Adsorption-multistage rectification coupling impurity removal technology for efficiently converting coal-based electronic grade ethanol

Abstract

The invention discloses an adsorption-multistage rectification coupling impurity removal technology for efficiently converting coal-based electronic grade ethanol. An impurity removal technology device comprises an ethanol dehydration system, a methanol removal tower, an isopropanol removal tower and a vacuum device, the ethanol dehydration system is connected with the methanol removal tower; the methanol removal tower is connected with the isopropanol removal tower; and the top of the isopropanol removal tower kettle is connected with a vacuum device. According to the technology disclosed by the invention, on the premise of not introducing new substances, an ethanol separation cutting strategy and a separation sequence (water-methanol-isopropanol) are adopted, so that the contents of other impurities such as water, methanol, crude ester and isopropanol in an ethanol product can be remarkably reduced, the purity and the quality stability of the ethanol product are improved, and the technology is suitable for the production requirements of electronic grade ethanol.

Description

Technical Field

[0001] The present application relates to an adsorption-multi-stage distillation coupled decontamination technology for efficiently converting coal-based electronic-grade ethanol, and belongs to the field of ethanol production from synthesis gas. Background Art

[0002] Ethanol is an important organic solvent, widely used in medicine, coatings, sanitary products, cosmetics, oils and fats, accounting for about 50% of the total ethanol consumption. Ethanol is also an important fuel and fuel additive, which can be used as energy. High-purity ethanol refers to products with extremely high ethanol content, and its purity is usually much higher than that of ordinary industrial ethanol. The production methods of high-purity ethanol mainly include fermentation and synthesis, and the purity is further improved through processes such as distillation. Fermentation method: Use microorganisms (such as yeast) to ferment sugar-containing substances and convert sugars into ethanol and carbon dioxide. Then remove impurities and improve the purity of ethanol through processes such as distillation and rectification, but the production scale is limited. Synthesis method: Convert raw materials into ethanol through chemical reactions and purify them through processes such as distillation. Regardless of the method used, the production of high-purity ethanol requires strict control of process parameters to ensure the purity and quality of the product. Electronic grade ethanol also has a wide range of uses, such as ultra-clean cleaning, drying, ultra-clean cleaning of clean room utensils, scientific experiments, and important solvents in the pharmaceutical and chemical industries, such as chip cleaning in the semiconductor manufacturing process.

[0003] After more than 40 years of development, my country's ultra-clean or high-purity reagent industry has become one of the world's important production bases. Since the 1970s and 1980s, several research institutes and reagent manufacturers in Beijing, Shanghai, Tianjin and other places have begun to develop and produce MOS-grade reagents. In the first decade of this century, a number of private, joint-venture and restructured joint-stock enterprises in my country have emerged, gradually forming an industrial cluster of ultra-clean and high-purity reagents. In recent years, with the rapid recovery of semiconductor market demand and the vigorous development of new markets such as flat-panel displays and solar cells, my country's ultra-clean and high-purity chemical reagent companies have entered a new stage of development. The downstream market is expanding rapidly, especially the rise of my country's photovoltaic industry, battery and electrolyte industries, which has a huge market demand for ultra-clean and high-purity reagents.

[0004] At present, in the field of DMTE technology, the product ethanol can be further extended and purified to obtain electronic-grade ethanol. From the perspective of separation, there are many azeotropic systems in DMTE technology. Impurities include methanol (content ≤2000ppm), methyl acetate (content ≤50ppm), ethyl acetate (content ≤50ppm), water (content ≤0.5wt%), isopropanol (content ≤500ppm) and n-propanol (content ≤100ppm). The azeotropic system includes ethanol-water, isopropanol-water, methanol-methyl acetate, methanol-ethyl acetate, methyl acetate-water, ethyl acetate-water, n-propanol-water, methyl acetate-ethanol, ethyl acetate-ethanol and ethyl acetate-isopropanol. The composition characteristics of the above system determine that the impurity system in the ethanol raw material obtained by DMTE technology is very complex, and it is very difficult to deeply remove impurities and separate electronic-grade ethanol products that meet the (superior purity) specifications of GB-T678-2023 "Anhydrous Ethanol".

[0005] Chinese patent (CN 115340443 A) discloses a method for separating isopropanol-water-ethanol mixture by heat-coupled extractive distillation, using ethylene glycol as an extractant, and obtaining 99.9% ethanol through a multi-stage atmospheric pressure extractive distillation tower, but the isopropanol content in the raw material composition disclosed is 29wt%, and the extractive distillation is suitable for the case where the isopropanol content is high, otherwise, for the case of removing PPM-level isopropanol in this article, the amount of extractant is large, the energy consumption is too large, and the extractant is easy to polymerize. In addition, this patent does not disclose whether the isopropanol impurity content in the 99.9% ethanol product and the newly introduced extractant ethylene glycol content can meet the electronic grade ethanol requirements in this article, and the mixed system does not contain methanol, methyl acetate, ethyl acetate, etc.

[0006] Chinese patent (117843446A) discloses a separation method and system for producing ethanol by hydrogenating methyl acetate, but the isopropanol in the ethanol is only controlled at 200 ppm, which can only meet the industrial ethanol standard but cannot meet the electronic grade ethanol standard.

[0007] A Chinese patent (CN 111662161 A) discloses a method for separating a water-ethanol-isopropanol mixture by extractive distillation, using a low eutectic solvent composed of choline chloride and ethylene glycol as an extractant, and the purity of the obtained ethanol is only 99wt%.

[0008] Therefore, in large-scale industrial production, efficient conversion of coal-based electronic-grade ethanol is necessary, which can reduce raw material consumption and energy consumption, increase product added value, and significantly reduce production costs. It also improves the product upgrade of DMTE technology and enhances market competitiveness.

[0009] The electronic-grade ethanol production and separation technology invented this time aims to promote the further development of electronic-grade ethanol production technology through innovations in integration, intelligence, environmental protection, customization and high purity, and provide strong support for the rapid development of the electronics industry. Summary of the invention

[0010] The purpose of the present invention is to provide a separation method of electronic-grade ethanol specifications required by the market, develop an economically feasible coal-based electronic-grade ethanol process route, and achieve efficient impurity removal of complex multi-element azeotropic systems. After deep impurity removal, electronic-grade ethanol that meets the (superior purity) specification requirements of GB-T678-2023 "Anhydrous Ethanol" is obtained.

[0011] According to one aspect of the present application, an adsorption-multi-stage distillation coupled impurity removal technology for efficiently converting coal-based electronic-grade ethanol is provided, wherein the impurity removal technology device comprises an ethanol dehydration system, a methanol removal tower, an isopropanol removal tower, and a vacuum device;

[0012] The ethanol dehydration system is connected to the methanol removal tower;

[0013] The methanol removal tower is connected to the isopropanol removal tower;

[0014] The top of the isopropanol removal tower kettle is connected to a vacuum device.

[0015] Optionally, the ethanol dehydration system is provided with a raw material inlet, a raw material outlet, and a wastewater outlet;

[0016] The raw material outlet is connected to the methanol removal tower;

[0017] The demethanol tower is provided with a gas phase outlet I at the top;

[0018] The deisopropanol tower kettle is also provided with a heavy component outlet and a reboiler;

[0019] Optionally, the gas phase outlet I is connected to the reboiler of the deisopropanol tower kettle;

[0020] The demethanol tower kettle is provided with a liquid phase outlet I;

[0021] The top of the isopropanol removal tower is provided with a gas phase outlet II;

[0022] The gas phase outlet II is connected to a vacuum device;

[0023] The vacuum device is provided with an electronic-grade ethanol product outlet and a waste gas outlet.

[0024] According to another aspect of the present application, an application of an adsorption-multi-stage distillation coupled impurity removal technology is provided, wherein the crude ethanol is sequentially introduced into an ethanol dehydration system, a methanol removal tower, and an isopropanol removal tower of an impurity removal technology device for treatment to obtain an electronic ethanol product;

[0025] Optionally, the crude ethanol is composed of: 95-99.5% ethanol, 0.5-5% water, 0.5-5% methanol, 0.5-1% acetic acid, 0.02-0.5% methyl acetate, 0.02-0.5% isopropanol, and 0.02-0.5% n-propanol.

[0026] Optionally, the dehydration system uses any one of a permeable membrane, a water-absorbing resin, and a molecular sieve.

[0027] Optionally, the methanol removal tower is a normal pressure tower;

[0028] The number of plates of the methanol removal tower is 40 to 100;

[0029] The reflux ratio of the methanol removal tower is 20:1 to 100:1;

[0030] The top temperature of the methanol removal tower is 70-90°C;

[0031] The bottom temperature of the methanol removal tower is 80-120°C.

[0032] Optionally, the isopropanol removal tower is a vacuum tower;

[0033] The number of plates of the isopropanol removal tower is 40 to 150;

[0034] The reflux ratio of the isopropanol removal tower is 1:1 to 20:1;

[0035] The top temperature of the isopropanol removal tower is 30-70°C;

[0036] The bottom temperature of the isopropanol removal tower is 30-70°C.

[0037] Optionally, the recovery rate of ethanol in the electronic ethanol product is ≥95%.

[0038] Optionally, the electronic ethanol product comprises: an ethanol content of ≥99.99%, a water content of 65-70 ppm, and an isopropanol content of 0-30 ppm.

[0039] In the crude ethanol raw material, since impurities such as methanol, water, and isopropanol all produce azeotropy with ethanol, and there is also azeotropy between impurities, the separation cutting strategy and separation sequence are very important. The crude ethanol raw material is adsorbed in the D1 ethanol dehydration system, and the obtained anhydrous ethanol enters the de-methanol tower to separate light components such as methanol, methyl acetate, and ethyl acetate. The gas phase at the top of the de-methanol tower enters the de-isopropanol tower reboiler to effectively provide latent heat, and crude ethanol containing methanol, esters, etc. is produced from the top of the tower. The liquid phase at the bottom of the de-methanol tower enters the de-isopropanol tower to separate heavy substances such as isopropanol and n-propanol. Electronic grade ethanol is obtained at the top of the de-isopropanol tower, and crude ethanol containing acid, isopropanol, n-propanol, etc. is produced from the bottom of the de-isopropanol tower. The crude ethanol lost in the de-methanol tower and the de-isopropanol tower can be mixed and returned to the upstream methyl acetate hydrogenation system.

[0040] The beneficial effects of this application include:

[0041] 1) The impurity removal technology provided in this application, without introducing new substances, adopts an ethanol separation and cutting strategy and a separation sequence (water-methanol-isopropanol), which can significantly reduce the content of other impurities such as water, methanol, crude ester, isopropanol, etc. in the ethanol product, improve the purity and quality stability of the ethanol product, and is suitable for the production needs of electronic-grade ethanol.

[0042] 2) The impurity removal technology provided in this application organically integrates multiple separation technologies (such as distillation, adsorption, membrane separation, etc.) into a production system, realizes compactness and continuity of the process, improves production efficiency and reduces energy consumption.

[0043] 3) The impurity removal technology provided in this application aims to promote the further development of electronic-grade ethanol production technology through innovations in integration, intelligence, environmental protection, customization and high purity. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 A diagram of a device for removing impurities using the impurity removal technology used in the embodiment of the present application;

[0045] List of components and reference numerals: T1, methanol removal tower; T2, isopropanol removal tower; D1, ethanol dehydration system; VA, vacuum device; 1, raw material inlet; 2, liquid phase inlet I; 3, electronic grade ethanol product outlet; 4, heavy component outlet; 5, wastewater outlet; 6, gas phase outlet I; 7, gas phase outlet II. DETAILED DESCRIPTION

[0046] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0047] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0048] like Figure 1As shown, the device used in the embodiment of the present application includes an ethanol dehydration system, an isopropanol removal tower, a methanol removal tower, and a vacuum device;

[0049] The ethanol dehydration system is provided with a raw material inlet, a raw material outlet, and a wastewater outlet;

[0050] The demethanol tower is provided with a liquid phase inlet I at the top;

[0051] The raw material outlet is connected to the liquid phase inlet I at the top of the demethanol tower;

[0052] The demethanol tower kettle is provided with a gas phase outlet I;

[0053] The deisopropanol tower kettle is provided with a gas phase outlet II;

[0054] The top of the isopropanol removal tower is connected to a vacuum device;

[0055] The isopropanol removal tower kettle is also provided with a heavy component outlet;

[0056] The vacuum device is provided with an electronic-grade ethanol product outlet and a waste gas outlet.

[0057] Example 1

[0058] 20 wt / a anhydrous ethanol (ethanol content 98.78% (mass fraction, the same below), water content 1.0%, methanol content 0.1%, methyl acetate content 50 ppm, acetaldehyde content 30 ppm, ethyl acetate content 50 ppm, n-propyl acetate 100 ppm, isopropanol content 500 ppm and n-propanol content 500 ppm) produced by a factory with a raw material amount of 25000 kg / hr was introduced into the dehydration system inlet of the impurity removal technology device, and then entered the methanol removal tower and the isopropanol removal tower in sequence to obtain a product containing electronic ethanol. The specific parameters are shown in Table 1.

[0059] Table 1

[0060]

[0061] Example 2

[0062] 20 wt / a anhydrous ethanol (ethanol content 98.78% (mass fraction, the same below), water content 1.0%, methanol content 0.1%, methyl acetate content 50 ppm, acetaldehyde content 30 ppm, ethyl acetate content 50 ppm, n-propyl acetate 100 ppm, isopropanol content 500 ppm and n-propanol content 500 ppm) produced by a factory with a raw material amount of 25000 kg / hr was introduced into the dehydration system inlet of the impurity removal technology device, and then entered the methanol removal tower and the isopropanol removal tower in sequence to obtain a product containing electronic ethanol. The specific parameters are shown in Table 2.

[0063] Table 2

[0064]

[0065]

[0066] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. An adsorption-multi-stage distillation coupled impurity removal technology for efficient conversion of coal-based electronic-grade ethanol, characterized in that: The impurity removal technology device includes an ethanol dehydration system, a methanol removal tower, an isopropanol removal tower, and a vacuum device; The ethanol dehydration system is connected to the methanol removal tower; The methanol removal tower is connected to the isopropanol removal tower; The top of the isopropanol removal tower is connected to a vacuum device.

2. The impurity removal technology according to claim 1, characterized in that: The ethanol dehydration system is provided with a raw material inlet, a raw material outlet, and a wastewater outlet; The raw material outlet is connected to the methanol removal tower; The demethanol tower is provided with a gas phase outlet I at the top; The deisopropanol tower kettle is also provided with a heavy component outlet and a reboiler.

3. The impurity removal technology according to claim 1, characterized in that: The gas phase outlet I is connected to the reboiler of the tower kettle of the deisopropanol tower; The demethanol tower kettle is provided with a liquid phase outlet I; The top of the isopropanol removal tower is provided with a gas phase outlet II; The gas phase outlet II is connected to a vacuum device; The vacuum device is provided with an electronic-grade ethanol product outlet and a waste gas outlet.

4. An application of an adsorption-multi-stage distillation coupled impurity removal technology, characterized in that: The crude ethanol is sequentially fed into the ethanol dehydration system, methanol removal tower, and isopropanol removal tower of the impurity removal technology device for treatment to obtain an electronic ethanol product; The impurity removal technology device is the impurity removal technology described in any one of claims 1 to 3.

5. The use according to claim 4, characterized in that: The crude ethanol is composed of: 95-99.5% ethanol, 0.5-5% water, 0.5-5% methanol, 0.5-1% acetic acid, 0.02-0.5% methyl acetate, 0.02-0.5% isopropanol and 0.02-0.5% n-propanol.

6. The use according to claim 4, characterized in that: The dehydration system adopts any one of a permeable membrane, a water-absorbing resin and a molecular sieve.

7. The use according to claim 4, characterized in that: The methanol removal tower is a normal pressure tower; The number of plates of the methanol removal tower is 40 to 100; The reflux ratio of the methanol removal tower is 20:1 to 100:1; The top temperature of the methanol removal tower is 70-90°C; The bottom temperature of the methanol removal tower is 80-120°C.

8. The use according to claim 4, characterized in that: The isopropanol removal tower is a vacuum tower; The number of plates of the isopropanol removal tower is 40 to 150; The reflux ratio of the isopropanol removal tower is 1:1 to 20:1; The top temperature of the isopropanol removal tower is 30-70°C; The bottom temperature of the isopropanol removal tower is 30-70°C.

9. The use according to claim 4, characterized in that: The recovery rate of ethanol in the electronic ethanol product is ≥95%.

10. The use according to claim 4, characterized in that: The electronic ethanol product comprises: an ethanol content of ≥99.99%, a water content of 65-70 ppm, and an isopropanol content of 0-30 ppm.

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