(141f) Design and Analysis of Processes for Methane to Hydrogen Conversion Using the Piston Reactor Technology: A Comparative Analysis

Global hydrogen demand has tripled since the 1970s, and is projected to increase by around 50% in the next decade [1,2]. Its growth is credited to its versatility, sustainability, and high energy density. Currently, hydrogen is produced primarily from fossil fuels, where natural gas accounts for over three-quarters of the annual global production [1]. There are three main routes for hydrogen production from natural gas: steam methane reforming (SMR), partial oxidation (POX), and autothermal reforming (ATR). Although these processes are prevalent for hydrogen production, they produce substantial amounts of CO₂ emissions. Novelty in reactor design could potentially contribute to the reduction of emissions in hydrogen production processes.

The piston reactor technology is gaining prominence as a novel, safe and effective means for carrying out chemical reactions [3]. In principle, it is similar to the standard internal combustion engine, with the prime difference of producing chemicals, rather than power, as its primary function. Its advantages include high throughput and ability to provide high-pressure and temperature conditions for a limited time, followed by rapid cooling/quenching, thereby offering flexibility in controlling chemical reactions [4]. Piston reactors also act as “polygenerators”, where they could flexibly transition from power producers to chemical generators and energy storage devices. This could allow it to play a vital role in mitigating one of the primary challenges of future energy systems, where fluctuations in electricity supply and demand can be accommodated [5].

Most studies on piston reactors focus on the reactor on a laboratory scale, with very limited reported process-level analyses [3]. Moreover, almost all the studies focus on methane partial oxidation from natural gas for syngas production. In this work, processes are designed around the piston reactor technology to assess its performance for methane to hydrogen production via the various hydrogen production routes. Processes with conventional reactors are also designed to serve as benchmarks for comparison with the piston-reactor processes. Initially, a model is developed to mimic the piston reactor performance for methane to hydrogen production following the POX route. After literature validation, the model is utilized to predict the piston reactor’s performance following the SMR and ATR routes. Results show that SMR underperforms compared to conventional processes and is not considered for process-level analysis. Next, processes including subsequent water-gas shift reactions and separation, are designed around the POX and ATR piston reactors to assess their performance in terms of hydrogen production cost, and CO₂ emissions. Results show that the engine processes result in higher hydrogen production costs relative to the conventional ones; however, they are associated with significant amounts of excess heat that could be utilized for carbon capture and sequestration (CCS). After integration, excess heat reduces CO₂ emissions by around 90% and 60% in the POX and ATR processes, respectively. The performance of the piston reactor technology is also compared against the state-of-the-art electrolysis, and results show that the piston reactor is competitive and can be a viable option for hydrogen production.

Acknowledgments. This work was made possible by funding from Qatar National Research Fund (QNRF) project number NPRP12S-0304-190222 and co-funding by Qatar Shell Research and Technology Center (QSRTC). The statements made herein are solely the responsibility of the author(s).

References:

[1] IEA, The Future of Hydrogen, 2019. https://doi.org/10.1787/1e0514c4-en.

[2] IEA, Hydrogen, Paris, 2021. https://www.iea.org/reports/hydrogen.

[3] A. Ashok, M.A. Katebah, P. Linke, D. Kumar, D. Arora, K. Fischer, T. Jacobs, M. Al-Rawashdeh, Review of Piston Reactors for the Production of Chemicals, Reviews in Chemical Engineering. (2021). https://doi.org/10.1515/revce-2020-0116.

[4] M.A. Katebah, A. Abusrafa, M. Al-rawashdeh, P. Linke, Design and Analysis of a Process for Methane to Hydrogen Conversion Using Piston Reactor Technology, Chemical Engineering Transactions. 88 (2021) 829–834. https://doi.org/10.3303/CET2188138.

[5] B. Atakan, S.A. Kaiser, J. Herzler, S. Porras, K. Banke, O. Deutschmann, T. Kasper, M. Fikri, R. Schie, D. Schr, C. Rudolph, D. Kaczmarek, H. Gossler, S. Drost, V. Bykov, U. Maas, C. Schulz, Flexible energy conversion and storage via high-temperature gas-phase reactions : The piston engine as a polygeneration reactor, 133 (2020). https://doi.org/10.1016/j.rser.2020.110264.