Method for utilizing by-product tar in production of o-ethoxyphenol

Abstract

The present invention relates to a method for treating waste tar. In the process of preparing o-ethoxyphenol from ethanol and catechol, a large amount of tar is generated in the reaction and distillation process, which is directly incinerated in industry, resulting in huge waste. The present invention converts waste tar into high-value-added substances such as glyoxal, oxalic acid, phenol and catechol through ozone oxidation, ultraviolet irradiation, hydrogen peroxide oxidation and N2O treatment, thereby greatly improving the added value of the process.

Description

Technical Field

[0001] The invention relates to the field of chemical synthesis, and in particular to a method for utilizing waste tar produced as a by-product in the production of o-ethoxyphenol. Background Art

[0002] o-Ethoxyphenol, also known as 2-ethoxyphenol, is an important intermediate in spices. It can be used to prepare ethyl vanillin and is also an indispensable raw material in medicine. The o-aminophenyl ether method, diethyl sulfate method, diethyl carbonate method and ethanol method are commonly used in China and abroad. Among them, the ethanol method has become the current industrial development direction due to its relatively fewer steps, safer raw materials and lower price.

[0003] Due to the heat-sensitive properties of catechol, catechol will coke during gasification, reaction and distillation. The tar components produced are complex and have a high boiling point. It cannot be separated by conventional distillation methods. At present, it is basically incinerated in industry. In order to ensure the fluidity of tar during transportation, an equal amount of catechol must be added to the tar. Taking a 10,000-ton / year device as an example, about 200 tons of tar are produced each year, and 200 tons of catechol need to be added for compounding, which means that 400 tons of by-products are burned, which causes great economic losses. How to use these tars and improve the added value of the process has become a problem to be solved in the future. Summary of the invention

[0004] The invention aims to provide a method for treating by-product tar in the production of o-ethoxyphenol from catechol and ethanol, and adopts ozone oxidation, ultraviolet irradiation, hydrogen peroxide oxidation and N2O treatment to convert the tar into high value-added substances such as glyoxal, oxalic acid, phenol and catechol, thereby reducing the amount of incineration and greatly improving the added value of the process.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A method for utilizing by-product tar in the production of o-ethoxyphenol comprises the following steps:

[0007] (1) Add a certain amount of solvent to tar and mix well;

[0008] (2) Add a certain amount of O 3 / O2 is passed into the above solvent;

[0009] (3) O 3 / The reaction solution after O2 oxidation is irradiated under ultraviolet light and reacts for a period of time;

[0010] (4) passing the reaction solution of step (3) into a fixed bed containing TS-1 molecular sieves, and adding hydrogen peroxide;

[0011] (5) The reaction solution of step (4) is passed into a fixed bed containing TS-1 molecular sieve, and N2O is introduced at the same time.

[0012] In the present invention, in the step (1), the solvent is one or more of methanol or ethanol, and the mass ratio of the solvent to the tar is 3-15;

[0013] In the step (2), O 3 / The mass concentration of ozone in O2 is 5-12wt%, and the mass of ozone added is 3-10 times the mass of tar;

[0014] In step (3), the UV lamp used is a 15W ozone-free low-pressure mercury UV lamp with a radiation wavelength of 253.7nm and an incident light intensity of 4×10 -6 einstein / s; irradiation time is 2-12h, reaction temperature is room temperature;

[0015] In the step (4), the concentration of hydrogen peroxide is 5-30wt%, and the liquid hourly mass space velocity of hydrogen peroxide is 0.5-3.0h -1 The liquid hourly mass space velocity of the reaction liquid is 0.05-0.2h -1 , the reaction temperature is 35-70°C;

[0016] In step (5), the volume space velocity of N2O is 4-20h -1 The liquid hourly mass space velocity of the solution after the hydrogen peroxide treatment in step (4) is 0.1-0.3h -1 , the reaction temperature is 150-280℃.

