A precious metal-embedded porous carbon-coated honeycomb ceramic monolithic catalyst and applications

Abstract

The application discloses a precious metal embedded porous carbon coated honeycomb ceramic monolithic catalyst and application thereof. The liquid phenolic resin polymer containing chloroplatinic acid is uniformly coated on the surface of the cordierite honeycomb ceramic through impregnation treatment; in an oxygen-nitrogen mixed atmosphere, one-stage solidification makes the liquid phenolic resin polymer containing chloroplatinic acid coated on the surface of the cordierite honeycomb ceramic completely solidified; two-stage calcination makes oxygen react with chloroplatinic acid, so that the chloroplatinic acid is decomposed, and the negative influence of chloride ions on the catalyst is eliminated; in an inert gas argon atmosphere, carbonization makes the phenolic resin polymer carbonize under high-temperature conditions to form porous carbon, and meanwhile, platinum ions are reduced to platinum single elements and embedded by the porous carbon, so that the precious metal (platinum, iridium) embedded porous carbon coated honeycomb ceramic monolithic catalyst is finally prepared.

Description

Technical Field

[0001] This invention relates to a monolithic catalyst of noble metal embedded porous carbon coated cordierite honeycomb ceramic, its preparation method, and its high-performance application in the selective catalytic hydrogenation reaction of chlorinated aromatic nitro compounds to synthesize chloroaniline. Background Technology

[0002] Chloroaniline is an important raw material commonly used in pharmaceuticals, agriculture, and dyes, with broad application prospects. It is typically obtained by reducing chloroaromatic nitro compounds. Compared to highly polluting chemical reduction methods and energy-intensive electrolytic reduction methods, catalytic hydrogenation reduction offers unique advantages such as simple operation, less waste, low energy consumption, high product yield, and good product quality, thus gaining increasing attention and application in industrial production. However, this method also has a drawback: the hydrogenation reduction of the nitro group is accompanied by a hydrogenochlorination side reaction involving the breaking of the C-Cl bond (mechanism diagram shown below). The resulting hydrogen chloride byproduct not only reduces the selectivity of the reaction products but also corrodes the reaction equipment and may even poison the catalyst.

[0003]

[0004] Currently, in the research on the catalytic hydrogenation of chloronitrobenzene to chloroaniline, commonly used metal catalysts include platinum, palladium, nickel, and cobalt, among which the research on non-noble metal nickel and noble metals (platinum, palladium, iridium, etc.) is the most extensive. Correspondingly, there are three main methods to suppress the dechlorination side reaction: First, adding additional dechlorination inhibitors. For example, CN102757352A (production process for the catalytic hydrogenation of p-nitrochlorobenzene to p-chloroaniline) uses Raney nickel as a catalyst and dicyandiamide as a dechlorination inhibitor. Through the catalytic hydrogenation reaction, the selectivity of chloroaniline reaches over 98%. However, this method requires the continuous addition of dechlorination inhibitors, thus increasing production costs and affecting product purity. Second, adding non-metallic additives to modulate the interaction between the metal and the support. For example, CN115845919A (Nitrogen-doped phenolic resin embedded nickel porous carbon coated honeycomb ceramic monolithic catalyst) uses cordierite as a support and Ni(NO3)2 as a nickel precursor. A nitrogen-doped Ni-based catalyst is obtained by doping nitrogen into the porous carbon coating of the catalyst, achieving a selectivity of 99% for chloroaniline. Thirdly, bimetallic / multimetallic catalysts are prepared. For example, CN115739080B (Preparation of a Pt-based catalyst and its application in the selective hydrogenation of chloronitrobenzene to chloroaniline) uses TiO2 as a support and H2PtCl6·6H2O as a platinum precursor. A bimetallic system is formed by adding the auxiliary agent Mo, and a Pt-based catalyst is obtained by the equal-volume impregnation method, achieving a selectivity of over 99% for chloroaniline. All of the above methods suppress the dechlorination side reaction to some extent, but they also share the same drawback: they all achieve the effect of suppressing the dechlorination side reaction by adding auxiliary agents or a second metal component. No single-component catalyst has ever simultaneously exhibited high activity, high selectivity, and high stability in the catalytic hydrogenation of chloronitrobenzene to chloroaniline without the aid of a second component.

[0005] Based on in-depth research on monolithic catalysts with embedded nickel in porous carbon-coated honeycomb ceramics, monolithic catalysts with embedded noble metals (platinum, iridium) in porous carbon-coated honeycomb ceramics show great potential in the catalytic hydrogenation of chloronitrobenzene to chloroaniline. However, unlike nickel catalysts which typically use readily thermally decomposable nickel nitrate or nickel oxalate as metal precursors, noble metal catalysts usually use acidic chlorine complexes such as chloroplatinic acid or chloroiridium acid as precursors. This is mainly because readily thermally decomposable noble metal nitrates and other organic salts are difficult to prepare and extremely expensive. Furthermore, if noble metal precursors such as chloroplatinic acid or chloroiridium acid are used, their decomposition conditions do not match those of porous carbon precursors, requiring targeted adjustments to the nickel-embedded porous carbon-coated honeycomb ceramic monolithic catalyst. Therefore, this invention proposes a method for using monolithic catalysts with embedded noble metals (platinum, iridium) in porous carbon-coated honeycomb ceramics and its application. Summary of the Invention

[0006] The purpose of this invention is to provide a high-performance, low-cost monolithic catalyst with precious metals (platinum, iridium) embedded in porous carbon-coated honeycomb ceramic, and its application in the selective catalytic hydrogenation reaction of chlorinated aromatic nitro compounds.

[0007] The present invention adopts the following technical solution:

[0008] This invention provides a monolithic catalyst of porous carbon-coated honeycomb ceramic with embedded noble metal. The catalyst is prepared by the following method: cordierite honeycomb ceramic is immersed in liquid phenolic resin containing noble metal at an immersion temperature of 40℃~80℃ for 8~16h. After removal, excess liquid phenolic resin in the pores is blown off. Then, under an oxygen-nitrogen mixed atmosphere, it is cured sequentially at a curing temperature of 80~200℃ for 6~18h, calcined at a calcination temperature of 200~600℃ for 0.5~4h, and finally carbonized at a carbonization temperature of 500~1000℃ for 4~8h under an argon atmosphere to obtain the monolithic catalyst of porous carbon-coated honeycomb ceramic with embedded noble metal, wherein the noble metal is one or more of platinum or iridium.

[0009] Furthermore, the method for preparing the liquid phenolic resin containing precious metals is as follows: phenol, formaldehyde, and a precious metal salt solution are mixed and polymerized at 50℃~90℃ for 1~5h to obtain the liquid phenolic resin containing precious metals. The mass ratio of phenol to precious metal salt solution is 40:0.01~1 (preferably 40:0.1~0.5), and the volume of formaldehyde is 1-1.5ml / g based on the mass of phenol.

[0010] Furthermore, the noble metal salt in the noble metal salt solution is one or more of chloroplatinic acid or chloroiridium acid.

[0011] Furthermore, the precious metal salt solution is an aqueous solution of precious metal salt with a mass percentage concentration of 0.1-10% (preferably 0.5-2%).

[0012] Furthermore, in the oxygen-nitrogen mixed atmosphere, the volume ratio of oxygen to nitrogen is 1:1 to 6 (preferably 1:3 to 6).

[0013] Furthermore, the curing temperature is 100–150°C, and the curing time is 10–15 h.

[0014] Furthermore, the calcination temperature is 300–500°C, and the calcination time is 1–3 hours.

[0015] Furthermore, the carbonization temperature is 600–800℃, and the carbonization time is 5–7 hours.

[0016] The present invention also relates to the application of the aforementioned noble metal-embedded porous carbon-coated honeycomb ceramic monolithic catalyst in the selective catalytic hydrogenation reaction of chloronitrobenzene.

[0017] Furthermore, the application method is as follows: the precious metal-embedded porous carbon-coated honeycomb ceramic monolithic catalyst is loaded into a fixed-bed reactor, and a selective catalytic hydrogenation reaction is carried out under normal pressure at 60-150°C using p-chloronitrobenzene-n-butanol as raw material and hydrogen and nitrogen as carrier gases. The product p-chloroaniline is collected by condensation, and the conversion rate of p-chloronitrobenzene and the selectivity of p-chloroaniline are analyzed by gas chromatography.

[0018] The purpose of the impregnation treatment described in this invention is to uniformly coat the surface of cordierite honeycomb ceramic with a liquid phenolic resin polymer containing chloroplatinic acid. Under an oxygen-nitrogen mixed atmosphere, the first stage of curing aims to completely solidify the liquid phenolic resin polymer containing chloroplatinic acid coated on the cordierite honeycomb ceramic surface; the second stage of calcination aims to react oxygen with chloroplatinic acid, causing the chloroplatinic acid to decompose and eliminating the negative influence of chloride ions on the catalyst. Under an inert argon atmosphere, the carbonization aims to carbonize the phenolic resin polymer at high temperature to form porous carbon, while simultaneously reducing platinum ions to elemental platinum which is then encapsulated and embedded in the porous carbon, ultimately obtaining the monolithic catalyst of the noble metal (platinum, iridium) embedded in porous carbon coated honeycomb ceramic.

[0019] Compared with conventional catalysts, the noble metal-embedded porous carbon-coated honeycomb ceramic monolithic catalyst of this invention has significant advantages in many aspects such as selectivity, activity, stability, and ease of use: 1) The noble metal-porous carbon embedded structure can effectively suppress the dechlorination side reaction in the selective catalytic hydrogenation of chloronitrobenzene, achieving high selectivity without the addition of other additives; 2) The noble metals platinum and iridium embedded in the porous carbon structure have smaller and more uniform particle sizes, exhibiting extremely high catalytic activity under extremely low noble metal loading conditions; 3) The noble metal-porous carbon embedded structure can effectively suppress the agglomeration of noble metal particles caused by thermal migration during the reaction, and the catalyst has extremely high thermal stability; 4) The noble metals platinum and iridium embedded in the porous carbon structure are reduced in situ during the formation of porous carbon and have very good chemical stability in air, allowing for direct use without pre-reduction before the reaction; 5) The noble metal-embedded porous carbon-coated honeycomb ceramic monolithic catalyst is suitable for continuous selective catalytic hydrogenation reactions, which is in line with the development direction of industrial technology upgrading. Detailed Implementation

[0020] The following are specific embodiments to illustrate the technical solution of the present invention, but the scope of protection of the present invention is not limited thereto:

[0021] The following cordierite honeycomb ceramic was purchased from Jiangsu Yixing Non-metallic Chemical Machinery Factory Co., Ltd. It is cylindrical, with a diameter of 45.8 mm, a height of 80 mm, square holes, a pore density of 54 cells / cm2, and a wall thickness of 0.22 mm.

[0022] Examples 1-6

[0023] Examples 1-6 compared the effects of curing conditions on the performance of a monolithic catalyst made of platinum-embedded porous carbon-coated honeycomb ceramic. The catalyst preparation method is as follows:

[0024] 40g of phenol was mixed with 52ml of formaldehyde, and then 0.3g of a 1% (w / w) chloroplatinic acid solution was added. Polymerization was carried out at 70℃ for 3 hours. Cordierite honeycomb ceramics were then immersed in the above liquid resin polymer and impregnated at 60℃ for 12 hours. After removal, excess resin in the pores was blown away. Then, an oxygen-nitrogen mixed atmosphere (VO) with a flow rate of 30mL / min was applied. O2 :V N2 The platinum-embedded porous carbon-coated honeycomb ceramic monolithic catalyst was prepared by first-stage curing at 100-150℃ for 10-15 hours under an argon atmosphere of 60 mL / min.

