Terumitsu Kakumoto

Thermal unimolecular decomposition of formic acid

The initial steps involved in the thermal decomposition of formic acid in the temperature range of 1370–2000 K have been investigated by monitoring the IR emission intensities at 3.4 and 4.6 μm, corresponding to the reactant and carbon monoxide, respectively, behind reflected shock waves in mixtures diluted in Ar (0.1–1.5 mol%, total densities 5.3×10−6–3.2×10−5 mol cm−3). It was found that the decomposition proceeded via channel (1) HCOOH+Ar→CO+H2O+Ar dominantly and the contribution of channel (2) HCOOH+Ar→CO2+H2+Ar was very small. An Arrhenius expression of the second order rate constant was obtained as k1,0 =1014.32  exp(−40.4 kcal mol−1/RT) cm3 mol−1 s−1. Ab initio calculations were performed for probable transition states (TS) of channels (1) and (2). The results showed that the potential energy for a TS of channel (1) was lower than that of channel (2) by 20–30 kcal mol−1. On the basis of a RRKM weak collision, k2,0 values were estimated which was smaller than k1,0 by about two orders, being consiste...

Theoretical and experimental study on metal-loaded zeolite catalysts for direct NOx decomposition

Component effects such as a cocation and the zeolite support structure and the preparation condition effect of metal-loaded zeolites for the catalytic activity of direct NOx decomposition were examined using an experimental method. Regarding the cocation effect, the theoretical calculations were performed using a density functional method. The experimental results indicated that ZSM-5 was the best support of all of the zeolite tested such as ZSM-5, ZSM-11, SAPO-5, Y, and MOR. It was also experimentally found that the addition of a cocation such as Ca or Ni to Cu ion-exchanged ZSM-5 zeolite (Cu/ZSM-5) could prevent the catalyst from deactivation caused by O2 or H2O in the reaction gas. Regarding the cocation effect of Ca or Ni on Cu/ZSM-5, the theoretical calculations showed that the addition of these cocations increased the catalytic activity by promoting the desorption of oxygen yielded from NO decomposition and maintained NO adsorption on the catalyst under the coexistence of H2O. These results of the calculations supported the experimental results.

Thermal unimolecular decomposition of formyl fluoride in Ar

Abstract The thermal decomposition of formyl fluoride in Ar has been studied behind shock waves over the temperature range 1160–1480 K and the total density range (7.18–18.6) × 10 −6 mol cm −3 . The decomposition was monitored by means of IR emission from the CH stretching of the reactant and the fundamental band of the CO produced. The decomposition was found to be molecular elimination producing HF and CO and the process proceeded in the low-pressure region under the present conditions. The second-order rate constant was expressed as k /Ar = 10 14,74 exp(−35.2 kcal mol −1 / RT ) cm 3 mol −1 s −1 . Applying the RRKM strong collision theory, the value of the threshold energy and the collision efficiency were discussed.

A study of the isomerization of acetonitrile at high temperatures

Abstract The thermal isomerization of acetonitrile to methyl isocyanide was investigated in the temperature range 1600–2100 K behind reflected shock waves. An Arrhenius expression for the low-pressure rate constant was obtained as, k o /Ar = 10 13.40 exp(−159 kJ mol −1 / RT ) cm 3 mol −1 s −1 . By connecting with the data for the reverse reaction at lower temperatures, the temperature dependences of the weak collision parameters, β c and (Δ E ), were found to be large.