System for producing carbon nano tube by taking methanol or dimethyl ether as raw material
By using methanol or dimethyl ether as raw materials, and catalytically decomposing them into a mixed gas for simple processing, the problems of complex and costly raw material separation in carbon nanotube production are solved, thus achieving low-cost and high-efficiency production of carbon nanotubes.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-27
- Publication Date
- 2026-03-06
AI Technical Summary
The raw materials for carbon nanotube production are polymer-grade pure ethylene or pure propylene. The separation process is complex and costly, resulting in high production costs.
Methanol or dimethyl ether is used as raw material. The raw material is decomposed by a catalyst in the raw material decomposition device to generate a mixed gas. After cooling, washing and drying, the mixed gas is used in the carbon nanotube production device to produce carbon nanotubes.
It simplifies the raw material separation process, reduces equipment investment and operating costs, improves the production efficiency and quality of carbon nanotubes, and lowers the price of raw materials.
Smart Images
Figure CN223969939U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of carbon nanotube production technology, specifically relating to a system for producing carbon nanotubes using methanol or dimethyl ether as raw materials. Background Technology
[0002] In the field of carbon nanotube production, the most commonly used raw materials are pure ethylene or pure propylene, typically at the purity level of polymer-grade ethylene or propylene. Currently, the main methods for producing such high-purity raw materials include naphtha steam cracking, MTO, or MTP methanol-to-olefins processes. These processes require complex separation techniques and expensive separation equipment (such as cryogenic separation), especially for separating trace impurities. For example, the national standard GB / T 7716-2014 specifies impurities in polymer-grade propylene at levels ranging from a few to tens of PPM, resulting in very high equipment investment and operating costs for producing polymer-grade pure ethylene or propylene, indirectly leading to high production costs for carbon nanotubes. Utility Model Content
[0003] The technical problem to be solved by this invention is that the raw materials for the production of carbon nanotubes are currently polymer-grade pure ethylene or pure propylene. The separation process of these raw materials is complex and the production cost is high, resulting in a high price for the raw materials of carbon nanotubes. There is an urgent need in the field to develop lower-cost raw materials and to equip them with corresponding production systems.
[0004] This utility model provides a system for producing carbon nanotubes using methanol or dimethyl ether as raw materials, including a raw material decomposition device, a mixed gas treatment unit and a carbon nanotube production device connected in sequence. The raw material is methanol or dimethyl ether. The raw material enters the raw material decomposition device, which is equipped with a decomposition catalyst for catalytic decomposition of methanol or dimethyl ether to produce a mixed gas of hydrocarbons.
[0005] The mixed gas treatment unit includes a cooling device, a water washing device, and a drying device connected in sequence, used to remove carbon dioxide, water, and oxygen-containing organic matter from the mixed gas; the inlet of the cooling device is connected to the outlet of the raw material decomposition device, and the outlet of the drying device is connected to the inlet of the carbon nanotube production device, so that the treated hydrocarbon mixed gas is input into the carbon nanotube production device for the production of carbon nanotubes.
[0006] Optionally, the system further includes a vaporization device for vaporizing methanol or dimethyl ether, wherein the inlet of the vaporization device is connected to a raw material storage tank and the outlet of the vaporization device is connected to the inlet of a raw material decomposition device.
[0007] Optionally, the feedstock decomposition device includes a fixed-bed reactor or a fluidized-bed reactor, and the decomposition catalyst in the feedstock decomposition device is a molecular sieve catalyst, preferably SAPO-34 or ZSM-5 catalyst. In the feedstock decomposition device, in a temperature range of 523-1023 K, methanol or dimethyl ether decomposes under the action of the decomposition catalyst to obtain a mixed gas containing mixed hydrocarbons and impurities.
[0008] Further optionally, the raw material decomposition device includes two identical reactors, with the outlet of the vaporization device connected in parallel to the inlet of the two reactors. One reactor is in use and the other is on standby. When one reactor is undergoing a decomposition reaction, the catalyst bed or catalyst of the other reactor is regenerated.
