An acetic acid monitoring gas-sensitive material for ethyl acetate production and its preparation method

Abstract

The present invention discloses an acetic acid monitoring gas-sensitive material for ethyl acetate production. The acetic acid monitoring gas-sensitive material for ethyl acetate production is composed of the following substances: indium oxide doped with tungsten, graphene oxide, cellulose acetate, germanium phthalocyanine, and deionized water. In the present invention, indium oxide doped with tungsten is synthesized from a tungsten-containing compound and an indium-containing compound, and then the indium oxide doped with tungsten and germanium phthalocyanine composite are loaded on a graphene oxide and cellulose acetate composite material to prepare the acetic acid monitoring gas-sensitive material for ethyl acetate production. The gas-sensitive sensor prepared by using this gas-sensitive material is sensitive and accurate in monitoring acetic acid gas, which is conducive to quickly adjusting the reflux situation according to the acetic acid gas data during the ethyl acetate production process and saving energy consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of gas-sensitive materials, and particularly to an acetic acid monitoring gas-sensitive material for ethyl acetate production and a preparation method thereof. Background Art

[0002] Ethyl acetate is widely used as a solvent for coatings, inks, and adhesives, and can also be used as an extractant for pharmaceutical preparations and as a flavor and fragrance. Currently, the main production methods of ethyl acetate include ethanol-acetate esterification method, acetaldehyde condensation method, ethanol dehydrogenation method, ethanol oxidation method, and ethylene-acetate esterification method. Among them, the mainstream production process in China is the ethanol-acetate esterification method, that is, using ethanol and acetic acid as raw materials, and under the catalysis of catalysts such as sulfuric acid, methanesulfonic acid, or strongly acidic resin, an esterification reaction occurs in an esterification kettle to produce ethyl acetate. The reaction products of ethyl acetate, water, raw acetic acid, and ethanol are subjected to a series of rectification separations such as an esterification tower and a rectification tower to obtain ethyl acetate products.

[0003] During the purification process of ethyl acetate, although acetic acid has a high boiling point and does not form an azeotrope with substances such as ethyl acetate and ethanol, acetic acid has an association with water, and there is often a phenomenon that a small amount of acetic acid enters the tower, resulting in unqualified product acidity. To ensure that the acetic acid content at the top of the esterification tower is within the qualified range, a large amount of reflux liquid is required to suppress the acid. Since the association of acetic acid is random and cannot be tracked by conventional means, in the continuous chemical production process, when setting the reflux ratio to ensure stable operation, a relatively large reflux ratio is usually set, but this operation will increase energy consumption, reduce the separation ability of the tower, and is not conducive to efficient and stable production.

[0004] To overcome the deficiencies in acetic acid detection technology and reduce reflux to save energy, the present invention proposes a highly selective gas-sensitive material for rapid detection of acetic acid, which can quickly adjust the reflux situation according to data to save energy. Summary of the Invention

[0005] Based on the defects and deficiencies existing in the prior art, the present invention provides an acetic acid monitoring gas-sensitive material for ethyl acetate production. In the traditional esterification process for producing ethyl acetate, the gas-sensitive material of the present invention is prepared into an acetic acid monitoring gas-sensitive sensor and set on the 4th tray of the esterification tower. At the temperature required for ethyl acetate production, the sensitivity to 15 ppm acetic acid is as high as 98%.

[0006] The above-mentioned acetic acid monitoring gas-sensitive material for ethyl acetate production is composed of the following substances: indium oxide doped with tungsten, graphene oxide, cellulose acetate, germanium phthalocyanine, and deionized water;

[0007] Among them, the indium oxide doped with tungsten is prepared by reacting a tungsten-containing compound, an indium-containing compound, and ammonia water;

[0008] The tungsten-containing compound is selected from any one of ammonium tungstate, sodium tungstate, potassium tungstate, ammonium paratungstate, and ammonium metatungstate;

[0009] The indium-containing compound is selected from any one of indium trichloride, indium sulfate, and indium nitrate.

[0010] The acetic acid monitoring gas-sensitive material for ethyl acetate production described above has raw materials for preparation including the following substances in parts by weight: 2-10 parts of tungsten-containing compound, 40-120 parts of indium-containing compound, 10-20 parts of graphene oxide, 10-40 parts of cellulose acetate, 1-20 parts of germanium phthalocyanine, ammonia water, and deionized water;

[0011] Among them, the tungsten-containing compound is selected from any one of ammonium tungstate, sodium tungstate, potassium tungstate, ammonium paratungstate, and ammonium metatungstate;

[0012] The indium-containing compound is selected from any one of indium trichloride, indium sulfate, and indium nitrate.

[0013] Further, the mass ratio of the graphene oxide to the cellulose acetate is 0.3-1.2:1.

[0014] Another object of the present invention is to provide a preparation method of the acetic acid monitoring gas-sensitive material for ethyl acetate production, including the following steps:

[0015] S1. Prepare indium oxide doped with tungsten solution: Dissolve the tungsten-containing compound and the indium-containing compound in a certain amount of deionized water, add ammonia water to adjust the pH of the solution to 9-10, wash the product with deionized water and anhydrous ethanol respectively, and re-ultrasonically disperse the washed precipitate in an aqueous solution to obtain a mixed solution;

[0016] S2. Prepare a composite slurry of graphene oxide and cellulose acetate: Blend graphene oxide, cellulose acetate, and germanium phthalocyanine in water, stir ultrasonically, and then heat to 80-90 °C to evaporate and concentrate the solution to form a black suspension slurry;

[0017] S3. Dropwise add the mixed solution in step S1 into the black suspension slurry in step S2, carry out a constant-temperature reaction, cool after the reaction is completed, and obtain the product.

[0018] Further, in step S3, the temperature of the constant-temperature reaction is 160-220 °C, and the reaction time is 3-10 h.

[0019] Another object of the present invention is to provide an application of the acetic acid monitoring gas-sensitive material for ethyl acetate production in monitoring the concentration of acetic acid gas during the production process of ethyl acetate. Specifically, the acetic acid monitoring gas-sensitive material for ethyl acetate production is used to prepare a gas-sensitive sensor, which is then arranged on the 4th tray of the esterification tower. During the upward process of the material gas flow, a stream of the material gas flow is led to the gas-sensitive sensor through a pipeline, and the gas-sensitive sensor can monitor acetic acid gas in real time during the production process of ethyl acetate.

[0020] The beneficial effects of the present invention are as follows:

[0021] In the present invention, indium oxide doped with tungsten and germanium phthalocyanine are loaded in a composite slurry of graphene oxide and cellulose acetate. There are a large number of hydrogen bonds on the surface of the composite slurry of graphene oxide and cellulose acetate. After the indium oxide doped with tungsten is compounded with the composite slurry of graphene oxide and cellulose acetate, the interaction between the lattice defects of the indium oxide doped with tungsten and the hydrogen bonds can be utilized, which is beneficial to improving the stability of indium oxide in the gas-sensitive material and preventing it from being washed off by the upward gas flow. Moreover, after tungsten is doped into indium oxide, the structural integrity of indium oxide will be aggravated, forming more oxygen vacancies. The steric hindrances of oxygen atoms in acetic acid, ethanol, ethyl acetate, and water are all different, and the oxygen in acetic acid is more conducive to being adsorbed on the oxygen vacancies of indium oxide, causing a change in the carrier concentration of the gas-sensitive material, thereby improving the selectivity of the gas-sensitive material to acetic acid gas. At the same time, the addition of germanium phthalocyanine plays a role in amplifying the signal of acetic acid gas, further improving the sensitivity of the gas-sensitive material to monitor acetic acid gas. In some test examples of the present invention, the acetic acid monitoring gas-sensitive sensor prepared from the gas-sensitive material of the present invention has a sensitivity of 98% to 15 ppm acetic acid at a high temperature of 120 °C required for ethyl acetate production. Description of the Drawings

[0022] Figure 1 Shows the sensitivity test chart of Example 1 to acetic acid at different concentrations. Detailed Embodiments

[0023] In order to more clearly illustrate the technical solutions of the present invention, the following examples are listed. The raw materials, reactions, and post-treatment means appearing in the examples are all common raw materials on the market and technical means well-known to those skilled in the art, unless otherwise specified.

