An oxygen-rich vacancy Zn / CeMO catalyst for acetaldehyde production and a preparation method and application thereof

Abstract

The application discloses an oxygen-enriched vacancy Zn / CeMO catalyst for acetaldehyde preparation and a preparation method and application thereof. The preparation method of the oxygen-enriched vacancy Zn / CeMO catalyst for acetaldehyde preparation comprises the following steps: (1) dissolving cerium salt, sodium salt, hexamethylenetetramine and ammonium persulfate in water, and then performing heating and stirring reaction, and performing filtration, washing and vacuum drying to obtain layered double hydroxide of cerium; (2) performing high-temperature heat treatment on the layered double hydroxide of cerium to obtain an oxygen-enriched vacancy cerium oxide carrier; and (3) adding zinc active components and the cerium oxide carrier into water, and then performing stirring, impregnation and drying to obtain the oxygen-enriched vacancy Zn / CeMO catalyst for acetaldehyde preparation. The oxygen-enriched vacancy Zn / CeMO catalyst for acetaldehyde preparation and the preparation method and application thereof have the advantages that the CeMO carrier has rich oxygen vacancies, can effectively accelerate the water splitting speed control step of acetylene hydration reaction, and has the advantages of high hydrothermal stability, greenness and no pollution, and the obtained Zn / CeMO catalyst has excellent catalytic performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalysts, and particularly relates to an oxygen-enriched vacancy Zn / CeMO catalyst for preparing acetaldehyde and a preparation method and application thereof. BACKGROUND

[0002] Based on the energy structure characteristics of China being rich in coal and poor in oil, it is inevitable that the coal-to-acetylene process technology is continuously matured, and it is also an important cornerstone to ensure the energy security of China. The calcium carbide method for preparing acetaldehyde is an important way for China to produce acetaldehyde. A variety of chemical products such as acetic acid, peracetic acid and pyridine compounds can be obtained from acetaldehyde, which can effectively reduce the dependence on the petroleum-oriented ethylene oxidation method for preparing acetaldehyde. Therefore, the acetylene hydration method for preparing acetaldehyde has high research value.

[0003] At present, the catalytic active components of the acetylene hydration reaction are mainly concentrated on transition metals (Zn, Cu, Ag, Au, Hg and Cd) with full d orbitals. Initially, Hg-based and Cd-based catalysts are mainly used, and Ag and Au are less used. Considering economy and environmental protection, it is difficult to adapt to future development, and Cu ions are easily reduced to elemental Cu and deactivated. Therefore, the Zn-based catalyst with low price for catalyzing the acetylene hydration reaction seems to be the most ideal choice. At present, the Zn-based catalyst has the shortcomings of high initial activity and poor stability, which cannot be ignored. Therefore, it is very ideal to develop an environmentally friendly and efficient Zn-based catalyst for catalyzing the acetylene hydration to prepare acetaldehyde.

[0004] Therefore, the application provides a new Zn-based catalyst for acetylene hydration to prepare acetaldehyde, which is loaded with Zn through an oxygen-enriched vacancy material to achieve an effective structure-activity relationship, thereby playing a catalytic effect of efficiently catalyzing acetylene hydration to prepare acetaldehyde. SUMMARY

[0005] The application aims to provide a preparation method of an oxygen-enriched vacancy Zn / CeMO catalyst for preparing acetaldehyde,

[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted is as follows:

[0007] A preparation method of an oxygen-enriched vacancy Zn / CeMO catalyst for preparing acetaldehyde, comprising the following steps:

[0008] (1) Dissolving cerium salt, sodium salt, hexamethylenetetramine and ammonium persulfate in water, and then heating and stirring under inert protection gas to react, and then filtering, washing and vacuum drying to obtain layered double hydroxide of cerium;

[0009] (2) High-temperature heat treatment is performed on the layered double hydroxide of cerium to obtain an oxygen-enriched vacancy cerium oxide carrier;

[0010] (3) adding the active component of zinc and the cerium oxide carrier into water, stirring for 10-14 hours at room temperature, and drying to obtain the oxygen-enriched vacancy Zn / CeMO catalyst for acetaldehyde production.

[0011] Further, in the step (1), the molar ratio of cerium salt, sodium salt, hexamethylenetetramine and ammonium persulfate is 1:1-1.5:4-6:0.3-0.9;

[0012] In the step (2), the high-temperature heat treatment temperature is 850±100℃, and the time is 300-420min;

[0013] In the step (3), the content of the active component of zinc in the oxygen-enriched vacancy Zn / CeMO catalyst is 10-15wt%.

[0014] Further, in the step (1), the molar ratio of cerium salt, sodium salt, hexamethylenetetramine is 1:1.3:5;

[0015] In the step (2), the high-temperature heat treatment temperature time is 360min;

[0016] In the step (3), the content of the active component of zinc in the oxygen-enriched vacancy Zn / CeMO catalyst is 15wt%.