[0009] Further optionally, the raw material decomposition device includes a fluidized bed reactor and a catalyst regenerator. The fluidized bed reactor is provided with a feed inlet, a gas outlet, a regeneration outlet, and a regeneration inlet. Preheated methanol or dimethyl ether is fed into the fluidized bed reactor from the feed inlet. After decomposition, the mixed gas is discharged from the gas outlet and then fed into the mixed gas treatment unit.
[0010] The regeneration outlet of the fluidized bed reactor is connected to the feed inlet of the catalyst regenerator, and the discharge outlet of the catalyst regenerator is connected to the regeneration inlet of the fluidized bed reactor. The catalyst regenerator is also equipped with an air inlet. The catalyst in the fluidized bed reactor is output from the regeneration outlet to the catalyst regenerator for regeneration. The regenerated catalyst is returned to the fluidized bed reactor through the regeneration inlet. Air enters the catalyst regenerator through the air inlet and participates in the catalyst regeneration reaction.
[0011] When the feedstock decomposition unit includes a fluidized bed reactor, the internal catalyst needs to be regenerated after use. The catalyst to be regenerated is discharged into a catalyst regenerator. The catalyst regenerator is used to regenerate the deactivated catalyst by burning off the coke. Air is introduced into the catalyst regenerator, and the regenerated catalyst is then returned to the lower part of the fluidized bed reactor. The catalyst regenerator is a conventional regenerator.
[0012] Optionally, the cooling device is selected from a shell-and-tube heat exchanger or a quench tower, and cooling water can be sprayed into the quench tower;
[0013] The drying equipment is selected from one of the following: membrane dryer, adsorption dryer, or freeze dryer.
[0014] Optionally, the mixed gas treatment unit further includes a stripping tower device. The inlet of the stripping tower device is connected to the water phase outlet of the cooling device and the water washing device. The water after cooling the mixed gas in the cooling device and the water after washing the mixed gas in the water washing device are both fed into the stripping tower device to remove a small amount of oxygen-containing organic matter in the water. This oxygen-containing organic matter includes unreacted raw materials (methanol, dimethyl ether) and oxygen-containing compounds (mainly aldehydes, ketones, etc.) generated in the raw material decomposition device. The purified water at the bottom of the stripping tower is sent to the outside area for treatment and secondary utilization after heat exchange and cooling.
[0015] Optionally, the cooling and washing equipment can be further compactly designed as an integrated device that simultaneously has cooling and washing functions.
[0016] Optionally, the carbon nanotube production device is selected from one of a fluidized bed device, a fixed bed device, a moving bed device, a stirred bed device, or a rotary kiln device, and the catalyst in the carbon nanotube production device is a supported catalyst containing one or more of Fe, Ni, or Co.
[0017] Methanol or dimethyl ether is vaporized and then fed into a raw material decomposition unit. Within a temperature range of 523-1023 K (preferably 600-800 K), under the action of a decomposition catalyst, the methanol or dimethyl ether decomposes to obtain a mixed gas containing mixed hydrocarbons and impurities. Methanol decomposition also produces water; therefore, the impurities are mainly water, carbon dioxide, and oxygen-containing organic matter. The mixed gas is then fed into a cooling unit for cooling, followed by a water washing unit for washing. Alkali can be added during washing to neutralize organic acids or CO2 in the mixed gas. Finally, it is fed into a drying unit, controlling the H2O content in the dried mixed gas to ≤2.0 wt%. The mixed hydrocarbons then contact the catalyst in the carbon nanotube production unit, undergoing a high-temperature chemical vapor deposition reaction to produce carbon nanotubes.
[0018] The system for producing carbon nanotubes using methanol or dimethyl ether as raw materials, as described in this invention, has the following beneficial effects: The inventors accidentally discovered in experiments that the products of the catalytic decomposition of methanol or dimethyl ether include a mixed gas of C1-C6 hydrocarbons. Only by removing most of the impurities such as CO2, water, and oxygen-containing organic matter, which are toxic to the catalyst in the carbon nanotube production device, can the mixed hydrocarbon gas be used directly to produce carbon nanotubes. This invention abandons the traditional raw material for carbon nanotubes (polymerization-grade pure ethylene or pure propylene) and instead uses the mixed gas produced after the catalytic decomposition of methanol or dimethyl ether. Compared to separation and refining systems for producing polymer-grade pure ethylene or pure propylene, the mixed gas treatment unit of this invention is simpler, saving significant equipment investment and operating costs. This results in advantages such as low raw material costs and low equipment investment, which is beneficial for large-scale industrial production of carbon nanotubes. The inventors also discovered that if methanol or dimethyl ether is used directly for carbon nanotube production without decomposition, the production yield is low, the morphology is poor, the carbon nanotubes are highly deformed, and the quality of the produced carbon nanotubes is very poor. Furthermore, the catalyst consumption for carbon nanotube production is much higher. Therefore, the aforementioned raw material decomposition device is essential. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of the system for producing carbon nanotubes using methanol or dimethyl ether as raw materials, as described in Example 1.
