A Cs-doped CuNi / titanium dioxide catalyst and its preparation and application

Abstract

The present invention discloses a Cs-doped CuNi / titanium dioxide catalyst and its preparation and application. The preparation method of the Cs-doped CuNi / titanium dioxide catalyst comprises the following steps: Step 1: Weigh copper salt, nickel salt and cesium salt and dissolve them in deionized water, and fully stir at room temperature to obtain a mixed solution; Step 2: Take TiO 2 and add it to the above mixed solution, and stir the mixture at room temperature for 8-12 h, dry and grind it into powder to obtain a mixed sample powder; Step 3: Place the mixed sample powder obtained in Step 2 in an inert gas environment and calcine it at high temperature to obtain a Cs-doped CuNi / titanium dioxide catalyst. The present invention provides the application of the Cs-doped CuNi / titanium dioxide catalyst in the selective hydrogenation of acetylene to prepare ethylene, which shows excellent acetylene conversion rate, ethylene selectivity and catalyst stability.

Description

Technical Field

[0001] The present invention relates to a CuNi / titanium dioxide catalyst, its preparation and application in the selective hydrogenation reaction of acetylene. Background Art

[0002] Ethylene is one of the most important petrochemical products, and the global total production capacity reached 210 million tons in 2021. Among them, more than 50% is used for polymerization to produce polyethylene. Approximately 75% of ethylene is produced by steam cracking of naphtha, which also generates acetylene impurities that can irreversibly poison the polymerization catalyst. Therefore, the modern polyethylene industry requires the acetylene content in the ethylene feed to be less than 1 ppm. Achieving high ethylene purity through chemical separation will consume a large amount of energy. Therefore, the selective hydrogenation of acetylene to ethylene is regarded as the most advanced strategy for purifying the ethylene stream.

[0003] Cu-based catalysts have received extensive attention due to their strong adsorption ability for acetylene and weak adsorption ability for ethylene, resulting in high ethylene selectivity. However, due to their weak hydrogen dissociation ability, low catalytic activity, and easy occurrence of C-C polymerization to form green oil, the catalyst is deactivated. Ni shows a certain ability to dissociate hydrogen due to its unfilled d electron orbitals and has attracted much attention in terms of noble metal substitution. Although single-metal Ni catalysts have certain hydrogenation activity, their strong adsorption of acetylene and ethylene leads to poor ethylene selectivity, restricting the application of non-noble metal Ni catalysts. Intermetallic compounds have become an important research hotspot due to their ordered atomic arrangement, special geometric and electronic structures, and excellent thermodynamic stability. A large number of studies have shown that the surface structure of Ni-based alloy catalysts can be achieved by modulating the atomic arrangement of Ni atoms and doped atoms on the catalyst surface layer, thereby effectively regulating the reaction catalytic performance. TiO 2 is one of the most commonly used catalyst support materials in practical applications. Research shows that TiO 2 can be reduced by hydrogen to form oxygen vacancies during the reaction process, and then strongly interact with the metal active center, which is beneficial to the stability of the active center.

[0004] Based on the above background, the present invention proposes a highly uniform and ordered Cs-doped CuNi / titanium dioxide catalyst to improve the selectivity of ethylene in the acetylene hydrogenation reaction. Summary of the Invention

[0005] The object of the present invention is to provide a highly uniform and ordered Cs-doped CuNi / titanium dioxide catalyst, its preparation method, and its application in the selective hydrogenation of acetylene.

[0006] To achieve the above invention object, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a method for preparing a Cs-doped CuNi / titanium dioxide catalyst, and the preparation method includes the following steps:

[0008] Step 1: Weigh copper salt, nickel salt and cesium salt and dissolve them in deionized water, and fully stir at room temperature to obtain a mixed solution;

[0009] Step 2: Take TiO 2 and add it to the above mixed solution, and stir the mixture at room temperature for 8 - 12 h, dry and grind it into powder to obtain a mixed sample powder; the TiO 2 is selected from at least one of anatase type and P25 type TiO 2 ;

[0010] Step 3: Place the mixed sample powder obtained in Step 2 in an inert gas environment and calcine it at a high temperature to obtain a Cs-doped CuNi / titanium dioxide catalyst;

[0011] Among them, the feeding ratios of the copper salt, nickel salt, cesium salt and TiO 2 are controlled so that in the Cs-doped CuNi / titanium dioxide catalyst, the mass of copper accounts for 1.2% - 2.5% of the total mass of the catalyst, the mass of nickel accounts for 0.5% - 1.5% of the total mass of the catalyst, and the mass of cesium accounts for 0.5% - 2.5% of the total mass of the catalyst, where the total mass of the catalyst = m TiO2 +m 铜 +m 镍 +m 铯 .

[0012] Furthermore, in the Cs-doped CuNi / titanium dioxide catalyst, the mass of copper accounts for 1.25% of the total mass of the catalyst, the mass of nickel accounts for 1.25% of the total mass of the catalyst, and the mass of cesium accounts for 1.25% of the total mass of the catalyst.

[0013] Furthermore, in Step 1, the copper salt is selected from at least one of copper chloride, copper sulfate, copper nitrate, copper acetate, and copper carbonate; more preferably copper nitrate.

[0014] Furthermore, in Step 1, the nickel salt is selected from at least one of nickel chloride, nickel sulfate, nickel nitrate, nickel acetate, and nickel carbonate; more preferably nickel nitrate.

[0015] Furthermore, in Step 1, the cesium salt is selected from at least one of cesium chloride, cesium sulfate, cesium nitrate, cesium carbonate, and cesium acetate; more preferably cesium chloride.

[0016] Furthermore, in Step 2, the TiO 2 is selected from P25 type TiO 2 .

[0017] Further, in Step 2, the drying conditions are: drying at 80 - 120°C for 8 - 12 h.

[0018] Further, in Step 3, the calcination temperature is controlled at 200 - 500°C, more preferably 450°C; the calcination time is controlled at 0.5 - 3 h, more preferably 2 h.

[0019] In a second aspect, the present invention provides a Cs-doped CuNi / titanium dioxide catalyst prepared by the preparation method according to the first aspect.

[0020] In a third aspect, the present invention provides the application of the Cs-doped CuNi / titanium dioxide catalyst in the selective hydrogenation of acetylene to prepare ethylene.

[0021] The method of the application is as follows: After the Cs-doped CuNi / titanium dioxide catalyst is hydrogenated and reduced, it is added to the raw material gas containing acetylene and hydrogen, and under the conditions of a temperature of 70 - 250°C (more preferably 180°C), a pressure of 0.1 - 1 MPa (more preferably 0.1 MPa), and a space velocity of 5000 - 20000 h -1 (more preferably 10000 h -1 ), a hydrogenation reaction is carried out to convert acetylene into ethylene.

[0022] In the specific embodiment of the present invention, the composition of the raw material gas containing acetylene and hydrogen is: acetylene, hydrogen, ethylene, and the balance nitrogen, wherein the volume ratio of hydrogen to acetylene is 20 - 100:1.

[0023] Compared with the prior art, the advantages of the Cs-doped CuNi / titanium dioxide catalyst provided by the present invention for the selective hydrogenation of acetylene are mainly reflected in:

[0024] (1) All non-precious metals are used in this catalyst, which has a huge cost advantage compared with traditional catalysts.

[0025] (2) Due to the high uniformity and orderliness of its active centers, this catalyst has higher activity and selectivity compared with single copper and single nickel catalysts.

[0026] (3) The introduction of cesium can slow down the polymerization of nickel, contribute to the uniformity of the copper-nickel alloy, and is beneficial to the improvement of selectivity.

[0027] (4) During the reaction process, titanium dioxide forms defect sites and copper-nickel active centers due to the strong reducibility of the reaction gas, forming a strong interaction, making the catalyst have relatively excellent stability.

[0028] (5) The Cs-doped CuNi / titanium dioxide catalyst used in the selective hydrogenation of acetylene shows excellent acetylene conversion rate, ethylene selectivity, and catalyst stability. Description of the Drawings

[0029] Figure 1 Energy spectrum diagram of the Cs-doped CuNi / Titanium dioxide catalyst prepared in Specific Example 1 of the present invention before reaction.

[0030] Figure 2 TEM diagram of the Cs-doped CuNi / Titanium dioxide catalyst prepared in Specific Example 1 of the present invention before reaction.

[0031] Figure 3 TEM diagram of the Cs-doped CuNi / Titanium dioxide catalyst prepared in Specific Example 1 of the present invention after 150 h of reaction.

[0032] Figure 4 TEM diagram of the CuNi / Titanium dioxide catalyst prepared in Comparative Example 3 of the present invention before reaction.

[0033] Figure 5 TEM diagram of the CuNi / Titanium dioxide catalyst prepared in Comparative Example 3 of the present invention after 150 h of reaction.

[0034] Figure 6 XRD diagram of the catalysts of Specific Example 1 and Comparative Example 3 of the present invention. Specific Embodiments

[0035] The present invention will be described below with specific examples. It is necessary to point out that the examples are only for further illustration of the present invention, but should not be construed as limiting the protection scope of the present invention. The present invention is not limited in any way. Those skilled in the art can make some non-essential improvements and adjustments based on the content of the above invention.

[0036] The room temperature referred to in the present invention means 20 - 35 °C

[0037] Example 1

[0038] A preparation method of a Cs-doped CuNi / Titanium dioxide catalyst for selective hydrogenation of acetylene, the method comprising the following steps:

[0039] 1) Weigh 0.1845 g of copper nitrate, 0.1947 g of nickel nitrate and 0.079 g of cesium chloride, dissolve them in 6.14 mL of deionized water, and stir at room temperature for 30 min.

