阅读说明：本技术 一种对苯二胺的生产方法 (Production method of p-phenylenediamine ) 是由 赵思远 于 2018-08-07 设计创作，主要内容包括：本发明在传统的硫化碱法基础上,以硫磺代替部分硫化碱,在冷却结晶过程中加入水合肼,在大幅度生产成本降低、减少废水的情况下,同时延长对苯二胺的储存时间,对苯二胺储存期6个月以上。(On the basis of the traditional alkali sulfide method, the invention replaces partial alkali sulfide with sulfur, adds hydrazine hydrate in the cooling crystallization process, and prolongs the storage time of p-phenylenediamine by more than 6 months under the conditions of greatly reducing the production cost and reducing the waste water.)

1. A process for preparing p-phenylenediamine from p-nitroaniline and sodium sulfide at 80 deg.C includes such steps as reaction, adding sulfur in batches, cooling, adding hydrazine hydrate, cooling, crystallizing, rectifying and slicing.

2. The method according to claim 1, wherein the mass ratio of the paranitroaniline to the alkali sulfide is 1: 4-1: 1.6.

3. The method according to claim 1, wherein the sulfur is added in two portions at a reaction temperature of 95 to 100 ℃.

4. The method according to claim 1, wherein the total amount of sulfur added is 0.35 to 0.40 times the mass of the sodium sulfide.

5. The method of claim 1, wherein hydrazine hydrate is added after cooling to crystallize at 75-80 ℃.

6. The method of claim 1, wherein the hydrazine hydrate is added in an amount of 0.3% to 0.8% by mass of the paranitroaniline.

7. The method of claim 1, wherein the hydrazine hydrate is added in an amount of 0.6% by mass based on the amount of p-nitroaniline.

8. The process of claim 1, 2 or 4, wherein the alkali sulfide is sodium sulfide.

Technical Field

The invention relates to a process for producing p-phenylenediamine, belonging to the field of fine chemical engineering.

Background

At present, most production enterprises of p-phenylenediamine adopt sodium sulfide to reduce p-nitroaniline, and the consumption per ton is as follows: 1.7t of p-nitroaniline and 2.5t of sodium sulfide, high production cost and large amount of three wastes, and has the advantages of relatively long storage period of the rectified p-phenylenediamine, half a month in summer and one month in winter. Some small enterprises still adopt the traditional iron powder reduction method, the produced products have low purity, and the products are used by lower-end customers.

A small number of enterprises adopt a p-nitroaniline hydrogenation reduction process, methanol or ethanol is adopted as a solvent, p-nitroaniline is hydrogenated to synthesize p-phenylenediamine in the presence of a catalyst Raney nickel, the reaction temperature is 90-180 ℃, the pressure is 1.0-2.0 MPa, but the product selectivity and yield are low, the equipment investment is large, the process is long, the operation is complex, and a certain safety risk exists in the hydrogenation process; the product has shorter storage period, usually about one week, because the alcohol is used as solvent, the selectivity is about 96 percent, the generated impurities are not easy to separate from the p-phenylenediamine, the product has the defects of high rectification cost and the like, and the storage period is shorter than that of the alkali sulfide method.

The Jiangsu petrochemical industry institute reports that the yield of methyl esterification is 97%, the yield of amidation is 90%, the yield of chlorination is 98%, the yield of degradation is 92% and the total yield is about 79% when PTA is subjected to methyl esterification, amidation, chlorination and degradation processes. In the engineering, water is used as a reaction medium, so that the production cost is reduced, the operation is more convenient and safer, the solvent is easy to recycle, and the pollutant discharge is reduced. Compared with 40-45 tons of wastewater per ton of products by a polyester degradation method, the pollution is greatly reduced to 10-15 tons of wastewater per ton of products, but the process has no report of industrial application.

CN200910145075.8 discloses a method for synthesizing p-phenylenediamine, which comprises the steps of putting a magnetic magnesium aluminum hydrotalcite solid base catalyst and p-nitroaniline into a reaction vessel, heating, slowly dropwise adding hydrazine hydrate for reaction at 0-100 ℃ for 0.5-20 hours, filtering the reaction solution while the reaction solution is hot after the reaction is finished, cooling, standing to separate out white crystals, filtering the crystallized reaction solution, and drying to obtain the product. The patent only can produce common p-phenylenediamine, and high-quality p-phenylenediamine can be produced only after rectification.

The invention discloses a preparation method of CN201210492883.3 p-phenylenediamine, which comprises the following steps: 1) ammonolysis: crushing the waste polyester beverage bottles, and stirring and reacting the crushed polyester beverage bottles with ethylene glycol and liquid ammonia to obtain terephthalamide; 2) chlorination: reacting terephthalamide with chlorine to obtain chloride; 3) and (3) Hofmann degradation: heating the chlorination product NaOH or KOH aqueous solution to carry out Hofmann degradation to obtain the p-phenylenediamine. The mother liquor is used for increasing the yield and reducing the consumption of raw materials in the ammonolysis and chlorination reactions. The brown wastewater contains more p-phenylenediamine in the degradation process. The solvent is used to extract it from waste water, so increasing yield and reducing pollution-controlling cost. There is no report of the industrial application of this patent.

CN 201610552383.2A continuous synthesis method of p-phenylenediamine, the invention provides a new technology for producing p-phenylenediamine by a continuous method. The process takes paranitroaniline, a solvent and hydrogen as main raw materials, the p-phenylenediamine crude product is prepared by hydrogenation reaction in a fixed bed reactor or a tubular reactor in the presence of a catalyst, the crude product is subjected to rectification recovery process to prepare high-purity p-phenylenediamine, and the excessive hydrogen and the solvent are recycled for reuse.

CN201210234276.7 is a method for absorbing nitrogen oxide tail gas and byproduct p-phenylenediamine by aniline, the invention is a method for absorbing nitrogen oxide tail gas and byproduct p-phenylenediamine by aniline, part of aniline reacts with NOx to generate diazonium salt, the diazonium salt couples with unreacted aniline to generate 1, 3-diphenyl triazene, and the product contains a small amount of p-nitroaniline and o-nitroaniline; rearranging 1, 3-diphenyltriazene in a rearrangement reactor at the temperature of 30-120 ℃ to convert the 1, 3-diphenyltriazene into p-aminoazobenzene, converting 90% of the rearranged 1, 3-diphenyltriazene into p-aminoazobenzene, and converting the rest into o-aminoazobenzene and a small amount of impurities; and (3) carrying out hydrogenation reaction after separating low fractions from the rearranged material, continuously introducing hydrogen by taking skeletal nickel as a hydrogenation catalyst, and synthesizing p-phenylenediamine by controlling the reaction pressure and temperature to be 0.2-4 MPa and 25-150 ℃. The patent has no industrial value.

CN 201510829612.6A method for preparing p-phenylenediamine, the invention mainly relates to a method for preparing p-phenylenediamine. The method comprises the steps of taking p-dinitrobenzene as a raw material, selenium as a catalyst, alkali as a cocatalyst, carrying out a nitro selective reduction reaction in an organic solvent under high pressure at a reaction temperature of 80-150 ℃, a reaction pressure of 1-10 MPa and a reaction time of 2-10 hours, cooling to room temperature, discharging gas, introducing oxygen or air, stirring for 1-2 hours, filtering, cooling filtrate for crystallization, carrying out suction filtration, and carrying out vacuum drying on a filter cake to obtain a p-phenylenediamine finished product. The invention has high production cost, high equipment requirement and large one-time investment.

Cn00124406.x discloses a process for preparing p-phenylenediamine, which comprises the following steps: reacting urea and nitrobenzene with alkali in a polar solvent to generate 4-nitrosoaniline and 4-nitroaniline; the resulting mixed solution is then diluted in an alcohol and hydrogenated with a catalyst to produce a high purity p-phenylenediamine free of ortho or meta isomeric by-products. The patent has the advantages of complex process, large equipment investment, troublesome operation and no industrialized report

None of the technical routes of the reference documents is relevant to the present invention.

Disclosure of Invention

The purpose of the invention is as follows: on the basis of the traditional alkali sulfide method, cheap sulfur is added in batches in the reaction process to partially replace alkali sulfide, and hydrazine hydrate is added in the cooling crystallization process, so that the production cost is greatly reduced, the waste water is reduced, and the storage time of p-phenylenediamine is prolonged.

The main technical scheme of the invention is as follows: a process for preparing p-phenylenediamine from p-nitroaniline and sodium sulfide at 80 deg.C or higher includes such steps as reaction, adding sulfur in batches, cooling, adding hydrazine hydrate, cooling, crystallizing, rectifying and slicing.

Generally, the input amount of the paranitroaniline and the sodium sulfide is 1: 4-1: 1.6 (mass ratio).

The reaction temperature is 95-100 ℃, and sulfur is added in two batches.

The total adding amount of the sulfur is 0.35-0.40 times of the mass of the sodium sulfide.

And the cooling crystallization temperature is 75-80 ℃, and hydrazine hydrate is added at the temperature.

The addition amount of the hydrazine hydrate is 0.3-0.8% of the mass of the paranitroaniline, and the preferred addition amount is 0.6%.

The sodium sulfide is sodium sulfide.

In the invention, a certain amount of sulfur is added in batches at different temperatures in the reaction process of producing p-phenylenediamine from p-nitroaniline and sodium sulfide, after the reaction is finished, a certain amount of hydrazine hydrate is added in the cooling and crystallization process, and the crystal after the crystallization is finished and the crystal is centrifuged is subjected to rectification and slicing to obtain the high-quality p-phenylenediamine.

Detailed Description

The technical solution of the present invention is further illustrated by the following examples.