(222d) System Design and Testing of Bzcy Proton Conducting Ceramic Membranes for Electrochemical Steam Methane Reforming at High Temperature and Pressure

Hydrogen is traditionally produced through steam methane reforming (SMR) where natural gas and steam are reacted at high temperatures to produce a mixture of CO₂, CO, and H₂ from which H₂ must be separated. Due to the multiple reaction and separation steps involved and the need for heat recovery integration, SMR must be conducted at large scales in centralized plants to reach profitable efficiencies. Alternatively, water electrolyzers can be used to electrochemically produce H₂ from water. However, the minimum energy required to produce H₂ from electrolysis is still almost seven times higher than from SMR. A promising alternative process is the use of proton conducting ceramic BaZr_0.8-x-y Ce_xY_yO_3-δ (BZCY) membranes to perform SMR electrochemically. Combining the SMR process with these proton conductive ceramics enables H₂ separation and compression to be integrated into the reaction process through electrochemical pumping of the protons. The removal of H₂ also provides the benefit of shifting the equilibrium of the SMR reaction so that nearly complete conversion of methane can be reached. Additionally, the separation and compression of H₂ generates heat directly in the membrane that can be balanced with the energy consumed by the endothermic SMR reaction to provide micro-scale heat integration [1]. This technology has the potential to transform how H₂ is generated, and by pairing other reactions with the separated protons, alternative and more direct pathways to produce valuable chemicals such as ammonia can be developed [2].

In this study, we present the details of a system developed in our lab to test the performance of these proton conducting ceramic membranes and present the results of our study under a wide range of pressure, temperature, and gas compositions. Detailed considerations of the system design include pressures up to 50 bar, temperatures up to 900^oC, and electrical connections to the membrane. The details of how sensing and control were designed to allow for automated data collection are also discussed [3]. Additionally, results from tests performed on membrane assemblies provided by CoorsTek Membrane Sciences are presented for proton pumping and SMR. Lastly, the data from these tests is used to develop a reduced order model that can be used to inform engineering decisions in larger scale system design.

References:

1. Malerød-Fjeld, H., Clark, D., Yuste-Tirados, I., Zanόn, R., Catalán-Martinez, D., Beeaff, D., Morejudo, S. H., Vestre, P. K., Norby, T., Haugsrud, R., Serra, J. M., Kjølseth, C., "Thermo-electrochemical production of compressed hydrogen from methane with near-zero energy loss," Nature Energy 12 (2017): 923-931.
2. Kyriakou, V., Garagounis, I., Vourros, A., Vasileiou, W., Stoukides, M., "An electrochemical Haber-Bosch process," Joule 1 (2020): 142-158.
3. Çıtmacı, B., Luo, J., Jang, J., Korambath, P., Morales-Guio, C., Davis, J., Christofides, P. D., "Digitalization of an experimental electrochemical reactor via the smart manufacturing innovation platform," Digital Chemical Engineering 5 (2022): 100050.