer, so that the purity of the yield of the o-chloroaniline is improved.)

1. The preparation method of o-chloroaniline is characterized by comprising the following raw materials: o-nitrochlorobenzene, a catalyst, dicyandiamide, a solvent, nitrogen (steel cylinder) and hydrogen (steel cylinder);

the preparation method comprises the following steps:

step (1): weighing 80-200g of ortho-nitrochlorobenzene, 20-50g of catalyst, 3-6g of dicyandiamide and 2000ml of solvent according to parts by weight;

step (2) primary mixing: adding ortho-nitrochlorobenzene and a solvent into an autoclave, and then sequentially adding a catalyst and dicyandiamide;

and (3): sealing the autoclave, replacing the air in the autoclave with nitrogen for 3-7 times, then replacing the nitrogen in the autoclave with hydrogen, and boosting the pressure to 0.8-2 MPa; maintaining the pressure unchanged after boosting, stirring and heating to 60-120 ℃, and reacting for 2-5 hours in a timing manner;

in the step (4): after the reaction is finished, cooling water is added for cooling and pressure relief, after the pressure relief is finished, the upper layer material in the high-pressure kettle is taken out and poured into a rectifying device for rectification, and the o-chloroaniline is obtained after rectification.

2. The method according to claim 1, wherein the solvent is one of methanol, ethanol and isopropanol.

3. The method for preparing o-chloroaniline according to claim 1, wherein the catalyst is Ru/C, and the preparation method comprises the following steps: taking RuCl₃Mixing with pure water to obtain RuCl₃Adding pure concentrated hydrochloric acid into the solution to adjust the pH value to 1, then adding activated carbon into the solution, sealing the solution, standing the solution at room temperature for 12 to 24 hours, then placing the solution in a double-hole constant-temperature water bath to heat the solution at the temperature of 45 to 60 ℃, simultaneously stirring and refluxing the solution for 1 to 2 hours, finally adding NaOH to adjust the pH value to alkalinity, reducing the solution by using pure formaldehyde, filtering and washing the solution until no chloride ions exist in the filtrate, and carrying out suction filtration to obtain the Ru/C catalyst.

4. The method for preparing o-chloroaniline according to claim 1, wherein in step (1), the rectifying device comprises a rectifying tower, a reboiler, a condenser and a raw material preheater, and the rectifying tower comprises a rectifying tower body, a tower tray and a skirt;

the bottom of the rectifying tower body is fixed on the skirt, and the rectifying tower body is sequentially provided with a gas outlet, a reflux inlet, a feed liquid inlet, a gas inlet and a liquid outlet from top to bottom;

the rectifying tower body comprises a plurality of tower sections, two adjacent tower sections are connected through flanges, a plurality of tower trays are arranged in each tower section in a cross-flow mode from top to bottom, and the tower trays are arranged in a cross-flow mode;

the tray comprises a tray plate, a downcomer, an inflow weir and an overflow weir;

the two sides of the tower plate are respectively provided with an inflow weir and an overflow weir, and one side of the overflow weir, which is far away from the tower plate, is provided with a downcomer;

the tower plate is provided with a plurality of rectifying holes, each rectifying hole is provided with an auxiliary part, each auxiliary part comprises a main fin and an auxiliary fin, the main fins are of a door-shaped structure and comprise first flow deflectors and second flow deflectors, the first flow deflectors are positioned on the front side and the rear side of the second flow deflectors, the first flow deflectors are connected with the tower plate, the auxiliary fins are respectively arranged on the left side and the right side of the main fins, and the auxiliary fins are connected with the second flow deflectors; the section of the secondary fin is in a step shape.

5. The method for preparing o-chloroaniline according to claim 4, wherein the inflow weir comprises a plurality of inflow steps, the height of the inflow steps is gradually reduced along the X direction, the length of the inflow steps is gradually increased along the X direction, the inflow steps comprise a flat flow plate and a turbulent flow plate, the flat flow plate and the turbulent flow plate are connected in an inclined manner, a plurality of turbulent flow blocks are arranged on the flat flow plate, and the turbulent flow blocks are uniformly distributed along the Y direction.

6. The method for preparing o-chloroaniline according to claim 4, wherein the overflow weir is provided with a plurality of flow channels, the flow channels are distributed along the Y direction, and the cross section of each flow channel is in the shape of one of a semicircle, a triangle and a rectangle.

7. The method for preparing o-chloroaniline according to claim 4, wherein the downcomer comprises an upper pipe and a lower pipe, the inner diameter of the upper pipe is gradually reduced from top to bottom, a plurality of baffles are arranged in the upper pipe, and the baffles are arranged in a mutually crossed manner from top to bottom; the inner diameter of the lower pipe is gradually increased from top to bottom, a plurality of baffles are arranged in the lower pipe, and the baffles are arranged in a mutually crossed mode from top to bottom.

8. The method for preparing o-chloroaniline according to claim 7, wherein the inner diameter of the lower end of the upper pipe is R1, the inner diameter of the upper end of the lower pipe is R2, and R2 is R1; the baffle is connected with the downcomer in an inclined mode, and the included angle between the baffle and the horizontal plane is 30-60 degrees.

9. The method according to claim 5, wherein the angle between the turbulent plate and the advective plate is 60-90 °.

Technical Field

The invention relates to the technical field of fine chemical engineering, in particular to a preparation method of o-chloroaniline.

Background

O-chloroaniline is an important fine chemical intermediate, and is widely used for the production of pesticides, medicines, dyes, polyurethane industry and other chemicals. At present, o-chloroaniline is industrially produced by using o-nitrochlorobenzene as a raw material and preparing the o-chloroaniline by a reduction method. The traditional nitro reduction method comprises iron reduction, electrolytic reduction and sodium sulfide or hydrazine hydrate reduction, and has the insurmountable defects of serious pollution caused by the iron reduction, high energy consumption of the electrolytic reduction method and low yield of the sodium sulfide reduction method, so the traditional methods are gradually eliminated. The catalytic hydrogenation reduction method is increasingly emphasized due to the advantages of short reaction route, environmental friendliness, good product quality, high yield, recyclable catalyst and the like, but the catalytic hydrogenation reduction method has the following problems in the process of preparing o-chloroaniline: firstly, dechlorination reaction is easy to occur, so that equipment is corroded, the product yield is reduced, and the activity of a catalyst is reduced; and secondly, in the rectification process of the o-chloroaniline, because the existing tower tray generally has the defects in the structure, the vapor-liquid mass transfer performance in the aspects of heat transfer and mass transfer is not high, so that the yield and the purity of the o-chloroaniline are influenced.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a preparation method of o-chloroaniline, which has the characteristics of high yield and high conversion rate.

The technical scheme for solving the problems comprises the following steps: the preparation method of o-chloroaniline comprises the following raw materials: o-nitrochlorobenzene, a catalyst, dicyandiamide, a solvent, nitrogen (steel cylinder) and hydrogen (steel cylinder);

the preparation method comprises the following steps:

step (1): weighing 80-200g of ortho-nitrochlorobenzene, 20-50g of catalyst, 3-6g of dicyandiamide and 2000ml of solvent according to parts by weight;

step (2) primary mixing: adding ortho-nitrochlorobenzene and a solvent into an autoclave, and then sequentially adding a catalyst and dicyandiamide;

and (3): sealing the autoclave, replacing the air in the autoclave with nitrogen for 3-7 times, then replacing the nitrogen in the autoclave with hydrogen, and boosting the pressure to 0.8-2 MPa; maintaining the pressure unchanged after boosting, stirring and heating to 60-120 ℃, and reacting for 2-5 hours in a timing manner

In the step (4): after the reaction is finished, cooling water is added for cooling and pressure relief, after the pressure relief is finished, the upper layer material in the high-pressure kettle is taken out and poured into a rectifying device for rectification, and the o-chloroaniline is obtained after rectification.

Further, the solvent is one of methanol, ethanol and isopropanol.

Further, the catalyst is Ru/C, and the preparation method comprises the following steps: taking RuCl₃Mixing with pure water to obtain RuCl₃Adding pure concentrated hydrochloric acid into the solution to adjust the pH value to 1, then adding activated carbon into the solution, sealing the solution, standing the solution at room temperature for 12 to 24 hours, then placing the solution in a double-hole constant-temperature water bath to heat the solution at the temperature of 45 to 60 ℃, simultaneously stirring and refluxing the solution for 1 to 2 hours, finally adding NaOH to adjust the pH value to alkalinity, reducing the solution by using pure formaldehyde, filtering and washing the solution until no chloride ions exist in the filtrate, and carrying out suction filtration to obtain the Ru/C catalyst.