[0017] The beneficial effects of the present invention are:

[0018] The invention solves the problem that the by-product waste tar in the production of o-ethoxyphenol cannot be utilized. The tar can be converted into glyoxal, oxalic acid, phenol and catechol with high added value through steps such as ozonation, ultraviolet, hydrogen peroxide and N2O treatment. The conversion rate of tar can reach 45-83%, and the total selectivity of the four products can reach up to 85%. DETAILED DESCRIPTION

[0019] In order to better understand the present invention, the content of the present invention is further described below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0020] Source of raw materials:

[0021] Waste tar came from Wanhua Chemical's ethyl guaiacol unit, N2O was purchased from Mingju Gas Co., Ltd., ozone was produced by an ozone generator (Qingdao Guolin) using oxygen, and TS-1 molecular sieve was purchased from Tianjin Nanhua Catalyst Co., Ltd.

[0022] Embodiment 1:

[0023] The treatment of tar is as follows:

[0024] (1) At room temperature, a certain amount of methanol is added to tar and mixed evenly, with the mass ratio of methanol to tar being 5;

[0025] (2) Add a certain amount of O 3 / O2 is introduced into the above solvent, wherein the mass concentration of ozone is 6wt%, and the mass of ozone added is 4 times the mass of tar;

[0026] (3) The reaction solution after ozone oxidation was irradiated under ultraviolet light for 4 hours. The ultraviolet lamp used was a 15W ozone-free low-pressure mercury ultraviolet lamp with a radiation wavelength of 253.7nm and an incident light intensity of 4×10 -6 einstein / s, the reaction temperature is room temperature;

[0027] (4) The reaction solution of step (3) is passed into a fixed bed containing TS-1 molecular sieve, and hydrogen peroxide is added at the same time. The concentration of hydrogen peroxide is 25wt%, and the liquid hourly mass space velocity of hydrogen peroxide is 0.9h -1 The liquid hourly mass space velocity of the reaction liquid is 0.19h -1 , the reaction temperature is 40°C;

[0028] (5) The reaction solution of step (4) is passed into a fixed bed containing TS-1 molecular sieve, and N2O is simultaneously introduced. The volume space velocity of N2O is 11h -1 The liquid hourly mass space velocity of the reaction liquid is 0.2h -1 , the reaction temperature is 160℃.

[0029] The specific results of the reaction are shown in Table 1.

[0030] Embodiment 2:

[0031] The treatment of tar is as follows:

[0032] (1) At room temperature, a certain amount of ethanol is added to tar and mixed evenly, and the mass ratio of ethanol to tar is 1:1;

[0033] (2) Add a certain amount of O 3 / O2 is introduced into the above solvent, wherein the mass concentration of ozone is 9wt%, and the mass of ozone added is 6 times the mass of tar;

[0034] (3) The reaction solution after ozone oxidation was irradiated under ultraviolet light for 12 hours. The ultraviolet lamp used was a 15W ozone-free low-pressure mercury ultraviolet lamp with a radiation wavelength of 253.7nm and an incident light intensity of 4×10 -6 einstein / s, the reaction temperature is room temperature;

[0035] (4) The reaction solution of step (3) was passed into a fixed bed containing TS-1 molecular sieve, and hydrogen peroxide was added at the same time. The concentration of hydrogen peroxide was 8 wt % and the liquid hourly mass space velocity of hydrogen peroxide was 2.8 h -1 The liquid hourly mass space velocity of the reaction liquid is 0.13h -1 , the reaction temperature is 57°C;

[0036] (5) The reaction solution of step (4) is passed into a fixed bed containing TS-1 molecular sieve, and N2O is simultaneously introduced. The volume space velocity of N2O is 6h -1 The liquid hourly mass space velocity of the reaction liquid is 0.15h -1 , the reaction temperature is 210℃.

[0037] The specific results of the reaction are shown in Table 1.

[0038] Embodiment 3:

[0039] The treatment of tar is as follows:

[0040] (1) At room temperature, a certain amount of ethanol is added to tar and mixed evenly, and the mass ratio of ethanol to tar is 8;

[0041] (2) Add a certain amount of O 3 / O2 is introduced into the above solvent, wherein the mass concentration of ozone is 5wt%, and the mass of ozone added is 10 times the mass of tar.

[0042] (3) The reaction solution after ozone oxidation was irradiated under ultraviolet light for 8 hours. The ultraviolet lamp used was a 15W ozone-free low-pressure mercury ultraviolet lamp with a radiation wavelength of 253.7nm and an incident light intensity of 4×10 -6 einstein / s, the reaction temperature is room temperature.

