Electrification of the Chemical Industry with Plasma Technology
The project "Plasma Conversion of Methane" is part of the NXTGEN Hightech Growth Fund program, which focuses on developing innovative technologies for a more sustainable future. During the 2024 AIChE® Annual Meeting in San Diego, the leading educational forum for chemical engineers pursuing innovation and professional growth, Dirk van den Bekerom from TNO presented the latest developments within this project. His presentation emphasized the crucial role of electrification within the chemical industry to reduce CO₂ emissions and contribute to the 2030 and 2050 climate goals.
A Sustainable Future for the Chemical Industry
The chemical industry significantly contributes to global CO₂ emissions, with processes such as naphtha cracking and hydrogen production for fertilizers being major polluters. Naphtha cracking, an endothermic process heated by burning the by-product methane, produces approximately 1 ton of CO₂ per ton of olefins. When these processes are electrified and green electricity is used, CO₂ emissions can be significantly reduced. Hydrogen production for fertilizers even generates 9 tons of CO₂ per ton of H₂. Additionally, the production of nitric acid from ammonia results in the by-product N₂O, a greenhouse gas with 273 times the effect of CO₂. Electrification of these processes is essential to achieve the 2030 and 2050 climate goals.
Plasma Technology: The Power of Electrical Energy
Plasma technology offers an innovative way to electrify processes by directly applying electrical energy to the process gas, creating a plasma phase. This is comparable to an electric flame that quickly reaches very high temperatures. Since the heat is transferred locally into the gas, the reactor itself does not need to be heated. This allows for quick on-and-off switching, ideal for responding to the fluctuating availability of renewable energy. Plasma technology uses common materials like copper and steel, making it less dependent on critical resources. The NXTGEN Hightech consortium, a collaboration that includes Maastricht University, TNO, and Sitech Services, is working to scale up this technology on the Chemelot Campus.
Methane Plasma Pyrolysis: A Smart Solution for Residual Methane
Within the NXTGEN Hightech consortium, plasma technology is first being applied to methane pyrolysis, with the aim of converting excess methane generated by electrified steam crackers into useful products such as ethylene and acetylene. By converting methane into these forms, it gains economic value, and combustion is avoided, which would otherwise negate CO₂ reduction efforts. An example of an existing application is the Huels process, which converts methane into acetylene and hydrogen on an industrial scale. The project focuses on improving product yield and energy efficiency to make this technology more economically attractive.
New Applications for Plasma Processing
Besides methane, other stable molecules can also be processed with plasma technology. A potential area is plasma formation of nitrogen and oxygen to produce NOx as fertilizers. By directly producing NOx, the step of ammonia production, and the associated N₂O emissions, can be avoided. Other areas under investigation include the conversion of CO₂ into CO and the recycling of plastics.
Scaling for Industrial Use
In pyrolysis, various hydrocarbons can be formed, with ethylene and acetylene being the preferred products economically. By applying rapid cooling, reactions can be selectively stopped at the desired product. Scaling is being pursued with parallel development on different scales, aiming for efficient upscaling from lab to industrial levels, including a 500 kW pilot setup for the Huels process and a 50 kW reactor for improving ethylene production.
Experiments and Numerical Models Provide Insights
Experimental data, such as chromatography and laser diagnostics, provide insights into the optimal conditions for methane pyrolysis. Numerical modeling supports these experiments by refining the understanding of chemical reaction mechanisms and temperature profiles within the reactors.
Conclusion: A Green and Circular Chemical Industry
The chemical industry must quickly electrify to reduce CO₂ emissions. Plasma technology offers promising possibilities for processing stable molecules and closing product loops. The technology is being developed on an industrial scale within Brightsite, with an initial focus on methane pyrolysis. Through scaling up and collaboration with research institutions and industry, this plasma technology can enable a green and circular chemical industry.
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