Chemistry of inorganic compounds – Modifying or removing component of normally gaseous mixture
Reexamination Certificate
2000-01-21
2001-09-04
Griffin, Steven P. (Department: 1754)
Chemistry of inorganic compounds
Modifying or removing component of normally gaseous mixture
C423S245100, C423S248000, C502S324000, C502S326000, C502S343000, C502S345000
Reexamination Certificate
active
06284209
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an agent for treating an exhaust gas containing a metal hydride gas and/or an organometallic gas, and a process of treating the exhaust gas using the agent. More particularly, the present invention relates to a dry gas treating agent, which is used to remove an exhaust gas containing a low concentration of a metal hydride gas and an organometallic gas by passing it through the treating agent containing a solid metal oxide and a solid metal carbonate as a main component, and a treating process thereof.
2. Description of the Related Art
Various gases has been used as a gas for production of a semiconductor and called as a metal hydride gas such as SiH
4
, Si
2
H
6
, GeH
4
, PH
3
, and AsH
3
, or an organosilane. Among them, the organosilane gas such as methylsilane, ethylsilane, and phenylsilane has attracted special interest recently because it exerts a specific performance adequate for a dry photoresist agent in the production of a semiconductor device, or a low-dielectric material for formation of a layer insulation film.
However, any of these gases is drastically dangerous because of high toxicity, reactivity and spontaneous ignition property. Since these gases have high toxicity, e.g. severe irritation to the respiratory organ upon respiration, we can foresee a harmful influence on the human body and natural environment if these gases are released out of the system in a high concentration. Therefore, it is a natural responsibility for persons in charge to reduce the concentration of the organosilane gas contained in the exhaust gas from its production process and after the use semiconductor industry in view of retention of good working atmosphere and prevention of destruction of the natural environment.
Accordingly, it is required to make the exhaust gas harmless,before released in an air, and a dry treating agent made of a solid metal oxide (Examined Patent Publication (KOKOKU) No. 4-19886) or a solid metal carbonate (Unexamined Patent Publication (KOKAI) Nos. 59-160535 and 8-192024) and a treating process using the same have hitherto been suggested.
In case where these components are contained in the exhaust gas in a high concentration, heat is generated by the reaction with the treating agent made of the solid metal oxide and a sufficient treatment can be conducted by the successive reaction. However, in case of the exhaust gas having a comparatively low concentration, a sufficient treatment cannot be conducted because of poor reactivity.
In case of the treating agent made of the solid metal carbonate, a sufficient reaction takes place even in case of the exhaust gas having a comparatively low concentration, but the amount of the exhaust gas to be treated per volume of this treating agent is poor. If this treating agent is brought into contact with air after passing the exhaust gas through it, high temperature heat is generated, resulting in poor handling.
In a conventional process, it was considered to be effective to supply the exhaust gas while heating a packed bed so as to enhance the capability of treating the exhaust gas. However, this heating process requires high energy cost and gives rise to generation of particles from a heat insulating material in the vicinity of a heater and, therefore, it was a problem in a semiconductor factory where particles should be avoided.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a treating process which is capable of treating in an efficient and safe manner even in case of the exhaust gas having a low concentration as a subject to be treated, and which does not require heating and does not attend generation of particles, and a treating agent.
The present inventors have studied intensively to attain the above object. As a result, they have found that, by using a solid metal oxide in combination with a solid metal carbonate, not only drawbacks in case of using them alone are covered, but also a higher treating capability is exerted by a synergistic effect. Thus, the present invention has been completed.
That is, the present invention is directed to an agent for treating an exhaust gas, comprising a mixture of a solid metal oxide and a solid metal carbonate as a main component, said metal being selected from the group of metal elements consisting of Mn, Fe, Ni, Cu and Zn, said mixture having a peak intensity ratio A/B within a range from 0.2 to 8 with a proviso that a value of a maximum peak intensity at 2&thgr; within a range from 38.6 to 39.0 is A (cupric oxide) and a value of a maximum peak intensity at 2&thgr; within a range from 31.1 to 31.5° is B (basic copper carbonate) in XRD, said agent being made of a molded article obtained by granulation and/or pelletization and extrusion of the mixture.
The present invention is also directed to a process of treating an exhaust gas, which comprises packing a packing container with a treating agent comprising a mixture of a solid metal oxide and a solid metal carbonate as a main component, and passing the exhaust gas containing a metal hydride gas and/or an organometallic gas through a bed packed with the treating agent, thereby to treat the exhaust gas at room temperature.
The present inventors have found that, by mixing an agent for treating an exhaust gas containing a metal hydride gas and/or an organometallic gas with a solid metal oxide and a solid metal carbonate, which have conventionally been used, in a specific ratio, not only drawbacks in case of using them alone are covered, but also a higher treating capability is exerted by a synergistic effect. By using this treating agent, an increase in life of the treating agent and a reduction in size of the apparatus can be attained as compared with a conventional treating process. This fact exerts a relative effect in view of energy cost.
REFERENCES:
patent: 4996030 (1991-02-01), Kitahara
patent: 0194366 A (1986-09-01), None
patent: 0294142 A (1988-12-01), None
patent: 0335792 A (1989-10-01), None
patent: 53-028592 (1978-03-01), None
patent: 8-192024 A (1996-07-01), None
patent: 8-206444 A (1996-08-01), None
Harada Isao
Komohara Sadaichi
Burns Doane Swecker & Mathis L.L.P.
Griffin Steven P.
Medina Maribel
Mitsui Chemicals Inc.
LandOfFree
Agent for and process of treating exhaust gas does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Agent for and process of treating exhaust gas, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Agent for and process of treating exhaust gas will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2503616