CN102516817B - Method for preparing indigo white solution - Google Patents

Abstract

The invention discloses an environmentally friendly preparation method of indigo white solution. The preparation method comprises the following steps. Step 1. Take the oxidized indigo suspension that has not been washed and acidified, and mix the above suspension with the activated indigo Add the Raney nickel catalyst and sodium hydroxide into the high-pressure reactor, first replace the air in the reactor with nitrogen, then fill in hydrogen, adjust the temperature and pressure of the system, and carry out catalytic hydrogenation reaction; step 2, continue to feed hydrogen, Elevate the temperature and pressure of the system to carry out further hydrogenation reaction; step 3, stop the reaction, add a stabilizer, remove the catalyst by filtering to obtain an indigo white solution. The invention solves the disadvantages of polluted environment, high reaction pressure, high temperature and large amount of catalyst used in the prior art, and has higher yield.

Description

Environment-friendly preparation method of indigo white solution

technical field

The invention belongs to the category of indigo preparation, and in particular relates to a method for preparing indigo by catalytic hydrogenation.

Background technique

Indigo is a common vat dye used to dye cellulosic textile materials, especially blue denim. Indigo itself is insoluble in water. It must be converted into a water-soluble leuco indigo with fiber affinity when used. After being attached to the material to be dyed, it is oxidized into water-insoluble indigo by air to develop color. . In the traditional dyeing process, the reduction of indigo is carried out in an alkaline medium in a container upstream of the dye bath, using inorganic reducing agents, such as hydrosulfite and thiourea oxide, or organic reducing agents such as hydroxyacetone. The disadvantage of reducing indigo with the above-mentioned reducing agents is that when sodium hydrosulfite is used, the dyehouse wastewater contains high concentrations of sulfates; when hydroxyacetone is used, the wastewater contains high concentrations of oxygen-consuming substances. In this reduction method, the cost of wastewater treatment is high and has adverse effects on the environment.

WO-A-94/23114 discloses an environmentally friendly indigo reduction method, which uses catalytic reduction to prepare caustic indigo white solution from indigo suspension. Compared with conventional dyeing methods, it can reduce sulfate or organic matter in wastewater. content in.

The existing method of catalytic reduction to prepare indigo leuco indigo white needs to wash indigo to neutrality in advance, then add hydrochloric acid with a mass concentration of 10-15% for acidification, and then wash to neutrality before hydrogenation reaction. The washing and acidification process produces a large amount of waste liquid, which has adverse effects on the environment. At present, there is a lack of an environmentally friendly preparation method for indigo white that does not require washing and acidification of raw materials, low reaction temperature, low pressure, and less catalyst consumption.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for preparing indigo white solution with high reaction yield, low pressure, low temperature and less catalyst consumption. The method can avoid the washing and acidification process of raw materials, and has the characteristics of energy saving and environmental protection.

In order to solve the problems of the technologies described above, the technical solution adopted in the present invention is:

The environmental protection preparation method of indigo white solution is made up of following following steps,

Step 1: Take the oxidized indigo suspension that has not been washed and acidified, add the above suspension, Raney nickel catalyst, and sodium hydroxide into a high-pressure reactor, first replace the air in the reactor with nitrogen, and then Fill the hydrogen gas of 0.1~1MPa, seal the reaction kettle, raise the temperature to 80~110℃, continue to fill the hydrogen gas until the pressure in the reaction kettle is 1.5~3MPa, and react for 2.5~3.5h. During the reaction, when the pressure in the reaction kettle When the drop value is greater than 0.5 MPa, supplement hydrogen to restore the pressure in the reactor;

The proportioning of reaction materials is:

Solid indigo:Raney nickel mass fraction ratio=1:0.03~0.15;

Solid indigo: sodium hydroxide mass fraction ratio = 1: 0.075~0.35;

Solid indigo: water = 1: 0.5~3;

Step 2: After the reaction in step 1 is completed, raise the temperature of the reactor to 115~145°C, continue to fill in hydrogen until the pressure in the reactor is 3.5~5.5MPa, and react for 0.5~1h. During the reaction, when the reactor When the pressure drop value is greater than 0.5 MPa, supplement hydrogen to restore the pressure in the reactor;

Step 3: After the reaction in step 2 is completed, the reactor is cooled, the hydrogen in the reactor is replaced with nitrogen, the stabilizer is added into the reactor, and the Raney nickel is removed by filtration to obtain an indigo solution.

