Intensification of methane upgrading into ethylene via additive manufacturing of nanosecond pulsed plasma reactor

Project Information

DisCH4rg3D

Grant agreement ID: 101180605

DOI

10.3030/101180605

Project closed

EC signature date 25 June 2024

Start date 1 July 2024

End date 30 June 2026

Funded under

• Widening participation and spreading excellence

Total cost

No data

EU contribution

€ 153 486,72

Coordinated by

ETHNICON METSOVION POLYTECHNION
Greece

Periodic Reporting for period 1 - DisCH4rg3D (Intensification of methane upgrading into ethylene via additive manufacturing of nanosecond pulsed plasma reactor)

Reporting period: 2024-07-01 to 2026-06-30

Summary of the context and overall objectives of the project

Electrification of the chemical industry is a powerful tool to decarbonize a sector that is heavily reliant on fossil fuels, primarily for heat generation. Plasma processes are poised to play a central role in this transition because they deliver energy to the reactive mixture via electrons and enable quick on/off switching to follow intermittent production of renewable energy. This makes them ideal for decentralized operations that can exploit locally-produced feedstock, such as biogas, to manufacture high-value chemicals.

The DisCH4rg3D project aims at developing plasma-based processes to upgrade underutilized methane (CH4) streams -e.g. chemical byproducts or biogas- into building blocks for chemical manufacturing. This approach promotes the chemical valorization of a potent greenhouse gas (i.e. CH4), while reducing the emissions associated with producing platform chemicals.

The strategy followed in this project involves the design of structured catalysts for the post-plasma transformation of intermediates into the final products in a once-through configuration, and the tuning of electrical plasma variables to intensify energy efficiency and process throughput.

Ultimately, the DisCH₄rg3D concept demonstrates how fully electrified plasma reactors can curb CH4 emissions while creating economic value, showcasing the potential of modular reactors in the emerging paradigm of sustainable chemical manufacturing

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The operating conditions of the plasma reactor have been studied in relation to energy efficiency and product distribution. This involved testing different energy delivery schemes and inlet gas flow rates. The results indicate that the total energy dissipated in the plasma discharge is the main driver of reactant conversion and in turn of process throughput. Therefore, the different pulse repetition patterns have marginal effect on the production of the different olefins. Whilst the tests involved a substantial amount of investigated variables, including Optical Emission Spectroscopy analysis, the Artificial Neural Network built on these input values requires more datapoints for robust training and prediction. Hence, the objective of Work Package 1 'Optimization of reactor configuration and operating conditions' (M2.1) has been partially achieved as it does not involve the full utilization of the ANN, as also mentioned in the Objective 1) of Section 1.1. Nonetheless, the most performing operating conditions in terms of energy efficiency are reported in our scientific publication as a standard for operating post-plasma catalytic processes (https://doi.org/10.1016/j.cep.2024.109946).

New structured catalysts have been designed and tested for the once-through conversion of methane (CH4) into ethylene (C2H4). The metal structure that serves as catalyst support enables high thermal conductivity, hence the process can be run exclusively with electrical power. Different metal catalyst loadings have been tested for the hydrogenation reaction of acetylene (C2H2), which is the main product of CH4 coupling in the plasma discharge, into C2H4. Therefore, M3.1 M3.2. and M3.3 about catalysts synthesis, 3D printing of the metal electrode, and catalysts deposition have been fully achieved. Both experimental and modeling validation have been conducted to identify the optimal catalyst formulation, hence intensifying the C2H4 productivity. (DOI: 10.1039/D4EY00203B DOI: 10.1039/D5CY00529A https://doi.org/10.1016/j.cep.2024.109946). Therefore, objective 2) 'Intensify C2H$ production' has been fully achieved.

The plasma operating variables in the nanosecond-pulsed discharge operation have been optimized in the reforming of biogas surrogates (i.e. mixture of CH4 and CO2) into platform chemicals such as CO and H2. The energy efficiency of the process is controlled via tuning the energy dissipated in each discharge and the discharge frequency. Moreover, the plasma-driven CH4 coupling and CO2 dissociation can be tuned to attain a product composition that is suitable for downstream processes. (https://doi.org/10.1016/j.ijhydene.2025.150293) Different catalysts have been tested in the post-plasma zone, as per WP3 of the proposal; however, no significant effect was observed on the product distribution, owing to the gas temperature being to low for coupled reactions. Nonetheless, M4.1 of WP3 'NPD reactor for DRM operational with consistent product quality and performance' has been fully achieved. This relates to objective 3) 'Develop a blueprint for customized catalytic plasma processes' which is partially achieved due to the limited application of the DRM process to non-catalytic conditions.

Furthermore, plasma-assisted CH4 pyrolysis has been investigated in the framework of low-carbon H2 production. The nanosecond-pulsed discharge can activate pure CH4 streams with high selectivity to H2 and C2H2. The energy delivered to the plasma can be regulated to maximize H2 energy efficiency and throughput. While this application was not originally included in the proposal, it expands the range of processes suitable for the NPD plasma reactor. The work has been presented in a scientific publication (https://doi.org/10.1016/j.cep.2025.110483).

Owing to the earlier termination of the fellowship, WP4 has been only partially undertaken. Techno-Economic Analysis (TEA) of the plasma process has not been performed as planned for M5.1 while a simplified estimation of the process carbon footprint of H2 production from biogas has been realized and presented in a journal article (https://doi.org/10.1016/j.ijhydene.2025.150293). Thereby, M5.2 has been partially achieved. Therefore, Objective 5) on feasibility assessment is also partially achieved.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Plasma can drive conversion of CH4 without external heat supply. Hence, the nanosecond-pulsed discharge employed in the project drives conversion of CH4 close to 50%, which is beyond the thermodynamic limit at the same gas temperature. Moreover, the integrated plasma-catalytic system allows for the once-through conversion of CH4 into C2H4 with yield of 34%, the highest reported in literature for electrified processes. Therefore, this system could be implemented in existing chemical processes where CH4 is an underutilized byproduct, boosting the overall profit with the production of a value-added molecule such as C2H4.

After the lab scale demonstration and optimization with different structured catalysts, the next step to commercial implementation is reactor scale-up. This must be pursued by increasing the plasma volume with larger electrode distance and by reproducing the discharge in a numbering-up approach. Existing power supply systems with nominal power above 1 kW could allow processing CH4 flow rate in the order of few L/h, which would suit a small chemical plant.

Similarly, nanosecond pulsing of the plasma discharge can be tuned to maximize the efficiency of the dry reforming of CH4 process, where a biogas-surrogate is converted into valuable syngas. In this application, both CH4 and CO2 conversion is close to 50%, with high selectivity of syngas about 80%. More importantly, the energy conversion efficiency is almost 60%. This suggests an efficient energy delivery from the plasma discharge into the chemical products. Furthermore, the outlet composition is strictly linked to the CH4/CO2 ratio in the feedstock. Hence, this reactor is amenable to different biogas sources and downstream processes. A scale-up approach that involves both larger plasma volume and reactor numbering-up would allow processes in decentralized areas where biogas is produced. Thus, the plasma system could lead to direct profits for farmers and municipal waste plants via valorization of a waste stream.