Carbon dioxide carbon nanotube catalyst and application thereof

Abstract

The application relates to the technical field of carbon nanotube synthesis and air pollution treatment, and discloses a carbon nanotube catalyst prepared from carbon dioxide and application thereof, and a preparation method of the catalyst comprises the following steps: (1) mixing titanium white powder with a NaOH solution, then performing a hydrothermal reaction, performing solid-liquid separation, and obtaining a first powder; (2) performing plasma surface treatment on the first powder to obtain a second powder; (3) mixing a structure directing agent, an active component precursor, a cocatalyst precursor and water, adjusting the pH value to 9.5-10.5 to obtain a mixed solution, mixing the second powder with the mixed solution, performing a hydrothermal reaction, performing solid-liquid separation, and obtaining a third powder; and (4) mixing the third powder with a binder, a pore-forming agent and water, then drying and calcining. The catalyst provided by the application can make CO2 and H2S react at high temperature, and finally generate sulfur dioxide SO2, carbon nanotubes and H2O, not only the carbon nanotubes with low cost, stable structure and controllable size are prepared, but also H2S gas treatment is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of carbon nanotube synthesis and air pollution control, and particularly relates to a carbon dioxide preparation carbon nanotube catalyst and application thereof. BACKGROUND

[0002] Carbon nanotube is a one-dimensional carbon nanomaterial, which has excellent mechanical, electrical and chemical properties, and shows broad application prospects in the fields of material science, chemistry, physics and other cross disciplines.

[0003] There are a large number of researches on the synthesis and modification of carbon nanotubes, and the main synthesis methods include laser ablation method, solid phase pyrolysis method, chemical vapor deposition method and the like. Among them, the chemical vapor deposition method is widely used in industrial large-scale production due to its strong controllability and large yield.

[0004] At present, lipids organic compounds, methanol, methane, acetylene, ethylene, butane and the like are mainly used as carbon sources to synthesize carbon nanotubes, but the above raw materials are important resources themselves, and using them as raw materials is a waste of resources, which also leads to the increase of production cost. Therefore, it is necessary to find a cheap and common carbon source material to prepare carbon nanotubes, and carbon dioxide (CO2) is a good choice. At present, there is no report on the direct preparation of carbon nanotubes from carbon dioxide. SUMMARY

[0005] The present application aims to overcome the problem of high cost in the preparation of carbon nanotubes in the prior art, and provides a carbon dioxide preparation carbon nanotube catalyst and application thereof. The catalyst can convert carbon dioxide and hydrogen sulfide into SO2, H2O and carbon nanotubes, and the preparation cost of carbon nanotubes is low by using only low-cost carbon dioxide as a carbon source.

[0006] In order to achieve the above-mentioned purpose, the present application provides a carbon dioxide preparation carbon nanotube catalyst, which can convert carbon dioxide and hydrogen sulfide into SO2, H2O and carbon nanotubes. The catalyst uses TiO2 nanotube as a carrier, Ni-Fe bimetallic oxide as an active component, PdO as a cocatalyst, and carbamide as a structure directing agent, and is prepared by a secondary hydrothermal-plasma treatment method. The mass percentage content of the active component is 7-12% based on the mass of the carrier, and the mass percentage content of the cocatalyst is 0.5-1%. The mass ratio of NiO to Fe2O3 in the active component is 1:0.6-1.5.

[0007] The preparation method of the catalyst comprises the following steps:

[0008] (1) mixing titanium white powder with NaOH solution, then performing hydrothermal reaction, and then performing solid-liquid separation to obtain a first powder;

[0009] (2) performing plasma surface treatment on the first powder to obtain a second powder;

[0010] (3) mixing a structure-directing agent, a precursor of an active component, a precursor of a co-catalyst, and water, adjusting pH of the mixture to 9.5-10.5 to obtain a mixed solution, mixing the second powder with the mixed solution, and then performing hydrothermal reaction, followed by solid-liquid separation to obtain a third powder;

[0011] (4) mixing the third powder with a binder, a pore-forming agent, and water, and then drying and calcining;

[0012] In step (3), the precursor of the active component is a Ni source and a Fe source, and the precursor of the co-catalyst is a Pd source.

[0013] Preferably, in step (1), the concentration of the NaOH solution is 8-10 mol / L, and the ratio by amount of the titanium white powder to the NaOH solution is 1 g: 10-15 mL.

[0014] Preferably, in step (1), the hydrothermal reaction is performed under conditions including a temperature of 110-150 ℃ and a time of 10-15 h.

[0015] Preferably, in step (2), the plasma surface treatment is performed under conditions including a voltage of 220 V, a working distance of 6-12 mm, a plasma flame scanning rate of 60-100 mm / s, and a time of 30-60 min.

[0016] Preferably, in step (2), the plasma surface treatment is repeated 2-4 times.

[0017] Preferably, in step (3), the concentration of the structure-directing agent in the mixed solution is 0.5-0.8 mol / L.

[0018] Preferably, in step (3), the hydrothermal reaction is performed under conditions including a temperature of 150-180 ℃ and a time of 6-12 h.

[0019] Preferably, in step (4), the binder is selected from any one of a bamboo joint powder, polyethylene oxide, and carboxymethyl cellulose.

[0020] Preferably, in step (4), the pore-forming agent is selected from any one of carbon powder, ammonium chloride, and glucose.

[0021] Preferably, the particle size of the carbon powder is less than 200 mesh.

[0022] Preferably, based on the mass of the titanium white powder, the addition amount of the binder is 3-5%, the addition amount of the pore-forming agent is 30-50%, and the addition amount of the water is 80-100%.

[0023] Preferably, in step (4), the calcination temperature is 500-550℃, the calcination time is 3-5h, and the calcination environment is air atmosphere.

[0024] The second aspect of the present application provides a use of the carbon dioxide carbon nanotube catalyst in the preparation of carbon nanotubes from CO2 and H2S.

[0025] Preferably, the use is carried out at a temperature of 400-500℃.

[0026] In the technical solution provided by the present application, the catalyst uses TiO2 nanotubes as a carrier, Ni-Fe bimetallic oxide as an active component, and PdO as a cocatalyst. In the present application, titanium dioxide powder is first converted from a spherical microstructure to an amorphous nanotube structure with a large specific surface area by a hydrothermal method. Then, the powder is treated by a plasma surface processor to increase the surface defects of the TiO2 nanotubes and improve their hydrophilic properties. At the same time, the surface defect sites become the loading sites of the active component and the cocatalyst, avoiding the agglomeration phenomenon. Then, the active component and the cocatalyst are loaded on the surface of the TiO2 nanotubes by a hydrothermal method. Finally, the TiO2 is converted from an amorphous state to an anatase crystal form by shaping and calcination, and the carrier is tightly combined with the active component and the cocatalyst during the crystal form conversion process.

[0027] The catalyst provided by the present application can make carbon dioxide (CO2) and hydrogen sulfide (H2S) react at high temperature to ultimately generate SO2, carbon nanotubes and H2O. In this way, on the one hand, carbon nanotubes can be prepared from low-cost carbon dioxide as a carbon source, which can reduce the production cost of carbon nanotubes, and the synthesized carbon nanotubes have stable structure and controllable size, and have high economic value. On the other hand, H2S gas can be converted into SO2, and the H2S removal efficiency is high, which greatly reduces the toxicity of the gas and facilitates subsequent removal treatment, and has high economic value. The catalyst has low raw material cost, simple synthesis process and high catalytic activity, and has wide market application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a hydrogen sulfide removal efficiency graph in test example 1 of the present application;

[0029] Figure 2 is a field emission scanning electron microscope (FE-SEM) graph of the carbon nanotubes prepared in test example 1 of the present application. DETAILED DESCRIPTION

[0030] The specific embodiments of the present application are described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0031] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not considered critical for the purposes of the application. The ranges should be interpreted as being inclusive of the recited values and the ranges between the recited values.

[0032] The application provides a carbon dioxide carbon nanotube catalyst which can convert carbon dioxide and hydrogen sulfide into SO2, H2O and carbon nanotube, the catalyst is prepared by a secondary hydrothermal-plasma treatment method, and takes TiO2 nanotube as a carrier, takes Ni-Fe bimetallic oxide as an active component, takes PdO as a promoter, and takes a carbonamide as a structure directing agent; the mass percentage content of the active component is 7-12% based on the mass of the carrier, and the mass percentage content of the promoter is 0.5-1%; wherein the mass ratio of NiO:Fe2O3 in the active component is 1:0.6-1.5.

[0033] The preparation method of the catalyst comprises the following steps:

[0034] (1) mixing titanium white powder and a NaOH solution, then performing a hydrothermal reaction, and then performing solid-liquid separation to obtain a first powder;

[0035] (2) performing plasma surface treatment on the first powder to obtain a second powder;

[0036] (3) mixing a structure directing agent, an active component precursor, a promoter precursor and water, adjusting the pH to 9.5-10.5 to obtain a mixed solution, mixing the second powder and the mixed solution, then performing a hydrothermal reaction, and then performing solid-liquid separation to obtain a third powder;

[0037] (4) mixing the third powder, a binder, a pore-forming agent and water, then drying and calcining;

[0038] In step (3), the active component precursor is a Ni source and a Fe source, and the promoter precursor is a Pd source.

[0039] The application does not limit the specific selection of the Ni source, and in a specific embodiment, the Ni source is a nitrate of Ni and / or a chloride of Ni.

[0040] The application also does not limit the specific selection of the Fe source, and in a specific embodiment, the Fe source is a nitrate of Fe and / or a chloride of Fe.

[0041] In a specific embodiment, the Pd source is a nitrate of Pd and / or a chloride of Pd.

[0042] In the present application, the carrier is first made into an amorphous nanotube structure through a hydrothermal reaction, which can provide a larger specific surface area; then the carrier surface is enriched with defect sites through the combined use of plasma surface modification and hydrothermal method, and uniform dispersion of the active component and the promoter on the carrier surface is achieved; finally, the amorphous TiO2 is converted into anatase TiO2 through molding and calcination, and the carrier is closely combined with the active component and the promoter in the process of crystal type conversion.

[0043] CO2 has strong stability and H2S has weak reducing property, and under general conditions, they cannot react. However, the catalyst provided in the present application can promote the migration of the catalyst surface electrons in CO2 and H2S by using the excellent C-O and C=O bond breaking ability of NiO and the excellent oxidation and reduction ability of Fe2O3, so that H2S and CO2 can react at high temperature to finally generate carbon nanotubes, SO2 and H2O.

[0044] The catalyst can achieve high hydrogen sulfide removal efficiency at 400-500 DEG C, and carbon nanotubes are formed on the surface of the catalyst. The catalyst has simple preparation method, common raw materials, high catalytic efficiency, high economic value and wide market application prospect.

[0045] In the preferred embodiment, in step (1), the concentration of the NaOH solution is 8-10 mol / L (mol / L is abbreviated as M), and the dosage ratio of the titanium dioxide and the NaOH solution is 1g: 10-15 mL.

[0046] In the preferred embodiment, in step (1), the hydrothermal reaction conditions include a temperature of 110-150 DEG C and a time of 10-15 h.

[0047] In the preferred embodiment, in step (2), the plasma surface treatment conditions include a voltage of 220 V, a working distance of 6-12 mm, a plasma flame scanning rate of 60-100 mm / s, and a time of 30-60 min.

[0048] Further preferably, in step (2), the plasma surface treatment is repeated 2-4 times.

[0049] In the preferred embodiment, according to the specific mass of the powder, the first powder is divided into 2-4 batches for plasma surface treatment at each time of plasma surface treatment, so as to maximize the plasma modification of the first powder.

[0050] In a specific embodiment, the first powder is subjected to plasma surface treatment in two batches per plasma surface treatment, and the specific operation is as follows: 1 / 2 of the first powder is laid on a tray and transferred to a plasma surface treatment device, vacuumized, and then filled with 10 mL of N2, with an input voltage of 220 V, a working distance of 6-12 mm, a plasma flame scanning speed of 60-100 mm / s, and a surface treatment time of 30-60 min; and the remaining first powder is subjected to the same operation.

[0051] The application does not limit the amount relationship between the second powder, the active component precursor and the cocatalyst precursor, as long as the mass percentage of the active component in the prepared catalyst is 7-12% and the mass percentage of the cocatalyst is 0.5-1% based on the mass of the carrier. Therefore, the specific amount of each component in step (3) can be weighed according to the specific conditions of the catalyst to be prepared.

[0052] The application also does not limit the amount relationship between the Ni source and the Fe source in the active component precursor, as long as the mass ratio of NiO:Fe2O3 in the active component in the prepared catalyst is 1:0.6-1.5.

[0053] The application also does not limit the amount relationship between the second powder and the structure-directing agent, and in a preferred embodiment, the concentration of the structure-directing agent in the mixed solution in step (3) is 0.5-0.8 mol / L, and the amount ratio of the second powder to the mixed solution is 1:10-20.

[0054] In a preferred embodiment, the hydrothermal reaction conditions in step (3) include a temperature of 150-180°C and a time of 6-12 h.

[0055] In a preferred embodiment, ammonia, NaOH or KOH is used to adjust the pH in step (3).

[0056] In the application, the binder in step (4) is selected from any one of diatomite powder, polyethylene oxide (PEO) and carboxymethyl cellulose (CMC). Further preferably, the addition amount of the binder is 3-5% based on the mass of the titanium white powder.

[0057] In the application, the pore-forming agent in step (4) is selected from any one of ammonium chloride, glucose and carbon powder with a particle size of less than 200 mesh. Further preferably, the addition amount of the pore-forming agent is 30-50% based on the mass of the titanium white powder.

[0058] In a specific embodiment, the addition amount of water in step (4) is 80-100% based on the mass of the titanium white powder.

[0059] In a preferred embodiment, in step (4), the calcination temperature is 500-550℃, the calcination time is 3-5h, and the calcination environment is air atmosphere.

[0060] The application further provides a use of the carbon dioxide carbon nanotube catalyst in the preparation of carbon nanotubes from CO2 and H2S.

[0061] The catalyst has higher activity in the range of 400-500℃, and in order to make the catalyst have higher efficiency in the preparation of carbon nanotubes from CO2 and H2S, preferably, the use is carried out at 400-500℃.

[0062] The application will be described in detail through examples below, but the protection scope of the application is not limited thereto. In the following examples, the experimental materials used are commercially available products, unless otherwise specified.

[0063] In the following examples, the titanium white powder is purchased from Chaocai Titanium White Technology (Anhui) Co., Ltd., and the TiO2 purity is 98%;

[0064] The plasma surface processor with the model of Plasma clean-PL-5010 is purchased from Wenzhou Kelin Environmental Protection Technology Co., Ltd.

[0065] Example 1

[0066] (1) 20g of titanium white powder is dispersed in 200mL of 8M NaOH solution and stirred uniformly, and then transferred to a reaction kettle for hydrothermal reaction at 120℃ for 15h, and then filtered, washed and dried to obtain a first powder (i.e. TiO2 nanotube);

[0067] (2) First plasma surface treatment: the first powder is treated by plasma surface treatment in two batches, specifically: 10g of TiO2 nanotube is laid on a tray and transferred to a plasma surface processor, vacuumized first, and then filled with 10mL of N2, the input voltage is 220V, the working distance is 8mm, the plasma flame scanning rate is 60mm / s, and the surface treatment is carried out for 40min, and the remaining first powder is stirred and the above operation is repeated; the above plasma surface treatment is repeated three times to obtain a second powder;

[0068] (3) Weigh 9.01 g of carbamide, 1.42 g of Fe(N03)3-9H20, 3.27 g of Ni(N03)2-6H20 and 0.2318 g of PdCl2, dissolve them in deionized water, and adjust the pH value to 10 with ammonia water to obtain 300 g of a mixed solution (the concentration of the structure-directing agent is 0.5 M). The second powder obtained in step (2) is uniformly dispersed in the mixed solution, and then transferred to a reaction kettle for hydrothermal reaction at 160 °C for 12 h. After being filtered, washed and dried, a third powder is obtained.

[0069] (4) Weigh 0.6 g of Tianqin powder, 6 g of carbon powder (particle size less than 200 mesh), 20 g of deionized water and the third powder obtained in step (3), mix them uniformly and dry thoroughly, and then transfer them to a muffle furnace for calcination at 520 °C for 3 h in an air atmosphere to obtain a catalyst.

[0070] Example 2

[0071] (1) Weigh 20 g of titanium white powder, disperse it in 240 mL of a 9 M NaOH solution, and stir uniformly. Transfer it to a reaction kettle for hydrothermal reaction at 140 °C for 10 h. After being filtered, washed and dried, a first powder (i.e., Ti02nanotubes) is obtained;

[0072] (2) First plasma surface treatment: The first powder is treated by plasma surface treatment in two batches. Specifically, 10 g of Ti02nanotubes are placed on a tray and transferred to a plasma surface treatment device. First, vacuum treatment is performed, and then 10 mL of N2is filled. The input voltage is 220 V, the working distance is 10 mm, the plasma flame scanning rate is 80 mm / s, and the surface treatment is performed for 50 min. The remaining first powder is stirred uniformly and the above operation is repeated. The above plasma surface treatment is repeated three times to obtain a second powder;

[0073] (3) Weigh 8.65 g of carbamide, 1.52 g of FeCl3-6H20, 2.86 g of NiCl2-6H20 and 0.2768 g of Pd(N03)2, dissolve them in deionized water, and adjust the pH value to 10 with NaOH to obtain 240 g of a mixed solution (the concentration of the structure-directing agent is 0.6 M). The second powder obtained in step (2) is uniformly dispersed in the mixed solution, and then transferred to a reaction kettle for hydrothermal reaction at 150 °C for 10 h. After being filtered, washed and dried, a third powder is obtained;

[0074] (4) Weigh 1 g of CMC, 10 g of ammonium chloride, 16 g of deionized water and the third powder obtained in step (3), mix them uniformly and dry thoroughly, and then transfer them to a muffle furnace for calcination at 550 °C for 4 h in an air atmosphere to obtain a catalyst.

[0075] Example 3

[0076] (1) 20 g of titanium white powder was dispersed in 300 mL of 10 M NaOH solution and stirred uniformly, and then transferred to a reaction kettle for hydrothermal reaction at 150 °C for 12 h. After that, it was filtered, washed and dried to obtain a first powder (i.e., TiO2 nanotube);

[0077] (2) First plasma surface treatment: the first powder was divided into two batches for plasma surface treatment. Specifically, 10 g of TiO2 nanotube was placed on a tray and transferred to a plasma surface treatment device. First, vacuum treatment was performed, and then 10 mL of N2 was filled. The input voltage was 220 V, the working distance was 12 mm, the plasma flame scanning rate was 100 mm / s, and the surface treatment was performed for 30 min. The remaining first powder was stirred uniformly and the above operation was repeated. The above plasma surface treatment was repeated three times to obtain a second powder;

[0078] (3) 8.41 g of carbamide, 3.04 g of Fe(NO3)3·9H2O, 2.55 g of NiCl2·6H2O and 0.1661 g of Pd(NO3)2 were dissolved in deionized water, and the pH value was adjusted to 10 with KOH to obtain a 200 g mixed solution (the concentration of the structure directing agent was 0.7 M). The second powder obtained in step (2) was dispersed in the mixed solution and stirred uniformly, and then transferred to a reaction kettle for hydrothermal reaction at 180 °C for 8 h. After that, it was filtered, washed and dried to obtain a third powder;

[0079] (4) 0.8 g of PEO, 8 g of glucose, 18 g of deionized water and the third powder obtained in step (3) were mixed uniformly and dried completely, and then transferred to a muffle furnace for calcination at 500 °C for 5 h in air atmosphere to obtain a catalyst.

[0080] Example 4

[0081] (1) 20 g of titanium white powder was dispersed in 260 mL of 9 M NaOH solution and stirred uniformly, and then transferred to a reaction kettle for hydrothermal reaction at 110 °C for 14 h. After that, it was filtered, washed and dried to obtain a first powder (i.e., TiO2 nanotube);

[0082] (2) First plasma surface treatment: the first powder was divided into two batches for plasma surface treatment. Specifically, 10 g of TiO2 nanotube was placed on a tray and transferred to a plasma surface treatment device. First, vacuum treatment was performed, and then 10 mL of N2 was filled. The input voltage was 220 V, the working distance was 6 mm, the plasma flame scanning rate was 80 mm / s, and the surface treatment was performed for 60 min. The remaining first powder was stirred uniformly and the above operation was repeated. The above plasma surface treatment was repeated three times to obtain a second powder;

[0083] (3) Weigh 13.45 g of carbamide, 2.03 g of FeCl3-6H2O, 4.67 g of Ni(NO3)2-6H2O and 0.1449 g of Pd(NO3)2, dissolve them in deionized water, and adjust the pH value to 10 with NaOH to obtain 280 g of a mixed solution (the concentration of the structure-directing agent is 0.8 M). Disperse the second powder obtained in step (2) in the mixed solution, stir uniformly, and then transfer to a reaction kettle. Hydrothermal reaction is carried out at 170 °C for 6 h. After filtration, washing and drying, a third powder is obtained.

[0084] (4) Weigh 0.9 g of CMC, 9 g of ammonium chloride, 18 g of deionized water and the third powder obtained in step (3), mix uniformly and dry thoroughly, transfer to a muffle furnace, and calcine at 540 °C for 3 h in an air atmosphere to obtain a catalyst.

[0085] Comparative Example 1

[0086] The method is carried out according to the method described in Example 3, except that the hydrothermal reaction in step (1) is not carried out.

[0087] Specifically, the preparation method comprises the following steps:

[0088] (1) Weigh 20 g of titanium white powder, and perform first plasma surface treatment: divide the titanium white powder into two batches, and perform plasma surface treatment as follows: place 10 g of TiO2nanotubes on a tray, transfer to a plasma surface treatment device, perform vacuum treatment, then fill 10 mL of N2, input a voltage of 220 V, a working distance of 12 mm, and a plasma flame scanning rate of 100 mm / s, and perform surface treatment for 30 min. Stir the remaining titanium white powder, and repeat the above operation. Repeat the above plasma surface treatment three times to obtain a second powder.

[0089] (2) Weigh 8.41 g of carbamide, 3.04 g of Fe(NO3)3-9H2O, 2.55 g of NiCl2-6H2O and 0.1661 g of Pd(NO3)2, dissolve them in deionized water, and adjust the pH value to 10 with KOH to obtain 200 g of a mixed solution (the concentration of the structure-directing agent is 0.7 M). Disperse the second powder obtained in step (1) in the mixed solution, stir uniformly, and then transfer to a reaction kettle. Hydrothermal reaction is carried out at 180 °C for 8 h. After filtration, washing and drying, a third powder is obtained.

