Removal of phosgene from off-gases
First Claim
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1. In a process for removing phosgene from off-gases by washing with a liquid, the improvement which comprises:
- reacting the phosgene contained by the off-gas in a washing zone with a wash liquid which consists essentially of at least one compound of the formula ##STR9## where R1 and R2 are identical or different and are selected from the group consisting of alkyl of 1 to 8 carbons and cycloalkyl of 5 to 8 carbon atoms, or R1 and R2 when taken together may also represent --(CH2)n -- where n is 4 or 5, and R3 is selected from the group consisting of hydrogen, alkyl of 1 to 6 carbon atoms and cycloalkyl of 5 to 6 carbon atoms, or R1 or R2 when taken individually together with R3 may also represent --(CH2)m -- where m is 3, 4 or 5, to form a Vilsmeier salt; and
further reacting said salt with water to form an off gas containing HCl with the phosgene removed.
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Abstract
To remove phosgene from off-gases, the former is reacted in a washing zone with a liquid which contains or is composed of compounds of the formula ##STR1## where R1 and R2 are identical or different and are each aliphatic or cycloaliphatic alkyl of 1 to 8 carbons, or R1 and R2 are --(CH2)n -- where n is 4 or 5, R3 is hydrogen or aliphatic or cycloaliphatic alkyl of 1 to 6 carbon atoms, or R1 or R2 and R3 are --(CH2)m -- where m is 3, 4 or 5.
The liquid can be regenerated by the addition of water, and the regenerated liquid can be returned to the washing zone.
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Citations
7 Claims
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1. In a process for removing phosgene from off-gases by washing with a liquid, the improvement which comprises:
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reacting the phosgene contained by the off-gas in a washing zone with a wash liquid which consists essentially of at least one compound of the formula ##STR9## where R1 and R2 are identical or different and are selected from the group consisting of alkyl of 1 to 8 carbons and cycloalkyl of 5 to 8 carbon atoms, or R1 and R2 when taken together may also represent --(CH2)n -- where n is 4 or 5, and R3 is selected from the group consisting of hydrogen, alkyl of 1 to 6 carbon atoms and cycloalkyl of 5 to 6 carbon atoms, or R1 or R2 when taken individually together with R3 may also represent --(CH2)m -- where m is 3, 4 or 5, to form a Vilsmeier salt; and further reacting said salt with water to form an off gas containing HCl with the phosgene removed. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification