Tohru Okabayashi

A new method for recognizing organic vapor by spectroscopic image on cataluminescence-based gas sensor

Abstract ‘Cataluminescence’ is a kind of chemiluminescence emitted during catalytic oxidation of combustible gas. This paper describes a new method using a system which can measure spectroscopic images on a cataluminescence-based sensor to discriminate and determine concentrations of organic vapors in air. Using this equipment, we can measure continuously the image of ‘cataluminescence’ intensity, which reflects the type and concentration of organic vapor, as a function of wavelength and catalyst temperature. Not only the difference between alcohol and ketone, but also the kind of alcohol, e.g. ethanol and butanol, can be distinguished and determined quantitatively by means of this system.

High sensitive hydrocarbon gas sensor utilizing cataluminescence of γ-Al2O3 activated with Dy3+

A new method using cataluminescence (CTL)-based gas-sensor detecting hydrocarbon in air is proposed. CTL is a kind of chemiluminescence (CL), which is emitted during catalytic oxidation of organic vapors, e.g., ethanol and acetone. By depositing Dy on the γ-Al2O3 catalyst, we measured the extra CTL spectrum due to Dy3+ during the catalytic oxidation of hydrocarbon gas, while no such CTL was emitted from the γ-Al2O3 catalyst without Dy. By investigating the luminescence mechanism of Dy, the existence of active species produced in a course of catalytic oxidation to excite Dy directly was clarified. The CTL-based gas-sensor using γ-Al2O3 activated with Dy3+ has high sensitivity and linear characteristic. The detection limit of iso-butane in air is 0.2 ppm.

A Novel Sensing System for Glucose in a Solution Based on Cataluminescence

A novel sensing system for glucose in aqueous solution based on cataluminescence(CTL) is proposed. CTL is a kind of chemiluminescence emitted in a course of catalytic oxidation of combustible substances. A sensing system consisting of a CTL-based chemical-sensor made of the γ-Al 2 O 3 catalyst activated with Tb and an ultrasonic nebulizer is developed. CTL is emitted by injection of air containing mist of a glucose solution prepared by the nebulizer on the catalyst. The CTL intensity measured by a photomultiplier is reproducible for the repeated injection of the mist, and the system can measure glucose concentration in a range of 1-200 mg/dl.

A Chemiluminescence-Based Multi-Sensor System for the Analytical Detection of Gases

An analytical gas-detection system using an array of cataluminescence(CTL)-based gas-sensor is proposed for determination and discrimination of terpene vapors which have fragrance of lily of the valley, orange and pine needle. Chemiluminescence during catalytic oxidation is emitted by oxidation of these terpene vapors on catalysts of γ-Al2O3, CaCO3 and ZrO2 doped with Dy, and none-doped γ-Al2O3. In sequential heating-cooling course of the CTL-based sensors made of these catalysts between room temperature and 660 °C, the integrated CTL intensity L depends on the kind of catalysts and type of these vapors. Furthermore, the values of L measured by four kinds of sensors show a specific pattern depending on the type of vapors. By comparing these patterns, we can discriminate the type of vapors of limonene, linalool and pinene. The value of each L is proportional to the concentration of each vapor, and the detection limit of these terpene vapors in air is between 16 and 500 ppb.