[0090] (3) Weigh 0.8 g of PEO, 8 g of glucose, 18 g of deionized water and the third powder obtained in step (2), mix uniformly and dry thoroughly, transfer to a muffle furnace, and calcine at 500 °C for 5 h in an air atmosphere to obtain a catalyst.

[0091] Comparative Example 2

[0092] The procedure of Example 3 was followed except that step (2) was not performed.

[0093] (1) 20 g of titanium white powder was weighed and dispersed in 300 mL of 10 M NaOH solution and stirred uniformly, and then transferred to a reaction kettle for hydrothermal reaction at 150 °C for 12 h, and then filtered, washed and dried to obtain TiO2 nanotubes for standby use;

[0094] (2) 8.41 g of carbamide, 3.04 g of Fe(NO3)3-9H2O, 2.55 g of NiCl2-6H2O and 0.1661 g of Pd(NO3)2 were weighed and dissolved in deionized water, and the pH value was adjusted to 10 with KOH to obtain 200 g of a mixed solution (the concentration of the structure directing agent was 0.7 M), and the TiO2 nanotubes obtained in step (1) were dispersed in the mixed solution, and then transferred to a reaction kettle for hydrothermal reaction at 180 °C for 8 h, and then filtered, washed and dried for standby use;

[0095] (3) 0.8 g of PEO, 8 g of glucose, 18 g of deionized water and the powder obtained in step (2) were weighed and mixed uniformly and dried thoroughly, and then transferred to a muffle furnace for calcination at 500 °C for 5 h in an air atmosphere to obtain a catalyst.

[0096] The loading amounts of the active components and the promoters in the catalysts prepared in Examples 1-4 and Comparative Examples 1-2 above are shown in Table 1 (calculated according to the lossless raw materials).

[0097] Table 1

[0098]

[0099] Test Example 1

[0100] The catalysts prepared in Examples 1-4 and Comparative Examples 1-2 were subjected to catalyst activity evaluation, and the catalyst prepared in Example 1 was subjected to carbon nanotube evaluation.

[0101] 1. Catalyst activity evaluation: The catalyst performance was evaluated in a fixed bed microreactor, the reaction tube had an inner diameter of 10 mm and a length of 550 mm. 10 mL of 20-40 mesh catalyst was weighed and packed in the middle of the reaction tube, and quartz sand was packed on the upper and lower parts for support. CO2 and H2S mixed gas was mixed at a volume ratio of 1:30 and then introduced into the reactor at 10 mL / min, wherein the H2S mixed gas was mixed by H2S and N2, and the concentration of H2S in the mixed gas was 1000 ppm. The temperature was increased from room temperature, and the reaction was stabilized at 300-500 °C for 30 min at every 50 °C, and then the tail gas was collected and detected by a hydrogen sulfide detector (Qingdao Lubo, YQ3000-B type), and the removal efficiency of hydrogen sulfide was calculated according to the detection results, and the test results are shown in Table 2. Figure 1 Table 2

[0102] By Figure 1 It can be seen that the catalysts prepared in Examples 1-4 have H2S removal efficiency of 0.73 or more in the range of 400-500℃. Meanwhile, the catalyst prepared in Example 3 has particularly high catalytic activity, and has H2S removal efficiency of 0.83 or more in the range of 400-500℃. The catalysts prepared in Comparative Examples 1-2 have H2S removal efficiency of only 0.5-0.6 in the range of 400-500℃.