[0040] 2) Weigh 4.8125 g of P25-type TiO 2 , add it to the above solution, stir the mixed solution at a speed of 100 rpm at room temperature for 12 h. Place it in an oven and dry at 120 °C for 12 h. Then grind the sample into powder.

[0041] 3) Put the above mixed sample into a tubular furnace and heat it at 450 °C for 2 h in a nitrogen atmosphere. A Cs-doped CuNi / titanium dioxide catalyst with a copper loading of 1.25%, a nickel loading of 1.25%, and a cesium loading of 1.25% is obtained.

[0042] Place 0.3 g of the Cs-doped CuNi / titanium dioxide catalyst in a fixed-bed reactor. Before the reaction, introduce pure H 2 Reduce it at 450 °C for 1 h with a reduction gas flow rate of 50 mL / min; after reduction, introduce the acetylene mixed gas at a rate of 50 mL / min, and carry out the hydrogenation reaction at a space velocity of 10,000 h -1 , a pressure of 0.1 MPa, and 180 °C. Use gas chromatography to on-line detect the peak areas of ethane, ethylene, acetylene, and C4, and calculate the conversion rate of acetylene and the selectivity of ethylene by the area normalization method. The volume concentration composition of the acetylene mixed gas is: 0.33% acetylene, 6.6% hydrogen, 33% ethylene, and the balance nitrogen, with a total of 100%.

[0043] Calculated from the chromatographic data, the acetylene conversion rate is 99.2%, the ethylene selectivity is 93.4%, and even after 150 h of reaction, there is still a 99% acetylene conversion rate and a 90.3% ethylene selectivity.

[0044] Example 2

[0045] A preparation method of a Cs-doped CuNi / titanium dioxide catalyst for selective hydrogenation of acetylene, the method comprising the following steps:

[0046] 1) Weigh 0.369 g of copper nitrate, 0.3894 g of nickel nitrate, and 0.158 g of cesium chloride and dissolve them in 6.14 mL of deionized water, and stir at room temperature for 30 min.

[0047] 2) Weigh 4.625 g of P25-type TiO 2 , add it to the above solution, and stir the mixed solution at a speed of 100 rpm at room temperature for 12 h. Place it in an oven and dry it at 120 °C for 12 h. Then grind the sample into powder.

[0048] 3) Put the above mixed sample into a tubular furnace and heat it at 450 °C for 2 h in a nitrogen atmosphere. A Cs-doped CuNi / titanium dioxide catalyst with a copper loading of 2.5%, a nickel loading of 2.5%, and a cesium loading of 2.5% is obtained.

[0049] Place 0.3 g of the Cs-doped CuNi / titanium dioxide catalyst in a fixed-bed reactor. Before the reaction, introduce pure H 2 Reduce it at 450 °C for 1 h with a reduction gas flow rate of 50 mL / min; after reduction, introduce the acetylene mixed gas at a rate of 50 mL / min, and at a space velocity of 10,000 h-1 、The hydrogenation reaction is carried out at a pressure of 0.1 MPa and 180 °C. The peak areas of ethane, ethylene, acetylene, and C4 are detected online by gas chromatography, and the conversion rate of acetylene and the selectivity of ethylene are obtained by the area normalization method. The volume concentration composition of the acetylene mixed gas is: 0.33% acetylene, 6.6% hydrogen, 33% ethylene, and the balance is nitrogen, with a total of 100%.

[0050] Calculated from the chromatographic data, the conversion rate of acetylene is 99.6%, and the selectivity of ethylene is 12.5%.

[0051] Example 3

[0052] A preparation method of a Cs-doped CuNi / titanium dioxide catalyst for selective hydrogenation of acetylene, the method comprising the following steps:

[0053] 1) Weigh 0.0923 g of copper nitrate, 0.0974 g of nickel nitrate, and 0.04 g of cesium chloride and dissolve them in 6.14 mL of deionized water, and stir at room temperature for 30 min.

[0054] 2) Weigh 4.9063 g of P25-type TiO 2 , add it to the above solution, and stir the mixed solution at a speed of 100 rpm at room temperature for 12 h. Place it in an oven and dry it at 120 °C for 12 h. Then grind the sample into powder.

[0055] 3) Put the above mixed sample into a tubular furnace and heat it at 450 °C for 2 h in a nitrogen atmosphere. A Cs-doped CuNi / titanium dioxide catalyst with a copper loading of 0.625%, a nickel loading of 0.625%, and a cesium loading of 0.625% is obtained.

[0056] Place 0.3 g of the Cs-doped CuNi / titanium dioxide catalyst in a fixed-bed reactor. Before the reaction, pass pure H 2 Reduce it at 450 °C for 1 h, and the reduction gas flow rate is 50 mL / min; after reduction, pass the acetylene mixed gas at a speed of 50 mL / min, and at a space velocity of 10000 h -1 、The hydrogenation reaction is carried out at a pressure of 0.1 MPa and 180 °C. The peak areas of ethane, ethylene, acetylene, and C4 are detected online by gas chromatography, and the conversion rate of acetylene and the selectivity of ethylene are obtained by the area normalization method. The volume concentration composition of the acetylene mixed gas is: 0.33% acetylene, 6.6% hydrogen, 33% ethylene, and the balance is nitrogen, with a total of 100%.

