Azuchi Harano

Emission of O- Radical Anions from a Solid Electrolyte Surface into the Gas Phase

We have observed the emission of O- radical anions from a solid electrolyte surface. A simple experimental apparatus was designed to incorporate a gap between a YSZ (yttria stabilized zirconia) anode and a stainless steel space electrode. By applying a DC voltage of 100 V across the gap, O- radical anions and electrons were produced which could be detected using a quadrupole mass spectrometer. Recently, Greber et al.. reported the observation of O- radical anion emission from a cesium-coated surface when the surface was exposed to thermal oxygen molecules. However, this method cannot maintain O- emission without adsorbed oxygen molecules. In the present work, the possibility of obtaining continuous emission of O- from a YSZ surface was examined.

Decomposition of gaseous hydrocarbons in a laser-induced plasma as a novel carbonaceous source for cluster formation

Abstract Simple gaseous hydrocarbons included in a He carrier gas were decomposed in a laser-induced plasma on a graphite or silicon rod, which was found to be convenient for supplying carbonaceous species into the carrier gas for cluster formation. When a silicon rod was used, silicon—carbon mixed clusters and high-mass carbon clusters were produced. This fact implied that carbon clusters were formed via growth from smaller carbonaceous species. The mass distribution of carbon clusters was not dependent on the kind of the adopted hydrocarbons, which implied that the growth processes of the clusters were not appreciably influenced by the coexisting hydrocarbon gases.

Zeolite Sensor for Nitrogen Monoxide Detection at High Temperature

Development of new NO{sub x} sensors, which would be sensitive, selective, inexpensive and stable at elevated temperature, will greatly contribute to the reduction of the air pollution. In this paper, synthesis and performance of zeolite film applied for gas sensing are reported. Zeolite thin films (Cu ion-exchanged ZSM-5) were synthesized on the gold electrode at AT-cut quartz platelet by hydrothermal synthesis. In order to probe the target molecule (NO) selectively, Na in as-synthesized ZSM-5 film was ion-exchanged with Cu. The films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The synthesis condition for orientation to (0 x 0) face, on which the straight pores of ZSM-5 are opening, was optimized. The bulk type quartz oscillator coated with Cu-ZSM-5 thin layer was tested as NO sensor in a flowing stream of He. This sensing system could be operated at high temperature because of the thermal stability of the ZSM-5 film and the gold electrode. As a result, NO was successfully detected at 348 K.

Development of selective noncatalytic reduction by ammonia in the presence of phenol

Abstract The thermal de-NO x process is one of the most effective methods of reducing the NO x in flue gas. A shortcoming in this process is the narrow temperature range of 870°C to 1100°C in which effective reduction of NO occurs. We approach this problem by adding an agent to the system in order to shift the temperature range to a lower one. The agent that was added was an aqueous solution containing trace amounts of phenolic compounds which is one of the industrial waste products of fluidized catalytic cracking (FCC) in petroleum refinement. The effect of the addition of an aqueous phenol solution on the thermal de-NO x process was investigated in a quartz flow reactor at a temperature, pressure, and residence time of 650–820°C, 1.0 atm, and 1.0–1.2 s, respectively. In the case of 0–400 ppm phenol addition at NO/NH 3 = 1.0, O 2 = 4%, NO = 400 ppm, and H 2 O = 7.4%, profiles of NO, N 2 O, NO 2 , NH 3 , CO, CO 2 , C 2 H 2 , and phenol concentrations were experimentally obtained. The NO concentration significantly decreased over the wide temperature range of 675–820°C.

Cluster formation by laser ablation of zeolites

Several kinds of zeolites, crystal-SiO{sub 2} ({alpha}-quartz), amorphous SiO{sub 2} (quartz glass and ultrafine particles) and {alpha}-Al{sub 2}O{sub 3}, were ablated by an Nd:YAG laser. Generated positive ions from the targets were measured by TOF-MS (time-of-flight mass spectrometry). In the TOF mass spectra of ablated zeolites, TO{sub x} (x = 0--2, T = tetrahedral atom, e.g., Si, Al), T{sub 2}O{sub x} (x = 1) and T{sub 3}O{sub x} (x = 4,5) were observed up to m/z = 170 (m = mass, z = plus charge of clusters). In the spectra due to the {alpha}-quartz, quartz glass and an {alpha}-Al{sub 2}O{sub 3} plate, smaller species, T{sup +}, TO{sup +} and TO{sub 2}{sup +}, were mainly detected. These results demonstrate that the clusters from zeolites reflect the characters of the mother structure.