IMPROVED CONTROL AND OPTIMIZATION IN PRODUCTION METHOD OF PROPYLENE OXIDE

PROBLEM TO BE SOLVED: To provide a method for measuring oxygen concentration in propylene oxide, which is being processed, more quickly, correctly and precisely.SOLUTION: The method controls the limiting oxygen index of a reactor having an inlet port and/or an outlet port for producing propylene oxide. The method includes the steps of: (I) extracting a process sample through a tightly bound loop for an extraction sample, with an analyzer disposed close to a sampling point; (II) generating detected signals by irradiating, through a gas cell containing the process sample, an infrared light detector with a wavelength modulated light of near infrared ray from wavelength variable diode laser; (III) determining the oxygen concentration in the sample by analyzing detected signals of the spectral absorption at a wavelength specific to oxygen; and (IV) adjusting the oxygen concentration at the inlet port and/or the outlet port of the reactor for propylene oxide according to the oxygen concentration in the step (III) as necessary.