[0017] Further, in the step (1), the cerium salt is cerium nitrate hexahydrate, and the sodium salt is sodium chloride;

[0018] The inert protective gas is nitrogen or argon;

[0019] Deionized water and anhydrous ethanol are alternately washed for 3-4 times.

[0020] Further, in the step (1), the reaction temperature is 100-120℃, and the time is 22-26h;

[0021] The vacuum drying temperature is 55-65℃, and the time is 10-14h;

[0022] In the step (3), the drying temperature is 70-90℃, and the drying time is 16-20h.

[0023] Further, in the step (1), the reaction temperature is 110℃, and the time is 24h;

[0024] The vacuum drying temperature is 60℃, and the time is 12h;

[0025] In the step (3), the drying temperature is 80℃, and the time is 18h.

[0026] Another object of the present application is to provide an oxygen-rich vacancy Zn / CeMO catalyst for acetaldehyde production, which is prepared by the above preparation method, and can enhance the activation ability of water, improve the conversion rate of acetylene and the selectivity of acetaldehyde.

[0027] Another object of the present application is to provide the application of the above-mentioned oxygen-rich vacancy Zn / CeMO catalyst, which can efficiently produce acetaldehyde in the acetylene hydration reaction, and better overcome the defects of high initial activity and poor stability of Zn-based catalysts.

[0028] In order to achieve the above object, the technical scheme adopted is:

[0029] The application of the above-mentioned oxygen-rich vacancy Zn / CeMO catalyst in the production of acetaldehyde by calcium carbide method.

[0030] Further, in the gas-solid phase reaction for producing acetaldehyde by calcium carbide method, the reaction temperature is 220-280 DEG C, the acetylene space velocity is 70-110 h -1 , and the molar ratio of water vapor to acetylene is 3-5:1.

[0031] Further, in the gas-solid phase reaction for producing acetaldehyde by calcium carbide method, the acetylene space velocity is 90 h -1 , and the molar ratio of water vapor to acetylene is 4:1.

[0032] Compared with the prior art, the beneficial effects of the present application are:

[0033] 1. The technical scheme of the present application, the oxygen-rich vacancy CeMO loaded Zn is activated by water vapor, which produces more active zinc hydroxyl species that are beneficial to the reaction, and reduces the reaction activation energy.

[0034] 2. The technical scheme of the present application, the CeMO loaded Zn can improve the dispersion of Zn species and inhibit the production of carbon deposition during the reaction.

[0035] 3. The technical scheme of the present application, the Zn / CeMO catalyst for acetylene hydration to produce acetaldehyde can effectively overcome the defects of high initial activity and poor stability of Zn-based catalysts. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The catalyst prepared in the implementation example catalyzes the performance of acetylene hydration;

[0037] Figure 2 The EPR and UV-vis DRS characterization of the CeMO carrier prepared in the implementation example;

[0038] Figure 3 The XRD characterization of the catalyst prepared in the implementation example before and after the reaction;

[0039] Figure 4 Thermogravimetric characterization of the catalyst prepared in the case before and after the reaction. DETAILED DESCRIPTION

[0040] In order to further illustrate the present application, a kind of preparation of acetaldehyde oxygen vacancy rich Zn / CeMO catalyst and its preparation method, application, to achieve the intended purpose of the application, the following in conjunction with preferred embodiments, according to the present application, a kind of preparation of acetaldehyde oxygen vacancy rich Zn / CeMO catalyst and its preparation method, application, its specific implementation, structure, features and its efficacy, detailed description as follows. In the following description, different "an embodiment" or "embodiments" refer to the same embodiment. In addition, the specific features, structures or characteristics of one or more embodiments can be combined in any suitable form.

[0041] The present application will be further described in detail below with specific examples:

[0042] In order to overcome the problems of high activity and poor stability of Zn-based catalyst. Theoretical calculations show that the defect part in the defect graphene can produce electronic rearrangement, which is beneficial to the adsorption and activation of water, and reduces the reaction energy barrier. As we all know, oxygen vacancy is one of the typical defects in solid catalysts, which plays an important role in various catalytic reactions. During the heat treatment of layered double hydroxide (LDH), due to the removal of water molecules and the decomposition of interlayer anions, oxide (MMO) with certain nanopores and structural defects can be obtained. Compared with other methods of introducing oxygen vacancies, this anion-induced oxygen vacancy strategy can effectively form uniform oxygen vacancy defects. The technical scheme of the present application is:

[0043] A preparation method of a kind of preparation of acetaldehyde oxygen vacancy rich Zn / CeMO catalyst, comprising the following steps:

[0044] (1) Dissolve cerium salt, sodium salt, hexamethylene tetramine and ammonium persulfate in water, then heat and stir under inert protective gas, filter, wash and vacuum dry to obtain cerium layered double hydroxide;

[0045] (2) High temperature heat treatment of the cerium layered double hydroxide to obtain oxygen vacancy rich cerium oxide carrier;

[0046] (3) Add zinc active component and the cerium oxide carrier to water, stir for 10-14 hours at room temperature, then dry to obtain the oxygen vacancy rich Zn / CeMO catalyst for preparing acetaldehyde.

[0047] Preferably, in the step (1), the molar ratio of cerium salt, sodium salt, hexamethylenetetramine and ammonium persulfate is 1:1-1.5:4-6:0.3-0.9;

[0048] In the step (2), the high-temperature heat treatment temperature is 850±100℃, and the time is 300-420min;

[0049] In the step (3), the content of the active component of zinc in the oxygen vacancy-rich Zn / CeMO catalyst is 10-15wt%.

[0050] Further preferably, in the step (1), the molar ratio of cerium salt, sodium salt, hexamethylenetetramine is 1:1.3:5;

[0051] In the step (2), the high-temperature heat treatment temperature time is 360min;

[0052] In the step (3), the content of the active component of zinc in the oxygen vacancy-rich Zn / CeMO catalyst is 15wt%.

[0053] Preferably, in the step (1), the cerium salt is cerium nitrate hexahydrate, and the sodium salt is sodium chloride;

[0054] The inert protective gas is nitrogen or argon;

[0055] Deionized water and anhydrous ethanol are alternately washed for 3-4 times.

[0056] Preferably, in the step (1), the reaction temperature is 100-120℃, and the time is 22-26h;

[0057] The vacuum drying temperature is 55-65℃, and the time is 10-14h;

[0058] In the step (3), the drying temperature is 70-90℃, and the drying time is 16-20h.

[0059] Further preferably, in the step (1), the reaction temperature is 110℃, and the time is 24h;

[0060] The vacuum drying temperature is 60℃, and the time is 12h;

[0061] In the step (3), the drying temperature is 80℃, and the time is 18h.

[0062] An oxygen vacancy-rich Zn / CeMO catalyst for acetaldehyde production, prepared by the above preparation method, which can enhance the activation ability of water, improve the conversion rate of acetylene and the selectivity of acetaldehyde.

[0063] The above oxygen vacancy-rich Zn / CeMO catalyst is applied in the production of acetaldehyde by the calcium carbide method.

[0064] Preferably, in the gas-solid phase reaction for preparing acetaldehyde by the calcium carbide method, the reaction temperature is 220-280℃, the acetylene space velocity is 70-110h -1 , and the molar ratio of water vapor to acetylene is 3-5:1.

[0065] Further preferably, in the gas-solid phase reaction for preparing acetaldehyde by the calcium carbide method, the acetylene space velocity is 90h -1 , and the molar ratio of water vapor to acetylene is 4:1.

[0066] In the technical solution, the Zn / CeMO catalyst for preparing acetaldehyde by the calcium carbide method provided by the application has the advantages that the CeMO material is used as the carrier of Zn, can effectively load the metal active component and has the anti-coking performance, has more active sites, improves the dispersity of the metal component, reduces the generation of by-products such as acetone and butenal in the reaction process, and has good catalytic activity. The prepared catalyst is a mercury-free catalyst, and can solve the problems of the mercury-based catalyst, such as easy volatilization, environmental pollution and damage to human health.

[0067] The raw materials used in the examples are all commercially available materials.

[0068] Example 1.

[0069] The synthesis of the supported Zn / CeMO-850-0.3 catalyst is as follows:

[0070] (1) 4.342 g of cerium nitrate hexahydrate, 7.597 g of sodium chloride, 7.01 g of hexamethylenetetramine and 0.6845 g of ammonium persulfate were dissolved in 400 ml of deionized water to obtain a mixed solution (the molar ratio of ammonium persulfate to cerium nitrate hexahydrate was 0.3:1).

[0071] (2) The mixed solution obtained in step (1) was heated to 110℃ under argon and stirred for 24 h, then was washed with deionized water and anhydrous ethanol by alternating filtration for 3-4 times, and then was dried at 60℃ under vacuum for 12 h to obtain cerium layered double hydroxide (Ce-LDH).

[0072] (3) The Ce-LDH obtained in step (2) was placed in a muffle furnace and heat-treated at 850℃ for 6 h to obtain a Zn-loaded oxygen-rich vacancy cerium oxide (CeMO) carrier.

[0073] (4) About 20 ml of deionized water was measured in a beaker, 0.3533 g of zinc chloride and 2 g of the CeMO carrier obtained in step (3) were weighed and added to the beaker, and then was stirred at room temperature for 12 h and dried at 80℃ for 18 h to obtain a Zn / CeMO catalyst for preparing acetaldehyde by the calcium carbide method.