[0057] Calculated from the chromatographic data, the conversion rate of acetylene is 60.4%, and the selectivity of ethylene is 94.2%.

[0058] Example 4

[0059] A preparation method of Cs-doped CuNi / Titanium Dioxide catalyst for acetylene selective hydrogenation, the method comprising the following steps:

[0060] 1) Weigh 0.1845 g of copper nitrate, 0.0974 g of nickel nitrate and 0.079 g of cesium chloride, dissolve them in 6.14 mL of deionized water, and stir at room temperature for 30 min.

[0061] 2) Weigh 4.8437 g of P25-type TiO 2 , add it to the above solution, stir the mixed solution at a speed of 100 rpm at room temperature for 12 h. Place it in an oven and dry at 120 °C for 12 h. Then grind the sample into powder.

[0062] 3) Put the above mixed sample into a tubular furnace, heat it at 450 °C for 2 h in a nitrogen atmosphere. Obtain a Cs-doped CuNi / Titanium Dioxide catalyst with a copper loading of 1.25%, a nickel loading of 0.625%, and a cesium loading of 1.25%.

[0063] Place 0.3 g of Cs-doped CuNi / Titanium Dioxide catalyst in a fixed-bed reactor. Before the reaction, introduce pure H 2 Reduce it at 450 °C for 1 h, and the reduction gas flow rate is 50 mL / min; after reduction, introduce the acetylene mixed gas at a speed of 50 mL / min, and carry out the hydrogenation reaction at a space velocity of 10000 h -1 , a pressure of 0.1 MPa, and 180 °C. Use gas chromatography to on-line detect the peak areas of ethane, ethylene, acetylene, and C4, and calculate the conversion rate of acetylene and the selectivity of ethylene by the area normalization method. The volume concentration composition of the acetylene mixed gas is: 0.33% acetylene, 6.6% hydrogen, 33% ethylene, and the balance is nitrogen, with a total of 100%.

[0064] Calculated from the chromatographic data, the acetylene conversion rate is 90.2%, and the ethylene selectivity is 95.4%.

[0065] Example 5

[0066] A preparation method of Cs-doped CuNi / Titanium Dioxide catalyst for acetylene selective hydrogenation, the method comprising the following steps:

[0067] 1) Weigh 0.1845 g of copper nitrate, 0.3894 g of nickel nitrate and 0.079 g of cesium chloride, dissolve them in 6.14 mL of deionized water, and stir at room temperature for 30 min.

[0068] 2) Weigh 4.75 g of P25-type TiO 2 , add it to the above solution, stir the mixed solution at a speed of 100 rpm at room temperature for 12 h. Place it in an oven and dry at 120 °C for 12 h. Then grind the sample into powder.

[0069] 3) Place the above mixed sample into a tubular furnace and heat it at 450 °C for 2 h under a nitrogen atmosphere. A Cs-doped CuNi / titania catalyst with a copper loading of 1.25%, a nickel loading of 2.5%, and a cesium loading of 1.25% is obtained.

[0070] Place 0.3 g of the Cs-doped CuNi / titania catalyst in a fixed-bed reactor. Before the reaction, pass pure H 2 Reduce it at 450 °C for 1 h with a reduction gas flow rate of 50 mL / min; after reduction, pass the acetylene mixed gas at a rate of 50 mL / min, and carry out the hydrogenation reaction at a space velocity of 10,000 h -1 At a pressure of 0.1 MPa and 180 °C. Use gas chromatography to on-line detect the peak areas of ethane, ethylene, acetylene, and C4, and calculate the conversion rate of acetylene and the selectivity of ethylene by the area normalization method. The volume concentration composition of the acetylene mixed gas is: 0.33% acetylene, 6.6% hydrogen, 33% ethylene, and the balance nitrogen, with a total of 100%.

[0071] Calculated from the chromatographic data, the acetylene conversion rate is 99.2% and the ethylene selectivity is 40.4%.

[0072] Example 6

[0073] A preparation method of a Cs-doped CuNi / titania catalyst for selective hydrogenation of acetylene, the method comprising the following steps:

[0074] 1) Weigh 0.1845 g of copper nitrate, 0.1947 g of nickel nitrate, and 0.04 g of cesium chloride and dissolve them in 6.14 mL of deionized water, and stir at room temperature for 30 min.

[0075] 2) Weigh 4.8437 g of P25-type TiO 2 , add it to the above solution, and stir the mixed solution at a speed of 100 rpm at room temperature for 12 h. Place it in an oven and dry it at 120 °C for 12 h. Then grind the sample into powder.

[0076] 3) Place the above mixed sample into a tubular furnace and heat it at 450 °C for 2 h under a nitrogen atmosphere. A Cs-doped CuNi / titania catalyst with a copper loading of 1.25%, a nickel loading of 1.25%, and a cesium loading of 0.625% is obtained.

[0077] Place 0.3 g of the Cs-doped CuNi / titania catalyst in a fixed-bed reactor. Before the reaction, pass pure H 2 Reduce it at 450 °C for 1 h with a reduction gas flow rate of 50 mL / min; after reduction, pass the acetylene mixed gas at a rate of 50 mL / min, and carry out the hydrogenation reaction at a space velocity of 10,000 h -1、Perform the hydrogenation reaction at a pressure of 0.1 MPa and 180 °C. Use gas chromatography to on-line detect the peak areas of ethane, ethylene, acetylene, and C4, and calculate the conversion rate of acetylene and the selectivity of ethylene by the area normalization method. The volume concentration composition of the acetylene mixed gas is: 0.33% acetylene, 6.6% hydrogen, 33% ethylene, and the balance is nitrogen, with a total of 100%.

[0078] Calculated from the chromatographic data, the conversion rate of acetylene is 99.2%, and the selectivity of ethylene is 93.4%. After 150 h of reaction, there is still 99% of the acetylene conversion rate and 83.6% of the ethylene selectivity.

[0079] Example 7

[0080] A preparation method of a Cs-doped CuNi / titanium dioxide catalyst for selective hydrogenation of acetylene, the method comprising the following steps:

[0081] 1) Weigh 0.1845 g of copper nitrate, 0.1947 g of nickel nitrate, and 0.158 g of cesium chloride, dissolve them in 6.14 mL of deionized water, and stir at room temperature for 30 min.

[0082] 2) Weigh 4.75 g of P25-type TiO 2 , add it to the above solution, and stir the mixed solution at a speed of 100 rpm at room temperature for 12 h. Place it in an oven and dry at 120 °C for 12 h. Then grind the sample into powder.

[0083] 3) Put the above mixed sample into a tubular furnace, heat it at 450 °C in a nitrogen atmosphere for 2 h. Obtain a Cs-doped CuNi / titanium dioxide catalyst with a copper loading of 1.25%, a nickel loading of 1.25%, and a cesium loading of 2.5%.

[0084] Place 0.3 g of the Cs-doped CuNi / titanium dioxide catalyst in a fixed-bed reactor. Before the reaction, pass pure H 2 Reduce it at 450 °C for 1 h, and the reduction gas flow rate is 50 mL / min; after reduction, pass the acetylene mixed gas at a speed of 50 mL / min, and at a space velocity of 10000 h -1 、Perform the hydrogenation reaction at a pressure of 0.1 MPa and 180 °C. Use gas chromatography to on-line detect the peak areas of ethane, ethylene, acetylene, and C4, and calculate the conversion rate of acetylene and the selectivity of ethylene by the area normalization method. The volume concentration composition of the acetylene mixed gas is: 0.33% acetylene, 6.6% hydrogen, 33% ethylene, and the balance is nitrogen, with a total of 100%.

[0085] Calculated from the chromatographic data, the conversion rate of acetylene is 92.2%, and the selectivity of ethylene is 93.4%.

[0086] Example 8

[0087] A preparation method of a Cs-doped CuNi / titanium dioxide catalyst for acetylene selective hydrogenation, the method comprising the following steps:

[0088] 1) Weigh 0.1845 g of copper nitrate, 0.1947 g of nickel nitrate and 0.079 g of cesium chloride and dissolve them in 6.14 mL of deionized water, and stir at room temperature for 30 min.

[0089] 2) Weigh 4.8125 g of rutile TiO 2 , add it to the above solution, and stir the mixed solution at a speed of 100 rpm at room temperature for 12 h. Place it in an oven and dry at 120 °C for 12 h. Then grind the sample into powder.

[0090] 3) Put the above mixed sample into a tubular furnace and heat it at 450 °C for 2 h in a nitrogen atmosphere. Obtain a Cs-doped CuNi / titanium dioxide catalyst with a copper loading of 1.25%, a nickel loading of 1.25%, and a cesium loading of 1.25%.

[0091] Place 0.3 g of the Cs-doped CuNi / titanium dioxide catalyst in a fixed-bed reactor. Before the reaction, introduce pure H 2 Reduce it at 450 °C for 1 h, and the reduction gas flow rate is 50 mL / min; after reduction, introduce the acetylene mixed gas at a speed of 50 mL / min, and carry out the hydrogenation reaction at a space velocity of 10000 h -1 , a pressure of 0.1 MPa, and 180 °C. Use gas chromatography to on-line detect the peak areas of ethane, ethylene, acetylene, and C4, and calculate the conversion rate of acetylene and the selectivity of ethylene by the area normalization method. The volume concentration composition of the acetylene mixed gas is: 0.33% acetylene, 6.6% hydrogen, 33% ethylene, and the balance nitrogen, with a total of 100%.

[0092] Calculated from the chromatographic data, the acetylene conversion rate is 99.3% and the ethylene selectivity is 70.3%.

[0093] Example 9

[0094] A preparation method of a Cs-doped CuNi / titanium dioxide catalyst for acetylene selective hydrogenation, the method comprising the following steps:

[0095] 1) Weigh 0.1845 g of copper nitrate, 0.1947 g of nickel nitrate and 0.079 g of cesium chloride and dissolve them in 6.14 mL of deionized water, and stir at room temperature for 30 min.

[0096] 2) Weigh 4.8125 g of anatase TiO 2 , add it to the above solution, and stir the mixed solution at a speed of 100 rpm at room temperature for 12 h. Place it in an oven and dry at 120 °C for 12 h. Then grind the sample into powder.

[0097] 3) Put the above mixed sample into a tubular furnace and heat it at 450 °C for 2 h in a nitrogen atmosphere. A Cs-doped CuNi / titanium dioxide catalyst with a copper loading of 1.25%, a nickel loading of 1.25%, and a cesium loading of 1.25% is obtained.

[0098] Place 0.3 g of the Cs-doped CuNi / titanium dioxide catalyst in a fixed-bed reactor. Before the reaction, pure H 2 is introduced and reduced at 450 °C for 1 h with a reduction gas flow rate of 50 mL / min; after reduction, an acetylene mixed gas is introduced at a rate of 50 mL / min, and a hydrogenation reaction is carried out at a space velocity of 10,000 h -1 , a pressure of 0.1 MPa, and 180 °C. The peak areas of ethane, ethylene, acetylene, and C4 are detected online by gas chromatography, and the conversion rate of acetylene and the selectivity of ethylene are calculated by the area normalization method. The volume concentration composition of the acetylene mixed gas is: 0.33% acetylene, 6.6% hydrogen, 33% ethylene, and the balance nitrogen, with a total of 100%.

[0099] Calculated from the chromatographic data, the acetylene conversion rate is 93.2% and the ethylene selectivity is 96.4%.

[0100] Comparative Example 1

[0101] A preparation method of a Cs-doped Cu / titanium dioxide catalyst for selective hydrogenation of acetylene, the method comprising the following steps:

[0102] 1) Weigh 0.369 g of copper nitrate and 0.079 g of cesium chloride and dissolve them in 6.14 mL of deionized water, and stir at room temperature for 30 min.

[0103] 2) Weigh 4.8125 g of P25-type TiO 2 , add it to the above solution, and stir the mixed solution at a speed of 100 rpm at room temperature for 12 h. Place it in an oven and dry it at 120 °C for 12 h. Then grind the sample into powder.

[0104] 3) Put the above mixed sample into a tubular furnace and heat it at 450 °C for 2 h in a nitrogen atmosphere. A Cs-doped Cu / titanium dioxide catalyst with a copper loading of 2.5% and a cesium loading of 1.25% is obtained.

[0105] Place 0.3 g of the Cs-doped Cu / titanium dioxide catalyst in a fixed-bed reactor. Before the reaction, pure H 2 is introduced and reduced at 450 °C for 1 h with a reduction gas flow rate of 50 mL / min; after reduction, an acetylene mixed gas is introduced at a rate of 50 mL / min, and at a space velocity of 10,000 h -1、Perform the hydrogenation reaction at a pressure of 0.1 MPa and 180 °C. Use gas chromatography to on-line detect the peak areas of ethane, ethylene, acetylene, and C4, and calculate the conversion rate of acetylene and the selectivity of ethylene by the area normalization method. The volume concentration composition of the acetylene mixed gas is: 0.33% acetylene, 6.6% hydrogen, 33% ethylene, and the balance is nitrogen, with a total of 100%.

[0106] Calculated from the chromatographic data, the conversion rate of acetylene is 83%, and the selectivity of ethylene is 96.6%.

[0107] Comparative Example 2

[0108] A preparation method of a Cs-doped Ni / titanium dioxide catalyst for acetylene selective hydrogenation, the method comprising the following steps:

[0109] 1) Weigh 0.3894 g of nickel nitrate and 0.079 g of cesium chloride and dissolve them in 6.14 mL of deionized water, and stir at room temperature for 30 min.

[0110] 2) Weigh 4.8125 g of P25 type TiO 2 , add it to the above solution, and stir the mixed solution at a speed of 100 rpm at room temperature for 12 h. Place it in an oven and dry it at 120 °C for 12 h. Then grind the sample into powder.

[0111] 3) Put the above mixed sample into a tubular furnace and heat it at 450 °C for 2 h in a nitrogen atmosphere. Obtain a Cs-doped Ni / titanium dioxide catalyst with a nickel loading of 2.5% and a cesium loading of 1.25%.

[0112] Place 0.3 g of the Cs-doped Ni / titanium dioxide catalyst in a fixed-bed reactor. Before the reaction, introduce pure H 2 Reduce it at 450 °C for 1 h, and the reduction gas flow rate is 50 mL / min; after reduction, introduce the acetylene mixed gas at a speed of 50 mL / min, and carry out the hydrogenation reaction at a space velocity of 10000 h -1 、a pressure of 0.1 MPa and 180 °C. Use gas chromatography to on-line detect the peak areas of ethane, ethylene, acetylene, and C4, and calculate the conversion rate of acetylene and the selectivity of ethylene by the area normalization method. The volume concentration composition of the acetylene mixed gas is: 0.33% acetylene, 6.6% hydrogen, 33% ethylene, and the balance is nitrogen, with a total of 100%.

[0113] Calculated from the chromatographic data, the conversion rate of acetylene is 99.4%, and the selectivity of ethylene is 40.3%.

[0114] Comparative Example 3

[0115] A preparation method of a CuNi / titanium dioxide catalyst for acetylene selective hydrogenation, the method comprising the following steps:

[0116] 1) Weigh 0.1845 g of copper nitrate and 0.1947 g of nickel nitrate, dissolve them in 6.14 mL of deionized water, and stir for 30 min at room temperature.

[0117] 2) Weigh 4.875 g of P25 TiO 2 , add it to the above solution, and stir the mixed solution at 100 rpm for 12 h at room temperature. Place it in an oven and dry at 120 °C for 12 h. Then grind the sample into powder.

[0118] 3) Put the above mixed sample into a tubular furnace, heat it at 450 °C for 2 h in a nitrogen atmosphere. Obtain a CuNi / titanium dioxide catalyst with a copper loading of 1.25% and a nickel loading of 1.25%.

[0119] Place 0.3 g of the CuNi / titanium dioxide catalyst in a fixed-bed reactor. Before the reaction, pass pure H 2 Reduce it at 450 °C for 1 h, and the reduction gas flow rate is 50 mL / min; after reduction, pass the acetylene mixed gas at a speed of 50 mL / min, and carry out the hydrogenation reaction at a space velocity of 10000 h -1 , a pressure of 0.1 MPa, and 180 °C. Use gas chromatography to on-line detect the peak areas of ethane, ethylene, acetylene, and C4, and calculate the conversion rate of acetylene and the selectivity of ethylene by the area normalization method. The volume concentration composition of the acetylene mixed gas is: 0.33% acetylene, 6.6% hydrogen, 33% ethylene, and the balance is nitrogen, with a total of 100%.

[0120] Calculated from the chromatographic data, the acetylene conversion rate is 99.9%, and the ethylene selectivity is 90.6%. After 150 h of reaction, only 99% of the acetylene conversion rate and 50.3% of the ethylene selectivity are obtained.

[0121] Comparative Example 4

[0122] A preparation method of a Cs-doped CuNi / aluminum oxide catalyst for selective hydrogenation of acetylene, the method comprising the following steps:

[0123] 1) Weigh 0.1845 g of copper nitrate, 0.1947 g of nickel nitrate and 0.079 g of cesium chloride, dissolve them in 6.14 mL of deionized water, and stir for 30 min at room temperature.

[0124] 2) Weigh 4.8125 g of γ-Al 2 O 3 , add it to the above solution, and stir the mixed solution at 100 rpm for 12 h at room temperature. Place it in an oven and dry at 120 °C for 12 h. Then grind the sample into powder.

[0125] 3) Put the above mixed sample into a tubular furnace and heat it at 450 °C for 2 h under a nitrogen atmosphere to obtain a Cs-doped CuNi / titania catalyst with a copper loading of 1.25%, a nickel loading of 1.25%, and a cesium loading of 1.25%.

[0126] Place 0.3 g of the Cs-doped CuNi / aluminum oxide catalyst in a fixed-bed reactor. Before the reaction, introduce pure H 2 Reduce it at 450 °C for 1 h with a reduction gas flow rate of 50 mL / min. After reduction, introduce the acetylene mixed gas at a rate of 50 mL / min and carry out the hydrogenation reaction at a space velocity of 10,000 h -1 , a pressure of 0.1 MPa, and 180 °C. Use gas chromatography to on-line detect the peak areas of ethane, ethylene, acetylene, and C4, and calculate the conversion rate of acetylene and the selectivity of ethylene by the area normalization method. The volume concentration composition of the acetylene mixed gas is: 0.33% acetylene, 6.6% hydrogen, 33% ethylene, and the balance nitrogen, with a total of 100%.

[0127] Calculated from the chromatographic data, the acetylene conversion rate is 99.9%, and the ethylene selectivity is 80.4%. After 150 h of reaction, only 99.6% of the acetylene conversion rate and 50.3% of the ethylene selectivity are obtained.

