JPS61168518A - Treatment of waste gas containing silane - Google Patents

Abstract

PURPOSE:To eliminate monosilane from waste gas containing monosilane at a low concentration, economically and safely, by contacting the silane-containing waste gas with alumina at a temperature within a specific range, thereby decomposing the monosilane. CONSTITUTION:A silane-containing gas is made to contact with an alumina [preferably gamma-alumina having large specific surface area (>=100m<2>/g) at >=100 deg.C (especially preferably 100-600 deg.C) to effect the decomposition of silane. An example of the apparatus is shown in the figure. The silane-containing waste gas is introduced through the line 1 into the reactor 2 packed with alumina particles. The reactor is heated with the heater 4 and controlled to a proper temperature of >=100 deg.C. The silane is decomposed into silicon and hydrogen in the reactor. The most part of the produced silicon is deposited on the alumina, and there is little entrainment of silicon in the treated gas.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a method for treating waste gas containing silanes.

In particular, it relates to a method for treating waste gas containing dilute silanes.

BACKGROUND OF THE INVENTION Silanes such as monosilane, disilane, and chlorosilane have been used in large quantities in recent years as raw material gases for semiconductors, amorphous solar cells, electrophotographic photoreceptors, and the like. With increasing usage.

Eliminating harmful silanes from silane-containing waste gases generated from silane-handling equipment, including manufacturing processes, has become an important issue.

Conventionally, these silane-containing waste gases are treated by 1) diluting them with inert gas to a safe concentration, 2) burning them in contact with air and releasing them as safe silicon oxide, and 3) selectively removing silanes using an adsorbent. It was treated using methods such as adsorption treatment.

The problem that the invention aims to solve Conventional method (1) does not reduce the total amount of silanes.

It may lead to environmental pollution. (2) is 100%
For example, in the case of monosilane, about 1 liter of untreated monosilane is released into the atmosphere. Method (3) has high removal efficiency, but has drawbacks such as requiring a large amount of adsorbent and being expensive.

In particular, it is desired to develop a simple method for treating silane-containing waste gas in which the concentration of silanes in the waste gas is low (for example, monosilane cannot be directly combusted with air at 1% or less).

゛ Means for Solving the Problems The inventor of the present invention conducted extensive research in order to solve the above-mentioned problems, and finally completed the present invention.

In other words, the method for treating waste gas containing silanes of the present invention is as follows:
This is a method for treating a silane-containing gas, characterized by contacting the silane-containing waste gas with alumina at a temperature of 100° C. or higher.

In the present invention, silane-containing waste gas is a gas containing toxic and self-combustible silanes such as monosilane, disilane, chlorosilane, etc., and is mostly inert gas such as helium, chino, argon, hydrogen, etc. It consists of In particular, the present invention is effective when applied to waste gas having a relatively low concentration of silanes.

In the present invention, it is not necessary to use a special alumina, but r-
Preferably, alumina is used.

Although there is no particular restriction on the particle size, when a fluidized bed type reactor is used, as will be described later, it is necessary to use alumina having a particle size suitable for the reactor.

In the present invention, the contact treatment temperature is preferably 100°C or higher, particularly 100 to 600°C. If it is less than 100°C, the decomposition rate of silanes is slow and a considerable amount of silanes remains in the gas after treatment, which is not preferable. In addition, raising the temperature above 600° C. is not particularly effective, wastes energy, and in some cases decomposes and produces silane, which is not preferred because it is entrained in the processing gas.

FIG. 1 shows an example of an apparatus suitable for applying the method of the present invention.

The waste gas containing silanes is introduced from a pipe 1 into a reactor 2 filled with alumina particles. The reactor is heated by a heating heater 4 and controlled to an appropriate temperature of 100'C or higher. In the reactor, the silanes are decomposed into silicon and hydrogen.

Most of the produced silicon adheres to the alumina and is hardly entrained in the treated gas.

The treated gas is cooled through a cooler 5 if necessary and then discharged to the outside of the system. Although there is no particular restriction on the shape of the reactor, it is preferable to use a fluidized bed type reactor since there are no problems such as clogging.

Function In the present invention, silane decomposes when it comes into contact with alumina at a temperature of 100°C or higher, forming silicon and hydrogen.

However, since the silicon produced adheres to the alumina, it is thought that the treated gas will contain almost no toxic silanes.

Effects of the Invention By using the method of the present invention, waste gas containing low concentrations of monosilano, which could not be economically and safely removed using conventional techniques, can be removed at low cost by using the alumina catalyst of the present invention. This makes it possible to treat waste gases from the semiconductor industry, amorphous solar cells, electrophotographic photosensitive drums, and other manufacturing processes.

Example The present invention will be specifically explained below using examples.

γ- particle size 60-150 mesh, surface area zbom/g
25φx 500 filled with 100 cc of alumina
Waste gas containing 2,500 ppm of monosilane was supplied to the reactor of h at a rate of 2,001/h, and the reactor was heated at 50°C, 150°C, 2
50℃.

When treated at temperatures of 350°G, 450°C, and 550°C, processing gases with monosilane concentrations shown in Table 1 were obtained.

[Brief explanation of drawings]

FIG. 1 is a flow sheet showing an example of an apparatus suitable for applying the method of the present invention.

Claims (1)

[Claims] (1) A method for treating silane-containing waste gas, which comprises decomposing the silane-containing waste gas by bringing it into contact with alumina at a temperature of 100° C. or higher.