Method and apparatus for decomposing N2O

An apparatus for thermally decomposing N2O, which is a global warming agent, in a N2O-containing gas, said apparatus comprising:

• (a) an introduction portion for the N2O-containing gas to be treated;
• (b) a preheating portion for the thus introduced gas to be treated;
• (c) a thermal decomposition portion adjacent to the preheating portion, said thermal decomposition portion having a component for supplying the gas to be treated and having a porous plate and/or a multi-pipe nozzle, said supplying component being provided at one or more positions in the flow direction of a gas stream;
• and
• (d) a discharging portion for the thermally decomposed gas.

An apparatus for catalytic decomposition of N2O, which is a global warming agent, in a N2O-containing gas, said apparatus comprising:

• a device which comprises:
• (a) an introduction portion for the gas to be treated and/or a diluent gas;
• (b) a mixing portion for the gas to be treated and/or the diluent gas;
• (c) a catalytic decomposition portion having a catalytic bed;
• and
• (d) a discharging portion for the catalytically decomposed gas;
• and
• one or more devices each of which comprises:
• (e) an introduction portion for the discharged gas having been catalytically decomposed, the gas to be treated and/or a diluent gas;
• (f) a mixing portion for the discharged gas having been catalytically decomposed, the gas to be treated and/or the diluent gas;
• (g) a catalytic decomposition portion having a catalytic bed;
• and
• (h) a discharging portion for the catalytically decomposed gas.

A process for producing adipic acid with reduced release of N2O that causes global warming, comprising:

• (1) a nitric acid-oxidation step in which cyclohexanol and/or cyclohexanone are oxidized with nitric acid to form adipic acid;
• (2) a nitric acid recovery step in which HNO3 is recovered from a N2O-containing gas caused in the nitric acid-oxidation step;
• (3) a N2O decomposition step in which the remaining N2O-containing gas stream to be treated, from which HNO3 has been recovered, is divided, a portion thereof is preheated to exothermally decompose N2O in the gas stream to form a hot gas stream, and the remainder of the divided gas stream to be treated is supplied into said hot gas stream to thereby continuously decompose N2O;
• and
• (4) a N2O decomposition heat recovery step in which the N2O decomposition heat emitted from the N2O decomposition step is recovered.

An apparatus for thermally decomposing N2O-containing gas, said apparatus comprising:

• (a) an introduction section wherein the N2O-containing gas is divided into at least two portions;
• (b) a preheating section for at least one of the at least two portions of the N2O-containing gas from the introduction section (a);
• (c) a thermal decomposition section positioned adjacent to the preheating section, said thermal decomposition section having a component for supplying at least one of the at least two portions of the N2O-containing gas from the introduction section (a) without entering preheating section (b), said supplying component being provided at one or more positions in the flow direction of a gas stream;
• and
• (d) a discharging section for the thermally decomposed gas.

An apparatus for bringing N2O, which is a global warming agent, in a N2O-containing gas into contact with a catalytic bed to thereby catalytically decompose N2O, said apparatus comprising:

• (a) an introduction portion for the gas to be treated and/or a diluent gas;
• (b) a mixing portion for the gas to be treated and/or the diluent gas;
• (c) a mixing portion having one or more components for supplying the gas to be treated and/or the diluent gas at different positions in the longitudinal direction of the apparatus;
• (d) a catalytic decomposition portion having the catalytic bed;
• and
• (e) a discharging portion for the catalytically decomposed gas.