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Hydrogen Production from Ethanol Decomposition by Two Microwave Atmospheric Pressure Plasma Sources: Surfatron and TIAGO Torch

Molecular hydrogen production from ethanol decomposition by two microwave atmospheric pressure plasma sources (surfatron and Torche a Injection Axiale sur Guide d’Onde (TIAGO) torch) was studied by optical emission spectroscopy and mass spectrometry. In both cases ethanol was almost completely decomposed, thus giving place to molecular hydrogen. However, the atmosphere surrounding the discharge significantly influences the overall decomposition process. When the surfatron is used, C2H2 and CO are obtained as exhaust gases. Likewise, H2O and HCN are also detected at plasma exit when sustained with the TIAGO torch.

Decomposition of Ethanol in a Surface Wave Discharge at Atmospheric Pressure

Surface wave discharges at atmospheric pressure for synthesis processes are attractive since low power and flow gas are required; in addition, no catalyst is necessary. These features have been used to develop a process for hydrogen production using ethanol as a reagent. Different plasma gas flows have been used, resulting in a different magnitude of alcohol decomposition. Images of the resulting plasmas are presented.

Synthesis of multi-layer graphene and multi-wall carbon nanotubes from direct decomposition of ethanol by microwave plasma without using metal catalysts

The synthesis of nanostructured carbon materials by using microwave plasmas at atmospheric pressure is presented. This technique involves only one step and without any other supplementary chemical process or metal catalyst. Multi-layer graphene, multi-wall carbon nananotubes and H2 were obtained by the plasma after ethanol decomposition. Strong emissions of both C2 molecular bands and C carbon were emitted by the plasma during the process. Futhermore, plasma parameters were studied. Our research shows that both C2 radicals and high gas temperatures (>3000 K) are required for the synthesis of these materials, which contribute to the understanding of materials synthesis by plasma processes.

Hydrogen and By-Products Formation After the Decomposition of Ethanol by Means of a Microwave Plasma Torch at Atmospheric Pressure

Argon TIAGO torch plasma in air ambience has been studied to produce the decomposition of ethanol obtaining hydrogen at the plasma exit. Dependence of by-products formed on ethanol flows has been studied. Ethanol molecules were completely decomposed, and an important conversion to hydrogen was obtained. Images of plasma generated in these conditions are presented.

Tailored Waveform of Dielectric Barrier Discharge to Control Composite Thin Film Morphology

Nanocomposite thin films of TiO2 in a polymer-like matrix are grown in a filamentary argon (Ar) dielectric barrier discharge (DBD) from a suspension of TiO2 nanoparticles in isopropanol (IPA). The sinusoidal voltage producing the plasma is designed to independently control the matrix growth rate and the transport of nanoparticle (NP) aggregates to the surface. The useful FSK (frequency shift keying) modulation mode is chosen to successively generate two sinusoidal voltages: a high frequency of 15 kHz and a low frequency ranging from 0.5 to 3 kHz. The coating surface coverage by the NPs and the thickness of the matrix are measured as a function of the FSK parameters. The duty cycle between these two signals is varied from 0 to 100%. It is observed that the matrix thickness is mainly controlled by the power of the discharge, which largely depends on the high-frequency value. The quantity of NPs deposited in the composite thin film is proportional to the duration of the low frequency applied. The FSK waveform has a double modulation effect, allowing us to obtain a uniform coating as the NPs are not affected by the high frequency and the matrix growth rate is limited when the low frequency is applied. When it is close to a frequency limit, the low frequency acts like a filter for the NP aggregates. The higher the frequency, the smaller the size of the aggregates transferred to the surface. By changing only the FSK modulation parameters, the thin film can be switched from superhydrophobic to superhydrophilic, and under suitable conditions, a nanocomposite thin film is obtained.

Influence of Ambient-Air Nitrogen on the Argon Plasma Generated by a TIAGO Torch Open to Atmosphere

Microwave-torch plasmas sustained in easy-to-ionize gases such as argon are strongly affected by the presence of nitrogen when emerging into ambient air. Examination of pictures of their flame as a function of distance from the torch tip provides information to the setting of operating conditions (gas flow and microwave power) such as to minimize contamination of the discharge by nitrogen.