A method for the preparation of a monolithic copper / silicon oxide catalyst

Abstract

The application discloses a preparation method of a monolithic copper / silicon oxide catalyst, and the catalyst comprises a support material of a cordierite honeycomb ceramic and an active component of copper / silicon oxide. The preparation method is as follows: taking the cordierite honeycomb ceramic matrix as the support material, filling the precursor of the catalyst active component into the pore channels of the cordierite honeycomb ceramic through deposition and self-filling, naturally depositing in the pore channels, and then washing, drying and roasting, so that the active component of the catalyst, copper / silicon oxide, is fixed in the pore channels of the cordierite honeycomb ceramic, and the monolithic copper / silicon oxide catalyst with the cordierite honeycomb ceramic as the support material is obtained. The catalyst disclosed by the application has higher catalytic activity in the reaction of preparing methoxypropanone by dehydrogenating propylene glycol methyl ether, the catalyst is easy to load and unload, the stability of the active component is good, and the pressure drop of the catalyst bed is small.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation technology, specifically relating to a method for preparing a monolithic copper / silicon oxide catalyst. Background Technology

[0002] Copper / silicon oxide is a classic catalyst with wide applications in catalytic hydrogenation and dehydrogenation. Copper / silicon oxide catalysts are mostly composite oxide catalysts with a specific surface area generally less than 120 m². 2 / g, typically prepared using precipitation, mixing, and ammonia stripping methods. Catalysts usually need to be shaped before use, such as into strips or cylinders. In practical applications, due to the influence of reactor size, mass and heat transfer, and bed pressure drop, the particle size of the catalyst should not be too small (usually greater than 4 mm, mostly 5–6 mm). However, in actual reactions, large catalyst particles may not effectively contact the reactants due to internal diffusion, leading to waste of internal catalyst.

[0003] Chinese Patent 200810203883.0 discloses a catalyst for the hydrogenation of oxalate to ethylene glycol, its molding method, and its application. The main component of the catalyst is copper / silicon oxide. The method controls the moisture content of the filter cake after washing, and molding and gelling are performed before drying, followed by aging, drying, and calcination. The resulting catalyst has better copper dispersion and higher catalyst activity. After molding, the catalyst is a typical homogeneous (composite oxide) catalyst. During use, due to the influence of internal diffusion, the active components inside the catalyst may not fully exert their catalytic activity. To solve this problem, the active components are usually loaded onto the surface of a support, allowing the actual reaction to occur on the surface of the particles. Chinese Patent 202211251129.0 reports a Cu-based eggshell-shaped catalyst, its preparation method, and a method for the hydrogenation of dimethyl oxalate. In this method, the active component Cu in the Cu-based eggshell-shaped catalyst is distributed in an eggshell pattern on the support. A slurry containing Cu is impregnated onto the support using a slurry impregnation method, followed by drying and calcination to obtain the eggshell-shaped catalyst. This catalyst exhibits good catalytic activity in the hydrogenation reaction of dimethyl oxalate, achieving a 90% ethylene glycol yield. However, due to the weak interaction between Cu oxide and the support, and the significant differences in their physical properties, the Cu oxide exhibits low loading strength on the support. High surface loading can easily lead to friction and detachment, while low loading results in insufficient activity and potential side reactions. Therefore, large-scale production and application require addressing the issues of interaction and loading strength.

[0004] Cordierite honeycomb ceramics are widely used as catalyst supports, serving as a typical support for monolithic catalysts in catalytic combustion. Many catalysts are coated onto the surface of cordierite honeycomb ceramics to exert their catalytic effect, as illustrated in Chinese patents 201910382340.8, 202111134000.7, and 201610790165.2. These catalysts have low loading capacity, wide channels, and high space velocities, but still suffer from weak interaction between the active component and the cordierite honeycomb ceramic. At high loading rates, they are prone to detachment and affect gas velocity. Cordierite honeycomb ceramics are an excellent catalyst support. If copper / silica catalysts can be loaded into the channels of cordierite honeycomb ceramics to increase loading capacity and strength, it is expected to improve the activity and stability of monolithic copper / silica catalysts and facilitate further industrial applications. Summary of the Invention

[0005] To improve the utilization efficiency and activity of copper / silica catalysts, this invention provides a method for preparing a monolithic copper / silica catalyst with high catalytic activity and convenient and quick disassembly. This method loads highly active copper / silica into the channels of cordierite honeycomb ceramic, increasing the catalyst's outer surface area and the degree of copper dispersion, thereby improving catalyst activity and catalytic reaction efficiency.

