Catalyst for preparing acetaldehyde by ethylene glycol gas-solid phase method as well as preparation method and application of catalyst

Abstract

The invention belongs to the technical field of catalyst preparation, and particularly relates to a catalyst for preparing acetaldehyde from ethylene glycol by a gas-solid phase method as well as a preparation method and application of the catalyst. The preparation method comprises the following steps: dispersing an aluminum source in water, and treating with nitric acid and phosphoric acid to obtain colloid A; adding tetraethyl orthosilicate into the colloid A, and stirring to obtain colloid B; adding tetrabutyl titanate into the colloid B, and stirring to obtain colloid C; adding a dopant into the colloid C, adjusting the pH value, stirring, standing and drying to obtain a solid material; and roasting the solid material to obtain the catalyst for preparing acetaldehyde by the ethylene glycol gas-solid phase method. The preparation method is simple and easy to operate, in the reaction for synthesizing acetaldehyde through a gas-solid phase method by taking ethylene glycol as a single raw material, the catalytic reaction activity is high, the acetaldehyde selectivity is high, the reaction stability is high, few by-products are produced, the by-product selectivity is low, and meanwhile, the reaction process has the advantages of continuity, greenness and no pollution.

Description

Technical Field

[0001] The invention relates to the technical field of catalyst preparation, and in particular to a catalyst for preparing acetaldehyde by a gas-solid phase method of ethylene glycol, and a preparation method and application thereof. Background Art

[0002] Acetaldehyde is an important organic chemical intermediate and solvent. It can be used to synthesize organic chemical products such as acetate, pentaerythritol, glyoxal, trichloroacetaldehyde, lactic acid and pyridine compounds. It is also a basic raw material for the synthesis of chemicals such as medicines, pesticides, fragrances and food additives, and has important industrial application value.

[0003] At present, there are four main methods for producing acetaldehyde in industry: acetylene hydration, ethanol oxidation or dehydrogenation, alkane oxidation and ethylene oxidation. The mainstream production processes are mainly ethanol oxidation (30%) and ethylene oxidation (70%), in which the conversion rate of acetaldehyde is about 35%, and the yield is 90-95%, but some deep oxidation products are easily generated in this reaction and part of ethanol is consumed, and the raw material source requirements are strict; although the ethylene oxidation method has cheap raw materials, low cost, high acetaldehyde yield and few side reactions, the hydrochloric acid solution of palladium chloride and copper chloride is used as a catalyst, which is extremely corrosive to the equipment, and the equipment material design requires special materials such as precious metal titanium (high equipment investment). It can be seen that the process of synthesizing acetaldehyde by the two process technologies mainly stays in the homogeneous catalytic system or oxidation / dehydrogenation process, which will bring a series of problems, such as low operating safety, high energy consumption, high pollution, low yield and other problems. Based on this, it is particularly important to develop a heterogeneous, non-oxidation / dehydrogenation process for the task of synthesizing acetaldehyde from ethylene glycol. Summary of the invention

[0004] The purpose of the present invention is to provide a catalyst for preparing acetaldehyde by a gas-solid phase method of ethylene glycol, and a preparation method and application thereof, so as to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] One of the technical solutions of the present invention is to provide a method for preparing acetaldehyde from ethylene glycol using a catalyst by a gas-solid phase process, the steps comprising:

[0007] The aluminum source is dispersed in water and treated with nitric acid and phosphoric acid to obtain colloid A;

[0008] Adding a silicon source to the colloid A and stirring to obtain a colloid B;

[0009] Adding a titanium source to the colloid B and stirring to obtain a colloid C;

[0010] Adding a dopant into the colloid C, adjusting the pH value, stirring, standing, and drying to obtain a solid material;

[0011] The solid material is subjected to calcination to obtain the catalyst for preparing acetaldehyde by the ethylene glycol gas-solid phase method.

[0012] The main function of the dopant is to adjust the acidity and alkalinity of the catalyst surface and thus regulate the catalytic performance.

[0013] Furthermore, the aluminum source is pseudo-boehmite, α-alumina or γ-alumina.

[0014] Furthermore, the silicon source includes tetraethyl orthosilicate, silicon dioxide powder or sodium silicate.

[0015] Furthermore, the titanium source includes tetrabutyl titanate, titanium tetrachloride or titanium dioxide powder.

[0016] Furthermore, the usage ratio of the aluminum source and water is 100g:100-500mL, preferably 100g:200-300mL.

[0017] Furthermore, the usage ratio of the nitric acid and the aluminum source is 10-50 mL:100 g, preferably 20-40 mL:100 g.

[0018] Furthermore, the temperature for preparing the colloid A, colloid B and colloid C is room temperature to 90°C, preferably 40 to 70°C.

[0019] Furthermore, the dopant is a nitrate containing at least one of potassium, lanthanum, zirconium, nickel and cerium.

[0020] Furthermore, the molar ratio of P to Al in the catalyst is 0.5-1.2, the molar ratio of Si to Al is 0.2-1.0, the molar ratio of Ti to Al is 0.01-0.6, and the molar ratio of the metal element to Al in the dopant is 0.1-0.4.

[0021] Preferably, the molar ratio of P to Al in the catalyst is 0.9-1.2, the molar ratio of Si to Al is 0.4-0.6, the molar ratio of Ti to Al is 0.1-0.4, and the molar ratio of the metal element to Al in the dopant is 0.04.

[0022] Furthermore, the pH value is adjusted to 7.5.

[0023] Furthermore, the standing is standing at room temperature for 24 hours.

[0024] Furthermore, the drying temperature is 90°C.

[0025] Furthermore, the calcination temperature is 300-600°C and the calcination time is 10 hours.

[0026] Preferably, the calcination temperature is 350-550°C.

[0027] The second technical solution of the present invention is to provide a catalyst prepared by the above method.

[0028] The third technical solution of the present invention is to provide an application of the above catalyst in catalyzing the dehydration of ethylene glycol to synthesize acetaldehyde.

[0029] Furthermore, the application is specifically: using ethylene glycol as a single raw material to catalytically synthesize acetaldehyde through a gas-solid phase method.

[0030] Technical solution 4 of the present invention: Provide a method for synthesizing acetaldehyde by dehydrating ethylene glycol, the steps comprising:

[0031] The acetaldehyde is prepared by using ethylene glycol as a single raw material through a gas-solid phase method and a catalytic reaction using the above catalyst.

[0032] Furthermore, the reaction temperature of the catalytic reaction is 350°C and the reaction space velocity is 3 mL g -1 h -1 .

[0033] The present invention discloses the following technical effects:

[0034] The method for preparing aluminum-phosphorus-titanium-silicon series solid catalysts by a colloid-precipitation method has simple steps, is easy to operate, does not require high-pressure reactor treatment, and is easy to carry out industrial-scale production.

[0035] The catalyst prepared by the present invention is a solid acid-base catalyst, which mainly contains compounds of aluminum, phosphorus, silicon and titanium, and also contains at least one of compounds of potassium, lanthanum, zirconium, nickel and cerium. In the reaction of synthesizing acetaldehyde by gas-solid phase method with ethylene glycol as the single raw material, the catalyst has high catalytic reaction activity, high selectivity for acetaldehyde, high reaction stability, few by-products and low by-product selectivity. At the same time, the reaction process has the advantages of continuity, greenness and pollution-free. Among them, the ethylene glycol conversion rate is more than 90%, the acetaldehyde selectivity is 60-90%, and the by-products 1,4-dioxane, dimethyl 1,3-dioxolane and water can flexibly adjust the selectivity and yield of each product by adjusting the reaction conditions. When the reaction temperature is 350°C and the reaction space velocity is 3mL g -1 h -1 Under the conditions of high temperature, the stability can reach more than 2000 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1 This is a diagram showing the reaction evaluation results of the catalyst prepared in Example 1 under different reaction temperatures;

[0038] Figure 2 This is a graph showing the reaction evaluation results of the catalyst prepared in Example 1 under different reaction space velocities;

[0039] Figure 3 This is a graph showing the reaction stability evaluation results of the catalyst prepared in Example 1. DETAILED DESCRIPTION

[0040] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0041] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0042] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0043] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0044] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0045] The raw materials and reagents used in the specific embodiments of the present invention are all commercially available products.

[0046] In a specific implementation manner of the present invention, the mass percentage of Al2O3 in the pseudo-boehmite used is 66.4%; the mass percentage concentration of the concentrated nitric acid used is between 68% and 70%.

[0047] Example 1

[0048] The preparation steps of the catalyst for preparing acetaldehyde by ethylene glycol gas-solid phase method are as follows:

[0049] S1. Under room temperature, 100 g of pseudo-boehmite powder was dispersed in 200 mL of distilled water, 25 mL of concentrated nitric acid was added, and after vigorous stirring, 89 mL of phosphoric acid was added to obtain colloid A;

[0050] S2, heating colloid A to 60°C and stirring evenly, then dropping 145 mL of tetraethyl orthosilicate into the colloid mixture, and after the addition is complete, maintaining 60°C and stirring for 4 hours to obtain colloid B;

[0051] S3, maintaining 60°C, slowly dripping 10 mL of ethanol solution containing 0.26 mol of tetrabutyl titanate into colloid B, and stirring for 4 hours after the completion of the dripping to obtain colloid C;

[0052] S4, maintaining 60° C., dripping 30 mL of a mixed aqueous solution containing 0.026 mol of cerium nitrate, 0.013 mol of potassium nitrate and 0.013 mol of lanthanum nitrate into colloid C, adjusting the pH to 7.5 with aqueous ammonia after the dripping is complete, continuing to stir for 4 hours and then placing at room temperature for 24 hours to obtain colloid D;

[0053] S5, placing the colloid D in a 90° C. oven and drying to obtain a solid material;

[0054] S6. The solid material was calcined at 450° C. for 10 hours in an air atmosphere to obtain a catalyst for preparing acetaldehyde by a gas-solid phase method of ethylene glycol, which was recorded as Al-P-0.5Si-0.2Ti-0.02Ce-0.01K-0.01La-O.

[0055] Example 2

[0056] Compared with Example 1, the only difference is that the molar ratio of P to Al is 0.9, that is, the amount of pseudo-boehmite is 100 g, and the amount of phosphoric acid is 80 mL.

[0057] Example 3

[0058] Compared with Example 1, the only difference is that the molar ratio of P to Al is 1.1, that is, the amount of pseudo-boehmite is 100 g, and the amount of phosphoric acid is 98 mL.

[0059] Example 4

[0060] Compared with Example 1, the only difference is that the molar ratio of P to Al is 1.2, that is, the amount of pseudo-boehmite is 100 g, and the amount of phosphoric acid is 107 mL.

[0061] Example 5

[0062] Compared with Example 1, the only difference is that the molar ratio of Si to Al is 0.4, that is, the amount of pseudo-boehmite is 100 g, and the amount of tetraethyl orthosilicate is 116 mL.

[0063] Example 6

[0064] Compared with Example 1, the only difference is that the molar ratio of Si to Al is 0.6, that is, the amount of pseudo-boehmite is 100 g, and the amount of tetraethyl orthosilicate is 174 mL.

[0065] Example 7

[0066] Compared with Example 1, the only difference is that the molar ratio of Ti to Al is 0.1, that is, the amount of pseudo-boehmite is 100 g, and the amount of tetrabutyl titanate is 0.13 mol.

[0067] Example 8

[0068] Compared with Example 1, the only difference is that the molar ratio of Ti to Al is 0.3, that is, the amount of pseudo-boehmite is 100 g, and the amount of tetrabutyl titanate is 0.39 mol.

[0069] Example 9

[0070] Compared with Example 1, the only difference is that the molar ratio of Ti to Al is 0.4, that is, the amount of pseudo-boehmite is 100 g, and the amount of tetrabutyl titanate is 0.52 mol.

[0071] Example 10

[0072] Compared with Example 1, the only difference is that cerium nitrate is replaced by an equimolar amount of zirconium nitrate.

[0073] Comparative Example 1

[0074] Compared with Example 1, the only difference is that phosphoric acid is not added.

[0075] Comparative Example 2

[0076] Compared with Example 1, the only difference is that the molar ratio of P to Al is 1.3, that is, the amount of pseudo-boehmite is 100 g, and the amount of phosphoric acid is 116 mL.

[0077] Test example

[0078] The catalysts prepared in Examples 1 to 10 and Comparative Examples 1 to 2 were used to prepare acetaldehyde by ethylene glycol gas-solid phase catalytic method. The reaction was carried out on a fixed bed device. The reaction conditions were: reaction temperature 350°C, reaction space velocity 3 mL g -1 h -1 The conversion rate of ethylene glycol, the selectivity of acetaldehyde and other by-products are shown in Table 1.

[0079] Table 1

[0080]

[0081]

[0082] The catalyst prepared in Example 1 was tested for reaction performance at different temperatures, and the performance test method was as follows:

[0083] The catalyst prepared in Example 1 was placed in a reaction tube, and then the reaction tube was heated to the reaction temperature (320-380° C.) under a nitrogen atmosphere. 3 mL g -1 h -1 The reaction liquid is sent into the reaction tube through a horizontal flow pump at a flow rate of (the amount of catalyst passing through per gram per hour), so that ethylene glycol reacts under the action of the catalyst. After the reaction is completed, the products acetaldehyde, 1,4-dioxane and dimethyl 1,3-dioxolane and other by-products are collected.

