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Method for purifying cycling hydrogen in production of polysilicon

A polysilicon and hydrogen technology, applied in the direction of separation of silicon and hydrogen, can solve problems such as affecting the quality of polysilicon products, difficult to remove trace and trace impurities, limiting the purity and quality of polysilicon products, etc., to reduce energy consumption, improve purity and Quality, the effect of reducing hydrogen consumption

Inactive Publication Date: 2013-06-19
DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, due to various reasons, the recovered hydrogen usually contains tens of ppm of methane and nitrogen, several ppm of oxygen and water vapor, and also contains ppb level of PCl 3 and BCl 3 Impurities such as metal chlorides, even at such a low level, can seriously affect the quality of polysilicon products
[0006] For the existing cryogenic technology and pressure swing adsorption technology, due to the limitation of phase balance and adsorption balance, it is difficult to further remove these micro and trace impurities in the hydrogen recovered by the dry method of polysilicon production, thus limiting the purity of polysilicon products and further improvement in quality

Method used

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  • Method for purifying cycling hydrogen in production of polysilicon
  • Method for purifying cycling hydrogen in production of polysilicon
  • Method for purifying cycling hydrogen in production of polysilicon

Examples

Experimental program
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Effect test

Embodiment 1

[0029] with 1% HCl in H 2 As raw material gas, adopt metal palladium composite membrane to carry out hydrogen purification (use metal palladium composite membrane hydrogen purifier to operate, the same below). The parameters of the metal-palladium composite membrane are: diameter 12mm, length 50mm, palladium membrane thickness 10μm, hydrogen permeability at 300°C is 57ml / min.bar, and nitrogen permeability at room temperature is 0.06ml / min.bar. H with 1% HCl was first 2 Pass dechlorination agent (CaO / Al 2 o 3 ) for dechlorination, and the temperature of the dechlorination agent is controlled at 380°C. The raw material gas after dechlorination enters the metal-palladium composite membrane for hydrogen purification, the temperature is 300°C, the raw material gas pressure is 0.2MPa, and the pressure of hydrogen permeation is normal pressure. The results show that within 27 hours of the experiment, no impurities can be detected in the hydrogen gas passing through the palladium ...

Embodiment 2

[0033] with 1% HCl and 1% SiCl 4 H 2 As raw material gas, a metal-palladium composite membrane is used for hydrogen purification. The parameters of the metal-palladium composite film are: diameter 12mm, length 40mm, palladium film thickness 5μm, the hydrogen permeability at 300°C is 88ml / min.bar, and the nitrogen permeability at room temperature is 0.04ml / min.bar. First place the 1% HCl and 1% SiCl 4 H 2 Pass dechlorination agent (CaO / Al 2 o 3 ) for dechlorination, and the temperature of the dechlorination agent is controlled at 380°C. The raw material gas after dechlorination enters the metal-palladium composite membrane for hydrogen purification, the temperature is 300°C, the raw material gas pressure is 0.17MPa, and the pressure of hydrogen permeation is normal pressure. The results show that within 8.5 hours of the experiment, no impurities can be detected in the hydrogen gas passing through the palladium membrane by gas chromatography, indicating that the purity of ...

Embodiment 3

[0037] Using hydrogen containing 4ppm methane and 5ppm oxygen after simulated dechlorination as raw material gas, a multi-channel metal palladium composite membrane is used for hydrogen purification. The palladium composite membrane is 1m in length and 30mm in diameter. It consists of 19 channels with a channel diameter of 4mm. Structural diagram see attached image 3 . The hydrogen purification temperature is 400°C, the feed gas pressure is 0.9MPa, and the permeated hydrogen pressure is 0.6MPa. The results in Table 1 show that when H 2 When the recovery rate is 85%, the purity of hydrogen passing through the palladium membrane is >99.999999%, when H 2 When the recovery rate is greater than 90%, the purity of hydrogen passing through the palladium membrane is greater than 99.99999%. After the experiment, the system was purged with nitrogen for 2 h, and then cooled to room temperature.

[0038] Table 1 Hydrogen purification results of multi-channel metal palladium composite...

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Abstract

Provided is a method for purifying cycling hydrogen in production of polysilicon. According to the invention, a metal palladium composite membrane hydrogen purifier is used to intercept a variety of impurities in cycling hydrogen reduced by trichlorosilane, which enables the purity of hydrogen to be increased by one to three order of magnitude and the concentration of the variety of impurities tobe reduced by one to three order of magnitude; when the content of hydrogen chloride HCl in cycling hydrogen exceeds 3 ppm, necessary dechlorination measures have to be taken to allow the content of hydrogen chloride HCl to decrease to less than 0.5 ppm. Utilization of hydrogen purified by the method for production of polysilicon not only enables purity and quality of polysilicon products to be obviously improved, but also enables consumption of hydrogen and energy in the process of production to be obviously reduced and discharge of pollution to be minimized.

Description

technical field [0001] The invention is a method for purifying hydrogen by using trichlorosilane to reduce and circulate hydrogen in the polysilicon production process. Through the invention, the purity of trichlorosilane hydrogen reduction and circulated hydrogen can be increased by 1-3 orders of magnitude, and the impurity concentration can be reduced by 1-3 orders of magnitude. Specifically, a metal-palladium composite membrane hydrogen purifier is used to purify hydrogen from trichlorosilane reduction cycle hydrogen in the polysilicon production process. When the chlorine content in the circulating hydrogen is high, first use physical adsorption or chemical conversion to dechlorinate the circulating hydrogen from the condensation and dry separation process, so that the chlorine content is reduced to below 0.5ppm, and then use metal palladium The composite membrane hydrogen purifier purifies hydrogen to obtain high-purity hydrogen and ultra-pure hydrogen with a purity of 99...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B3/50C01B33/03
Inventor 徐恒泳王新平唐雨东孙剑
Owner DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI