CN101250113B - Method for refining p-phenylene diamine - Google Patents

Abstract

The invention provides a refining method of p-phenylenediamine, which combines distillation and melting crystallization, uses the distillation product condensate to directly process melt crystallization for purification and processes fractional crystallization composed of one crystallization at least and one transpiration to obtain high-purity product. The invention combines distillation and melting crystallization to refine p-phenylenediamine and the invention can obtain high-purity and high-qaulity p-phenylenediamine product whose purity can reach 99.99-99.999% via controlling operation parameters, while the product quality can satisfy the quality demand of polymerization level product and the high-quality p-phenylenediamine can not be produced only by distillation. The refining method of p-phenylenediamine has the advantages of high product purity and flexible production set according to different standards, high yield of high-quality product and low cost, while the operation is processed without solvent to reduce pollution.

Description

A kind of process for purification of Ursol D

(1) technical field

The present invention relates to a kind of process for purification of Ursol D, especially higher process for purification such as the Ursol D of producing usefulness such as p-aramid fiber, video picture to quality requirements.

(2) background technology

Ursol D is a kind of broad-spectrum intermediate, can be used for raw material PPDI of producing dyestuff, pigment, hair dye, rubber antioxidant, p-aramid fiber, production urethane etc., being the check iron used always and the sensitive reagents of copper in addition, is the raw material of the poly-and photochromatic coupler of gasoline resistance etc.

Usually, the p-Nitroaniline reduction after the ammonification of Ursol D employing p-Nitrophenyl chloride makes.For obtaining high-purity Ursol D raw material, the Ursol D product that obtains through reduction all needs purification, and domestic traditional technology adopts the molten-castings method of cooling, but has shortcomings such as product quality is poor, operating environment is poor, economic benefit is low.

Based on molten-castings crystalline defective, people have developed the technology of rectifying separation, but rectification process is for the close Ursol D system of boiling point, conventional rectification often needs higher piece theoretical stage and very high reflux ratio, the requirement of the product of certain purity can be reached, but still the requirement of high purity product can not be satisfied; And the higher vacuum tightness of separation purification needs for the thermo-sensitivity system because vaporization heat is generally 3-5 times of melting heat, consider the influence of reflux ratio again, so the energy consumption of rectifying will be higher than fusion-crystallization.

Have the characteristics of easy oxidation discoloration based on Ursol D, both at home and abroad about the research emphasis of Ursol D all aspect the crystallization and purification.Xu Yaoliang has been described a kind of method of crystal refining Ursol D in China Patent No. CN100358860C, Ursol D through dissolving, crystallisation by cooling, forms the crystalline particulate body in aqueous solvent, is finished product through separation and vacuum-drying again.

Develop water/dimethylbenzene binary solvent extracting Ursol D crude product abroad.Impurity is dissolved in the dimethylbenzene, and Ursol D is dissolved in the water, and vaporize water is got the product Ursol D.

Solution crystal process need use solvent, in the solvent crystallization process, except that the crystallization operating unit, also need operating units such as centrifugal, drying and solvent recuperation, so long flow path, main equipment is more, and the existence investment is high, the treating process energy consumption is higher, the environmental problem of discharge of wastewater.

Because fusion-crystallization is showing huge superiority aspect some organism of separation purification, in the separation of specific system, brought into play important effect, it is refining to be used for product separation such as dichlorobenzene, nitro-chlorobenzene, smart Cai, dihydroxyphenyl propane, p-Xylol, Mono Chloro Acetic Acid, vinylformic acid, but does not still have the precedent of using in the purification of Ursol D system.Ursol D is in process of cooling, and the molecule activity ability is hindered, and is difficult to form the nucleus of oneself, in order to guarantee the throughput of crystallization apparatus, usually crystallization is difficult to reach equilibrium state, controlled by heat transfer, mass transfer and kinetics of crystallization, and crystal can produce inevitably and contain phenomenon, the mother liquor that contains impurity is contained, be mixed in the crystal, or stick to plane of crystal, make crystal purity descend, depart from equilibrium composition, separating effect obviously descends.

(3) summary of the invention

The objective of the invention is to overcome above-mentioned deficiency, a kind of superior product quality, with short production cycle, the process for purification of producing yield height, production cost is low, environmental effect is good Ursol D are provided.

The process for purification of Ursol D of the present invention carries out combination with rectifying and fusion-crystallization, utilizes rectifying product phlegma directly to carry out fusion-crystallization and purifies, by the fractional crystallization acquisition high purity product of primary crystallization and sweating at least.

Said method comprising the steps of:

(1) fusion-crystallization: the Ursol D crude product that rectifying separation is obtained adds in the crystallizer, after being heated to whole fusions,, being cooled to 120～125 ℃ and keeping 5～12h with the slow decrease temperature crystalline of 1.0～5.0 ℃/h speed, discharge mother liquor after the crystallization, obtain Ursol D crystal layer 1;

(2) sweating: the Ursol D crystal layer that heating steps (1) obtains makes partial melting (this step is called " sweating process ", and the liquid that fusion obtains is called " sweating raffinate ") for 1 to 130～140 ℃; Can adopt the classification sweating, keep lesser temps when sweating is initial, after a period of stabilisation, temperature be raise, keep for some time, so near temperature rises to the fusing point of pure product in this temperature;

(3) discharge the sweating raffinate, obtain Ursol D crystal layer 2;

(4) the Ursol D crystal layer 2 that obtains of heating steps (3) obtains Ursol D crystal layer 3 to whole fusions;

(5) the Ursol D crystal layer 3 of Shou Jiing is through cooling, section, the Ursol D finished product after must making with extra care.

Mother liquor can reuse after collecting storage tank in the described step (1).

The sweating raffinate reclaims the conduct middle crystallizer charging of step (1) during the commercial benzene diamines next time through distilling after in the described step (2).

Described step (2) sweating progression adopts 2～4 grades.Described sweating progression is 2～4 grades and is meant that intensification sweating process is divided into 2～4 temperature sections and carries out, be warming up to the temperature end value of each temperature section with given pace after, insulation for some time (at least 20 minutes), be warming up to the temperature end value of next temperature section again.

The operation of described step (1)～(4) can repeat 1～3 time, the Ursol D fused solution that upper level obtains purifying mixes with the part sweating of next stage, as the raw material of inferior one-level fusion-crystallization,, carry out step (5) operation again to the product that obtains required purity.

Described method needs to carry out in the presence of airtight and nitrogen, and used crystallizer, storage tank and pipeline all need nitrogen replacement and sealing.

Concrete, described method is as follows:

(1) fusion-crystallization: the Ursol D crude product that rectifying separation is obtained adds in the crystallizer, be heated to 143 ± 2 ℃, make the whole fusions of material, treat material and heat-conducting medium homo(io)thermism, with 2～5 ℃/h speed cooling, be cooled to 140 ℃ after, slowly lower the temperature with 1～3 ℃/h speed, be cooled to 120～125 ℃ and keep 5～12h, Open valve is discharged mother liquor after the crystallization, obtains Ursol D crystal layer 1;

(2) sweating: the Ursol D crystal layer 1 that heating steps (1) obtains is warming up to 130～140 ℃ with 1～3 ℃/h speed, adopt 2～4 thermogrades, keep for some time (each is more than the 20min) in each thermograde, total time 1～3h (is meant the total time that keeps in each thermograde this total time, do not comprise the time used in the temperature-rise period), make partial melting, discharge the sweating raffinate, obtain Ursol D crystal layer 2;

(3) repeat step (1)～(2) operation 1～3 time after Ursol D crystal layer 2 fusions that step (2) obtains, the Ursol D fused solution that upper level obtains purifying mixes with the part sweating of secondary fusion-crystallization, raw material as secondary fusion-crystallization, repeat fusion-crystallization, to the product that obtains required purity, obtain Ursol D crystal layer 3;

(4) the Ursol D crystal layer 3 that obtains of heating steps (3) is to whole fusions, cooling, section, the Ursol D finished product after must making with extra care.

The present invention adopts rectifying and fusion-crystallization bonded technology that Ursol D is made with extra care, by the red-tape operati parameter, can obtain 99.99～99.999% high purity, high-quality Ursol D product, quality product satisfies the requirement of polymerization-grade quality product, has obtained the high-quality Ursol D that only adopts rectification process to realize.

Operate in the closed reactor and carry out, cut off the source (air etc.) with Ursol D generation oxidizing reaction, prevent oxidizing reaction.

Whole crystal system does not have moving-member and adopts computer to control automatically, reduced labour cost and maintenance cost, compared, can improve the yield of high purity product with other process for refining, cut down the consumption of raw materials and the energy consumption for the treatment of process, significantly reduce the production cost of high purity Ursol D.

Because fusion-crystallization does not need solvent, avoided solution crystallization to produce the influence of waste water, so reduced pollution to environment to environment; Production technique is improved work situation, the protection worker health.

Beneficial effect of the present invention is mainly reflected in: the product purity height, and can require to arrange production according to different size, high purity product yield height, cost is low, operates under the condition of no solvent to carry out, pollute to lack.

(4) description of drawings

Fig. 1 is rectifying, fusion-crystallization device technique synoptic diagram;

Fig. 2 is the crystallization processes schema.

(5) embodiment

The present invention is described further below in conjunction with specific embodiment, but protection scope of the present invention is not limited in this:

Embodiment 1:

P-Nitroaniline shortening product removes moisture and solvent, be mixed into rectifying tower with the mother liquor of first step fusion-crystallization, under the about 0.096MPa of vacuum tightness, remove front-end volatiles such as low-boiling-point substance through rectification under vacuum, tower bottoms enters second rectifying tower, and rectifying steams Ursol D, condensation, obtain the Ursol D of purity 99%, put into (1) number medial launder, be used for follow-up crystallization purifying (flow process is referring to Fig. 2); Used crystallizer, storage tank and pipeline all seal, and with the wherein original air of nitrogen replacement.

In the stainless steel shell and tube of 3000L falling-film crystallizer, storage tank and tubing system (referring to Fig. 1): rectifying gained Ursol D phlegma, one-level crystalline second stage sweating, the mother liquor of secondary crystallization and the mixed solution of first step sweating of (1) number medial launder are put into reactor, add about 1200 kilograms;

Use thermal oil to make thermal barrier crystallizer is heated to 144 ℃, make material keep molten state, treat fused solution and thermal oil homo(io)thermism, by regulating the thermal oil temperature fused solution is slowly lowered the temperature with 5 ℃/h speed, slow down speed of cooling when being cooled to 140 ℃, cooling rate is kept 2.5 ℃/h, and continuing slowly lowers the temperature is cooled to 120～125 ℃, keeps 5～12h;

Open dispensing valve and put mother liquor, mother liquor enters elementary mother liquor medial launder;

Improve the thermal oil temperature,, adopt the secondary sweating according to temperature control program, first step sweating temperature of charge is brought up to 132 ℃, the 2nd grade of sweating temperature brought up to 138 ℃, and first step sweating is put into No. 1 mother liquor storage tank and collected, and second stage sweating is put into (1) number medial launder; Improve the thermal oil temperature, the heating crystal layer all melts crystallization, discharging naturally, and fused solution enters (2) number medial launder, obtains about 99.9% Ursol D, as the feeding liquid of secondary crystallization;

The secondary fusion-crystallization adopts and one-level crystallization phases technology together, and crystalline mother solution enters (1) number medial launder, and sweating temperature is adjusted into 135 ℃ and 139.2 ℃, and first step sweating enters (1) medial launder, and second stage sweating enters (2) number medial launder;

The heating crystal layer all melts crystallization, and discharging is collected product with holding tank naturally; Fused product adopts slicing machine to cool off section fast, packing, Ursol D purity 99.99%.

Single-stage crystalline product yield is about 70%, through the secondary groups trap with after, total yield of products can reach about 90%.

By the adjustment of crystallization progression and sweating temperature and sweating progression, can produce the product that meets various demands according to user's requirement.The product of above-mentioned secondary crystallization is as adopting three grades of sweatings, and the whole temperature of sweating is brought up to 139.6 ℃, and product purity can reach 99.995%, and technology adopts three grades of crystallization Ursol D purity can reach 99.999% according to this.

Claims (5)

1. the process for purification of a Ursol D, described method is carried out in the presence of airtight and nitrogen, may further comprise the steps:

(1) fusion-crystallization: the Ursol D crude product that rectifying separation is obtained adds in the crystallizer, after being heated to whole fusions,, being cooled to 120～125 ℃ and keeping 5～12h with the slow decrease temperature crystalline of 1.0～5.0 ℃/h speed, discharge mother liquor after the crystallization, obtain Ursol D crystal layer 1;

(2) sweating: the Ursol D crystal layer that heating steps (1) obtains makes partial melting for 1 to 130～140 ℃;

(3) discharge the sweating raffinate, obtain Ursol D crystal layer 2;

(4) the Ursol D crystal layer 2 that obtains of heating steps (3) obtains Ursol D crystal layer 3 to whole fusions;

(5) the Ursol D crystal layer 3 of Shou Jiing is through cooling, section, the Ursol D finished product after must making with extra care.

2. the method for claim 1 is characterized in that: mother liquor reuse after collecting storage tank in the described step (1).

3. the method for claim 1 is characterized in that: the sweating raffinate reclaims after distilling as crystallizer charging in the step (1) in the described step (2).

4. as the described method of one of claim 1～3, it is characterized in that: step (2) sweating progression adopts 2～4 grades, and the operation of step (1)～(4) repeats 1～3 time, carries out step (5) operation again.

5. the method for claim 1 is characterized in that described method is as follows:

(1) fusion-crystallization: the Ursol D crude product that rectifying separation is obtained adds in the crystallizer, be heated to 143 ± 2 ℃, make the whole fusions of material, treat material and heat-conducting medium homo(io)thermism, with 2～5 ℃/h speed cooling, be cooled to 140 ℃ after, slowly lower the temperature with 1～3 ℃/h speed, be cooled to 120～125 ℃ and keep 5～12h, Open valve is discharged mother liquor after the crystallization, obtains Ursol D crystal layer 1;

(2) sweating: the Ursol D crystal layer 1 that heating steps (1) obtains is warming up to 130～140 ℃ with 1～3 ℃/h speed, adopts 2～4 thermogrades, keeps more than the 20min in each thermograde, total time 1～3h, make partial melting, discharge the sweating raffinate, obtain Ursol D crystal layer 2;

(3) repeat step (1)～(2) operation 1～3 time after Ursol D crystal layer 2 fusions that step (2) obtains, the Ursol D fused solution that upper level obtains purifying mixes with the part sweating of secondary fusion-crystallization, raw material as secondary fusion-crystallization, repeat fusion-crystallization, obtain Ursol D crystal layer 3;

(4) the Ursol D crystal layer 3 that obtains of heating steps (3) is to whole fusions, cooling, section, the Ursol D finished product after must making with extra care.

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