CN116425146B - A method for growing carbon nanotube arrays using iron-nickel-molybdenum alloy to catalyze propylene - Google Patents

Abstract

The invention belongs to the field of new materials, relates to a carbon nanotube preparation technology, and particularly provides a method for catalyzing propylene to grow a carbon nanotube array by using Fe-Ni-Mo alloy, which comprises the following steps: step 1, taking Fe-Ni-Mo alloy as a catalyst, placing the Fe-Ni-Mo alloy in a CVD rotary furnace, and introducing inert gas to remove air in the furnace; and 2, heating the CVD rotary furnace to 650-750 ℃ by taking propylene gas as a carbon source, introducing the propylene gas at a gas flow rate of 20-150 ml/min for reaction for 5-60 min, cooling to room temperature along with the furnace, and finally purifying to remove the catalyst to obtain the carbon nanotube array. The technology can be applied to other Fe-based alloys in a expanding way. The invention takes propylene as a carbon source and Fe-Ni-Mo alloy as a catalyst, and utilizes a catalytic chemical vapor deposition method to realize the efficient mass production of the carbon nanotube array, has mild reaction conditions, simple process flow and high utilization rate of the carbon source, and lays an important application foundation for mass and low-cost production of the carbon nanotube array.

Description

A method for growing carbon nanotube arrays using iron-nickel-molybdenum alloy to catalyze propylene

Technical Field

The invention belongs to the field of new materials, relates to a carbon nanotube preparation technology, and specifically provides a method for using an iron-nickel-molybdenum alloy to catalyze propylene to grow a carbon nanotube array.

Background technique

As one of the earliest elements that humans have come into contact with and used, carbon plays a vital role in the development of mankind. Carbon-based compounds are indispensable substances in our daily lives. Nanomaterials have also received widespread attention due to their excellent physical and chemical properties. Nanomaterials with unique structures and excellent properties are constantly being explored and developed. Among them, carbon nanomaterials have excellent properties in mechanics, thermal, electrical, optical and other aspects, becoming one of the most popular objects among many nanomaterials. However, since free-growing carbon nanotubes are easy to entangle with each other, their application and development are limited; the aspect ratio of carbon nanotubes in the form of arrays is almost the same, with good orientation and high purity, showing excellent performance; even if the orientation of the carbon nanotube array is destroyed, the carbon nanotube array still has better performance than agglomerated single-walled carbon nanotubes and multi-walled carbon nanotubes in improving the electronic, mechanical and thermal properties of polymers.

At present, the most commonly used carbon sources in the growth process of carbon nanotube arrays are methane, ethylene and acetylene, etc. The molecular structure of the carbon source will affect the shape of the grown carbon nanotubes. Linear hydrocarbons (methane, ethylene, acetylene) are thermally decomposed into atomic carbon or linear dimers/trimers of carbon, which usually grow straight and hollow carbon nanotubes; for example, a method of using sheet iron silicon aluminum to catalytically crack acetylene to grow carbon nanotube arrays is disclosed in the Chinese patent document with publication number CN112875680A, but due to the large number of by-products produced by acetylene at the reaction temperature, the carbon conversion rate is low and the carbon source utilization rate is low; another example is a method of plasma-modified iron silicon aluminum to improve the utilization rate of acetylene disclosed in the Chinese patent document with publication number CN114644337A, but this method is more complicated. Therefore, a method with high carbon source utilization rate, simple process, low cost and mass production of carbon nanotube arrays is still an important research difficulty.

Summary of the invention

The purpose of the present invention is to provide a method for growing a carbon nanotube array by catalyzing propylene with an iron-nickel-molybdenum alloy in view of the defects of the prior art. The present invention uses propylene as a carbon source and an iron-nickel-molybdenum alloy as a catalyst to achieve the preparation of a carbon nanotube array with good compactness and good growth potential at a high carbon source conversion rate.