[0006] The monolithic copper / silicon oxide catalyst used to solve the above-mentioned technical problems includes a cordierite honeycomb ceramic support material and an active component of copper / silicon oxide. The mass content of copper / silicon oxide is 26% to 39%, with the remainder being cordierite honeycomb ceramic. The proportion of copper in the copper / silicon oxide is 40% to 70%. The preparation method of this catalyst includes the following steps:

[0007] Step 1: Turn on the gel mill and activate the self-circulation mode. Add nano copper oxide aqueous solution, silica sol, and nano silica powder. The total amount of these three substances should be 20% to 25% of the volume of the gel mill. Then, pass copper nitrate aqueous solution and alkali aqueous solution into the gel mill. When the volume of the suspension formed in the gel mill reaches 70% to 85% of the volume of the gel mill, stop passing copper nitrate aqueous solution and alkali aqueous solution into the mill. Continue to circulate for 2 to 4 hours.

[0008] Step 2: Lay the cordierite honeycomb ceramic flat in the suction funnel, with the channels perpendicular to the bottom of the funnel. The inner dimension of the funnel is equal to the outer dimension of the cordierite honeycomb ceramic. Then pour the suspension from Step 1 into the suction funnel, turn on the negative pressure of the suction funnel, and gradually increase the negative pressure to 0.06-0.09 MPa, so that the suspension forms a filter cake in the channels of the cordierite honeycomb ceramic.

[0009] Step 3: Wash the filter cake in the cordierite honeycomb ceramic with deionized water until the conductivity of the filtrate is lower than 90 μS / cm; transfer the washed cordierite honeycomb ceramic to a drying and calcining integrated furnace for heat treatment to obtain an integral copper / silicon oxide catalyst.

[0010] Furthermore, in step one above, the mass concentration of the nano-copper oxide in the nano-copper oxide aqueous solution is 5% to 30%, and the size of the nano-copper oxide is 20 to 40 nm; the mass concentration of the silica sol is 5% to 20%; and the size of the nano-silica is 20 to 50 nm.

[0011] Furthermore, in step one above, the feeding ratio of the nano copper oxide aqueous solution, silica sol, and nano silicon oxide powder is 8-12:8-12:1.

[0012] Furthermore, in step one above, the grinding disc gap of the rubber mill is 0.05-0.5mm and the volume is 20-50L.

[0013] Furthermore, in step one above, the ratio of the copper nitrate aqueous solution to the alkali aqueous solution is 1:1, the mass concentration of the copper nitrate aqueous solution is 10% to 20%, and the mass concentration of the alkali aqueous solution is 5% to 10%.

[0014] Furthermore, in step one above, the alkali is sodium carbonate or sodium hydroxide.

[0015] Furthermore, in step two above, the cordierite honeycomb ceramic is a cuboid or a cylinder. The length, width, and height of the cuboid are all within the range of 5 to 30 cm, the diameter of the cylinder is 5 to 30 cm, the height is 10 to 30 cm, the shape of the hole is a square hole, the holes are vertically distributed along the axial direction, the length and width of the hole are 1 to 2 mm, and the height of the hole is the same as the height of the cuboid or cylinder.

[0016] Furthermore, in step two above, the rate at which the negative pressure is increased is 0.01 MPa / hour.

[0017] Furthermore, in step three above, the cordierite honeycomb ceramics in the drying and calcining integrated furnace are placed horizontally so that the channels are parallel to the ground. The drying temperature is 100-130℃ and maintained for 20-24 hours, and the calcining temperature is 400-500℃ and maintained for 2-4 hours.

