Development of an Atmospheric Plasma Generator for Nitrogen Fixation in Air

Nitric acid (HNO3) is used to produce fertilizers, explosives, nylons, polyurethanes, and a variety of other industrial chemicals. The state-of-the-art manufacturing method uses methane (CH4) as a feedstock for hydrogen and an energy intensive thermal process that emits a large amount of carbon dioxide. A new low-temperature plasma system, which can be driven electrically by a renewable or nuclear energy source, could reduce the energy consumed by the synthesis of nitric acid while eliminating the emission of greenhouse gases. Recent technology advances will be leveraged to meet a unique customer need in creating the first commercially successful low-temperature plasma-enhanced system. A novel low-temperature plasma generator will be developed that will synthesize nitric acid using electricity, air, and water while reducing energy consumption and greenhouse gas emissions. The system uses a new atmospheric-pressure pulsed-DC driven dielectric barrier discharge plasma generator with key features designed to selectively optimize the generation of NO2, which will mix with water to form nitric acid. The novel generator design offers advantages in rise time, multi-frequency operation, and locally enhanced electric field strength for efficient nitrogen fixation. The Phase I project will demonstrate and quantify the efficiency of the new process relative to existing state-of-the-art techniques. An advanced low-temperature plasma generator for NO2 synthesis from air will be built and tested using a custom pulsed-DC power supply. The production rates of NO and NO2 will be measured experimentally using industry-standard equipment for a wide range of operational conditions to determine parameter sensitivity and scaling behavior. Additional tasks include investigating catalysts for improving the NO2 yield and reducing energy consumption, measuring the ozone and N2O rates to confirm negligible production of hazardous byproducts, and designing a larger scale prototype for Phase II testing. The explosives industry would like to have the ability to manufacture their product in-situ at the point of use. One key ingredient is nitric acid, which is combined with ammonia to form ammonium nitrate. The proposed low-temperature plasma process will allow nitric acid to be synthesized on-site and in-situ using little more than air, water, and electricity. Success in the explosives market will create opportunities in the much larger (but harder to penetrate) fertilizer industry, as well as other industrial markets. A process that can synthesize nitric acid at lower energy cost and – when powered by a renewable energy source – emitting no greenhouse gases will have significant commercial and societal value.