Chemistry of inorganic compounds – Nitrogen or compound thereof – Oxygen containing
Reexamination Certificate
2001-08-02
2004-05-18
Langel, Wayne A. (Department: 1754)
Chemistry of inorganic compounds
Nitrogen or compound thereof
Oxygen containing
C203S013000, C423S390100, C423S393000, C423S394000
Reexamination Certificate
active
06737034
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a unique method of converting Inhibited Red Fuming Nitric Acid (IRFNA) and/or nitrogen tetraoxide to either concentrated (98%+) nitric acid or dilute nitric acid. The unique process includes a process to remove the inhibitors commonly used in Inhibited Red Fuming Nitric Acid (IRFNA). The requirement to remove the inhibitors relates to the end use of the nitric acid. If the requirement to control the inhibitor content is eliminated the steps associated are deleted and the same equipment is used to provide the desired concentration of nitric acid with varying purity and dilution.
The preferred method described below was selected from several options available for each step i.e. sparging or distillation for N
2
O
4
removal from IRFNA and inhibitor removal via reaction to form solids and/or cooling with separation and filtration. These options might be used under certain conditions depending on the desired end products.
It is therefore an object of this invention to provide nitric acid from (98%+) by weight concentration or dilute nitric acid to any specified concentration.
Another object of this invention is to remove the commonly used inhibitors from IRFNA, if required, to meet the requirements associated with reaction of these inhibitors when they remain in the end product nitric acid.
Yet another object of this invention is to provide a relatively simple conversion process minimizing expensive and time consuming steps.
SUMMARY OF INVENTION
This invention provides a unique process to convert IRFNA and/or nitrogen tetraoxide into nitric acid based on various experimental data never previously combined.
The preferred method steps described below were selected from several options available for each step; i.e., sparging or distillation for N
2
O
4
removal from IRFNA; and inhibitor removal via reaction to form solids and/or cooling with separation and filtration. These options might be used under certain conditions depending on the desired end products.
REFERENCES:
patent: 3876752 (1975-04-01), Wendel
patent: 3927183 (1975-12-01), Oushiba
patent: 4018872 (1977-04-01), Barba et al.
patent: 4018873 (1977-04-01), Barba et al.
patent: 4031187 (1977-06-01), Barba et al.
patent: 4064221 (1977-12-01), Rodrigo et al.
patent: 5500098 (1996-03-01), Brown et al.
patent: 5603811 (1997-02-01), Lucas et al.
patent: 5632866 (1997-05-01), Grant
patent: 6284212 (2001-09-01), O'Brien
Beam Dayn T.
Chang Hay Kyung
Langel Wayne A.
The United States of America as represented by the Secretary of
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