[0084] The results obtained at different reaction temperatures are as follows Figure 1 As shown in the figure, it can be seen that with the increase of reaction temperature, the conversion rate of ethylene glycol increases and the selectivity of acetaldehyde decreases.

[0085] The catalyst prepared in Example 1 was tested for its reaction performance at different reaction space velocities, and the performance test method was as follows:

[0086] The catalyst prepared in Example 1 was placed in a reaction tube, and then the reaction tube was heated to 350° C. under a nitrogen atmosphere. The reaction solution was fed into the reaction tube by a horizontal flow pump at different flow rates to allow ethylene glycol to react under the action of the catalyst. After the reaction was completed, the products acetaldehyde, 1,4-dioxane and dimethyl 1,3-dioxolane and other by-products were collected.

[0087] The results obtained at different reaction space velocities are as follows Figure 2 As shown in the figure, it can be seen that with the increase of reaction space velocity, the conversion rate of ethylene glycol decreases and the selectivity of acetaldehyde increases.

[0088] The catalyst prepared in Example 1 was subjected to a stability evaluation test, and its performance test method was as follows:

[0089] The catalyst prepared in Example 1 was placed in a reaction tube, and then the reaction tube was heated to a reaction temperature of 350°C under a nitrogen atmosphere. -1 h -1 The reaction liquid is sent into the reaction tube through a horizontal flow pump at a flow rate of (the amount of catalyst passing through per gram per hour), so that ethylene glycol reacts under the action of the catalyst. After the reaction is completed, the products acetaldehyde, 1,4-dioxane and dimethyl 1,3-dioxolane and other by-products are collected.

[0090] Figure 3 The result diagram of the catalyst reaction stability evaluation obtained in Example 1 is shown in FIG. Figure 3 It can be seen that within the 2000 hours of investigation, there was no significant change in the ethylene glycol conversion rate and product selection, indicating that the catalyst prepared in Example 1 has excellent stability.

[0091] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing acetaldehyde from ethylene glycol using a catalyst by a gas-solid phase process, characterized in that the steps include: The aluminum source is dispersed in water and treated with nitric acid and phosphoric acid to obtain colloid A; Adding a silicon source to the colloid A and stirring to obtain colloid B; Adding a titanium source to the colloid B and stirring to obtain a colloid C; Adding a dopant into the colloid C, adjusting the pH value, stirring, standing, and drying to obtain a solid material; The solid material is subjected to calcination to obtain the catalyst for preparing acetaldehyde by ethylene glycol gas-solid phase method; The aluminum source is pseudo-boehmite, α-alumina or γ-alumina; The silicon source includes tetraethyl orthosilicate, silicon dioxide powder or sodium silicate; The titanium source includes tetrabutyl titanate, titanium tetrachloride or titanium dioxide powder.

2. The method according to claim 1, characterized in that The dosage ratio of the aluminum source to water is 100g:100-500mL; the dosage ratio of the nitric acid to the aluminum source is 10-50mL:100g; and the dopant is a nitrate containing at least one of potassium, lanthanum, zirconium, nickel and cerium.

3. The method according to claim 2, characterized in that The molar ratio of P to Al in the catalyst is 0.5-1.2, the molar ratio of Si to Al is 0.2-1.0, the molar ratio of Ti to Al is 0.01-0.6, and the molar ratio of the metal element to Al in the dopant is 0.1-0.

4.

4. The method according to claim 1, characterized in that The pH value is adjusted to 7.

5.

5. The method according to claim 1, characterized in that The standing is standing at room temperature for 24 hours.

6. The method according to claim 1, characterized in that The drying temperature is 90°C.

7. The method according to claim 1, characterized in that The calcination temperature is 300-600° C. and the calcination time is 10 hours.

8. A catalyst prepared by the method according to any one of claims 1 to 7.

9. Use of the catalyst as claimed in claim 8 in catalyzing the dehydration of ethylene glycol to synthesize acetaldehyde.

10. A method for synthesizing acetaldehyde by dehydrating ethylene glycol, characterized in that: Acetaldehyde is prepared by using ethylene glycol as a single raw material through a gas-solid phase method and a catalytic reaction using the catalyst described in claim 8.

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