[0024] The terms "preferred", "preferably", "more preferred", etc. in the present invention refer to embodiments of the present invention that can provide certain beneficial effects in certain cases. However, in the same or other cases, other embodiments may also be preferred. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not available, nor is it intended to exclude other embodiments from the scope of the present invention.

[0025] It should be understood that, except in any operating instance or otherwise indicated, all numbers representing amounts of ingredients used in the specification and claims, for example, should be understood to be modified in all instances by the term "about". Thus, unless indicated to the contrary, the numerical parameters set forth in the following specification and appended claims are approximations that vary depending upon the desired properties sought to be obtained by the present invention.

[0026] In the examples of the present invention, the cellulose acetate used was purchased from Merck Chemicals;

[0027] In the examples of the present invention, the germanium phthalocyanine used was purchased from Aladdin Reagents.

[0028] Example 1

[0029] A gas-sensitive material for monitoring acetic acid used in the production of ethyl acetate, the preparation raw materials of which include the following substances in parts by weight: 5 mg of sodium tungstate, 60 mg of indium trichloride, 10 mg of graphene oxide, 15 mg of cellulose acetate, 5.8 mg of germanium phthalocyanine, ammonia water, and deionized water.

[0030] The preparation method is as follows:

[0031] S1. Prepare an indium oxide doped with tungsten solution: Dissolve 5 mg of sodium tungstate and 60 mg of indium trichloride in 50 mL of deionized water, adjust the pH of the solution to 10 with 0.5 mol / L ammonia water, stir for 1 h, then wash the precipitate with deionized water and absolute ethanol twice each, and redisperse the washed precipitate in 10 mL of aqueous solution by ultrasonic treatment to obtain a mixed solution;

[0032] S2. Prepare a graphene oxide and cellulose acetate composite slurry: Blend 10 mg of graphene oxide, 15 mg of cellulose acetate, and 5.8 mg of germanium phthalocyanine in 100 mL of deionized water, ultrasonic stir for 30 min, and then heat to 90 °C to evaporate and concentrate the solution to 20 mL to form a black suspension slurry;

[0033] S3. Gradually add the mixed solution from step S1 dropwise to the black suspension slurry from step S2. After the addition is complete, transfer the solution to a 50 mL microwave reaction kettle, react at 200 °C for 4 h, and cool to obtain the gas-sensitive material.

[0034] Example 2

[0035] A gas-sensitive material for monitoring acetic acid used in the production of ethyl acetate, the preparation raw materials of which include the following substances in parts by weight: 3 mg of ammonium tungstate, 45 mg of indium sulfate, 12 mg of graphene oxide, 22 mg of cellulose acetate, 6.5 mg of germanium phthalocyanine, ammonia water, and deionized water.

[0036] The preparation method is as follows:

[0037] S1. Prepare indium oxide solution doped with tungsten: Dissolve 3 mg of ammonium tungstate and 45 mg of indium sulfate in 50 mL of deionized water. Adjust the pH of the solution to 9.2 with 0.5 mol / L ammonia water. After stirring for 1 h, wash the product with deionized water and absolute ethanol twice each. Redisperse the washed precipitate in 10 mL of aqueous solution by ultrasonic treatment to obtain a mixed solution;

[0038] S2. Prepare a composite slurry of graphene oxide and cellulose acetate: Blend 12 mg of graphene oxide, 22 mg of cellulose acetate, and 6.5 mg of germanium phthalocyanine in 100 mL of deionized water. After ultrasonic stirring for 30 min, heat the solution to 85 °C and evaporate and concentrate it to 20 mL to form a black suspension slurry;

[0039] S3. Dropwise add the mixed solution from step S1 into the black suspension slurry from step S2. After the addition is complete, transfer the solution to a 50 mL microwave reaction kettle and react at 180 °C for 6 h. After cooling, a gas-sensitive material is obtained.

[0040] Example 3

[0041] A gas-sensitive material for acetic acid monitoring used in ethyl acetate production, and its preparation raw materials include the following substances in parts by weight: 7 mg of ammonium tungstate, 105 mg of indium sulfate, 16 mg of graphene oxide, 35 mg of cellulose acetate, 15 mg of germanium phthalocyanine, ammonia water, and deionized water.

