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Understanding non-thermal plasma reactivity is a complicated task as many reactions take place due to a large energy spectrum. In this work, we used a well-defined photo-triggered non-filamentous discharge to study acetone decomposition in N2/O2 gas mixtures. The plasma reactor is associated to a compact chemical ionization FTICR mass spectrometer (BTrap) in order to identify and quantify in real-time acetone and by-products in the plasma. Presence of oxygen (1 to 5%) decreased notably acetone degradation. A tremendous change is observed in the by-products distribution concomitantly to a global decrease of their total concentration. While main products observed in oxygen-free gas mix are nitrile compounds, in oxygenated media they are replaced by formaldehyde, methanol and ketene. Methanol is maximum for 1% of O2 whereas formaldehyde and ketene concentration reach their maximum value at the highest oxygen concentration tested (5%). A number of nitrate, nitrite and isocyanate organic compounds (C1 and C2) are observed as well with HNO2, HNO3 and HNCO. [ABSTRACT FROM AUTHOR]

We compare the predictions of our recently developed statistical molecular fragmentation (SMF) model with experimental results from plasma induced hydrocarbon decay. The SMF model is an exactly solvable statistical model, able to calculate the probabilities for all possible fragmentation channels as a function of the deposited excitation energy. The weights of the channels are calculated from the corresponding volume of the accessible phase space of the system, taking into account all relevant degeneracies, symmetries and density functions. An experiment designed to study the abatement of propene in N2 using a photo-triggered discharge producing a homogeneous plasma at sub-atmospheric pressure was also performed. Using a 0D model that simulates the complex chemical kinetics in the plasma, it was possible to assess the percentages of the original parent hydrocarbon's fragmentation channels based on the detected species. These results were compared to those obtained from the SMF model. Previous plasma induced hydrocarbon fragmentation experiments for ethene, ethane and propane, were also compared to the predictions of the SMF model. For energies below that of metastable dinitrogen (i.e. below 6.17 eV and 8.4 eV), the SMF model and the experimental fragmentation channels coincide. This study allows one to draw conclusions both on the range of excitation energies transferred to the parent hydrocarbon molecules during plasma discharge and on the probability of the dynamical coupling of two H atoms from neighbouring carbon atoms to form H2 molecules. [ABSTRACT FROM AUTHOR]

The fragmentation of molecules under conditions that result in yields of products that are thermodynamically controlled can be readily studied with statistical models. We explore which parameters influence the branching ratios using our recently developed Statistical Molecular Fragmentation model (SMF) and apply it to the decomposition of propane. We find that the fragmentation process has low sensitivity to the differences between the molecular descriptions given by commonly used ab initio methods (B3LYP, CCSD(T) and composite methods with different atom-centered basis sets). However, the branching ratios are most influenced by the vibrational frequencies of the molecules and radicals present in the decomposition pathways. [ABSTRACT FROM AUTHOR]

Nanosized EMT-type zeolite crystals in sodium (Na-EMT) and ion-exchanged lithium (Li-EMT) forms were prepared. The sorption behavior of Li(Na)-EMT samples towards water, methanol and a mixture of both (50 : 50) was studied by combined thermogravimetric and infrared spectroscopic methods. The stability of the samples prior to and after the sorption measurements in two subsequent cycles was confirmed by X-ray diffraction, N2 sorption and NMR spectroscopy. The high sorption capacity of the Li-EMT sample towards water was demonstrated. It was found that the methanol is replaced by water faster in the Li-EMT sample in comparison to the Na-EMT sample. At low temperature, the methanol shows weak adsorption on each cationic site and no side products during desorption for both samples were obtained. [ABSTRACT FROM AUTHOR]

Understanding non-thermal plasma reactivity is a complicated task as many reactions take place due to a large energy spectrum. In this work, we used a well-defined photo-triggered non-filamentous discharge to study acetone decomposition in N 2 /O 2 gas mixtures. The plasma reactor is associated to a compact chemical ionization FTICR mass spectrometer (BTrap) in order to identify and quantify in real-time acetone and by-products in the plasma. Presence of oxygen (1 to 5%) decreased notably acetone degradation. A tremendous change is observed in the by-products distribution concomitantly to a global decrease of their total concentration. While main products observed in oxygen-free gas mix are nitrile compounds, in oxygenated media they are replaced by formaldehyde, methanol and ketene. Methanol is maximum for 1% of O 2 whereas formaldehyde and ketene concentration reach their maximum value at the highest oxygen concentration tested (5%). A number of nitrate, nitrite and isocyanate organic compounds (C1 and C2) are observed as well with HNO 2 , HNO 3 and HNCO.

An improved micro-reactor cell for IR spectroscopic studies of heterogeneous catalysis was built around a 5.8 GHz microwave cavity. The reactor can operate at 20 bars and with conventional heating up to 720 K, with reactant gas flows velocities (GHSV) from 25,000 to 50,000 h(-1). The temperature of the sample under microwave irradiation was measured by time resolved IR emission spectroscopy. The first experiment performed was the IR monitoring of the desorption of carbonates induced by irradiating an alumina sample by microwaves at 5.8 GHz.