[0018] The beneficial effects of this invention are as follows:

[0019] 1. This invention uses cordierite honeycomb ceramic matrix as support material. Through precipitation and self-filling, the precursor of the catalyst active component is filled into the channels of cordierite honeycomb ceramic, where it is naturally deposited. After washing, drying and calcination, the active component of the catalyst, copper / silicon oxide, is fixed in the channels of cordierite honeycomb ceramic, thus obtaining an integral copper / silicon oxide catalyst with cordierite honeycomb ceramic as support material. During catalyst preparation, the precipitate formed by the reaction of copper nitrate and alkali in a gel mill encapsulates nano-copper oxide. The precipitate is then ground to form a suspension, which continuously circulates within the gel mill. As copper nitrate and alkali solutions are introduced, the volume of the suspension increases. Due to the lack of stirring, the suspension (can only) slowly precipitate into the channels of the cordierite honeycomb ceramic under static conditions. Under negative pressure, the suspension slowly precipitates within the channels. As moisture is lost, the precipitate becomes increasingly compacted. During heat treatment, the cordierite honeycomb ceramic remains unchanged. The precipitate filling the channels (the filter cake formed by the aforementioned suspension) shrinks during heat treatment, forming crack-shaped channels within the channels.

[0020] 2. Compared with traditional copper / silica catalysts, the monolithic copper / silica catalyst of this invention is easier to load and disassemble, and the operation is simpler and more convenient; it can expose more of the catalyst's external specific surface area, thereby improving the catalyst's catalytic reaction efficiency; the copper nanoparticles on the copper / silica substrate are more dispersed, which is beneficial to improving catalyst activity. Furthermore, during the self-filling process, larger crystallites first deposit at the bottom of the pores, followed by smaller crystallites, naturally forming a vertical distribution of catalyst crystallite size within the pores during subsequent filtration and washing.

[0021] 3. The catalyst of this invention has higher catalytic activity in the dehydrogenation of propylene glycol methyl ether to prepare methoxyacetone. The catalyst is easy to load and disassemble, the active component has good stability, and the pressure drop of the catalyst bed is small. Attached Figure Description

[0022] Figure 1 This is a photo of cordierite honeycomb ceramic. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited to these embodiments.

[0024] Example 1

[0025] In this embodiment of the monolithic copper / silicon oxide catalyst, the mass content of copper / silicon oxide is 30%, and the remainder is cordierite honeycomb ceramic. The proportion of copper in the copper / silicon oxide is 45.5%. The specific preparation method of the catalyst is as follows:

[0026] Step 1: Turn on the grinding mill and activate the self-circulation mode. The grinding mill has a grinding disc gap of 0.2 mm and a volume of 30 L. Add a 10% (w / w) aqueous solution of nano-copper oxide (nano-copper oxide size 20-40 nm), a 10% (w / w) silica sol, and nano-silica powder with a size of 20-50 nm to the grinding mill. The feeding ratio of the three is 10:10:1, and the total amount added is 21% of the volume of the grinding mill. Then, simultaneously introduce a 20% (w / w) aqueous solution of copper nitrate into the grinding mill. A 10% sodium carbonate aqueous solution and a copper nitrate solution are added in a 1:1 ratio. The copper nitrate and sodium carbonate react in a grinding mill, and the resulting precipitate encapsulates the nano-copper oxide. The precipitate is then ground to form a suspension, which continuously circulates within the grinding mill. As the copper nitrate and sodium carbonate aqueous solutions are introduced, the volume of the suspension increases. When the volume of the suspension in the grinding mill reaches 71% of the mill's volume, the introduction of the copper nitrate and sodium carbonate aqueous solutions is stopped, and circulation continues for 2 hours.

[0027] Step Two: Lay the cordierite honeycomb ceramic flat in the suction funnel, with the ceramic channels perpendicular to the bottom surface of the funnel. The inner dimension of the funnel is equal to the outer dimension of the cordierite honeycomb ceramic. The cordierite honeycomb ceramic is cylindrical, with a diameter of 15cm and a height of 15cm. The holes are square, vertically distributed along the axial direction, with a length and width of 1mm and a height of 15cm (see...). Figure 1 (Right). Then, the suspension from step one is poured into a vacuum filter funnel. Since there is no stirring, the suspension slowly settles into the channels of the cordierite honeycomb ceramic in a static state. The suspension accumulates relatively loosely in the channels of the cordierite honeycomb ceramic. The negative pressure of the vacuum filter funnel is turned on and gradually increased to 0.08 MPa at a rate of 0.01 MPa / hour. Under the action of negative pressure, the suspension slowly settles in the channels. As water is lost, the sediment becomes more and more compact, thus forming a filter cake in the channels of the cordierite honeycomb ceramic.

