Low temperature catalytic methane decomposition for COx-free hydrogen production

Project Information

112CO2

Grant agreement ID: 952219

DOI

10.3030/952219

Project closed

EC signature date 29 June 2020

Start date 1 September 2020

End date 30 November 2024

Funded under

• EXCELLENT SCIENCE - Future and Emerging Technologies (FET)

Total cost

€ 3 585 178,75

EU contribution

€ 3 585 178,75

Coordinated by

UNIVERSIDADE DO PORTO
Portugal

Periodic Reporting for period 3 - 112CO2 (Low temperature catalytic methane decomposition for COx-free hydrogen production)

Reporting period: 2023-03-01 to 2024-11-30

Summary of the context and overall objectives of the project

The world needs a disruptive technology to decarbonize energy very quickly; the success of this technology depends heavily on its social acceptance, sustainability, and fast and easy implementation. 112CO2 aimed at developing this technology: the low-temperature catalytic methane decomposition (MD); recently, proposed to be named methane splitting. This reaction would allow the production of COx-free hydrogen and graphitic carbon from natural gas in a very short time. The MD technology enables using the present storage and distribution infrastructure for natural gas. When biomethane is used, it removes CO2 from the atmosphere and produces clean hydrogen at very competitive costs. High-value applications for graphitic carbon include electrically conductive inks/pastes for photovoltaics and advanced electrodes for electrochemical devices.
The MD industrialization has been hindered by the extremely fast catalyst deactivation, which is caused by the coverage of catalytic sites by the formed solid carbon. Competitors are developing high-temperature processes involving either metal liquid reactors or reactors using carbon catalyst particles; however, these approaches are energy-intensive, dangerous to operate, and display low catalytic activity. The 112CO2 reactor uses a proprietary Ni-based catalyst, which is very active but needs to be cyclically regenerated. The regeneration was done by feeding back H2, promoting the carbon methanation at the catalyst interface, leading to the peal out of the carbon particles.The reactor ran for 5000 h without any loss of activity, displaying >0.5 gH2 gCat-1 h-1 at 550 ºC and 1 bar.

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 proposed goals of the 112CO2 project were successfully addressed. CSIC was responsible to synthesize the Ni-based catalysts; activities > 0.45 gH2 gcat-1 h-1 target productivity could be sustained for several hundreds of hours on stream. Research efforts aimed at fundamental knowledge for understanding the reaction mechanisms and the chemical processes involved in Ni-based catalysts, combining in-situ synchrotron spectroscopy and DFT studies. DLR developed proton conducting ceramic (PCC) half-cells in metal-supported architecture (MS-PCC), aiming to achieve 1 μm-thick gas-tight PCC electrolyte in button-sized cells, but the stable operation of the PCC under methane flow without steam supply is still a challenge. Therefore, a Palladium membrane was used instead of a purification unit to selectively remove the hydrogen from the reactor. A planar catalytic reactor was selected by UPORTO as the optimum design, which allowed to reach >3000 h of reactor operation at 550 ºC, and employ cyclic regeneration. 3D modeling was an important tool to simulate and optimize a wide set of reactor and process parameters, as well as for the technology scale-up, under the responsibility of Pixel Voltaic.
Two new and large-scale experimental set-ups were designed to test multiple reactors at the same time. The new set-up developed by Pixel Voltaic allows testing the prototype demonstration, including the ability to remove periodical carbon without stopping the process, electrical heating of the reactor through heating elements, safety measures/hardware, and robust process automation through electronic hardware used in industrial applications. An average catalytic activity of 0.75 gH2 gcat-1 h-1 was achieved, with an unprecedented 100 % methane conversion at 550 °C. This experiment was later extended until ca. 200 h of operation and the catalytic system did not present any signs of deactivation.
The life cycle assessment reveals that, using biomethane as a feedstock, combined with renewable energy, reduces the cradle-to-gate carbon footprint to ca. 3.9 kg CO2-eq per kg of hydrogen produced, significantly lower than conventional methods. The solid carbon by-product offers an opportunity to further offset environmental impacts if repurposed in applications like tire manufacturing or concrete reinforcement. In terms of economic impacts, the levelized cost of hydrogen (LCOH) by MD for various scenarios was estimated considering the CAPEX and OPEX, showing that the H2 cost from MS technology would be ca. 2.08 €·kg-1 of H2, which is lower than the one produced from steam methane reforming + carbon capture and storage and solid oxide electrolyzer cells.

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)

Low-temperature (500-650 ºC) catalytic MD has been only used in industry to produce solid carbon structures because, after short operation times, these completely deactivate the catalyst and shut-down the reactor. This has been hindering continuous H2 production that is much cheaper than electrolysis and that can replace the reforming of hydrocarbons, which requires expensive carbon capture and sequestration systems.
Competing institutions/companies are developing high temperatures (> 1000 ºC) MD processes, involving either metal liquid reactors or using carbon catalysts; however, these approaches are energy-intensive, dangerous to operate, and display low catalytic activity. Though the promising advantages of fast reaction kinetics, high power density and lower costs, the low-temperature catalytic MD process has never been successfully demonstrated for periods longer than 200 h. EU Project 112CO2 overcame the challenges by developing a unique cyclic regeneration strategy (WO/2020/121287), which combined with a disruptive reactor design and a nickel-based supported catalyst, made the catalytic MD process to be fully stable for thousands of hours. The reaction in these conditions is 100 % selective, allowing the hydrogenation of the catalyst/carbon interface, making the produced carbon to detach periodically from the catalyst surface; this hydrogenation process uses ca. 5 % of the H2 produced. At the end, the consortium proved >3000 h of continuous operation at 550 °C with a constant catalyst productivity of 0.64 gH2 gcat-1 h-1. The carbon by-product is metal-free graphitic nanofilaments, which is a quite valorized carbon (predicted to cost ca. 3 €/kg) and especially suitable for making electric conductive carbon paints and electrodes for electrochemical devices, among a variety of other high-value applications.
This reaction is equilibrium limited, where at 600 °C and 1 bar the equilibrium conversion is ca. 60 %, but it reaches ca. 88 % between 700-750 ºC and the H2 concentration 94 %. Therefore, the 112CO2 team is continuing to improve the catalyst aiming at displaying higher catalytic activities; very recently, new catalysts/catalytic substrates were engineered. UPORTO and CSIC filed three patents disclosing this new process at intermediate-temperature. Also, the reactor design is being optimized to reach even higher power densities – a target power density of 1.5 kW L-1.
112CO2 consortium had an ambitious program for delivering a demonstrative system by the end of 2024, reaching TRL 4.
The other direction to look is when the MD reaction is applied to the biomethane from biogas, i.e. CO2-negative hydrogen is produced along with graphitic carbon, which has a high market price and supports carbon credits; this makes the produced bright-hydrogen – the proposed color-code for H2 produced from a renewable source, with negative-CO2 emissions and low-cost. The CO2 from the biogas can then be hydrogenated to produce very low-cost green methanol with an estimated cost of ca. 200 € t-1, which compares quite nicely with the present price from Methanex.

Image of the new test bench for catalytic methane decomposition

112CO2 logo

Schematic view of 112CO2 objectives

Image of the demonstration system