Integrated process for preparing isocyanates
First Claim
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1. A process for preparing organic isocyanates, which comprises(a) introducing a first partial amount of chlorine, wherein the first partial amount of chlorine has a content of free and bound bromine and iodine of at least 50 ppm and less than 400 ppm;
- (b) introducing a second partial amount of chlorine;
(c) reacting the first and second partial amounts of chlorine with carbon monoxide to form phosgene;
(d) reacting the phosgene with one or more primary amines to form an isocyanate and hydrogen chloride;
(e) separating off and optionally purifying the isocyanate;
(f) separating off and optionally purifying the hydrogen chloride;
(g) catalytically oxidizing at least part of the hydrogen chloride separated off and optionally purified in step (e) with a gas comprising oxygen to form chlorine;
(h) separating off the chlorine formed in step (g) wherein the second partial amount of chlorine in step (b) comprises at least a partial amount of the chlorine formed in step (g).
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Abstract
Process for preparing organic isocyanates, which comprises the steps
- (a) making available a first partial amount of chlorine, with the chlorine of this first partial amount having a content of free and bound bromine and iodine of <400 ppm;
- (b) making available a second partial amount of chlorine;
- (c) reacting the first and second partial amounts of chlorine with carbon monoxide to form phosgene;
- (d) reacting the phosgene from step (c) with one or more primary amines to form the corresponding isocyanates and hydrogen chloride;
- (e) separating off and, if necessary, purifying the isocyanates formed in step (d);
- (f) separating off and, if necessary, purifying the hydrogen chloride formed in step (d);
- (g) catalytically oxidizing at least part of the hydrogen chloride separated off in step (e) by means of oxygen to form chlorine;
- (h) separating off the chlorine formed in step (g) and using at least a partial amount of the chlorine which has been separated off as second partial amount of chlorine in step (b).
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10 Claims
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1. A process for preparing organic isocyanates, which comprises
(a) introducing a first partial amount of chlorine, wherein the first partial amount of chlorine has a content of free and bound bromine and iodine of at least 50 ppm and less than 400 ppm; -
(b) introducing a second partial amount of chlorine;
(c) reacting the first and second partial amounts of chlorine with carbon monoxide to form phosgene;
(d) reacting the phosgene with one or more primary amines to form an isocyanate and hydrogen chloride;
(e) separating off and optionally purifying the isocyanate;
(f) separating off and optionally purifying the hydrogen chloride;
(g) catalytically oxidizing at least part of the hydrogen chloride separated off and optionally purified in step (e) with a gas comprising oxygen to form chlorine;
(h) separating off the chlorine formed in step (g) wherein the second partial amount of chlorine in step (b) comprises at least a partial amount of the chlorine formed in step (g). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification