Selective conversion of methane to synthetic fuels using dielectric barrier discharge contacting liquid film

Abstract

This paper presents the reaction mechanism of single-step methane partial oxidation to methanol at room temperature using non-thermal plasma microreactor. Macroscopic quantities of hydrogen peroxide (H2O2) and methyl hydroperoxide (CH3OOH) are produced when methane is partially oxidized at room temperature (about 5 °C). CH3OOH is known to be the principle intermediate of incomplete methane oxidation product such as CH3OH and HCHO, but has not been demonstrated experimentally so far. H2O2 promotes post-plasma oxidation of oxygenates in the condensed plasma-synthesized liquid. At an early stage of in-liquid oxidation, H2O2 oxidizes HCHO into HCOOH preferentially; subsequently, HCOOH is fully oxidized to CO2 and H2O. Depending upon the concentration of oxygenates and H2O2, electrical conductivity of the plasma solution dramatically increased, which detrimentally influences plasma properties. Methane partial oxidation with air was also investigated from a practical viewpoint. Generation of active nitrogen species (ANS) is the key to promoting overall methane conversion in the presence of oxygen; however, fragile oxygenates were also decomposed by ANS, thus selectivity for useful oxygenates was degraded in the presence of nitrogen. When oxygen is fully consumed, CH4 conversion is also terminated and water gas shift reaction (CO + H2O = CO2 + H2) becomes predominant.

Effects of Reactor Packing Materials on H2 Production by CO2 Reforming of CH4 in a Dielectric Barrier Discharge

“…The low CO 2 conversions may also be the result of the water gas shift (WGS) reaction as shown in Equation (14). Previous study suggested that an appropriate combination of plasma and catalyst could enhance the WGS reaction at low temperatures 48. In our study, it is interesting to note that fully packing different materials into the discharge gap leads to an increase in H 2 /CO molar ratio and a decrease in the selectivity of CO in comparison to the plasma dry reforming reaction with no packing material, which confirms the enhancement of the WGS reaction.…”

The Dominant Pathways for the Conversion of Methane into Oxygenates and Syngas in an Atmospheric Pressure Dielectric Barrier Discharge

“…On the other hand, in the 70/30 CH 4 /O 2 gas mixture, these reactions are negligible compared to the three-body recombination reaction with O 2 molecules, forming CH 3 O 2 radicals (see figure10(b)). This is in good agreement with Nozaki et al40 and Goujard et al41 , who also discussed the importance of the formation of CH 3 O 2 in the methane partial oxidation mechanism towards the formation of (c) Formation of syngas In Figure 11(a) and figure 11(b) the most important channels for production and loss of CO in a 70/30 CH 4 /CO 2 and a 70/30 CH 4 /O 2 gas mixture are illustrated, respectively. 90% of the CO formation occurs through the reaction of O 2 molecules with CHO radicals.…”

Surface-engineered silicon nanocrystals

“…19,31,34,[86][87][88]97,98,102 and a much wider range of materials and applications are possible. 103,104 Here we will focus however only on the surface treatment of Si-ncs that have been presynthesized by electrochemical etching and dispersed either in water or ethanol. For the electrochemical etching process, similarly to our previous work, 105 we have used p-type borondoped silicon wafers (h100i, 0.1 U cm, thickness 0.525 mm).…”