초록 ▼

The present invention relates to a novel process for the preparation of high-purity chemicals with an extremely low particle count, such as ammonia gas, hydrogen fluoride and hydrogen chloride, which are also used as aqueous solutions in semiconductor technology the corrosive gas is enriched with an

The present invention relates to a novel process for the preparation of high-purity chemicals with an extremely low particle count, such as ammonia gas, hydrogen fluoride and hydrogen chloride, which are also used as aqueous solutions in semiconductor technology the corrosive gas is enriched with an absorbent which is miscible with the gas and in which impurities present in the gas are soluble, and the gas is subsequently subjected to membrane filtration.

대표청구항 ▼

The invention claimed is: 1. A continuous process for the removal of particulate, metallic, ionic inorganic, ionic organic, and nonionic organic impurities, and traces of salts or oils, from a corrosive gas, comprising enriching the gas in at least one process step with an absorbent readily miscibl

The invention claimed is: 1. A continuous process for the removal of particulate, metallic, ionic inorganic, ionic organic, and nonionic organic impurities, and traces of salts or oils, from a corrosive gas, comprising enriching the gas in at least one process step with an absorbent readily miscible with the gas and in which the impurities present in the gas are readily soluble, and subsequently subjecting the absorbent-enriched gas to membrane filtration, wherein the purified gas stream flows through the membrane, and the absorbent with solubilized impurities is taken off continuously. 2. A continuous process for the removal of particulate, metallic, ionic inorganic, ionic organic, nonionic organic impurities, and traces of salts or oils from corrosive gases, comprising: a) converting a chemical in the liquid state into the gaseous state in an evaporator, b) freeing the resultant gas phase from coarse particulate impurities and impurities which are partially in the form of an aerosol by means of a pre-filter, the latter impurities being fed to a collecting tank, c) setting the pressure to 2-8 bar, and simultaneously reducing the temperature to 20-50째C., and depositing organic impurities present in the gas stream, d) passing the pre-purified gas stream through at least two ultrafine filters with decreasing pore size connected in series, to remove ultrafine particles present in the gas phase, e) separating organic impurities still present with an organics separator and feeding resultant organic impurities into a collecting tank, f) feeding an absorbent which is readily miscible with the gas to be purified, and in which the impurities present in the gas are readily soluble and which has a surface tension of >50 dynes to the gas stream via a saturation tank, and g) filtering the resultant absorbent-containing at least one gas stream with at least one membrane, removing the absorbent with solubilized impurities, and subsequently feeding the resultant gas stream in a mixer with a constantly circulating solution whose concentration is monitored and regulated by an acoustic velocity measurement. 3. A process according to claim 2, wherein the pressure and the saturation of the gas with absorbent are set with the aid of a pressure reducer and a heat exchanger. 4. A process according to claim 2, wherein in an organics separator, low-boiling and high-boiling organic impurities are separated from the multiphase mixture by setting the pressure and temperature so the low-boiling impurities are in the form of a gas or vapor mixture and the high-boiling impurities are in the form of a condensed oil or aerosol, and are subsequently separated off by membranes. 5. A process according to claim 2, further comprising setting the pressure to 1-6 bar downstream of the organics separator. 6. A process according to claim 2, wherein in step (g) the at least one membrane is a membrane comprising a hydrophobic support material for removing ultrafine particulate, metallic, ionic inorganic, ionic organic, and nonionic organic impurities, and traces of salts or oils. 7. A process according to claim 1, wherein the absorbent used is ultra-high-purity water. 8. A process according to claim 2, further comprising providing a gas scrubber in the form of a packed column with integrated demister, which serves as buffer volume in the event of a fault downstream of the membrane filtration in process step g). 9. A process according to claim 2, wherein the gas stream in process step g) is fed into a mixer having a plurality of inlet tubes, wherein the solution is circulated and exothermic heat formed on dissolution is dissipated in a loop or one or more heat exchangers. 10. A process according to claim 2, wherein the concentration of the dissolved purified gas is monitored and regulated by acoustic velocity measurement combined with precise determination of the solution temperature. 11. A continuous process for the removal of particulate, metallic, ionic inorganic, ionic organic, nonionic organic impurities, and traces of salts or oils, from corrosive gases, comprising: a) converting a chemical in the liquid state of ammonia, hydrogen fluoride or hydrochloric acid into the gaseous state in an evaporator, b) freeing the resultant gas phase from coarse particulate impurities and impurities which are partially in the form of an aerosol with a prefilter, the latter impurities being fed to a collecting tank, c) setting the pressure to 2-8 bar, simultaneously reducing the temperature to 20-50째C., and depositing organic impurities present in the gas stream, d) passing the resultant pre-purified gas stream through at least two ultrafine filters with decreasing pore size connected in series, to remove ultrafine particles present in the gas phase, e) separating organic impurities still present with an organics separator and feeding resultant organic impurities into a collecting tank, f) feeding an absorbent which is readily miscible with a gas to be purified and has a surface tension of >50 dynes to the gas stream via a saturation tank, and g) filtering the absorbent-containing gas stream with at least one membrane, removing the absorbent, and subsequently feeding the resultant gas stream in a mixer with a constantly circulating solution whose concentration is monitored and regulated by an acoustic velocity measurement. 12. A process according to claim 1, wherein the membrane comprises polytetrafluoroethylene, perfluoroethylene-propylene, or polyethylene. 13. A process according to claim 1, wherein the membrane has a pore size less than 3.5 μms. 14. A process according to claim 1, wherein the absorbent is a hydrophilic organic or inorganic solvent. 15. A process according to claim 1, wherein the absorbent has a surface tension of >50 dynes/cm. 16. A process according to claim 12, wherein the absorbent is ultra-high-purity water. 17. A process according to claim 12, wherein the absorbent is a water-miscible, hydrophilic organic solvent. 18. A process according to claim 12, wherein the absorbent comprises a low-molecular-weight alcohol. 19. A process according to claim 12, wherein the absorbent comprises isopropanol or normal-propanol. 20. A process for removing a contaminant from a gas, comprising filtering the gas enriched with an absorbent through a membrane filter, wherein the contaminant in the gas is soluble in the absorbent and the absorbent becomes enriched with the contaminant, wherein the gas flows through the membrane filter so as to obtain a purified gas and the absorbent enriched with contaminant is continuously removed. 21. A process according to claim 1, wherein a liquid film of the absorbent forms on the membrane surface and the absorbent with solubilized impurities is taken off continuously after falling, by the effect of gravity, down the liquid film.