[0020] Figure 2 Transmission electron microscope image of the carbon nanotubes generated in Application Example 1;
[0021] Figure 3 Scanning electron microscope image of the carbon nanotubes generated in Application Example 1;
[0022] Figure 4 This is a schematic diagram of the raw material decomposition device in Example 2;
[0023] Figure 5 Transmission electron microscopy (TEM) image of the carbon nanotubes generated in Application Example 2;
[0024] Figure 6 The image shows a scanning electron microscope (SEM) image of the carbon nanotubes generated in Application Example 2.
[0025] In the attached diagram, 1-vaporization equipment, 2-raw material decomposition device, 3-cooling equipment, 4-washing equipment, 5-drying equipment, 6-carbon nanotube production device, 7-catalyst regenerator, 8-methanol feed pipeline, 9-stripping tower equipment, 10-catalyst discharge pipe, 11-medium-sized circulating fluidized bed reactor, 12-regeneration outlet, 13-air outlet, 14-regeneration inlet, 15-air inlet. Detailed Implementation
[0026] Example 1
[0027] This embodiment provides a system for producing carbon nanotubes using methanol or dimethyl ether as raw materials, such as Figure 1 As shown, it includes a raw material decomposition device 2, a mixed gas treatment unit and a carbon nanotube production device 6 connected in sequence. The raw material is methanol. The raw material enters the raw material decomposition device 2, which is equipped with a decomposition catalyst for catalytic decomposition of methanol or dimethyl ether to produce a mixed gas of hydrocarbons.
[0028] The mixed gas treatment unit includes a cooling device 3, a water washing device 4, and a drying device 5 connected in sequence, used to remove carbon dioxide, water, and oxygen-containing organic matter from the mixed gas; the inlet of the cooling device 3 is connected to the outlet of the raw material decomposition device 2, and the outlet of the drying device 5 is connected to the inlet of the carbon nanotube 6 production device, so that the treated hydrocarbon mixed gas is input into the carbon nanotube production device 6 for the production of carbon nanotubes.
[0029] The system also includes a vaporization device 1 for vaporizing methanol. The inlet at the bottom of the vaporization device 1 is connected to a raw material storage tank, and the outlet at the top of the vaporization device 1 is connected to the inlet at the bottom of the raw material decomposition device. In this embodiment, the vaporization device 1 is a preheater.
[0030] The raw material decomposition device 2 includes a fluidized bed reactor. The decomposition catalyst in the raw material decomposition device is a molecular sieve catalyst, specifically SAPO-34 or ZSM-5 catalyst. A gas distribution plate is installed at the bottom of the fluidized bed reactor, and a heating furnace and temperature control device are located outside the fluidized bed reactor to control and display the temperature inside and outside the fluidized bed reactor.
[0031] Methanol feed line 8 is connected to the inlet of the preheater, which feeds methanol aqueous solution into the preheater. The methanol aqueous solution is vaporized in the preheater and then enters the raw material decomposition unit 2 (i.e., fluidized bed reactor).
[0032] The cooling device 3 is a quench tower, into which cooling water is sprayed by a pump; the drying device 5 is an adsorption dryer, which is equipped with 3A molecular sieve.
[0033] The carbon nanotube production device 6 is a fixed-bed reactor. The fixed-bed reactor has an external heating electric furnace and an internal quartz boat. The quartz boat contains a supported catalyst, which is supported on Fe-Ni-Mo.