To achieve the above object, the technical solution adopted by the present invention is:

A method for growing a carbon nanotube array by catalyzing propylene with an iron-nickel-molybdenum alloy, characterized by comprising the following steps:

Step 1, using an iron-nickel-molybdenum alloy as a catalyst, placing the iron-nickel-molybdenum alloy in a CVD rotary furnace, and introducing an inert gas to remove air in the furnace;

Step 2: Using propylene gas as the carbon source, heat the CVD rotary furnace to 650-750°C, then introduce propylene gas at a gas flow rate of 20-150 ml/min for 5-60 min, cool to room temperature with the furnace, and finally purify to remove the catalyst to obtain a carbon nanotube array.

Furthermore, in step 1, the inert gas is nitrogen or argon, the flow rate of the inert gas is 30 to 100 ml/min, and the introduction time is 10 to 30 min.

Furthermore, in step 1, the iron-nickel-molybdenum alloy is a flaky alloy, and the flaky alloy is FeNiMo.

Furthermore, in step 1, the iron-nickel-molybdenum alloy uses a flaky alloy FeNiMo, in which Fe accounts for 30-35%, Ni accounts for 30-35%, and Mo accounts for 30-40%.

Furthermore, in step 1, the amount of the iron-nickel-molybdenum alloy used is 0.5 to 10 g, and the weighing process is carried out under the protection of an inert gas.

Furthermore, in step 2, the heating rate of the CVD rotary furnace is 1 to 15° C./min.

Furthermore, in step 2, the specific steps of purification are: first, soak the iron-nickel-molybdenum alloy grown with the carbon nanotube array in dilute nitric acid or dilute sulfuric acid for 10 to 24 hours, filter and wash with deionized water until neutral; then, soak it in dilute hydrofluoric acid for 10 to 24 hours, filter and wash with deionized water until neutral; finally, dry it in a forced air drying oven at 60 to 80°C for 10 to 48 hours.

Furthermore, in step 2, the reaction process is carried out under the protection of an inert gas, the inert gas is nitrogen or argon, and the flow rate of the inert gas is 30 to 60 ml/min.

Based on the above technical solution, the beneficial effects of the present invention are:

The present invention provides a method for growing carbon nanotube arrays by catalyzing propylene with an iron-nickel-molybdenum alloy, using propylene as a carbon source and an iron-nickel-molybdenum alloy as a catalyst, and utilizing a catalytic chemical vapor deposition method to realize efficient batch production of carbon nanotube arrays; in the present invention, propylene is cracked into hydrogen and carbon atoms at high temperature, hydrogen will reduce the oxide on the surface of the iron-based catalyst, and carbon atoms will dissolve, diffuse, and nucleate on the surface of the iron-based catalyst to generate carbon nanotubes, with less propylene carbon source byproducts and a carbon source conversion rate of up to 98.44%; this technology can also be expanded and applied to other Fe-based alloys. In summary, the present invention is based on the catalytic growth of carbon nanotube arrays by propylene with an iron-nickel-molybdenum alloy, with mild reaction conditions, simple process flow, and high carbon source utilization, laying an important application foundation for the mass and low-cost production of carbon nanotube arrays.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a SEM image of the iron-nickel-molybdenum flake alloy used in Examples 1 to 4 of the present invention.

FIG. 2 is a SEM image of the carbon nanotube arrays grown by catalysis in Examples 1 to 4 of the present invention; wherein a to d represent the carbon nanotube arrays obtained in Examples 1 to 4, respectively.

FIG. 3 is an XRD diagram of the carbon nanotube array obtained in Example 3 of the present invention.

FIG. 4 is a Raman graph of the iron-nickel-molybdenum sheet alloy material on which carbon nanotubes are grown in Examples 1 and 2 of the present invention.

