Process for recovery and recycle of ammonia from an acrylonitrile reactor effluent stream using an ammonium phosphate quench system
First Claim
1. A process for the recovery of unreacted ammonia from the effluent obtained from a reaction zone wherein oxygen, ammonia and a hydrocarbon are reacted at an elevated temperature in the presence of an ammoxidation catalyst to produce an unsaturated nitrile comprising the steps of:
- quenching the effluent containing the nitrile and unreacted ammonia with an aqueous ammonium phosphate solution having an initial ratio R of ammonium ions to phosphate ions to absorb substantially all of the unreacted ammonia present in the reactor effluent to form an ammonium phosphate solution having an increased ratio R of ammonium ions to phosphate ions;
heating the solution to an elevated temperature sufficient to reduce the ratio R of ammonium ions to phosphate ions and to generate a vaporous stream containing ammonia;
passing the heated solution through a 31P nuclear magnetic resonance detector to detect a chemical shift of a 31P nuclear magnetic resonance peak;
determining the ratio R of ammonium ions to phosphate ions in the solution based on the chemical shift; and
controlling the heating step to maintain the initial ratio R within a desired range.
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Abstract
The present invention provides a process for the recovery of unreacted ammonia from the effluent obtained from a reaction zone wherein oxygen, ammonia and a hydrocarbon are reacted at an elevated temperature in the presence of an ammoxidation catalyst to produce an unsaturated nitrile is provided, including the steps of:
quenching the effluent containing the nitrile and unreacted ammonia with an aqueous ammonium phosphate solution having an initial ratio R of ammonium ions to phosphate ions to absorb substantially all of the unreacted ammonia present in the reactor effluent to form an ammonium phosphate solution having an increased ratio R of ammonium ions to phosphate ions;
heating the solution to an elevated temperature sufficient to reduce the ratio R of ammonium ions to phosphate ions and to generate a vaporous stream containing ammonia;
passing the heated solution through a 31P nuclear magnetic resonance detector to detect a chemical shift of a 31P nuclear magnetic resonance peak;
determining the ratio R of ammonium ions to phosphate ions in the solution based on the chemical shift; and
controlling the heating step to maintain the initial ratio within a desired range.
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Citations
20 Claims
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1. A process for the recovery of unreacted ammonia from the effluent obtained from a reaction zone wherein oxygen, ammonia and a hydrocarbon are reacted at an elevated temperature in the presence of an ammoxidation catalyst to produce an unsaturated nitrile comprising the steps of:
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quenching the effluent containing the nitrile and unreacted ammonia with an aqueous ammonium phosphate solution having an initial ratio R of ammonium ions to phosphate ions to absorb substantially all of the unreacted ammonia present in the reactor effluent to form an ammonium phosphate solution having an increased ratio R of ammonium ions to phosphate ions;
heating the solution to an elevated temperature sufficient to reduce the ratio R of ammonium ions to phosphate ions and to generate a vaporous stream containing ammonia;
passing the heated solution through a 31P nuclear magnetic resonance detector to detect a chemical shift of a 31P nuclear magnetic resonance peak;
determining the ratio R of ammonium ions to phosphate ions in the solution based on the chemical shift; and
controlling the heating step to maintain the initial ratio R within a desired range. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A process for the recovery of unreacted ammonia from the effluent obtained from a reaction zone wherein oxygen, ammonia and a hydrocarbon are reacted at an elevated temperature in the presence of an ammoxidation catalyst to produce an unsaturated nitrile comprising the steps of:
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quenching the effluent containing the nitrile and unreacted ammonia with an ammonium phosphate solution having an initial ratio R of ammonium ions to phosphate ions to absorb substantially all of the unreacted ammonia present in the reactor effluent whereby the ammonium phosphate solution has an increased ratio R of ammonium ions to phosphate ions;
heating the solution to an elevated temperature sufficient to reduce the ratio R and to generate a vaporous stream containing ammonia for recycling to the reaction zone;
passing the solution through a 31P nuclear magnetic resonance detector to detect a chemical shift of a 31P nuclear magnetic resonance peak;
determining the ratio of ammonium ions to phosphate ions in the solution based on the chemical shift; and
controlling the heating step to maintain the first ratio within a desired range. - View Dependent Claims (17, 18, 19)
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20. A process for the recovery of unreacted ammonia from the effluent obtained from a reaction zone wherein oxygen, ammonia and a hydrocarbon selected from propane and isobutane are reacted at an elevated temperature in the presence of an ammoxidation catalyst to produce a corresponding unsaturated nitrile, comprising the steps of:
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quenching the effluent containing the corresponding nitrile and unreacted ammonia with an ammonium phosphate solution wherein the ratio R of ammonium ions to phosphate ions is between about 0.7 to about 1.3 to absorb substantially all of the unreacted ammonia present in the reactor effluent to form an ammonium phosphate solution having an increased ratio R ammonium ions to phosphate ions;
heating the solution to an elevated temperature sufficient to reduce the amount of ammonium ions in the solution to substantially the initial ratio R present in the solution and to generate a vaporous stream containing ammonia for recycling to the fluid bed reactor;
passing the ammonium phosphate solution through a 31P nuclear magnetic resonance detector to detect a chemical shift of a 31P nuclear magnetic resonance peak;
determining the ratio of ammonium ions to phosphate ions in the solution based on the chemical shift; and
controlling the heating step to maintain the ratio R within a desired range.
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Specification