[0034] The mixed gas treatment unit also includes a stripping tower device 9. The inlet of the stripping tower device is connected to the water phase outlet of the cooling equipment and the water washing equipment. The water after cooling the mixed gas in the cooling equipment and the water after washing the mixed gas in the water washing equipment are both fed into the stripping tower device to remove a small amount of oxygen-containing organic matter in the water. This oxygen-containing organic matter includes unreacted raw materials (methanol, dimethyl ether) and oxygen-containing compounds (mainly aldehydes, ketones, etc.) generated in the raw material decomposition device. The purified water at the bottom of the stripping tower is sent to the outside area for treatment and secondary utilization after heat exchange and cooling.
[0035] Application Example 1
[0036] This application example demonstrates the production of carbon nanotubes using the system described in Example 1. In this system, the decomposition catalyst in the raw material decomposition device is 50g of SAPO-34 molecular sieve catalyst. In a fluidized bed reactor, methanol is decomposed under the action of the decomposition catalyst within a temperature range of 400-550°C to obtain a mixed gas containing mixed hydrocarbons and impurities.
[0037] The temperature of the methanol feed line is controlled at 150℃. The methanol feed line feeds a methanol aqueous solution with a concentration of 91.6wt% into the preheater at a rate of 72.8g / h. The temperature of the preheater is adjusted to about 300℃. After the methanol aqueous solution is vaporized, it enters the raw material decomposition unit 2.
[0038] Before introducing methanol gas, the temperature of the fluidized bed reactor is controlled at around 550℃, and helium gas is introduced at a rate of 300 ml / min for 1 hour to activate the catalyst. Then, the temperature is lowered to around 500℃, and the helium gas is stopped. The inlet gas of the fluidized bed reactor is switched to methanol gas, and the reaction temperature of the fluidized bed reactor is controlled between 400-550℃.
[0039] Analysis by gas chromatography revealed that the approximate contents of each component in the mixed gas produced by the fluidized bed reactor were as follows: CH4 2.49 wt%, C2H4 48.32 wt%, C2H6 2.18 wt%, C3H6 31.23 wt%, C3H8 2.78 wt%, C4 7.72 wt%, C5 3.43 wt%, with trace components such as H2, CO, and CO2 remaining in the balance.
[0040] A 5% concentration of alkaline solution is sprayed into the washing equipment 4 to neutralize CO2 and oxygen-containing organic matter in the mixed gas.
[0041] After being processed by the above-mentioned mixed gas treatment unit, most of the water, carbon dioxide, oxygen-containing organic matter and other impurities in the mixed gas are removed, resulting in purified mixed hydrocarbons. The mixed hydrocarbons are mainly composed of ethylene and propylene, with a water content of 318 PPM.
[0042] The carbon nanotube production device 6 contains 115.2 mg of catalyst in a quartz boat. The catalyst is a MgO-Al2O3 supported catalyst with Fe-Ni-Mo support.
[0043] Before introducing the mixed hydrocarbon gas into the fixed-bed reactor, it was purged with nitrogen at 500 ml / min for 30 minutes to fully replace the air and moisture inside the reactor. Then, the mixed hydrocarbon gas was introduced into the fixed-bed reactor, and after chemical vapor deposition (CVD) at 660°C for 40 minutes, 5299.2 mg of carbon nanotubes were obtained after deducting the catalyst weight. The catalyst ratio was 46 times. Figures 2-3 As shown, the obtained carbon nanotubes have diameters ranging from 5 to 20 nm, an average diameter of 9.5 nm, and a specific surface area BET = 307 m². 2 / g.
[0044] Example 2
[0045] This embodiment provides a system for producing carbon nanotubes using methanol or dimethyl ether as raw materials, which is the same as in Example 1, except that... Figure 4 As shown, the raw material decomposition device includes two identical medium-sized circulating fluidized bed reactors 11 and a catalyst regenerator 7. The outlet of the vaporization equipment is connected in parallel to the inlet of the two medium-sized circulating fluidized bed reactors, with one medium-sized circulating fluidized bed reactor in use and the other on standby.
[0046] The medium-sized circulating fluidized bed reactor is provided with a feed inlet and a catalyst discharge pipe 10 at the bottom, a regeneration outlet 12 at the bottom of the catalyst discharge pipe 10, an air outlet 13 at the top of the medium-sized circulating fluidized bed reactor, and a regeneration inlet 14 at the top.
[0047] The regeneration outlets of the two medium-sized circulating fluidized bed reactors are connected to the feed inlets at the top of the catalyst regenerator 7. The discharge outlets at the bottom of the catalyst regenerator are connected in parallel to the regeneration inlets of the two medium-sized circulating fluidized bed reactors. An air inlet 15 is also provided in the lower middle part of the catalyst regenerator. The catalyst in the medium-sized circulating fluidized bed reactor is output from the regeneration outlet to the catalyst regenerator for regeneration. The regenerated catalyst is returned to the medium-sized circulating fluidized bed reactor through the regeneration inlet. Air enters the catalyst regenerator through the air inlet for catalyst coking regeneration.
[0048] Application Example 2
[0049] This application example demonstrates the production of carbon nanotubes using the system described in Example 2. The decomposition catalyst within the medium-sized circulating fluidized bed reactor 11 is a microsphere catalyst with dual active components of SAPO-18 and SAPO-34. Dimethyl ether gas is introduced into a gas preheater at 300°C via a mass flow controller. After preheating, the dimethyl ether enters the fluidized bed reactor, which is heated to 450°C, for the decomposition reaction.
[0050] Analysis by gas chromatography revealed that the approximate contents of each component in the mixed gas produced by the raw material decomposition unit were as follows: CH4 1.12 wt%, C2H4 42.56 wt%, C2H6 0.85 wt%, C3H6 45.83 wt%, C3H8 0.97 wt%, C4 6.05 wt%, C5 1.21 wt%, C6 0.36 wt%, with trace components such as H2, CO, and CO2 remaining in the balance.
[0051] After being processed by the mixed gas treatment unit, most of the water, carbon dioxide, oxygen-containing organic matter and other impurities in the mixed gas are removed, resulting in purified mixed hydrocarbons. The mixed hydrocarbons are mainly composed of ethylene and propylene, with a water content of 175 PPM.
[0052] The quartz boat in the carbon nanotube production apparatus contained 1.75 g of catalyst, which was a Fe-Ni-Mn-Mo catalyst supported on a MgO-Al2O3 carrier. After chemical vapor deposition at 650°C for 40 minutes (other reaction conditions were the same as in Example 1), 66.5 g of carbon nanotubes were obtained after deducting the catalyst weight, resulting in a catalyst ratio of 38 times. Figures 5-6 As shown, the obtained carbon nanotubes have diameters ranging from 10 to 60 nm, an average diameter of 38.0 nm, and a specific surface area BET = 86 m². 2 / g.
[0053] The system of the present invention uses methanol or dimethyl ether as raw materials and has the following advantages: ① It reduces the requirements for purchasing and using raw materials for carbon nanotube production. Ethylene and propylene are special chemical raw materials that are strictly regulated by the state, and there are strict qualification requirements for their purchase and use areas; at the same time, it also reduces the difficulty of building a carbon nanotube production plant, as it does not need to be built in one of the few chemical industrial parks designated by the state.
[0054] ②Methanol and dimethyl ether are liquids at room temperature, so ordinary storage tanks are sufficient. The management requirements for storage tanks are also low, which reduces the transportation and storage costs of raw materials.
[0055] ③ Polymer-grade ethylene and propylene require a few qualified intermediaries to repackage them at large petrochemical plants using tank trucks or small storage tanks. The repackaging and long-distance, fragmented transportation process not only significantly increases the price of ethylene and propylene raw materials, but also adds multiple distribution links and more safety risks, which is detrimental to the inherent safety of the carbon nanotube production process.
[0056] ④ The production of polymer-grade ethylene or propylene requires complex separation equipment and refrigerants to separate trace impurities from the raw materials. It also requires multiple expensive distillation columns and repeated pressurization processes, as well as complex refrigeration, compression, and heat exchange processes.
[0057] This invention uses methanol or dimethyl ether as raw materials, which are inexpensive. Methanol or dimethyl ether is decomposed to produce mixed hydrocarbons. Most of the water, oxygen-containing organic matter, CO2 and other impurities in the mixed hydrocarbons are removed, and carbon nanotubes can be produced directly, which greatly reduces equipment investment and operating costs.
