## 4 Conclusions  
A new plasma reactor was designed for H\({}_{2}\) formation from C\({}_{4}\)H\({}_{10}\)/C\({}_{3}\)H\({}_{8}\) gas mixture (LPG) conversion. The plasma discharge was formed by an AC voltage applied to the developed plasma reactor at atmospheric pressure. The discharge was investigated in two phases, namely, the stationary and rotating power electrodes. A filamentary mode was found in the plasma, where the electron current was due to high numbers of current discharges between the electrodes. The dissociation processes were attributed to two processes: the electron collision with propane and butane molecules and the dynamic of these filaments. The present discharge produced the dissociation of C\({}_{4}\)H\({}_{10}\)/C\({}_{3}\)H\({}_{8}\) molecules, and H\({}_{2}\) and C\({}_{2}\) formations under all the studied conditions. GC measurements permitted the estimation of the conversion factors for these species and the obtained values were 70% and 60%, respectively. The energy efficiency of converted LPG in the designed reactor was also investigated and it was shown that the energy efficiency reduced by increasing the applied voltage and gas flow rate while it increased with an increase in the rotation frequency of the power electrode. The energy efficiency was equal to 1.17 mmol/kJ for the rotation frequency of 9000 rpm that increased to 1.35 mmol/kJ for the rotation frequency of 18,000 rpm, showing the efficiency of the rotating electrode design. The dependence of conversion factors and energy efficiency on the experimental conditions was explained by the number of filaments formed in the reactor. These good results of the LPG conversion were accompanied by an efficient formation of H\({}_{2}\). The selectivity in this plasma reactor reached 98% for the highest electrode rotation frequency. The results are explained by the plasma condition in the filamentary discharge. A spectroscopic study was performed to determine the species presented in the discharge and the values of the main parameter of this plasma. Hydrogen atoms and molecules, C\({}_{2}\) molecules and CN radicals were the predominant species detected using OES measurements. These species were the results of the dissociation of C\({}_{4}\)H\({}_{10}\)/C\({}_{3}\)H\({}_{8}\) molecules by the electron collision processes and recombination with air contaminants in the discharge. The high values obtained of the electron densities and temperatures confirm that the kinetic of the dissociation is governed by electron impact. The gas temperatures were obtained by a spectra simulation of the C\({}_{2}\) band. Moreover, the first five lines of hydrogen atoms were used to calculate the electron temperature by a modified Boltzmann plot. By the comparison of these temperature values, a 2-temperatures non-equilibrium plasma was found, where the electron temperature was much higher than the translational heavy particles, about 15,000 K and 1200 K, respectively. Figure 15: Variations of the electron number density in terms of (**a**) different voltages applied on the stationary power electrode at 1 sLm gas flow rate (1% error), (**b**) rotational frequencies of power electrode at 14 kV applied voltage and 1 sLm gas flow rate (1% error), and (**c**) gas flow rates at 14 kV applied voltage and 18,000 rpm rotation frequency of the power electrode (2% error). The electron density was found to grow with the rotating electrode, passing from \(1.9\times 10^{15}\) cm\({}^{-3}\) to \(2.7\times 10^{15}\) cm\({}^{-3}\). The secondary ionization processes of the H\({}_{2}\) molecules, whose numbers were increased, can explain this behavior. Conversely, the gas and electron temperatures decreased with the electrode rotation frequency, therefore, it is obvious that the electric power is shared between a high number of particles, reducing their kinetic energy. In conclusion, the rotating electrode stage permits the improvement of H\({}_{2}\) production in comparison to the stationary stage with a reduction in the power and LPG gas consumption.