Further, the rectifying device comprises a rectifying tower, a reboiler, a condenser and a raw material preheater, wherein the rectifying tower comprises a rectifying tower body, a tower tray and a skirt;

the bottom of the rectifying tower body is fixed on the skirt, and the rectifying tower body is sequentially provided with a gas outlet, a reflux inlet, a feed liquid inlet, a gas inlet and a liquid outlet from top to bottom;

the rectifying tower body comprises a plurality of tower sections, two adjacent tower sections are connected through flanges, a plurality of tower trays are arranged in each tower section in a cross-flow mode from top to bottom, and the tower trays are arranged in a cross-flow mode;

the tray comprises a tray plate, a downcomer, an inflow weir and an overflow weir;

the two sides of the tower plate are respectively provided with an inflow weir and an overflow weir, and one side of the overflow weir, which is far away from the tower plate, is provided with a downcomer;

the tower plate is provided with a plurality of rectifying holes, each rectifying hole is provided with an auxiliary part, each auxiliary part comprises a main fin and an auxiliary fin, the main fins are of a door-shaped structure and comprise first flow deflectors and second flow deflectors, the first flow deflectors are positioned on the front side and the rear side of the second flow deflectors, the first flow deflectors are connected with the tower plate, the auxiliary fins are respectively arranged on the left side and the right side of the main fins, and the auxiliary fins are connected with the second flow deflectors; the section of the secondary fin is in a step shape.

Furthermore, the inflow weir comprises a plurality of inflow steps, the height of the inflow steps is gradually reduced along the X direction, the length of the inflow steps is gradually increased along the X direction, the inflow steps comprise a flat flow plate and a turbulent flow plate, the turbulent flow plate is obliquely connected with the flat flow plate, a plurality of turbulent flow blocks are arranged on the flat flow plate, and the turbulent flow blocks are uniformly distributed along the Y direction;

furthermore, a plurality of circulation grooves are arranged on the overflow weir, the circulation grooves are distributed along the Y direction, and the cross section of each circulation groove is in one of a semicircular shape, a triangular shape and a rectangular shape.

Further, the downcomer comprises an upper pipe and a lower pipe, the inner diameter of the upper pipe is gradually reduced from top to bottom, a plurality of baffles are arranged in the upper pipe, and the baffles are arranged in a mutually crossed manner from top to bottom; the inner diameter of the lower pipe is gradually increased from top to bottom, a plurality of baffles are arranged in the lower pipe, and the baffles are arranged in a mutually crossed mode from top to bottom.

Further, the inner diameter of the lower end of the upper pipe is R1, the inner diameter of the upper end of the lower pipe is R2, and R2 is R1.

Further, the inclination angle between the turbulence plate and the advection plate is 60-90 degrees.

Furthermore, the baffle is connected with the downcomer in an inclined manner, and the included angle between the baffle and the horizontal plane is 30-60 degrees.

The invention has the following beneficial effects: according to the invention, Ru/C is used as the catalyst, so that the catalyst is simple in component, stable in activity and high in selectivity, and meanwhile, dicyandiamide is used as a dechlorination inhibitor, so that the dechlorination side reaction is effectively inhibited, and the catalyst is high in conversion rate and selectivity; the structure of the rectifying tower is improved, the vapor-liquid mass transfer performance in the aspects of heat transfer and mass transfer is improved, and the contact area between gas and liquid is increased by using an auxiliary component; the turbulence degree is effectively increased through the inflow weir with the step structure and the turbulence block, so that the mass transfer and heat exchange efficiency and speed of gas-liquid interphase are improved; the liquid phase treatment and circulation capacity is improved through the circulation groove, and the gas-liquid interphase contact time is favorably prolonged by utilizing the baffle arrangement and the inner diameter change of the downcomer, so that the purity of the yield of the o-chloroaniline is improved.

Drawings

FIG. 1 is a schematic view of the structure of the present invention.

FIG. 2 is a schematic view of a rectifying column according to the present invention.

Fig. 3 is a schematic diagram of the tray structure of the present invention.

Fig. 4 is a sectional view taken along a-a in fig. 3.

Fig. 5 is a schematic view of the structure of the tray of the present invention without the auxiliary members.

FIG. 6 is a schematic view of an inflow weir of the present invention.

Fig. 7 is a schematic structural view (1) of the auxiliary member of the present invention.

Fig. 8 is a schematic structural view (2) of the auxiliary member of the present invention.

In the figure: 1-a rectifying tower body, 2-a tray, 3-a skirt, 4-a liquid outlet, 5-a gas outlet, 6-a reflux liquid inlet, 7-a feed liquid inlet, 8-a gas inlet, 9-a tray, 10-a downcomer, 11-an inflow weir, 12-an overflow weir, 13-a rectifying hole, 14-an auxiliary part, 15-a main fin, 16-an auxiliary fin, 17-a first flow deflector, 18-a second flow deflector, 19-an inflow step, 20-a flat flow plate, 21-a turbulent flow plate, 22-a circulation groove, 23-an upper pipe, 24-a lower pipe, 25-a baffle, 26-a turbulent flow block, 101-a rectifying tower, 102-a 103-a condenser and 104-a raw material preheater.

Detailed Description

The invention is further described with reference to the following drawings and detailed description.