[0028] Step 3: Wash the filter cake in the cordierite honeycomb ceramic with deionized water until the conductivity of the filtrate is below 90 μS / cm. Transfer the washed cordierite honeycomb ceramic to an integrated drying and calcining furnace for heat treatment. The cordierite honeycomb ceramic is placed horizontally with the channels parallel to the ground. The drying temperature is 120℃ for 24 hours, and the calcination temperature is 450℃ for 2.5 hours. During the heat treatment, the cordierite honeycomb ceramic does not change. The filter cake filling the channels shrinks at high temperature, cracks, and forms crack-shaped channels within the channels, ultimately obtaining an integral copper / silicon oxide catalyst. Since the copper / silicon oxide is formed in situ within the channels, it has strong adhesion within the channels. The channels formed by shrinkage are the main channels for the catalytic reaction, while also increasing the external specific surface area of ​​the copper / silicon oxide. Because the copper / silicon oxide is inside the channels and protected by the pores of the cordierite honeycomb ceramic, there is no mutual friction during transportation and filling, so there is almost no wear. An evaluation was conducted using a monolithic copper / silicon oxide catalyst containing 14.13 mL of copper / silicon oxide. The copper / silicon oxide was embedded in square pores of cordierite honeycomb ceramic, with each pore measuring 1 mm in length and width. This translates to a copper / silicon oxide length of approximately 1413 cm and a surface area of ​​approximately 565.2 cm². 2 .

[0029] Comparative Example 1

[0030] Step 1: Add a 10% (w / w) aqueous solution of nano-copper oxide (30nm size), a 10% (w / w) silica sol, and nano-silica powder (20-50nm size) to a high-pressure reactor (30L volume). The ratio of these three components is 10:10:1, and the total amount added is 21% of the reactor volume. Then, add a 20% (w / w) aqueous solution of copper nitrate and a 10% (w / w) aqueous solution of sodium carbonate to the reactor. The ratio of these two components is 1:1. Under stirring, the copper nitrate and sodium carbonate react in the high-pressure reactor, and the resulting precipitate forms a suspension. The suspension is continuously stirred in the high-pressure reactor. As the copper nitrate and sodium carbonate aqueous solutions are added, the volume of the suspension increases. When the volume of the suspension in the high-pressure reactor reaches 71% of the reactor volume, stop adding the copper nitrate and sodium carbonate aqueous solutions and continue stirring for 2 hours.

[0031] Step Two: Pour the suspension from Step One into a suction filtration funnel for solid-liquid separation. Then wash the filter cake with deionized water until the conductivity of the filtrate is below 90 μS / cm. Transfer the washed filter cake to a drying and calcining integrated furnace for heat treatment. The drying temperature is 120℃ for 24 hours, and the calcination temperature is 450℃ for 2.5 hours. During the heat treatment, the filter cake shrinks into irregular blocks. After heat treatment, it is crushed and shaped into cylinders to obtain a shaped traditional copper / silicon oxide catalyst with a diameter of 6 mm and a height of 5 mm. The surface area of ​​a single catalyst particle can be calculated to be 1.5072 cm². 2 The volume was 0.1413 mL. In comparison with Example 1, 14.13 mL of a conventional copper / silica catalyst was still used for evaluation; the catalyst surface area was approximately 150.72 cm². 2 .

[0032] Example 2

[0033] In this embodiment of the monolithic copper / silicon oxide catalyst, the mass content of copper / silicon oxide is 29%, and the remainder is cordierite honeycomb ceramic. The proportion of copper in the copper / silicon oxide is 43.6%. The specific preparation method of the catalyst is as follows:

[0034] Step 1: Turn on the grinding mill and activate the self-circulation mode. The grinding mill has a grinding disc gap of 0.05 mm and a volume of 20 L. Add a 30% (w / w) aqueous solution of nano-copper oxide (nano-copper oxide size 20-40 nm), a 20% (w / w) silica sol, and nano-silica powder with a size of 20-50 nm to the grinding mill. The feeding ratio of the three is 8:12:1, and the total amount added is 20% of the volume of the grinding mill. Then, simultaneously introduce a 15% (w / w) aqueous solution of copper nitrate into the grinding mill. A 7.5% sodium carbonate aqueous solution was added in a 1:1 ratio. Copper nitrate and sodium carbonate reacted in a grinding mill, and the resulting precipitate encapsulated nano-copper oxide. The precipitate was then ground to form a suspension, which continuously circulated within the grinding mill. As the copper nitrate and sodium carbonate aqueous solutions were introduced, the volume of the suspension increased. When the volume of the suspension in the grinding mill reached 85% of the mill's volume, the introduction of the copper nitrate and sodium carbonate aqueous solutions was stopped, and circulation continued for 3 hours.