[0074] The activity test was carried out under the conditions that the reaction temperature was 240℃, the flow rate of C2H2 was 2.7ml / min, the flow rate of H2O was 0.012ml / min, and the acetylene space velocity was adjusted to 90h-1. -1 The Zn / CeMO-850-0.3 catalyst was used for the gas-solid phase acetylene hydration reaction. The activity test results showed that after 10h of reaction, the acetylene conversion rate was 92.05%, and the acetaldehyde selectivity was 79.84%.

[0075] Example 2.

[0076] The synthesis of the supported Zn / CeMO-850-0.45 catalyst was carried out according to the following specific operation steps:

[0077] (1) 4.342g of cerium nitrate hexahydrate, 7.597g of sodium chloride, 7.01g of methenamine, and 1.0267g of ammonium persulfate were dissolved in 400ml of deionized water to obtain a mixed solution (the molar ratio of ammonium persulfate to cerium nitrate hexahydrate was 0.45:1).

[0078] (2) The mixed solution obtained in step (1) was heated to 110℃ under argon and stirred for 24h, then filtered and washed with deionized water and anhydrous ethanol for 3-4 times, and then dried at 60℃ under vacuum for 12h to obtain cerium layered double hydroxide (Ce-LDH).

[0079] (3) The Ce-LDH obtained in step (2) was placed in a muffle furnace and heat-treated at 850℃ for 6h to obtain a Zn-loaded oxygen-rich vacancy cerium oxide (CeMO) carrier.

[0080] (4) About 20ml of deionized water was measured in a beaker, 0.3533g of zinc chloride and 2g of the CeMO carrier obtained in step (3) were weighed and added to the beaker, and stirred at room temperature for 12h, and then dried at 80℃ for 18h to obtain a Zn / CeMO catalyst for acetaldehyde production by the calcium carbide method.

[0081] The activity test was carried out under the conditions that the reaction temperature was 240℃, the flow rate of C2H2 was 2.7ml / min, the flow rate of H2O was 0.012ml / min, and the acetylene space velocity was adjusted to 90h -1 The activity test results showed that after 10h of reaction, the acetylene conversion rate was 86.21%, and the acetaldehyde selectivity was 83.92%.

[0082] Example 3.

[0083] The synthesis of the supported Zn / CeMO-850-0.6 catalyst was carried out according to the following specific operation steps:

[0084] (1) Dissolve 4.342 g of cerium nitrate hexahydrate, 7.597 g of sodium chloride, 7.01 g of methenamine, and 1.369 g of ammonium persulfate in 400 ml of deionized water to obtain a mixed solution (the molar ratio of ammonium persulfate to cerium nitrate hexahydrate is 0.6:1).

[0085] (2) After the mixed solution obtained in step (1) is heated at 110°C under argon and stirred for 24 h, it is filtered and washed with deionized water and anhydrous ethanol alternately for 3-4 times, and then dried at 60°C under vacuum for 12 h to obtain a cerium layered double hydroxide (Ce-LDH).

[0086] (3) The Ce-LDH obtained in step (2) is heat-treated in a muffle furnace at 850°C for 6 h to obtain a Zn-loaded oxygen vacancy-rich cerium oxide (CeMO) carrier.

[0087] (4) About 20 ml of deionized water is measured in a beaker, 0.3533 g of zinc chloride and 2 g of the CeMO carrier obtained in step (3) are weighed and added to the beaker, stirred at room temperature for 12 h, and then dried at 80°C for 18 h to obtain a Zn / CeMO catalyst for acetaldehyde production by the calcium carbide method.

[0088] During the activity test, the Zn / CeMO-850-0.6 catalyst is used for the gas-solid phase acetylene hydration reaction under the conditions that the reaction temperature is 240°C, the C2H2 flow rate is 2.7 ml / min, the H2O flow rate is 0.012 ml / min, and the acetylene space velocity is adjusted to 90 h-1. -1 The activity test results show that after 10 h of reaction, the acetylene conversion rate is 91.62%, and the selectivity of acetaldehyde is 84.08%.

[0089] Example 4.

[0090] The synthesis of the supported Zn / CeMO-850-0.75 catalyst is as follows:

[0091] (1) Dissolve 4.342 g of cerium nitrate hexahydrate, 7.597 g of sodium chloride, 7.01 g of methenamine, and 1.369 g of ammonium persulfate in 400 ml of deionized water to obtain a mixed solution (the molar ratio of ammonium persulfate to cerium nitrate hexahydrate is 0.6:1).

[0092] (2) After the mixed solution obtained in step (1) is heated at 110°C under argon and stirred for 24 h, it is filtered and washed with deionized water and anhydrous ethanol alternately for 3-4 times, and then dried at 60°C under vacuum for 12 h to obtain a cerium layered double hydroxide (Ce-LDH).

[0093] (3) The Ce-LDH obtained in step (2) was placed in a muffle furnace for heat treatment at 850°C for 6h to obtain a Zn-loaded oxygen vacancy-rich cerium oxide (CeMO) carrier.

[0094] (4) About 20ml of deionized water was measured in a beaker, 0.3533g of zinc chloride and 2g of the CeMO carrier obtained in step (3) were weighed and added to the beaker, stirred at room temperature for 12h, and then dried at 80°C for 18h to obtain a Zn / CeMO catalyst for acetaldehyde production by the calcium carbide method.

[0095] During the activity test, the Zn / CeMO-850-0.75 catalyst was used for the gas-solid phase acetylene hydration reaction under the conditions of a reaction temperature of 240°C, a C2H2 flow rate of 2.7ml / min, a H2O flow rate of 0.012ml / min, and an acetylene space velocity of 90h-1. -1 The activity test results showed that after 10h of reaction, the acetylene conversion rate was 52.16% and the acetaldehyde selectivity was 55.27%.

[0096] Example 5.

[0097] The synthesis of the supported Zn / CeMO-850-0.9 catalyst was carried out according to the following specific operation steps:

[0098] (1) 4.342g of cerium nitrate hexahydrate, 7.597g of sodium chloride, 7.01g of hexamethylenetetramine, and 2.0535g of ammonium persulfate were dissolved in 400ml of deionized water to obtain a mixed solution (the molar ratio of ammonium persulfate to cerium nitrate hexahydrate was 0.9:1).

[0099] (2) The mixed solution obtained in step (1) was heated to 110°C under argon and stirred for 24h, then filtered and washed with deionized water and anhydrous ethanol for 3-4 times alternately, and then dried at 60°C under vacuum for 12h to obtain cerium layered double hydroxide (Ce-LDH).

[0100] (3) The Ce-LDH obtained in step (2) was placed in a muffle furnace for heat treatment at 850°C for 6h to obtain a Zn-loaded oxygen vacancy-rich cerium oxide (CeMO) carrier.

[0101] (4) About 20ml of deionized water was measured in a beaker, 0.3533g of zinc chloride and 2g of the CeMO carrier obtained in step (3) were weighed and added to the beaker, stirred at room temperature for 12h, and then dried at 80°C for 18h to obtain a Zn / CeMO catalyst for acetaldehyde production by the calcium carbide method.

[0102] During the activity test, the Zn / CeMO-850-0.75 catalyst was used for the gas-solid phase acetylene hydration reaction under the conditions of a reaction temperature of 240°C, a C2H2 flow rate of 2.7ml / min, a H2O flow rate of 0.012ml / min, and an acetylene space velocity of 90h-1.-1 Under the conditions of 100 °C, the Zn / CeMO-850-0.9 catalyst was used for the gas-solid phase acetylene hydration reaction. Activity test results showed that after 10 hours of reaction, the acetylene conversion rate was 73.49% and the acetaldehyde selectivity was 45.20%.

[0103] Example 6.

[0104] The synthesis of supported Zn / CeMO-750-0.6 catalyst, the specific steps are as follows:

[0105] (1) 4.342 g of cerium nitrate hexahydrate, 7.597 g of sodium chloride, 7.01 g of hexamethylenetetramine, and 1.369 g of ammonium persulfate were dissolved in 400 ml of deionized water to obtain a mixed solution (the molar ratio of ammonium persulfate to cerium nitrate hexahydrate was 0.6:1).

[0106] (2) The mixed solution obtained in step (1) was heated at 110° C. under argon and stirred for 24 h, then filtered and washed 3-4 times with deionized water and anhydrous ethanol, and then vacuum-dried at 60° C. for 12 h to obtain cerium layered double hydroxide (Ce-LDH).

[0107] (3) The Ce-LDH obtained in step (2) was placed in a muffle furnace and heat-treated at 750° C. for 6 h to obtain a Zn-loaded oxygen-vacancy-rich cerium oxide (CeMO) carrier.

[0108] (4) About 20 ml of deionized water was measured in a beaker, and 0.3533 g of zinc chloride and 2 g of the CeMO support obtained in step (3) were weighed and added to the beaker. After stirring at room temperature for 12 h, the mixture was dried at 80 ° C for 18 h to obtain a Zn / CeMO catalyst for acetaldehyde production by the calcium carbide process.

[0109] During the activity test, the reaction temperature was 240℃, the C2H2 flow rate was 2.7ml / min, the H2O flow rate was 0.012ml / min, and the acetylene space velocity was adjusted to 90h -1 Under the conditions of 100 °C, the Zn / CeMO-750-0.6 catalyst was used for the gas-solid phase acetylene hydration reaction. Activity test results showed that after 10 hours of reaction, the acetylene conversion rate was 74.06% and the acetaldehyde selectivity was 82.25%.

[0110] Example 7.

[0111] The synthesis of supported Zn / CeMO-950-0.6 catalyst is as follows:

[0112] (1) 4.342 g of cerium nitrate hexahydrate, 7.597 g of sodium chloride, 7.01 g of hexamethylenetetramine, and 1.369 g of ammonium persulfate were dissolved in 400 ml of deionized water to obtain a mixed solution (molar ratio of ammonium persulfate to cerium nitrate hexahydrate was 0.6:1).

[0113] (2) The mixed solution obtained in step (1) was heated under argon at 110°C and stirred for 24 h, then filtered and washed with deionized water and anhydrous ethanol alternately for 3-4 times, and then dried at 60°C under vacuum for 12 h to obtain a cerium layered double hydroxide (Ce-LDH).

[0114] (3) The Ce-LDH obtained in step (2) was heat-treated in a muffle furnace at 950°C for 6 h to obtain a Zn-loaded oxygen vacancy-rich cerium oxide (CeMO) carrier.

[0115] (4) About 20 ml of deionized water was measured in a beaker, 0.3533 g of zinc chloride and 2 g of the CeMO carrier obtained in step (3) were weighed and added to the beaker, stirred at room temperature for 12 h, and then dried at 80°C for 18 h to obtain a Zn / CeMO catalyst for acetaldehyde production by the calcium carbide method.

[0116] During the activity test, the Zn / CeMO-950-0.6 catalyst was used for the gas-solid phase acetylene hydration reaction under the conditions that the reaction temperature was 240°C, the C2H2 flow rate was 2.7 ml / min, the H2O flow rate was 0.012 ml / min, and the acetylene space velocity was adjusted to 90 h-1. -1 The activity test results showed that after 10 h of reaction, the acetylene conversion rate was 71.60%, and the selectivity of acetaldehyde was 83.86%.

[0117] Example 8.

[0118] The synthesis of the supported Zn / CeMO-800-0.45 catalyst was carried out according to the following specific operation steps:

[0119] (1) 4.342 g of cerium nitrate hexahydrate, 7.597 g of sodium chloride, 7.01 g of hexamethylenetetramine, and 1.369 g of ammonium persulfate were dissolved in 400 ml of deionized water to obtain a mixed solution (molar ratio of ammonium persulfate to cerium nitrate hexahydrate was 0.6:1).

[0120] (2) The mixed solution obtained in step (1) was heated under argon at 110°C and stirred for 24 h, then filtered and washed with deionized water and anhydrous ethanol alternately for 3-4 times, and then dried at 60°C under vacuum for 12 h to obtain a cerium layered double hydroxide (Ce-LDH).

[0121] (3) The Ce-LDH obtained in step (2) was placed in a muffle furnace and heat treated at 800°C for 7h to obtain a Zn-loaded oxygen vacancy-rich cerium oxide (CeMO) support.

[0122] (4) About 20ml of deionized water was measured in a beaker, 0.2222g of zinc chloride and 2g of the CeMO support obtained in step (3) were weighed and added to the beaker, stirred at room temperature for 10h, and then dried at 70°C for 20h to obtain a Zn / CeMO catalyst for acetaldehyde production by the calcium carbide method.

[0123] During the activity test, the Zn / CeMO-800-0.45 catalyst was used for the gas-solid phase acetylene hydration reaction under the conditions of a reaction temperature of 220°C, a C2H2 flow rate of 2.7ml / min, a H2O flow rate of 0.019ml / min, and an acetylene space velocity of 70h-1. -1

[0124] Example 9.

[0125] The synthesis of the supported Zn / CeMO-900-0.75 catalyst was carried out according to the following specific operation steps:

[0126] (1) 4.342g of cerium nitrate hexahydrate, 7.597g of sodium chloride, 7.01g of hexamethylenetetramine, and 1.7112g of ammonium persulfate were dissolved in 400ml of deionized water to obtain a mixed solution (the molar ratio of ammonium persulfate to cerium nitrate hexahydrate was 0.75:1).

[0127] (2) The mixed solution obtained in step (1) was heated and stirred at 120°C for 20h under argon, then washed with deionized water and anhydrous ethanol by alternating filtration for 3-4 times, and then dried at 65°C under vacuum for 10h to obtain cerium layered double hydroxide (Ce-LDH).

[0128] (3) The Ce-LDH obtained in step (2) was placed in a muffle furnace and heat treated at 900°C for 5h to obtain a Zn-loaded oxygen vacancy-rich cerium oxide (CeMO) support.

[0129] (4) About 20ml of deionized water was measured in a beaker, 0.3000g of zinc chloride and 2g of the CeMO support obtained in step (3) were weighed and added to the beaker, stirred at room temperature for 14h, and then dried at 90°C for 16h to obtain a Zn / CeMO catalyst for acetaldehyde production by the calcium carbide method.