Detailed ways

In order to make the purpose, technical solution and beneficial effects of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

Example 1

This embodiment provides a method for growing a carbon nanotube array using propylene catalyzed by an iron-nickel-molybdenum alloy, comprising the following steps:

Step 1, weigh 1g of iron-nickel-molybdenum flake alloy under argon atmosphere protection, and place it in a CVD rotary furnace, check the air tightness of the device to ensure airtightness, then pass argon gas at a gas flow rate of 100ml/min for 20min to completely evacuate the air in the furnace;

Step 2, first, set the temperature program, and heat the CVD rotary furnace (i.e., growth temperature) to 675°C at a rate of 5°C/min; then, introduce propylene gas at a gas flow rate of 40 ml/min, turn on the rotary switch to react for 30 minutes, then stop introducing propylene, and naturally cool to room temperature to obtain an iron-nickel-molybdenum sheet alloy with a carbon nanotube array grown thereon. The entire process is carried out under the protection of an argon atmosphere; finally, the iron-nickel-molybdenum sheet alloy with the carbon nanotube array grown thereon is soaked in dilute nitric acid for 24 hours, filtered, and washed with deionized water until neutral, then soaked in dilute hydrofluoric acid for 24 hours, filtered, and washed with deionized water until neutral, and dried in a forced air drying oven at 80°C for 36 hours to obtain a carbon nanotube array (abbreviated as: sample), marked as CNT-675°C.

Example 2

The only difference between this embodiment and embodiment 1 is that in step 2, the CVD rotary furnace (ie, the growth temperature) is 700° C.; the obtained carbon nanotube array is marked as CNT-700° C.

Example 3

The only difference between this embodiment and embodiment 1 is that in step 2, the CVD rotary furnace (ie, the growth temperature) is 725° C.; the obtained carbon nanotube array is marked as CNT-725° C.

Example 4

The only difference between this embodiment and embodiment 1 is that in step 2, the CVD rotary furnace (ie, the growth temperature) is 750° C.; the obtained carbon nanotube array is marked as CNT-750° C.

The iron-nickel-molybdenum flake alloy (catalyst), the iron-nickel-molybdenum flake alloy with carbon nanotube arrays grown thereon, and the prepared carbon nanotube arrays in Examples 1 to 4 were tested, and the corresponding results are as follows:

As shown in FIG. 1 , it is a SEM image of the iron-nickel-molybdenum sheet alloy used in Examples 1 to 4. As can be seen from the image, the catalyst is a sheet alloy with many nanoparticles on the surface, which play a catalytic role in the growth process of the carbon nanotube array.

As shown in Figure 2, it is the SEM images of the carbon nanotube arrays prepared in Examples 1 to 4; wherein a is the carbon nanotube array obtained in Example 1, b is the carbon nanotube array obtained in Example 2, c is the carbon nanotube array obtained in Example 3, and d is the carbon nanotube array obtained in Example 4; it can be seen from the figure that the iron-nickel-molybdenum flake alloy has a good catalytic effect, and an orderly arranged carbon nanotube array is successfully prepared on the surface of the iron-nickel-molybdenum flake alloy. At high temperature, propylene is cracked into hydrogen and carbon atoms. Hydrogen will reduce the oxide on the surface of the iron-based catalyst, and the carbon atoms will dissolve, diffuse, and nucleate on the surface of the iron-based catalyst to generate carbon nanotubes. The directional growth of carbon nanotubes interacts with each other and forms an array under the action of van der Waals forces. The yield and carbon source conversion rate of the carbon nanotube array catalyzed by the iron-nickel-molybdenum alloy for propylene growth in Examples 1 to 4 are shown in Table 1, wherein the theoretical carbon supply is: (3×12×40×30)/(1000×22.4)=1.9286g, and the carbon source conversion rate is defined as the ratio of the carbon nanotube array yield to the theoretical carbon supply. In particular, in Example 2, the carbon conversion rate of the carbon nanotube array catalyzed by the iron-nickel-molybdenum alloy for propylene growth at 700°C is as high as 98.44%.