[0035] Step Two: Lay the cordierite honeycomb ceramic flat in the suction funnel, with the ceramic channels perpendicular to the bottom of the funnel. The inner dimension of the funnel is equal to the outer dimension of the cordierite honeycomb ceramic. The cordierite honeycomb ceramic is cylindrical, with a diameter of 15cm and a height of 12cm. The holes are square, vertically distributed along the axial direction, and have a length and width of 1mm and a height of 12cm (see...). Figure 1(Right). Then, the suspension from step one is poured into a vacuum filter funnel. Since there is no stirring, the suspension slowly settles into the channels of the cordierite honeycomb ceramic in a static state. The suspension accumulates relatively loosely in the channels of the cordierite honeycomb ceramic. The negative pressure of the vacuum filter funnel is turned on and gradually increased to 0.06 MPa at a rate of 0.01 MPa / hour. Under the action of negative pressure, the suspension slowly settles in the channels. As water is lost, the sediment becomes more and more compact, thus forming a filter cake in the channels of the cordierite honeycomb ceramic.

[0036] Step 3: Wash the filter cake in the cordierite honeycomb ceramic with deionized water until the conductivity of the filtrate is below 90 μS / cm. Transfer the washed cordierite honeycomb ceramic to an integrated drying and calcining furnace for heat treatment. The cordierite honeycomb ceramic is placed horizontally with the channels parallel to the ground. The drying temperature is 100℃ for 24 hours, and the calcination temperature is 500℃ for 2 hours. During the heat treatment, the cordierite honeycomb ceramic does not change. The filter cake filling the channels shrinks at high temperature, cracks, and forms crack-shaped channels within the channels, ultimately obtaining an integral copper / silicon oxide catalyst. Since the copper / silicon oxide is formed in situ within the channels, it has strong adhesion within the channels. The channels formed by shrinkage are the main channels for the catalytic reaction, while also increasing the external specific surface area of ​​the copper / silicon oxide. Because the copper / silicon oxide is inside the channels and protected by the pores of the cordierite honeycomb ceramic, there is no mutual friction during transportation and filling, so there is almost no wear. An evaluation was conducted using a monolithic copper / silicon oxide catalyst containing 14.13 mL of copper / silicon oxide. The copper / silicon oxide was embedded in square pores of cordierite honeycomb ceramic, with each pore measuring 1 mm in length and width. This translates to a copper / silicon oxide length of approximately 1413 cm and a surface area of ​​approximately 565.2 cm². 2 .

[0037] Example 3

[0038] In this embodiment of the monolithic copper / silicon oxide catalyst, the mass content of copper / silicon oxide is 35%, and the remainder is cordierite honeycomb ceramic. The proportion of copper in the copper / silicon oxide is 41.2%. The specific preparation method of the catalyst is as follows:

[0039] Step 1: Turn on the grinding mill and activate the self-circulation mode. The grinding mill has a grinding disc gap of 0.5 mm and a volume of 50 L. Add a 20% (w / w) aqueous solution of nano-copper oxide (nano-copper oxide size 20-40 nm), a 5% (w / w) silica sol, and nano-silica powder with a size of 20-50 nm to the grinding mill. The feeding ratio of the three is 12:8:1, and the total amount added is 25% of the volume of the grinding mill. Then, simultaneously introduce a 10% (w / w) aqueous solution of copper nitrate into the grinding mill. A 5% sodium carbonate aqueous solution was added in a 1:1 ratio. Copper nitrate and sodium carbonate reacted in a grinding mill, and the resulting precipitate encapsulated nano-copper oxide. The precipitate was then ground to form a suspension, which continuously circulated within the grinding mill. As the copper nitrate and sodium carbonate aqueous solutions were introduced, the volume of the suspension increased. When the volume of the suspension in the grinding mill reached 85% of the mill's volume, the introduction of the copper nitrate and sodium carbonate aqueous solutions was stopped, and circulation continued for 4 hours.