[0042] The preparation method is as follows:

[0043] S1. Prepare indium oxide solution doped with tungsten: Dissolve 7 mg of ammonium tungstate and 105 mg of indium sulfate in 50 mL of deionized water. Adjust the pH of the solution to 9.8 with 0.5 mol / L ammonia water. After stirring for 1 h, wash the product with deionized water and absolute ethanol twice each. Redisperse the washed precipitate in 10 mL of aqueous solution by ultrasonic treatment to obtain a mixed solution;

[0044] S2. Prepare a composite slurry of graphene oxide and cellulose acetate: Blend 16 mg of graphene oxide, 35 mg of cellulose acetate, and 15 mg of germanium phthalocyanine in 100 mL of deionized water. After ultrasonic stirring for 30 min, heat the solution to 90 °C and evaporate and concentrate it to 50 mL to form a black suspension slurry;

[0045] S3. Dropwise add the mixed solution from step S1 into the black suspension slurry from step S2. After the addition is complete, transfer the solution to a 50 mL microwave reaction kettle and react at 200 °C for 6 h. After cooling, a gas-sensitive material is obtained.

[0046] Comparative Example 1

[0047] An acetic acid monitoring gas-sensitive material for ethyl acetate production. The preparation method, raw materials used and raw material dosage in comparative example 1 are the same as those in embodiment 1, with the only difference being that step S2 in comparative example 1 does not contain germanium phthalocyanine, but is replaced by an equal weight of copper phthalocyanine.

[0048] Comparative Example 2

[0049] An acetic acid monitoring gas-sensitive material for ethyl acetate production. The preparation method, raw materials used and raw material dosage in comparative example 2 are the same as those in embodiment 1, with the only difference being that step S1 in comparative example 2 does not contain sodium tungstate, but is replaced by an equal weight of sodium nitrate.

[0050] Comparative Example 3

[0051] An acetic acid monitoring gas-sensitive material for ethyl acetate production. The preparation method, raw materials used and raw material amounts in Comparative Example 3 are the same as those in Example 1, with the only difference being that step S2 in Comparative Example 3 does not contain cellulose acetate, but is replaced by silicon nanosheets of the same weight.

[0052] Test Case

[0053] Test sample preparation: The gas-sensitive materials of Example 1 and Comparative Examples 1-3 were respectively coated on the sensor probe by drop coating, the probe was a palladium metal electrode prepared by screen printing technology, model 220AT-Pd110, and the gas-sensitive slurry was evenly coated on the electrode surface with a thickness of 2 mm. After coating, it was placed in a UV oven at 390 nm and 30° C. to dry to obtain a gas sensor.

[0054] Test method: prepare a mixed solution of ethanol, acetic acid, ethyl acetate and water, wherein the ethanol content is 5wt%, the ethyl acetate content is 90wt% and the water content is 4.9wt%; at the same time, add acetic acid of different concentrations at one time (each concentration is regarded as an independent experiment), gasify at 120°C, respectively set the gas sensors prepared above at the gas phase inlet of the condenser, and the gas flow leads the gasified material flow to the gas sensor through the external pipeline. The gas sensor monitors the acetic acid content of the gas in real time and records the data. At the same time, collect the mixed liquid at the liquid phase outlet of the condenser, and compare the liquid phase composition and the gas sensor data. The results are shown in Table 1. The sensitivity conversion results of Example 1 to acetic acid are close to 100% at different concentrations, such as Figure 1 shown.

[0055] Table 1 Acetic acid detection results of Example 1 and Comparative Examples 1-3

[0056]

[0057] As can be seen from the results in Table 1, the results of Example 1 indicate that the gas sensor prepared by the gas-sensitive material of the present invention has a high sensitivity to acetic acid detection of various gradients at a high temperature of 120°C required for ethyl acetate production, especially a sensitivity of up to 98% to 15ppm acetic acid, which is beneficial to quickly adjust the reflux conditions according to data to save energy during the ethyl acetate production process.