[0130] During the activity test, the Zn / CeMO-800-0.45 catalyst was used for the gas-solid phase acetylene hydration reaction under the conditions of a reaction temperature of 220°C, a C2H2 flow rate of 2.7ml / min, a H2O flow rate of 0.019ml / min, and an acetylene space velocity of 70h-1. -1 ​The Zn / CeMO-900-0.75 catalyst was used for the gas-solid phase acetylene hydration reaction under the conditions of the present application.

[0131] Example 10.

[0132] In a self-made fixed bed reactor (φ10x500mm) device, the acetylene hydration reaction was carried out using the catalysts prepared in Examples 1-7. 2ml of the above-mentioned catalyst Zn / CeMO was taken in the acetylene hydration reaction device for gas-solid acetylene hydration reaction. First, N2was blown for 30min to remove the air in the reaction tube. Then heating was started, and the temperature of the condensation circulating pump was set to about -2℃. After the reaction tube was heated to 240℃ and the reaction water temperature reached 160℃, the catalyst was activated with steam (about 0.06ml / min, 30min) by a peristaltic pump. Then N2was closed and C2H2was opened, and acetylene and water vapor were injected into the reactor according to GHSV(C2H2)=90h-1and n(H2O) / n(C2H2)=4. Finally, every hour, the product content was detected by manual sampling into a gas chromatograph (GC-2014C). The evaluation index was as follows: -1

[0133] X C2H2 = (φ A0 - φ A ) / φ A0 x 100%

[0134] S CH3CHO = φ AA / (φ A0 - φ A ) x 100%

[0135] wherein X C2H2 is the conversion rate of acetylene, S CH3CHO is the selectivity of acetaldehyde; φ A0 represents the volume fraction of acetylene in the initial reactant, φ A represents the volume fraction of residual acetylene in the product, and φ AA represents the volume fraction of acetaldehyde in the product.

[0136] The acetylene conversion rate and acetaldehyde selectivity of different Zn / CeMO catalysts are shown in Table 1. Figure 1 The test results of the catalytic performance show that the CeMO loaded with Zn catalyzing the acetylene hydration reaction has good acetylene conversion rate and acetaldehyde selectivity due to the rich oxygen vacancies. In addition, when the molar ratio of ammonium persulfate to cerium nitrate hexahydrate is 0.6:1 and the heat treatment temperature is 850℃, the performance of the Zn / CeMO-850-0.6 catalyst is the best. That is, too high amount of ammonium persulfate cannot well synthesize the CeMO precursor Ce-LDH, and thus it is difficult to improve the vacancy content by heat treatment.

[0137] From​Figure 1 The performance results of (b), (c), (d) show that the optimal Zn / CeMO-850-0.6 catalyst still has an acetaldehyde selectivity of more than 80% after 32 h of reaction, indicating that the Zn-loaded CeMO with rich oxygen vacancies can better overcome the problem of high initial selectivity of acetaldehyde and rapid subsequent decline of Zn-based catalysts.

[0138] Example 11.

[0139] The catalyst prepared in the examples of the present application was subjected to various characterization tests.

[0140] Through electron paramagnetic resonance (EPR) tests, the strength of the oxygen vacancy signal of the CeMO material can be indicated.

[0141] Through solid UV-vis diffuse reflectance spectrophotometer (UV-vis DRS) tests, the optical properties of the CeMO material can be obtained.

[0142] The results are shown in Figure 2 As shown in Figure 2 (a), the CeMO material was characterized by EPR and solid UV-vis DRS. The EPR results show that the CeMO material detects a clear oxygen vacancy signal at g = 2.003. The solid UV-Vis DRS spectrum Figure 2 (b) shows that the two absorption characteristic peaks of CeMO at 280 nm and 320 nm are related to the absorption of Ce 3+ and Ce 4+ , which also indicates that the CeMO material has vacancy defects.

[0143] Example 12.

[0144] In order to determine the change in the crystal structure of Zn in the Zn / CeMO catalyst during the reaction, XRD spectrum analysis was performed on the catalyst before and after the reaction, and the results are shown in Figure 3 .

[0145] X-ray Diffraction (XRD) uses a D8 ADVANCE instrument from Bruker, Germany, to record XRD data, which is used to analyze the crystal phase structure of the catalyst. The radiation source used is Cu Kα, the working current is 10 mA, the voltage is 40 mV, and the 2θ angle range is between 10°-90°.

[0146] Figure 3(a) The results show that no diffraction peaks of Zn-containing substances were detected in the catalyst before the reaction, indicating that the active component ZnCl2 has good dispersibility.

