Device and method for continuously preparing high-purity single/double-wall carbon nano tubes

Abstract

The invention discloses a device and a method for continuously preparing high-purity single / double-wall carbon nano tubes, and belongs to the technical field of preparation of carbon nano tubes. A downer of the device is sleeved into a lifting pipe, and the gas-solid outlet of the downer is adjacent to the lower end of a conical structure or a partition board in the lifting pipe. The method for preparing the single / double-wall carbon nano tubes comprises the following steps of: feeding a process gas and a catalyst from the top of the downer to finish cracking of a carbon source and the nucleation and growth process of the single / double-wall carbon nano tubes, discharging the gas and the solid from the bottom of the downer to enter the lifting pipe and flow upwards, introducing the carbon source from the bottom of the lifting pipe to ensure that the ratio of the carbon source to the hydrogen at the position is as same as that at the inlet of the downer, and further growing the single / double-wall carbon nano tubes with high selectivity. The method has the characteristics of high product purity, high yield, low preparation cost and easily amplified processes.

Description

technical field [0001] The invention belongs to the technical field of carbon nanotube preparation, and in particular relates to a device and method for continuously preparing high-purity single / double-wall carbon nanotubes. Background technique [0002] Most single / double-walled carbon nanotubes have a diameter between 0.6-2nm and a length of hundreds of microns or even tens of centimeters. They have good electrical conductivity, thermal conductivity, mechanical properties and huge specific surface area, and can be widely used in polymers. Enhancement, conductive material, field emission material, absorbing or shielding material, catalyst carrier or used in nano-circuits, etc. There are three methods for preparing single / double-walled carbon nanotubes: graphite arc, laser ablation, and chemical vapor deposition. The first two methods have expensive equipment, are not easy to scale up, and the local temperature is too high, which is easy to generate carbon impurities such a...

AI Technical Summary

Problems solved by technology

However, a large number of catalysts quickly cracks hydrocarbons and produces a large amount of hydrogen, which leads to the rapid reduction and sintering of nano-metal catalysts, which easily produces multi-walled carbon nanotubes with large diameters, resulting in a decrease in product selectivity.

In the type (2) method, the residence time of the catalyst in the reactor is too short, and when it is still active, it has already left the reactor. The activity is not fully utilized, and the catalyst becomes an impurity in the product. Purification is time-consuming, laborious and pollutes the environment.

The catalyst preparation scale of the (3) class method is small, not easy to enlarge, compared with the (1), (2) class method, the product output is too small

There is a coupled reactor technology that uses riser, down-bed and turbulent fluidized bed to solve the contradiction between product selectivity and low yield, but the device is relatively complicated and the operation is relatively difficult

Due to technical defects and bottlenecks, the absolute output of single / double-walled carbon nanotubes in the world is very low at present, and the price is expensive, generally reaching 100-1000 US dollars / gram, which seriously limits the application research of single / double-walled carbon nanotubes and commercialization

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