[0058] However, since germanium phthalocyanine was not added in Comparative Example 1, the prepared gas sensor was not sensitive enough to acetic acid, resulting in no detection data and failing to indicate the acetic acid content in the gas phase well; indium oxide in Comparative Example 2 was not doped with tungsten, and the prepared gas sensor was not responsive enough to acetic acid, resulting in small data; cellulose acetate was not added in Comparative Example 3, and the hydrogen bonding effect of graphene oxide was not fully exerted, resulting in the prepared gas sensor's acetic acid monitoring effect not being as good as that of Example 1. This is mainly because:

[0059] By adding germanium phthalocyanine, germanium will partially replace some positions in the indium lattice, resulting in an increase in free electrons, which can effectively improve the conductivity of the gas-sensitive material, amplify the signal of acetic acid gas, and further improve the sensitivity of the gas-sensitive material in monitoring acetic acid gas.

[0060] Tungsten-doped indium oxide will aggravate the structural incompleteness of indium oxide and form more oxygen vacancies. The steric hindrance of oxygen atoms in acetic acid, ethanol, ethyl acetate and water are different, and the oxygen in acetic acid is more conducive to adsorbing on the oxygen vacancies of indium oxide, which changes the carrier concentration of the gas-sensitive material, thereby improving the selectivity of the gas-sensitive material to acetic acid gas.

[0061] The specific surface area of ​​cellulose acetate is larger than that of silicon nanosheets. During the preparation process, it can quickly form a stable suspension with graphene oxide through ultrasound. At the same time, the addition of cellulose acetate can be compounded with graphene oxide to increase the amount of hydrogen bonds. After tungsten-doped indium oxide is compounded with graphene oxide and cellulose acetate composite slurry, the interaction between the lattice defects and hydrogen bonds of tungsten-doped indium oxide can be utilized, which is beneficial to improve the stability of indium oxide in gas-sensitive materials and prevent it from being washed away by rising airflow.

[0062] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0063] In addition, it should be understood that although this specification is described in terms of embodiments, not every embodiment contains only an independent technical solution. This narrative style of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An acetic acid monitoring gas-sensitive material for ethyl acetate production, characterized in that, The acetic acid monitoring gas-sensitive material for ethyl acetate production consists of the following substances: indium oxide doped with tungsten, graphene oxide, cellulose acetate, germanium phthalocyanine, deionized water; Among them, the indium oxide doped with tungsten is prepared by reacting a tungsten-containing compound, an indium-containing compound and ammonia water; The tungsten-containing compound is selected from any one of ammonium tungstate, sodium tungstate, potassium tungstate, ammonium paratungstate, ammonium metatungstate; The indium-containing compound is selected from any one of indium trichloride, indium sulfate, indium nitrate; The raw materials for preparing the acetic acid monitoring gas-sensitive material for ethyl acetate production include the following substances: 2-10 parts by weight of tungsten-containing compound, 40-120 parts by weight of indium-containing compound, 10-20 parts by weight of graphene oxide, 10-40 parts by weight of cellulose acetate, 1-20 parts by weight of germanium phthalocyanine, ammonia water, deionized water; the weight ratio of graphene oxide to cellulose acetate is 0.3-1.2:

1.

2. The preparation method of the acetic acid monitoring gas-sensitive material for ethyl acetate production according to claim 1, characterized in that, It includes the following steps: S1. Prepare indium oxide doped with tungsten solution: Dissolve the tungsten-containing compound and the indium-containing compound in deionized water, add ammonia water to adjust the pH of the solution to 9-10, stir ultrasonically, wash, and re-disperse the washed precipitate ultrasonically in an aqueous solution to obtain a mixed solution; S2. Prepare a graphene oxide and cellulose acetate composite slurry: Blend graphene oxide, cellulose acetate and germanium phthalocyanine in water, stir ultrasonically, and then heat to 80-90 °C to evaporate and concentrate the solution to form a black suspension slurry; S3. Dropwise add the mixed solution in step S1 into the black suspension slurry in step S2, carry out a constant-temperature reaction, cool after the reaction is completed to obtain the acetic acid monitoring gas-sensitive material for ethyl acetate production.

3. The preparation method of the acetic acid monitoring gas-sensitive material for ethyl acetate production according to claim 2, characterized in that, In step S3, the temperature of the constant-temperature reaction is 160-220 °C, and the reaction time is 3-10 h.

4. Application of the acetic acid monitoring gas-sensitive material for ethyl acetate production according to claim 1 in monitoring acetic acid gas during the production process of ethyl acetate.

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