The stabilizer of the present invention is a bisphosphite antioxidant.

The improvement of the present invention is: the reaction temperature in step 1 is 105 DEG C, the pressure in the reactor is 2.5MPa, the reaction temperature in the step 2 is 130 DEG C, and the pressure in the reactor is 4.5 MPa; The ratio is:

Solid indigo:Raney nickel mass fraction ratio=1:0.1;

Solid indigo: sodium hydroxide mass fraction ratio = 1: 0.2;

Solid indigo: water = 1:1.

Owing to having adopted above-mentioned technical scheme, the technological progress that the present invention obtains is:

In the preparation method of indigo white of the present invention, firstly, the indigo suspension is subjected to catalytic hydrogenation treatment at a lower reaction temperature of 80-110°C and a pressure of 1.5-3 MPa, and then the reaction temperature of the system is raised to 115-145°C And pressure 3.5~5.5MPa, carry out further hydrogenation treatment to indigo. When the hydrogenation reaction is carried out at a lower reaction temperature and pressure, the catalytic effect of the catalyst can be fully exerted, and the occurrence of side reactions can be reduced. Increase the temperature and pressure of the reaction system for 2~3 hours to promote the reaction and increase the yield of indigo white. Due to the above-mentioned preparation method adopted, the present invention can react to obtain an indigo white solution with high yield and few by-products without washing and acidifying the raw material indigo, thereby avoiding the adverse effects of the wastewater produced by washing and acidifying processes on the environment Influence.

Add 0.1 mass part of Raney nickel catalyst and 0.2 mass part of sodium hydroxide to the suspension obtained by mixing 1 mass part of raw material solid indigo with 1 mass part of water, and react under the conditions of 110 ° C and 2.5 MPa The yield of indigo white can reach 85~90% in 5~8 hours; then react the above reaction solution at 130°C and 4.5 MPa for 2~3 hours, and the yield of indigo white can reach 95~98%. The above condition parameters can effectively reduce the occurrence of side reactions, and the obtained product has high purity and good solubility.

Detailed ways

The present invention will be described in further detail below in conjunction with specific embodiments.

Example 1

The indigo raw material of this embodiment is the indigo solid obtained by the oxidation method without washing and acidification treatment. Prepare indigo white solution as follows,

Step 1: Carry out leak detection of the autoclave, clean, dry and seal the autoclave, fill it with 0.8MP nitrogen, and keep it for 30 minutes. If the pressure does not drop significantly, it means that the autoclave is well sealed, and proceed to follow-up operations; Take a certain amount of solid indigo raw material, disperse it in water, and prepare it as a suspension. Add the suspension, Raney nickel catalyst, and sodium hydroxide into the reaction kettle, wherein the mass ratio of each component is indigo solid:Raney nickel:sodium hydroxide:water=1:0.15:0.35:3. Seal the reactor well, then use nitrogen to replace the air in the reactor for 3 times, and then replace it with hydrogen for 3 times, so that the hydrogen pressure in the reactor is 0.5MPa, seal the reactor, raise the temperature to 80°C, and fill it with hydrogen until the reaction The pressure in the kettle is 1.5MPa, and the reaction is 2.5h. During the reaction, when the pressure drop in the reactor is greater than 0.5MPa, hydrogen is added to restore the pressure in the reactor.

Step 2: After the reaction in step 1 is over, raise the temperature of the reactor to 115°C, continue to fill the reactor with hydrogen until the pressure in the reactor is 3.5MPa, and react for 0.5h. During the reaction, when the pressure drop in the reactor is greater than At 0.5 MPa, add hydrogen to restore the pressure in the reactor.

Step 3: After the reaction in step 2 is completed, lower the temperature in the reaction system to room temperature, vent the hydrogen in the reactor, and then replace it with nitrogen for 3 minutes, and add the bisphosphite antioxidant 626 into the reactor , to ensure that the reaction solution is not easily oxidized and deteriorated when exposed to air. Then filter out Raney nickel to obtain indigo white solution. Among them, the chemical name of antioxidant 626 is bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, which was purchased from Ningbo Jinhai Yabao Chemical Co., Ltd.

Calculate the yield of the indigo white solution prepared by the above method, and the result is 95.3%.

Example 2

The difference between the indigo white solution preparation method of the present embodiment and embodiment 1 is:

The mass ratio of each component in step 1 is indigo solid:Raney nickel:sodium hydroxide:water=1:0.1:0.2:1, the reaction temperature is 105°C, the reactor pressure is 2.5MPa, and the time is 3h;

In step 2, the reaction temperature is 130°C, the reactor pressure is 4.5 MPa, and the time is 0.8h.

The yield of gained indigo solution is 98.5%.

Example 3

The difference between the indigo white solution preparation method of the present embodiment and embodiment 1 is:

The mass ratio of each component in step 1 is indigo solid: Raney nickel: sodium hydroxide: water=1: 0.03: 0..075: 0.5, the reaction temperature is 110°C, the reactor pressure is 3 MPa, and the time is 3.5 h;

In step 2, the reaction temperature is 145° C., the pressure of the reactor is 5.5 MPa, and the time is 1 h.

The yield of gained indigo solution is 95.7%.

Example 4

The difference between the indigo white solution preparation method of the present embodiment and embodiment 1 is:

The mass ratio of each component in step 1 is indigo solid: Raney nickel: sodium hydroxide: water=1: 0.12: 0.22: 1.5, the reaction temperature is 110°C, the reactor pressure is 3 MPa, and the time is 2.8h;

In step 2, the reaction temperature is 135° C., the pressure of the reactor is 4 MPa, and the time is 0.6 h.

The yield of gained indigo solution is 96.3%.

Claims (3)

1. the environment-friendly preparation method of leucoindigo solutions, is characterized in that being comprised of following steps,

Step 1: get without the indigo suspension liquid after the oxidation of washing and acidification, above-mentioned suspension liquid and Raney's nickel catalyst, sodium hydroxide are added in autoclave, first use the air in the nitrogen replacement reactor, use again hydrogen exchange instead 3 times, be filled with again the hydrogen of 0.1～1MPa, closed reactor, be warmed up to 80～110 ℃, continuing to be filled with hydrogen to the pressure in reactor is 1.5～3MPa, reaction 2.5～3.5h, in reaction process, when the pressure drop value in reactor is greater than 0.5MPa, hydrogen make-up is recovered the pressure in reactor;

The proportioning of reaction mass is:

Solid is indigo: Raney's nickel ratio of quality and the number of copies=1: 0.03～0.15;

Solid is indigo: sodium hydroxide ratio of quality and the number of copies=1: 0.075～0.35;

Solid is indigo: water=1: 0.5～3;

Step 2: after the reaction in step 1 finishes, reactor is warming up to 115～145 ℃, continuing to be filled with hydrogen to the pressure in reactor is 3.5～5.5MPa, reaction 0.5～1h, in reaction process, when the pressure drop value in reactor is greater than 0.5MPa, hydrogen make-up is recovered the pressure in reactor;

Step 3: after the reaction in step 2 finishes, the question response still is cooling, and the hydrogen with in the nitrogen replacement reactor, add stablizer in reactor, adopts the method for filtering to remove Raney's nickel, obtains leucoindigo solutions.

2. the environment-friendly preparation method of leucoindigo solutions according to claim 1, it is characterized in that: described stablizer is bisphosphite anti-oxidant.

3. the environment-friendly preparation method of leucoindigo solutions according to claim 2, it is characterized in that: the temperature of reaction in step 1 is 105 ℃, and the pressure in reactor is 2.5MPa, and the temperature of reaction in described step 2 is 130 ℃, and the pressure in reactor is 4.5MPa; The proportioning of described reaction mass is:

Solid is indigo: Raney's nickel ratio of quality and the number of copies=1: 0.1;

Solid is indigo: sodium hydroxide ratio of quality and the number of copies=1: 0.2;

Solid is indigo: water=1: 1.