[0128] According to the analysis of Examples 1 to 7, the Cs-doped CuNi / titania catalyst with a copper loading of 1.25%, a nickel loading of 1.25%, and a cesium loading of 1.25% is the optimal ratio. Excessive copper and nickel loadings will lead to a decrease in ethylene selectivity, and too little copper and nickel loadings will lead to a decrease in acetylene conversion rate. Although cesium can improve the catalyst stability, too high a loading will reduce the catalyst activity. According to Examples 8 to 9, it is found that P25-type titania is generally superior to anatase-type and rutile-type titania. Figure 6 Only the characteristic peaks of the carrier P25 titania are observed in the XRD pattern, Figure 2 , Figure 4 It can be seen from the TEM image shown that the active centers are evenly distributed on the carrier. Combining with Figure 1 the energy spectrum diagram, it is proved that copper and nickel are evenly distributed on the P25 titania carrier.

[0129] By comparing Example 1 with Comparative Examples 1 to 2, it is found that the copper-nickel alloy catalyst is indeed superior to the copper and nickel single-metal catalysts, which is in line with the known conclusion. Example 1 and Comparative Example 3 show that the appropriate introduction of cesium can improve the ethylene selectivity and stability of the catalyst, which benefits from the unique electronic structure of cesium that can effectively alleviate the agglomeration of nickel. Figure 1 , Figure 3 , Figure 4 and Figure 5It is proved that in the long-term reaction, the introduction of cesium can effectively prevent the aggregation of nanoparticles, which is consistent with the results of Example 1 and Comparative Example 3. Example 1 and Comparative Example 4 show that titanium dioxide has better stability.

Claims

1. Preparation method of Cs-doped CuNi / titanium dioxide catalyst for selective hydrogenation of acetylene to prepare ethylene, characterized in that: The preparation method includes the following steps: Step 1: Weigh copper salt, nickel salt and cesium salt and dissolve them in deionized water, and fully stir at room temperature to obtain a mixed solution; Step 2: Take TiO 2 and add it to the above-mentioned mixed solution. Stir the mixture at room temperature for 8 - 12 h, dry it and grind it into powder to obtain a mixed sample powder; the TiO 2 is selected from at least one of anatase type and P25 type TiO 2 ; Step 3: Place the mixed sample powder obtained in Step 2 in an inert gas environment and calcine at a high temperature. The calcination temperature is controlled at 200-500 °C, and the calcination time is controlled at 0.5-3 h to obtain a Cs-doped CuNi / titanium dioxide catalyst. After hydrogen reduction of the Cs-doped CuNi / titanium dioxide catalyst, it is used for selective hydrogenation of acetylene to prepare ethylene; Among them, controlling the feeding ratios of copper salt, nickel salt, cesium salt and TiO 2 such that in the Cs-doped CuNi / titanium dioxide catalyst, the mass of copper accounts for 1.25% of the total mass of the catalyst, the mass of nickel accounts for 1.25% of the total mass of the catalyst, and the mass of cesium accounts for 0.5%-1.25% of the total mass of the catalyst, where the total mass of the catalyst = m TiO2 +m 铜 +m 镍 +m 铯 .

2. The preparation method according to claim 1, characterized in that: In the Cs-doped CuNi / titanium dioxide catalyst, the mass of copper accounts for 1.25% of the total mass of the catalyst, the mass of nickel accounts for 1.25% of the total mass of the catalyst, and the mass of cesium accounts for 1.25% of the total mass of the catalyst.

3. The preparation method according to claim 1 or 2, characterized in that: In Step 1, the copper salt is selected from at least one of copper chloride, copper sulfate, copper nitrate, copper acetate, and copper carbonate; the nickel salt is selected from at least one of nickel chloride, nickel sulfate, nickel nitrate, nickel acetate, and nickel carbonate; the cesium salt is selected from at least one of cesium chloride, cesium sulfate, cesium nitrate, cesium carbonate, and cesium acetate.

4. The preparation method according to claim 1 or 2, characterized in that: In Step 2, the drying conditions are: drying at 80-120 °C for 8-12 h.

5. The preparation method according to claim 1 or 2, characterized in that: In Step 3, the calcination temperature is controlled at 450 °C; the calcination time is controlled at 2 h.

6. A Cs-doped CuNi / titanium dioxide catalyst prepared by the preparation method according to any one of claims 1-5.

7. Application of the Cs-doped CuNi / titanium dioxide catalyst according to claim 6 in selective hydrogenation of acetylene to prepare ethylene.

8. The application according to claim 7, characterized in that: The method of the application is as follows: After hydrogenation reduction of the Cs-doped CuNi / titanium dioxide catalyst, it is added to the raw material gas containing acetylene and hydrogen, and the hydrogenation reaction is carried out under the conditions of a temperature of 70 to 250 °C, a pressure of 0.1 to 1 MPa, and a space velocity of 5000 to 20000 h -1 to convert acetylene into ethylene.

9. The application according to claim 8, characterized in that: The composition of the raw material gas containing acetylene and hydrogen is: acetylene, hydrogen, ethylene, and the balance nitrogen, wherein the volume ratio of hydrogen to acetylene is 20-100:1.

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