[0025] One platinum-embedded porous carbon-coated honeycomb ceramic monolithic catalyst was loaded into a fixed-bed reactor. A 5% p-chloronitrobenzene-n-butanol solution (by mass) was introduced into the fixed-bed reactor at a flow rate of 0.5 mL / min. A nitrogen-hydrogen mixture (V... N2 :V H2 The product p-chloroaniline (r=1:3) was introduced into a fixed-bed reactor at a flow rate of 60 mL / min and subjected to catalytic hydrogenation at 110 °C under atmospheric pressure. The product p-chloroaniline was collected by condensation, and the conversion rate of p-chloronitrobenzene and the selectivity of p-chloroaniline were analyzed by gas chromatography. The results of the analysis of samples taken after 5 h of reaction are shown in Table 1 below.

[0026]

[0027] Comparative Example 1, Examples 7-12

[0028] Comparative Examples 1 and Examples 7-12 compared the effects of two-stage calcination conditions on the performance of a platinum-embedded porous carbon-coated monolithic honeycomb ceramic catalyst. The catalyst preparation method is as follows:

[0029] 40g of phenol was mixed with 52ml of formaldehyde, and then 0.3g of a 1% (w / w) chloroplatinic acid solution was added. Polymerization was carried out at 70℃ for 3 hours. Cordierite honeycomb ceramics were then immersed in the above liquid resin polymer at 60℃ for 12 hours. After immersion, excess resin in the pores was blown away. Then, an oxygen-nitrogen mixed atmosphere (VO) with a flow rate of 30mL / min was applied. O2 :V N2The platinum-embedded porous carbon-coated honeycomb ceramic monolithic catalyst was prepared by first-stage curing at 130℃ for 14 hours at a ratio of 1:4, followed by second-stage calcination at 300-500℃ for 1-3 hours. Finally, it was carbonized at 700℃ for 6 hours under an argon atmosphere with a flow rate of 60 mL / min to obtain the monolithic catalyst.

[0030] One platinum-embedded porous carbon-coated honeycomb ceramic monolithic catalyst was loaded into a fixed-bed reactor. A 5% p-chloronitrobenzene-n-butanol solution (by mass) was introduced into the fixed-bed reactor at a flow rate of 0.5 mL / min. A nitrogen-hydrogen mixture (V... N2 :V H2 The product p-chloroaniline (r=1:3) was introduced into a fixed-bed reactor at a flow rate of 60 mL / min and subjected to catalytic hydrogenation at 110 °C under atmospheric pressure. The product p-chloroaniline was collected by condensation, and the conversion rate of p-chloronitrobenzene and the selectivity of p-chloroaniline were analyzed by gas chromatography. The results of the analysis of samples taken after 5 h of reaction are shown in Table 2 below.

[0031]

[0032] Examples 13-20

[0033] Examples 13-20 compared the effects of polymerization conditions during the preparation of liquid phenolic resin containing noble metals on the performance of a platinum-intercalated porous carbon-coated honeycomb ceramic monolithic catalyst. The catalyst preparation method is as follows:

[0034] 40g of phenol was mixed with 52ml of formaldehyde, and then 0.3g of a 1% (w / w) chloroplatinic acid solution was added. Polymerization was carried out at 50℃–90℃ for 1–5 hours. Cordierite honeycomb ceramics were then immersed in the above liquid resin polymer at 60℃ for 12 hours. After removal, excess resin in the pores was blown away. Then, an oxygen-nitrogen mixture (VO) was introduced at a flow rate of 30mL / min. O2 :V N2 The platinum-embedded porous carbon-coated honeycomb ceramic monolithic catalyst was prepared by first-stage curing at 130℃ for 14 hours at a ratio of 1:4, followed by second-stage calcination at 400℃ for 2 hours. Finally, it was carbonized at 700℃ for 6 hours under an argon atmosphere with a flow rate of 60 mL / min to obtain the monolithic catalyst.

[0035] One platinum-embedded porous carbon-coated honeycomb ceramic monolithic catalyst was loaded into a fixed-bed reactor. A 5% p-chloronitrobenzene-n-butanol solution (by mass) was introduced into the fixed-bed reactor at a flow rate of 0.5 mL / min. A nitrogen-hydrogen mixture (V... N2 :V H2The product (ratio 1:3) was introduced into a fixed-bed reactor at a flow rate of 60 mL / min, and catalytic hydrogenation was carried out at 110 °C under atmospheric pressure. The product was collected by condensation, and the conversion rate of p-chloronitrobenzene and the selectivity of p-chloroaniline were analyzed by gas chromatography. The results of the analysis of samples taken after 5 h of reaction are shown in Table 3 below.

[0036]

[0037]

[0038] Examples 21-28

[0039] Examples 21-28 compared the effects of cordierite honeycomb ceramic impregnation conditions on the performance of platinum-embedded porous carbon-coated monolithic honeycomb ceramic catalysts. The catalyst preparation methods are as follows:

[0040] 40g of phenol was mixed with 52ml of formaldehyde, and then 0.3g of a 1% (w / w) chloroplatinic acid solution was added. Polymerization was carried out at 70℃ for 3 hours. Cordierite honeycomb ceramics were then immersed in the above liquid resin polymer at 40℃~80℃ for 8~16 hours. After immersion, excess resin in the pores was blown away. Then, an oxygen-nitrogen mixture (VO) was introduced at a flow rate of 30mL / min. O2 :V N2 The platinum-embedded porous carbon-coated honeycomb ceramic monolithic catalyst was prepared by first-stage curing at 130℃ for 14 hours at a ratio of 1:4, followed by second-stage calcination at 400℃ for 2 hours. Finally, it was carbonized at 700℃ for 6 hours under an argon atmosphere with a flow rate of 60 mL / min to obtain the monolithic catalyst.

[0041] One platinum-embedded porous carbon-coated honeycomb ceramic monolithic catalyst was loaded into a fixed-bed reactor. A 5% p-chloronitrobenzene-n-butanol solution (by mass) was introduced into the fixed-bed reactor at a flow rate of 0.5 mL / min. A nitrogen-hydrogen mixture (V... N2 :V H2 The product (ratio 1:3) was introduced into a fixed-bed reactor at a flow rate of 60 mL / min, and catalytic hydrogenation was carried out at 110 °C under atmospheric pressure. The product was collected by condensation, and the conversion rate of p-chloronitrobenzene and the selectivity of p-chloroaniline were analyzed by gas chromatography. The results of the analysis of samples taken after 5 h of reaction are shown in Table 3 below.

[0042]

[0043]

[0044] Comparative Example 2, Comparative Example 3, Example 29, Example 30

[0045] Comparative Examples 2, 3, 29, and 30 compared the effect of the volume ratio of oxygen to nitrogen in an oxygen-nitrogen mixed atmosphere on the performance of a platinum-embedded porous carbon-coated honeycomb ceramic monolithic catalyst. The catalyst preparation method is as follows:

[0046] 40g of phenol was mixed with 52ml of formaldehyde, and then 0.3g of a 1% (w / w) chloroplatinic acid solution was added. Polymerization was carried out at 70℃ for 3 hours. Cordierite honeycomb ceramics were then immersed in the above liquid resin polymer at 60℃ for 12 hours. After immersion, excess resin in the pores was blown away. Then, an oxygen-nitrogen mixed atmosphere (VO) with a flow rate of 30mL / min was applied. O2 :V N2 The platinum-embedded porous carbon-coated honeycomb ceramic monolithic catalyst was prepared by first-stage curing at 130℃ for 14 hours under an argon atmosphere with a flow rate of 60 mL / min.

[0047] One platinum-embedded porous carbon-coated honeycomb ceramic monolithic catalyst was loaded into a fixed-bed reactor. A 5% p-chloronitrobenzene-n-butanol solution (by mass) was introduced into the fixed-bed reactor at a flow rate of 0.5 mL / min. A nitrogen-hydrogen mixture (V... N2 :V H2 The product p-chloroaniline (r=1:3) was introduced into a fixed-bed reactor at a flow rate of 60 mL / min and subjected to catalytic hydrogenation at 110 °C under atmospheric pressure. The product p-chloroaniline was collected by condensation, and the conversion rate of p-chloronitrobenzene and the selectivity of p-chloroaniline were analyzed by gas chromatography. The results of the analysis of samples taken after 5 h of reaction are shown in Table 3 below.

[0048]

[0049] Comparative Example 4, Examples 31-34

[0050] Comparative Examples 4 and Examples 31-34 compared the effects of carbonization and calcination conditions on the performance of a platinum-embedded porous carbon-coated honeycomb ceramic monolithic catalyst. The catalyst preparation method is as follows:

[0051] 40g of phenol was mixed with 52ml of formaldehyde, and then 0.3g of a 1% (w / w) chloroplatinic acid solution was added. Polymerization was carried out at 70℃ for 3 hours. Cordierite honeycomb ceramics were then immersed in the above liquid resin polymer at 60℃ for 12 hours. After immersion, excess resin in the pores was blown away. Then, an oxygen-nitrogen mixed atmosphere (VO) with a flow rate of 30mL / min was applied. O2 :V N2The platinum-embedded porous carbon-coated honeycomb ceramic monolithic catalyst was prepared by first-stage curing at 130℃ for 14 hours under an argon atmosphere with a flow rate of 60 mL / min, followed by second-stage calcination at 400℃ for 2 hours.

[0052] One platinum-embedded porous carbon-coated honeycomb ceramic monolithic catalyst was loaded into a fixed-bed reactor. A 5% p-chloronitrobenzene-n-butanol solution (by mass) was introduced into the fixed-bed reactor at a flow rate of 0.5 mL / min. A nitrogen-hydrogen mixture (V... N2 :V H2 The product p-chloroaniline (r=1:3) was introduced into a fixed-bed reactor at a flow rate of 60 mL / min and subjected to catalytic hydrogenation at 110 °C under atmospheric pressure. The product p-chloroaniline was collected by condensation, and the conversion rate of p-chloronitrobenzene and the selectivity of p-chloroaniline were analyzed by gas chromatography. The results of the analysis of samples taken after 5 h of reaction are shown in Table 4 below.

[0053]

[0054] Examples 35-41

[0055] Examples 35-41 compared the effects of chloroplatinic acid concentration and dosage on the performance of a platinum-intercalated porous carbon-coated honeycomb ceramic monolithic catalyst. The catalyst preparation method is as follows:

[0056] 40g of phenol was mixed with 52ml of formaldehyde, and then 0.1-0.5g of a 0.5-2% (w / w) chloroplatinic acid solution was added. Polymerization was carried out at 70℃ for 3 hours. Cordierite honeycomb ceramics were then immersed in the above liquid resin polymer at 60℃ for 12 hours. After removal, excess resin in the pores was blown away. Then, an oxygen-nitrogen mixed atmosphere (VO) with a flow rate of 30mL / min was applied. O2 :V N2 The platinum-embedded porous carbon-coated honeycomb ceramic monolithic catalyst was prepared by first-stage curing at 130℃ for 14 hours at a ratio of 1:4, followed by second-stage calcination at 400℃ for 2 hours. Finally, it was carbonized at 700℃ for 6 hours under an argon atmosphere with a flow rate of 60 mL / min to obtain the monolithic catalyst.

[0057] One platinum-embedded porous carbon-coated honeycomb ceramic monolithic catalyst was loaded into a fixed-bed reactor. A 5% p-chloronitrobenzene-n-butanol solution (by mass) was introduced into the fixed-bed reactor at a flow rate of 0.5 mL / min. A nitrogen-hydrogen mixture (V... N2 :V H2The product p-chloroaniline (r=1:3) was introduced into a fixed-bed reactor at a flow rate of 60 mL / min and subjected to catalytic hydrogenation at 110 °C under atmospheric pressure. The product p-chloroaniline was collected by condensation, and the conversion rate of p-chloronitrobenzene and the selectivity of p-chloroaniline were analyzed by gas chromatography. The results of the analysis of samples taken after 5 h of reaction are shown in Table 5 below.

[0058]

[0059] Examples 42-46

[0060] Examples 42-46 compared the effect of reaction temperature on the performance of a monolithic catalyst made of platinum-intercalated porous carbon-coated honeycomb ceramic in the selective catalytic hydrogenation of p-chloronitrobenzene. The catalyst preparation method is as follows:

[0061] 40g of phenol was mixed with 52ml of formaldehyde, and then 0.3g of a 1% (w / w) chloroplatinic acid solution was added. Polymerization was carried out at 70℃ for 3 hours. Cordierite honeycomb ceramics were then immersed in the above liquid resin polymer at 60℃ for 12 hours. After immersion, excess resin in the pores was blown away. Then, an oxygen-nitrogen mixed atmosphere (VO) with a flow rate of 30mL / min was applied. O2 :V N2 The platinum-embedded porous carbon-coated honeycomb ceramic monolithic catalyst was prepared by first-stage curing at 130℃ for 14 hours at a ratio of 1:4, followed by second-stage calcination at 400℃ for 2 hours. Finally, it was carbonized at 700℃ for 6 hours under an argon atmosphere with a flow rate of 60 mL / min to obtain the monolithic catalyst.

[0062] One platinum-embedded porous carbon-coated honeycomb ceramic monolithic catalyst was loaded into a fixed-bed reactor. A 5% p-chloronitrobenzene-n-butanol solution (by mass) was introduced into the fixed-bed reactor at a flow rate of 0.5 mL / min. A nitrogen-hydrogen mixture (V... N2 :V H2 The product p-chloroaniline (r=1:3) was introduced into a fixed-bed reactor at a flow rate of 60 mL / min and subjected to catalytic hydrogenation at 90–130 °C under atmospheric pressure. The product p-chloroaniline was collected by condensation, and the conversion rate of p-chloronitrobenzene and the selectivity of p-chloroaniline were analyzed by gas chromatography. The results of the analysis of samples taken after 5 h of reaction are shown in Table 6 below.

[0063]

[0064] Example 47

[0065] Example 47 compared the effect of reaction time in the selective catalytic hydrogenation of p-chloronitrobenzene on the performance of a monolithic catalyst with platinum intercalation into porous carbon-coated honeycomb ceramic. The catalyst preparation method is as follows:

[0066] 40g of phenol was mixed with 52ml of formaldehyde, and then 0.3g of a 1% (w / w) chloroplatinic acid solution was added. Polymerization was carried out at 70℃ for 3 hours. Cordierite honeycomb ceramics were then immersed in the above liquid resin polymer at 60℃ for 12 hours. After immersion, excess resin in the pores was blown away. Then, an oxygen-nitrogen mixed atmosphere (VO) with a flow rate of 30mL / min was applied. O2 :V N2 The platinum-embedded porous carbon-coated honeycomb ceramic monolithic catalyst was prepared by first-stage curing at 130℃ for 14 hours at a ratio of 1:4, followed by second-stage calcination at 400℃ for 2 hours. Finally, it was carbonized at 700℃ for 6 hours under an argon atmosphere with a flow rate of 60 mL / min to obtain the monolithic catalyst.

[0067] One platinum-embedded porous carbon-coated honeycomb ceramic monolithic catalyst was loaded into a fixed-bed reactor. A 5% p-chloronitrobenzene-n-butanol solution (by mass) was introduced into the fixed-bed reactor at a flow rate of 0.5 mL / min. A nitrogen-hydrogen mixture (V... N2 :V H2 The product p-chloroaniline (r=1:3) was introduced into a fixed-bed reactor at a flow rate of 60 mL / min and subjected to catalytic hydrogenation at 110 °C under atmospheric pressure. The product p-chloroaniline was collected by condensation, and the conversion rate of p-chloronitrobenzene and the selectivity of p-chloroaniline were analyzed by gas chromatography. Samples were taken every 10 h for analysis, and the results are shown in Table 7 below.

[0068]

[0069]

[0070] Example 48, Comparative Example 5

[0071] Example 48 and Comparative Example 5 compared the effects of different noble metals on a noble metal-embedded porous carbon-coated honeycomb ceramic monolithic catalyst. The catalyst preparation method is as follows:

[0072] 40g of phenol was mixed with 52ml of formaldehyde, and then 0.3g of a 1% (w / w) solution of chloroiridic acid or chloropalladic acid was added. Polymerization was carried out at 70℃ for 3 hours. Cordierite honeycomb ceramics were then immersed in the above liquid resin polymer and impregnated at 60℃ for 12 hours. After removal, excess resin in the pores was blown away. Then, an oxygen-nitrogen mixed atmosphere (VO) with a flow rate of 30mL / min was applied. O2 :V N2 The catalyst was cured at 130°C for 14 hours at a ratio of 1:4, followed by a second-stage calcination at 400°C for 2 hours. Finally, it was carbonized at 700°C for 6 hours under an argon atmosphere with a flow rate of 60 mL / min to obtain the monolithic noble metal-embedded porous carbon-coated honeycomb ceramic catalyst.

[0073] One of the above-mentioned monolithic catalysts, consisting of porous carbon-coated honeycomb ceramics embedded with precious metals, was loaded into a fixed-bed reactor. A 5% p-chloronitrobenzene-n-butanol solution (by mass) was introduced into the fixed-bed reactor at a flow rate of 0.5 mL / min. A nitrogen-hydrogen mixture (V... N2 :V H2 The product p-chloroaniline (r=1:3) was introduced into a fixed-bed reactor at a flow rate of 60 mL / min and subjected to catalytic hydrogenation at 110 °C under atmospheric pressure. The product p-chloroaniline was collected by condensation, and the conversion rate of p-chloronitrobenzene and the selectivity of p-chloroaniline were analyzed by gas chromatography. The results of the analysis of samples taken after 5 h of reaction are shown in Table 8 below.

[0074]

Claims

1. The application of a noble metal-embedded porous carbon-coated honeycomb ceramic monolithic catalyst in the selective catalytic hydrogenation reaction of chloronitrobenzene, characterized in that... The catalyst was prepared by the following method: cordierite honeycomb ceramic was immersed in liquid phenolic resin containing precious metals at an immersion temperature of 40℃~80℃ for 8~16h. After removal, excess liquid phenolic resin in the pores was blown off. Then, under an oxygen-nitrogen mixed atmosphere, it was cured sequentially at a curing temperature of 100~150℃ for 10~15h and calcined at a calcination temperature of 300~500℃ for 1~3h. Finally, the catalyst is carbonized at 600–800°C for 5–7 hours under an argon atmosphere to obtain the noble metal-embedded porous carbon-coated honeycomb ceramic monolithic catalyst, wherein the noble metal is one or more of platinum or iridium; the method for preparing the liquid phenolic resin containing the noble metal is as follows: phenol, formaldehyde, and a noble metal salt solution are mixed and polymerized at 50–90°C for 1–5 hours to obtain the liquid phenolic resin containing the noble metal, wherein the mass ratio of phenol to the noble metal salt solution is 40:0.01–1, the volume of formaldehyde is 1–1.5 ml / g based on the mass of phenol, and the noble metal salt solution is a noble metal salt aqueous solution with a mass percentage concentration of 0.1–10%; the noble metal salt in the noble metal salt solution is one or more of chloroplatinic acid or chloroiridium acid.

2. The application as described in claim 1, characterized in that, The mass ratio of phenol to noble metal salt solution is 40:0.1~0.

5.

3. The application as described in claim 1, characterized in that, In the oxygen-nitrogen mixed atmosphere, the volume ratio of oxygen to nitrogen is 1:1 to 6.

4. The application as described in claim 1, characterized in that, The application method is as follows: the precious metal embedded porous carbon-coated honeycomb ceramic monolithic catalyst is loaded into a fixed bed reactor, using chloronitrobenzene-n-butanol as raw material and hydrogen and nitrogen as carrier gases, and selective catalytic hydrogenation reaction is carried out under normal pressure at 60-150℃. The product chloroaniline is collected by condensation.

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