Masahiro Kaise

Rate constants for the reactions of OH radicals with CF3OCF=CF2 and CF3CF=CF2

Abstract The rate constants for the reactions of OH radicals with trifluoromethyl trifluorovinyl ether (CF 3 OCF=CF 2 ) and hexafluoropropene (CF 3 CF=CF 2 ) have been measured over the temperature range 250–430 K. Kinetic measurements have been carried out using the flash photolysis and laser photolysis methods combined, respectively, with the laser-induced fluorescence technique. The Arrhenius rate constants have been determined as k (CF 3 OCF=CF 2 )=1.01 −0.04 +0.04 ×10 −12 exp [(320±10)/T] , and k (CF 3 CF=CF 2 )=8.74 −0.33 +0.34 ×10 −13 exp [(260±10)/T] cm 3 molecule −1 s −1 .

Spontaneous ignition limits of silane and phosphine

Abstract Spontaneous ignition limits of silane and phosphine have been investigated at relatively low concentrations. For silane, the spontaneous ignition occurs if the mixture concentrations is such that the silane/oxygen ratio is higher than a certain threshold limit value. In other words, the mixture is not stable if the ratio is higher than a certain value. On the other hand, in the case of phosphine the threshold limit line has been found to be a little curved, though the reason for the fact is not clear. At any rate, it is concluded that the spontaneous ignition of both silane and phosphine occurs as a result of a competition of chain branching and chain breaking reactions, in a way that is qualitatively similar to that in hydrogen oxidation.

A Numerical Study of Low Temperature Silane Combustion

Abstract A mechanism of low temperature silane combustion has been proposed in the present work based on the assumption that a trace amount of water vapor helps the occurrence of spontaneous ignition at room temperature. This assumption has been made based upon the fact that the combustion product of silane influences positively the occurrence of spontaneous ignition. Energetic calculation of the reaction path way for low temperature silane combustion also supports this assumption [Kondo et al., 1999]. A numerical model has been constructed which can interpret the spontaneous ignition limit at room temperature, the ignition delay times, and the second explosion limit of silane mixtures simultaneously.

Rate constants for the reactions of OH radicals with CH3OCF2CHFCl, CHF2OCF2CHFCl, CHF2OCHClCF3, and CH3CH2OCF2CHF2

The rate constants for reactions of OH radicals with CH3OCF2CHFCl, CHF2OCF2CHFCl, CHF2OCHClCF3, and CH3CH2OCF2CHF2 have been measured over the temperature range 250–430 K. Kinetic measurements have been carried out using the flash photolysis, laser photolysis, and discharge flow methods, combined with the laser-induced fluorescence technique to monitor the OH radical concentration. The influence of impurities contained in the samples has been examined by means of sample purification using gas chromatography. No sizable effect of impurities was found on the measured rate constants of these four halogenated ethers when the purified samples were used in the kinetic measurements. The Arrhenius rate constants have been determined from the respective kinetic data as k(CH3OCF2CHFCl) = (2.59±0.51) × 10−12 exp [−(1260±60)/T], k(CHF2OCF2CHFCl) = (7.46±1.85) × 10−13 exp [−(1230±80)/T], k(CHF2OCHClCF3) = (1.12±0.18) × 10−12 exp [−(1280±50)/T], and k(CH3CH2OCF2CHF2) = (2.57±0.44) × 10−12 exp [−(730±50)/T] cm3 molecule−1 s−1.

Ab initio study of reactions between halogen atoms and various fuel molecules by Gaussian-2 theory

Ab initio calculations by using Gaussian-2 theory have been carried out for the reactions between halogen atoms and various fuel molecules, i.e. fluorine, chlorine, and bromine atoms vs. hydrogen, methane, ethane, ethylene, acetylene, ammonia, silane, dichlorosilane and phosphine. The activation energy for the reaction between a halogen atom and a fuel molecule seems to indicate whether the reaction between the fuel gas and the corresponding halogen gas occurs spontaneously when they are brought into contact to each other at room temperature.

Experimental study of spontaneous ignition limit of oxygen-lean silane mixtures

Abstract The spontaneous ignition of a premixed silaneoxygennitrogen system has been investigated under a variety of conditions. It has been found that the autoignition temperatures are lower than room temperature if the oxygen concentration is extremely low. The spontaneous ignition of silane results from the extremely oxygen-lean mixtures instantaneously produced when silane or silane mixture is poured into the air.

Preparation of 1,5-dinitrenonaphthalene in cryogenic matrices

1,5-Dinitrenonaphthalene was prepared in two cryogenic matrices by photolysis of 1,5-diazidonaphthalene; the cryogenic matrices were an argon matrix at 11 K and a glassy 2-methyltetrahydrofuran matrix at 77 K; the photolysis was analyzed by UV-VIS, FT-IR, and ESR matrix isolation spectroscopies.