Table 1

sample Yield (g) Carbon source conversion rate (%) CNT-675℃ 1.57 81.35 CNT-700℃ 1.90 98.44 CNT-725℃ 1.75 90.77 CNT-750℃ 1.61 83.41

As shown in Figure 3, it is the XRD pattern of the carbon nanotube array prepared in Example 3. It can be seen from the figure that the diffraction peaks of the sample CNT-700°C at ^2θ = 31.38°, 44.88°, 65.34° and 82.86° represent the (200), (220), (400) and (422) planes of the iron-based alloy, respectively, and the diffraction peak at ^2θ = 26.12° represents the diffraction peak of the carbon material.

As shown in Figure 4, it is a Raman graph of the iron-nickel-molybdenum sheet alloy material grown with carbon nanotubes prepared in Examples 1 to 4. It can be clearly seen from the figure that the iron-nickel-molybdenum alloy after the carbon nanotube array is formed has two obvious carbon nanotube characteristic peaks, one is the D peak at about 1300 cm ^-1 , and the other is the G peak at about 1580 cm ^-1 . As the growth temperature increases, the carbon atoms produced by the cracking of linear propylene molecules tend to form ^SP2 hybridization, and the grown carbon nanotubes have fewer defects. This is indicated by the decrease of the _ID / _IG value in the Raman spectrum with increasing temperature.

The above description is only a specific implementation mode of the present invention. Any feature disclosed in this specification, unless otherwise stated, can be replaced by other alternative features that are equivalent or have similar purposes; all the disclosed features, or all the steps in the methods or processes, except for mutually exclusive features and/or steps, can be combined in any way.

Claims (6)

1. The method for growing the carbon nanotube array by catalyzing propylene with the Fe-Ni-Mo alloy is characterized by comprising the following steps of:

Step 1, taking Fe-Ni-Mo alloy as a catalyst, placing the Fe-Ni-Mo alloy in a CVD rotary furnace, and introducing inert gas to remove air in the furnace; the Fe-Ni-Mo alloy comprises a sheet alloy, wherein the sheet alloy comprises FeNiMo, fe accounting for 30-35%, ni accounting for 30-35% and Mo accounting for 30-40%; the flow rate of the inert gas is 30-100 mL/min;

Step 2, taking propylene gas as a carbon source, heating the CVD rotary furnace to 650-750 ℃, and then introducing the propylene gas at a gas flow rate of 20-150 mL/min for reaction for 30-60 min, wherein the reaction process is carried out under the protection of inert gas, and the flow rate of the inert gas is 30-60 mL/min; and cooling to room temperature along with a furnace after the reaction is finished, and finally purifying to remove the catalyst to obtain the carbon nanotube array, wherein the carbon source conversion rate is 81.35% -98.44%.

2. The method for growing the carbon nanotube array by catalyzing propylene with the Fe-Ni-Mo alloy according to claim 1, wherein in the step 1, the inert gas is nitrogen or argon, and the introducing time is 10-30 min.

3. The method for catalyzing propylene to grow carbon nanotube arrays by using Fe-Ni-Mo alloy according to claim 1, wherein in step 1, the Fe-Ni-Mo alloy is used in an amount of 0.5-10 g, and the weighing process is performed under the protection of inert gas.

4. The method for catalyzing propylene to grow the carbon nanotube array by using the Fe-Ni-Mo alloy according to claim 1, wherein in the step 2, the heating rate of the CVD rotary furnace is 1-15 ℃/min.

5. The method for growing carbon nanotube arrays by catalyzing propylene with Fe-Ni-Mo alloy according to claim 1, wherein in the step 2, the specific steps of purification are as follows: firstly, soaking an iron-nickel-molybdenum alloy growing with a carbon nanotube array in dilute nitric acid or dilute sulfuric acid for 10-24 hours, filtering, and washing with deionized water to be neutral; then soaking in dilute hydrofluoric acid for 10-24 hours, filtering, and washing with deionized water to be neutral; and finally, drying in a forced air drying oven at 60-80 ℃ for 10-48 hours.

6. The method for growing carbon nanotube arrays by catalyzing propylene with Fe-Ni-Mo alloy according to claim 1, wherein in the step 2, the inert gas is nitrogen or argon.