Methanol Optimization in a DBD Plasma Reactor: Using RSM Method and Variables Survey

In this study, direct conversion of methane to methanol in the plasma process was attended. Besides, RSM modeling was used to optimize and evaluate parameters such as voltage, the flow rate of CH4, Ar, and external electrode length. RSM prediction model by the desired condition including minimized Ar (20 mL/min), O2 (2 mL/min), CH4 (2 mL/min), and voltage (4 kV) was used to determine the effect of Ar and CH4 in reactions. The results showed that increasing the Ar flow from 20 to 100 mL/min led to less methanol mole percent. On the other hand, enhancement in methane flow rate from 2 to 12 mL/min was the reason for raising the methanol mole percent at the reactor outlet. To determine how modifying the length of the external electrode affected the mole percent of methanol, the length was lowered from 12.5 to 2 cm, clearly reducing the amount of methane converted. However, it was effective in raising the methanol mole percent to 3% in E.EFF 0.13 mmole/kJ and length of electrode 4 cm. As well as the methanol mole percent in the least energy efficiency E.EFF 0.045 mmole/kJ detected at 2.27%. To summarize, in DBD plasma reactor by direct conversion of methane, increasing in voltage and Ar flow rate had a significant influence on the progress of the process which had an unfavorable effect on methanol mole percent. Meanwhile, the enhancement of CH4   flow rate had an impressive effect on the raising of methanol. Furthermore, the influence of oxygen flow was negligible.