[0043] (4) The reaction solution of step (3) is passed into a fixed bed containing TS-1 molecular sieve, and hydrogen peroxide is added at the same time. The concentration of hydrogen peroxide is 15wt%, and the liquid hourly mass space velocity of hydrogen peroxide is 1.5h -1 The liquid hourly mass space velocity of the reaction liquid is 0.08h -1 , the reaction temperature is 43°C.

[0044] (5) The solution of step (4) is passed into a fixed bed containing TS-1 molecular sieve, and N2O is simultaneously passed into the fixed bed. The volumetric space velocity of N2O is 15h -1 The liquid hourly mass space velocity of the solution is 0.25h -1 , the reaction temperature is 250℃.

[0045] The specific results of the reaction are shown in Table 1.

[0046] Embodiment 4:

[0047] The treatment of tar is as follows:

[0048] (1) At room temperature, a certain amount of methanol is added to tar and mixed evenly, with the mass ratio of methanol to tar being 13;

[0049] (2) Add a certain amount of O 3 / O2 is introduced into the above solvent, wherein the mass concentration of ozone is 11wt%, and the mass of ozone added is 8 times the mass of tar.

[0050] (3) The reaction solution after ozone oxidation was irradiated under ultraviolet light for 6 hours. The ultraviolet lamp used was a 15W ozone-free low-pressure mercury ultraviolet lamp with a radiation wavelength of 253.7nm and an incident light intensity of 4×10 -6 einstein / s, the reaction temperature is room temperature.

[0051] (4) The reaction solution of step (3) was passed into a fixed bed containing TS-1 molecular sieve, and hydrogen peroxide was added at the same time. The concentration of hydrogen peroxide was 20 wt % and the liquid hourly mass space velocity of hydrogen peroxide was 2.1 h -1 The liquid hourly mass space velocity of the reaction liquid is 0.15h -1 , the reaction temperature is 68°C.

[0052] (5) The solution of step (4) is passed into a fixed bed containing TS-1 molecular sieve, and N2O is simultaneously passed into the fixed bed. The volumetric space velocity of N2O is 19h -1 The liquid hourly mass space velocity of the solution is 0.3h -1 , the reaction temperature is 270℃.

[0053] The specific results of the reaction are shown in Table 1.

[0054] Table 1 The conversion rate of tar and the selectivity of each product in each example

[0055]

Claims

1. A method for utilizing by-product tar in the production of o-ethoxyphenol from catechol and ethanol, comprising the following steps: (1) Add a certain amount of solvent to tar and mix well; (2) Add a certain amount of O 3 / O2 is passed into the above solvent; (3) O 3 / The reaction solution after O2 oxidation is irradiated under ultraviolet light and reacts for a period of time; (4) passing the reaction solution of step (3) into a fixed bed containing TS-1 molecular sieves, and adding hydrogen peroxide; (5) passing the reaction solution of step (4) into a fixed bed containing TS-1 molecular sieve, and simultaneously passing N2O; in, In step (2), the mass concentration of ozone in O3 / O2 is 5-12wt%, and the mass of ozone added is 3-10 times the mass of tar; in step (4), the concentration of hydrogen peroxide is 5-30wt%, and the liquid hourly mass space velocity of hydrogen peroxide is 0.5-3.0h -1 The liquid hourly mass space velocity of the reaction liquid is 0.05-0.2h -1 , the reaction temperature is 35-70°C; in step (5), the volume space velocity of N2O is 4-20h -1 The liquid hourly mass space velocity of the reaction liquid is 0.1-0.3h -1 , the reaction temperature is 150-280℃.

2. The method according to claim 1, wherein: In step (1), the solvent is methanol and / or ethanol.

3. The method according to claim 2, wherein: In step (1), the mass ratio of the solvent to the tar is 3-15.

4. The method according to claim 1, wherein: In step (3), the UV lamp used is a 15W ozone-free low-pressure mercury UV lamp with a radiation wavelength of 253.7nm and an incident light intensity of 4×10 -6 einstein / s.

5. The method according to claim 4, wherein: In step (3), the irradiation time is 2-12 hours and the reaction temperature is room temperature.

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