[0147] Figure 3 (b) The results show that weak diffraction peaks of ZnCl2 were detected in the catalyst after the reaction. Among them, the Zn / CeMO-850-0.6 catalyst detected the weakest diffraction peak of ZnCl2 at about 16.01°. Accordingly, it is speculated that the higher the oxygen vacancy concentration of the CeMO material, the better the dispersibility of the active component ZnCl2.

[0148] Example 13.

[0149] Carbon deposition is an important factor for catalyst deactivation. In order to study the anti-carbon deposition performance of the catalyst, the TG characterization analysis was performed on the catalyst of Zn / CeMO-850-0.6 after 32h reaction and the fresh catalyst, and the results are shown in Figure 4 The carbon deposition was calculated by estimating the weight difference between the fresh catalyst and the used catalyst in the same temperature range. Between room temperature and 130℃, the mass loss of the sample is due to the evaporation of water combined with the catalyst sample. The TG curve and the DTG curve of the fresh catalyst and the used catalyst are basically the same, and both of them undergo ZnCl2 decomposition and (ZnOH) + dehydroxylation reaction between 350℃ and 600℃. The carbon deposition amount of the Zn / CeMO-850-0.6 catalyst is only 1.18%. The results show that the Zn catalyst supported by the CeMO with rich oxygen vacancies has good anti-carbon deposition performance and exhibits excellent catalytic performance in the acetylene hydration reaction.

[0150] The above is only the preferred embodiment of the present application, and does not limit the application in any form. Any simple modification, equivalent change and modification of the technical essence of the present application to the above embodiment are still within the scope of the technical solution of the present application.

Claims

1. A method for preparing an oxygen-rich vacancy Zn / CeMO catalyst for acetaldehyde production, characterized by, The method comprises the following steps: (1) Dissolving cerium salt, sodium salt, hexamethylenetetramine and ammonium persulfate in water, and then stirring and reacting under heating in an inert protective atmosphere, and then filtering, washing and vacuum drying to obtain layered double hydroxide of cerium; (2) High-temperature heat treating the layered double hydroxide of cerium to obtain an oxygen vacancy-rich cerium oxide carrier; (3) Adding active components of zinc and the oxygen vacancy-rich cerium oxide carrier into water, stirring and impregnating at room temperature, and then drying to obtain the oxygen vacancy-rich Zn / CeMO catalyst for acetaldehyde production.

2. The method according to claim 1, wherein in the step (1), the molar ratio of cerium salt, sodium salt, hexamethylenetetramine and ammonium persulfate is 1:1-1.5:4-6:0.3-0.9; in the step (2), the high-temperature heat treating temperature is 850±100℃, and the time is 300-420min; and in the step (3), the content of the active components of zinc in the oxygen vacancy-rich Zn / CeMO catalyst is 10-15wt%.

3. The method according to claim 2, wherein in the step (1), the molar ratio of cerium salt, sodium salt and hexamethylenetetramine is 1:1.3:5; in the step (2), the high-temperature heat treating temperature is 360min; and in the step (3), the content of the active components of zinc in the oxygen vacancy-rich Zn / CeMO catalyst is 15wt%.

4. The method according to claim 1, wherein in the step (1), the cerium salt is cerium nitrate hexahydrate, and the sodium salt is sodium chloride; the inert protective atmosphere is nitrogen or argon; and the washing is performed 3-4 times alternately using deionized water and anhydrous ethanol.

5. The method according to claim 1, wherein in the step (1), the reaction temperature is 100-120℃, and the time is 22-26h; the vacuum drying temperature is 55-65℃, and the time is 10-14h; and in the step (3), the stirring and impregnating time is 10-14h, the drying temperature is 70-90℃, and the drying time is 16-20h.

6. The method according to claim 5, wherein in the step (1), the reaction temperature is 110℃, and the time is 24h; the vacuum drying temperature is 60℃, and the time is 12h; and in the step (3), the stirring and impregnating time is 12h, the drying temperature is 80℃, and the time is 18h. The oxygen vacancy-rich Zn / CeMO catalyst is prepared by the method according to any one of claims 1-6.

8. The use of the oxygen vacancy-rich Zn / CeMO catalyst according to claim 7 in the production of acetaldehyde by the calcium carbide method.

9. The use according to claim 8, wherein the acetaldehyde production process is the calcium carbide method.

10. The use according to claim 9, wherein the acetaldehyde production process is the calcium carbide method. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 7. An oxygen-rich vacant Zn / CeMO catalyst for acetaldehyde production, characterized by, ​ ​ ​ The gas-solid phase reaction for preparing acetaldehyde by calcium carbide method is carried out at a temperature of 220-280 DEG C, an acetylene space velocity of 70-110 h -1 , and a molar ratio of water vapor to acetylene of 3-5:

1. ​ The gas-solid phase reaction for preparing acetaldehyde by calcium carbide method is characterized in that the acetylene space velocity is 90h -1 , and the molar ratio of water vapor to acetylene is 4:1.

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