Plasma synthesis of ammonia by asymmetric electrode arrangement

ABSTRACT

The plasma reactors are of great interest in ammonia synthesis because of their green performance, small-scale process capabilities, and various design and application options. The purpose of this research is to synthesize water-soluble ammonia by plasma electrolysis which utilizes nitrogen atmospheric pressure plasma generated by DC discharge. Then, we investigate the influence of the plasma characteristics such as the electron temperature and density on the resultant ammonia concentration. For this purpose, the model of the Hoffman electrolysis apparatus was designed for separating the anodic and the cathodic parts, producing plasma, and finally interacting with an aqueous solution surface. This procedure allows us to compare the mechanism of the classical electrolysis with plasma electrolysis. The concentration of synthesized ammonia resulting from the reaction of active species in the interaction between plasma and the liquid surface on the cathode side of the device was obtained. The plasma electron temperature and density were measured by the standard Boltzmann plot method and the Stark broadening of ${\mathrm{H}}_{\beta }$via optical emission spectroscopy (OES), respectively, and their effects on the interaction between plasma and the water surface were investigated, which leads to nitrite and ammonia synthesis. The intensity of the emitted light varied as the discharge voltage was increased according to 8kV, 9kV, 10kV, and 11kV. As a result, the plasma electron temperature, density, and the synthesis of additional water-soluble ammonia parameters increase. Multiple parameter linear regression was used to evaluate the effect of varying the voltage on these parameters, which was positive.

KEYWORDS:

• Plasma
• electrolysis
• ammonia
• temperature
• density

Disclosure statement

No potential conflict of interest was reported by the author(s).