[0058] ⑤ Traditional production processes for polymer-grade ethylene and polymer-grade propylene, with ethylene and propylene as the target products, generate a significant amount of methane, C4-C5 hydrocarbons, and acetylene as byproducts. These are either used as fuel gas, vented, or disposed of at low cost, resulting in resource waste. In this invention, mixed hydrocarbons of C1-C6 can be used as carbon sources for the production of carbon nanotubes, avoiding combustion, venting, or low-cost disposal. This improves resource utilization, protects the environment, and further reduces the production cost of carbon nanotubes.
Claims
1. A system for producing carbon nanotubes from methanol or dimethyl ether, characterized by comprising: The system comprises a raw material decomposition device, a mixed gas treatment unit and a carbon nanotube production device connected in sequence, the raw material is methanol or dimethyl ether, the raw material enters the raw material decomposition device, the raw material decomposition device is provided with a catalyst for catalytically decomposing the methanol or dimethyl ether to produce a mixed gas of hydrocarbons; The mixed gas treatment unit comprises a cooling device, a water washing device and a drying device connected in sequence for removing carbon dioxide, water and oxygen-containing organic substances in the mixed gas; the cooling device is connected to the raw material decomposition device at the gas outlet, the drying device is connected to the carbon nanotube production device at the feeding port, and the treated mixed gas of hydrocarbons is input into the carbon nanotube production device for producing carbon nanotubes.
2. The system for producing carbon nanotubes using methanol or dimethyl ether as a raw material according to claim 1, wherein The system further comprises a vaporization device for vaporizing the methanol or dimethyl ether, the vaporization device is connected to the raw material storage tank at the feeding port, and the vaporization device is connected to the raw material decomposition device at the feeding port.
3. The system for producing carbon nanotubes using methanol or dimethyl ether as a raw material according to claim 1, wherein The raw material decomposition device comprises a fixed bed reactor or a fluidized bed reactor, and the decomposition catalyst in the raw material decomposition device is a molecular sieve catalyst.
4. The system for producing carbon nanotubes using methanol or dimethyl ether as a raw material according to claim 3, wherein The raw material decomposition device comprises two identical reactors, the vaporization device is connected to the feeding ports of the two reactors in parallel, and the two reactors are used alternately.
5. The system for producing carbon nanotubes using methanol or dimethyl ether as a raw material according to claim 3, wherein The raw material decomposition device comprises a fluidized bed reactor and a catalyst regenerator, the fluidized bed reactor is provided with a feeding port, a gas outlet, a regeneration outlet and a regeneration inlet, the preheated methanol or dimethyl ether is input into the fluidized bed reactor from the feeding port, the mixed gas is discharged from the gas outlet after decomposition, and then is input into the mixed gas treatment unit; The regeneration outlet of the fluidized bed reactor is connected to the feeding port of the catalyst regenerator, the discharge port of the catalyst regenerator is connected to the regeneration inlet of the fluidized bed reactor, and the catalyst regenerator is further provided with an air inlet.
6. The system for producing carbon nanotubes using methanol or dimethyl ether as a raw material according to claim 1, wherein The cooling device is selected from a shell-and-tube heat exchanger or a quench tower, and the drying device is selected from one of a membrane dryer, an adsorption dryer and a freeze dryer.
7. The system for producing carbon nanotubes using methanol or dimethyl ether as a raw material according to Claim 1, wherein The mixed gas treatment unit further comprises a stripping tower device, the stripping tower device is connected to the water phase outlet of the cooling device and the water washing device at the inlet, the water body after cooling the cooled mixed gas of the cooling device and the water body after washing the mixed gas of the water washing device are both input into the stripping tower device to remove a small amount of oxygen-containing organic substances in the water, and the purified water at the bottom of the stripping tower is sent to an external treatment and secondary utilization after heat exchange and cooling.
8. The system for producing carbon nanotubes using methanol or dimethyl ether as a raw material according to Claim 1, wherein The carbon nanotube production device is selected from one of a fluidized bed device, a fixed bed device, a moving bed device, a stirred bed device and a rotary kiln device.