[0103] 2. Carbon nanotube evaluation: After the catalyst sample prepared in Example 1 is subjected to catalyst activity evaluation, it is taken out, sieved, and then placed in 100 mL of a hydrochloric acid solution with a mass concentration of 20%. The mixed solution is then placed in a hydrothermal reactor at 180℃ for 4 h. After cooling to room temperature, it is filtered to obtain black carbon nanotube solids. After two cycles of hydrothermal reaction, the carbon nanotubes are obtained. The carbon nanotube sample is observed for morphology using field emission electron microscopy, and the results are shown in FIG. 2. Figure 2

[0104] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.​

Claims

1. A carbon nanotube catalyst for carbon dioxide, characterized by, The catalyst can convert carbon dioxide and hydrogen sulfide into SO2, H2O and carbon nanotubes, and is prepared by a secondary hydrothermal-plasma treatment method, with TiO2 nanotubes as a carrier, Ni-Fe bimetallic oxide as an active component, PdO as a promoter, and carbamide as a structure directing agent; the mass percentage of the active component is 7-12% and the mass percentage of the promoter is 0.5-1% based on the mass of the carrier; the mass ratio of NiO to Fe2O3 in the active component is 1:0.6-1.5; The preparation method of the catalyst comprises the following steps: (1) mixing titanium white powder with a NaOH solution, then performing a hydrothermal reaction, and then performing solid-liquid separation to obtain a first powder; (2) performing plasma surface treatment on the first powder to obtain a second powder; (3) mixing a structure directing agent, an active component precursor, a promoter precursor and water, adjusting the pH to 9.5-10.5 to obtain a mixed solution, mixing the second powder with the mixed solution, then performing a hydrothermal reaction, and then performing solid-liquid separation to obtain a third powder; (4) mixing the third powder with a binder, a pore-forming agent and water, then drying and calcining; In step (2), the conditions of the plasma surface treatment include: a voltage of 220 V, a working distance of 6-12 mm, a plasma flame scanning rate of 60-100 mm / s, and a time of 30-60 min; In step (3), the active component precursor is a Ni source and a Fe source, and the promoter precursor is a Pd source.

2. The carbon dioxide-to-carbon nanotube catalyst of claim 1, wherein, In step (1), the concentration of the NaOH solution is 8-10 mol / L, and the dosage ratio of the titanium white powder to the NaOH solution is 1 g:10-15 mL; In step (1), the conditions of the hydrothermal reaction include: a temperature of 110-150 ℃, and a time of 10-15 h.

3. The carbon nanotube catalyst for carbon dioxide according to claim 1, wherein In step (2), the plasma surface treatment is repeated 2-4 times.

4. The carbon nanotube catalyst for carbon dioxide according to claim 1, wherein In step (3), the concentration of the structure directing agent in the mixed solution is 0.5-0.8 mol / L.

5. The carbon nanotube catalyst for carbon dioxide according to claim 1 or 4, wherein In step (3), the conditions of the hydrothermal reaction include: a temperature of 150-180 ℃, and a time of 6-12 h.

6. The carbon dioxide-to-carbon nanotube catalyst of claim 1, wherein, In step (4), the binder is selected from any one of corn powder, polyethylene oxide and carboxymethyl cellulose; In step (4), the pore-forming agent is selected from any one of carbon powder, ammonium chloride and glucose; The particle size of the carbon powder is less than 200 mesh.

7. The carbon nanotube catalyst for carbon dioxide according to claim 1 or 6, wherein In step (4), the addition amount of the binder is 3-5%, the addition amount of the pore-forming agent is 30-50%, and the addition amount of water is 80-100% based on the mass of the titanium white powder.

8. The carbon dioxide-to-carbon nanotube catalyst of claim 1, wherein, In step (4), the calcination temperature is 500-550 ℃, the calcination time is 3-5 h, and the calcination environment is an air atmosphere.

9. The carbon dioxide-to-carbon nanotube catalyst according to any one of claims 1-8 is applied to catalyze the conversion of CO2 and H2S into carbon nanotubes.

10. Use according to claim 9, characterized in that, The application is performed at a temperature of 400-500 ℃.

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