[0040] Step Two: Lay the cordierite honeycomb ceramic flat in the suction funnel, with the ceramic channels perpendicular to the bottom surface of the funnel. The inner dimension of the funnel is equal to the outer dimension of the cordierite honeycomb ceramic. The cordierite honeycomb ceramic is a cuboid, with a length and width of 12cm and a height of 15cm. The holes are square, vertically distributed along the axial direction, with a length and width of 2mm and a height of 15cm (see...). Figure 1 (Left). Then, the suspension from step one is poured into a vacuum filter funnel. Since there is no stirring, the suspension slowly settles into the channels of the cordierite honeycomb ceramic in a static state. The suspension accumulates relatively loosely in the channels of the cordierite honeycomb ceramic. The negative pressure of the vacuum filter funnel is turned on and gradually increased to 0.09 MPa at a rate of 0.01 MPa / hour. Under the action of negative pressure, the suspension slowly settles in the channels. As water is lost, the sediment becomes more and more compact, thus forming a filter cake in the channels of the cordierite honeycomb ceramic.

[0041] Step 3: Wash the filter cake in the cordierite honeycomb ceramic with deionized water until the conductivity of the filtrate is below 90 μS / cm. Transfer the washed cordierite honeycomb ceramic to an integrated drying and calcining furnace for heat treatment. The cordierite honeycomb ceramic is placed horizontally with the channels parallel to the ground. The drying temperature is 130℃ for 20 hours, and the calcination temperature is 400℃ for 4 hours. During the heat treatment, the cordierite honeycomb ceramic does not change. The filter cake filling the channels shrinks at high temperature, cracks, and forms crack-shaped channels within the channels, ultimately obtaining an integral copper / silicon oxide catalyst. Since the copper / silicon oxide is formed in situ within the channels, it has strong adhesion within the channels. The channels formed by shrinkage are the main channels for the catalytic reaction, while also increasing the external specific surface area of ​​the copper / silicon oxide. Because the copper / silicon oxide is inside the channels and protected by the pores of the cordierite honeycomb ceramic, there is no mutual friction during transportation and filling, so there is almost no wear. An evaluation was conducted using a monolithic copper / silicon oxide catalyst containing 14.13 mL of copper / silicon oxide. The copper / silicon oxide was contained within the square pores of a cordierite honeycomb ceramic substrate, with each pore measuring 2 mm in length and width. This translates to a copper / silicon oxide length of approximately 353.25 cm and a surface area of ​​approximately 282.68 cm². 2 .

[0042] To demonstrate the beneficial effects of this invention, conventional copper / silica catalysts of the same volume (14.13 mL) and monolithic copper / silica catalysts prepared in Examples 1-3 were used in the dehydrogenation of propylene glycol methyl ether to prepare methoxyacetone. The results are shown in Table 1. The monolithic copper / silica catalyst was crushed to remove the cordierite honeycomb ceramic portion, retaining only copper / silica. The catalyst was then evaluated, and the results are shown in Table 1. Catalyst volume is expressed as copper / silica ratio. The reaction conditions were the same: reaction temperature 220 °C, atmospheric pressure, and mass hourly space velocity (HHSV) of 0.6 h⁻¹. -1 .

[0043] Table 1

[0044] Example 1: Monolithic Copper / Silica Catalyst 51.9％ Example 1: After crushing the monolithic copper / silicon oxide catalyst 48.3％ Comparative Example 1: Conventional copper / silicon oxide catalyst 32.7％ Example 2 Monolithic copper / silicon oxide catalyst 50.4％ Example 3 Monolithic copper / silicon oxide catalyst 51.0％

[0045] As shown in Table 1, the monolithic copper / silica catalyst of this invention exhibits higher activity. The copper / silica in the monolithic copper / silica catalyst has a significantly larger surface area than that of conventional copper / silica catalysts, exceeding 3.75 times (565.2 / 150.72 = 3.75). The activity of the monolithic copper / silica catalyst of this invention decreases slightly after crushing, possibly due to catalyst wear, as the copper / silica after removing the cordierite honeycomb ceramic is easily broken and unsuitable for use alone or for long-term applications. Conventional copper / silica catalysts have the lowest activity, partly due to their small external specific surface area and partly due to the low dispersion of copper species. Therefore, the monolithic copper / silica catalyst prepared by the method of this invention inherently possesses higher catalytic activity, which is related to the better dispersion of copper on the catalyst. The use of cordierite honeycomb ceramic to create a monolithic catalyst allows for the full utilization of the catalyst's activity.

Claims

1. A method for preparing a monolithic copper / silicon oxide catalyst, characterized in that, The catalyst comprises a cordierite honeycomb ceramic support material and an active component copper / silicon oxide, wherein the mass content of copper / silicon oxide is 26%–39%, and the remainder is cordierite honeycomb ceramic, and the proportion of copper in copper / silicon oxide is 40%–70%; the preparation of the catalyst includes the following steps: Step 1: Turn on the gel mill and activate the self-circulation mode. Add nano copper oxide aqueous solution, silica sol, and nano silica powder. The total amount of these three components should be 20% to 25% of the gel mill volume. Then, pass copper nitrate aqueous solution and alkali aqueous solution into the gel mill. When the volume of the suspension formed in the gel mill reaches 70% to 85% of the gel mill volume, stop passing the copper nitrate aqueous solution and alkali aqueous solution. Continue to circulate for 2 to 4 hours. Step 2: Lay the cordierite honeycomb ceramic flat in the suction funnel, with the channels perpendicular to the bottom of the funnel. The inner dimension of the funnel is equal to the outer dimension of the cordierite honeycomb ceramic. Then pour the suspension from Step 1 into the suction funnel, turn on the negative pressure of the suction funnel, and gradually increase the negative pressure to 0.06-0.09 MPa, so that the suspension forms a filter cake in the channels of the cordierite honeycomb ceramic. Step 3: Wash the filter cake in the cordierite honeycomb ceramic with deionized water until the conductivity of the filtrate is lower than 90 μS / cm; transfer the washed cordierite honeycomb ceramic to a drying and calcining integrated furnace for heat treatment to obtain an integral copper / silicon oxide catalyst.

2. The method for preparing the monolithic copper / silicon oxide catalyst according to claim 1, characterized in that: In step one, the mass concentration of the nano-copper oxide in the aqueous solution is 5% to 30%, and the size of the nano-copper oxide is 20 to 40 nm; the mass concentration of the silica sol is 5% to 20%; and the size of the nano-silica is 20 to 50 nm.

3. The method for preparing the monolithic copper / silicon oxide catalyst according to claim 1 or 2, characterized in that: In step one, the feeding ratio of the nano copper oxide aqueous solution, silica sol and nano silicon oxide powder is 8-12:8-12:

1.

4. The method for preparing the monolithic copper / silicon oxide catalyst according to claim 1, characterized in that: In step one, the grinding disc gap of the rubber mill is 0.05-0.5mm and the volume is 20-50L.

5. The method for preparing the monolithic copper / silicon oxide catalyst according to claim 1, characterized in that: In step one, the ratio of the copper nitrate aqueous solution to the alkali aqueous solution is 1:1, the mass concentration of the copper nitrate aqueous solution is 10% to 20%, and the mass concentration of the alkali aqueous solution is 5% to 10%.

6. The method for preparing the monolithic copper / silicon oxide catalyst according to claim 1 or 5, characterized in that: In step one, the alkali is sodium carbonate or sodium hydroxide.

7. The method for preparing the monolithic copper / silicon oxide catalyst according to claim 1, characterized in that: In step two, the cordierite honeycomb ceramic is a cuboid or a cylinder. The length, width, and height of the cuboid are all within the range of 5 to 30 cm. The diameter of the cylinder is 5 to 30 cm and the height is 10 to 30 cm. The holes are square holes, which are vertically distributed along the axial direction. The length and width of the holes are 1 to 2 mm, and the height of the holes is the same as the height of the cuboid or cylinder.

8. The method for preparing the monolithic copper / silicon oxide catalyst according to claim 1, characterized in that: In step two, the negative pressure is increased at a rate of 0.01 MPa / hour.

9. The method for preparing the monolithic copper / silicon oxide catalyst according to claim 1, characterized in that: In step three, the cordierite honeycomb ceramics in the integrated drying and calcining furnace are placed horizontally so that the channels are parallel to the ground. The drying temperature is 100-130℃ and maintained for 20-24 hours, and the calcining temperature is 400-500℃ and maintained for 2-4 hours.

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