Low emission H2 production (Task 3)

Modular Protonic Membrane Reformer (PMR) technology developed by CoorsTek Membrane Sciences shows great promise for hydrogen production with high energy efficiency and CO2 capture rates.

The PMR technology uses electrical energy as an input, which is an increasing advantage as we transition towards renewable and intermittent energy. The goal of Task 3 is to develop the PMR technology together with CoorsTek Membrane Sciences, with an energy efficiency higher than 75% including CO₂ capture. For comparison, the energy efficiency of conventional hydrogen production by steam methane reforming without carbon capture is around 70-75 %.

Results 2021

Main results 2021

  • One of the previously identified potential challenges with the PMR technology is that the core material of the membrane (a BaZrCeYO₃ based electrolyte) is prone to degradation when it reacts with CO₂. However, we found that the currently utilized material composition can withstand being exposed to up to 10 bar of CO₂ in a wide range of relevant operating temperatures (400-800˚C) without measurable degradation.
  • We finalised a model description of the PMR module and used this to simulate a range of operating conditions for a given case study. The simulations allowed us to obtain performance maps according to selected key performance indicators and eventually to identify ideal operating conditions – primarily in terms of flow rates and current density – that ensure both a proper thermal integration of the process and good performance.
  • In collaboration with the KSP spin-out project MACH-2, we have performed a techno-economic study of a hybrid concept that comprises the PMR and a liquefaction-based CO₂ capture system. The optimisation results demonstrate that the hybrid process is able to recover 99% of the H₂ and CO₂ generated in the system, even when the PMR is operated at a relatively low hydrogen recovery (91%). The energy conversion efficiency is about 80%, which is 12% higher than a conventional method for natural gas-based hydrogen production with CO₂ capture. Depending on the PMR module cost, the hydrogen production cost of the hybrid concept is in the range between 13.6 and 17.7 c€/Nm3 while the reference process is at 16.5 c€/Nm3.
  • We established a new test set-up for testing single cell PMR membranes, which will be used for the long long-term durability test planned in 2022. The new set-up will allow us to determine the performance of the PMR membrane with higher accuracy because the resistance contributions from the test set-up can be eliminated.

Impact and innovation potential

PMR technology utilizes electrical energy as input, which becomes an increasing advantage in the transition towards renewable and intermittent energy (see Figure 1). Techno-economic analyses indicate that the hybrid concept of PMR and a liquefaction-based CO₂ capture system has the potential to become a more energy-efficient option for generating hydrogen with a low carbon intensity and reasonable production cost.

Module containing membrane segmengs and modeled H2 production
Figure 1: Module containing 36 membrane segments (left). Modeled H₂ production from PMR and competing technologies by variation of cost of natural gas, electricity, carbon tax and storage (right). Source: CoorsTek Membrane Sciences.

Results 2020

Detailed electrical characterization of PMR membranes

In order to further understand the electrical and electrochemical properties of the PMR membranes, detailed electrical characterization was performed on single-tube membranes supplied by CoorsTek, as a function of steam pressure (0.05-5 bar) and temperature (600-800°C). Using impedance spectroscopy, ohmic and electrode polarization resistances could be extracted, which serve as basis for further improvement of performance of the membranes see Figure.

Chemical and electrochemical degradation studies

Further experimental work in NCCS will focus on investigating potential chemical and electrochemical degradation of the PMR materials in relevant atmospheres as well as impurities in the natural gas such as H2S. The work so far has been to prepare different types of samples required for the chemical and electrochemical degradation experiments, and to make a test matrix including the relevant post-characterization methods. These have been chosen to address hypothesis regarding the degradation mechanism based on previous experimental and computational work in Task 3.

Electrical impedance spectra of a PMR membrane showing how the various contributions to the resistance can be extracted when fitting the data to an equivalent circuit model: ohmic (Rohm), parasitic (Rpar) and polarization resistances (Rp1-3).
Electrical impedance spectra of a PMR membrane showing how the various contributions to the resistance can be extracted when fitting the data to an equivalent circuit model: ohmic (Rohm), parasitic (Rpar) and polarization resistances (Rp1-3).

Hybrid PMR and CO2 liquefaction process

A hybrid process comprising PMR technology and CO2 liquefaction is being developed in the MACH-2 KSP spin-off project. By exploiting the advantages of both technologies and applying them in their preferred window of operation, significant cost and efficiency gains are expected. In optimizing the process, the configuration of the hybrid process was varied with respect to the type of liquefaction process for CO2 capture and the treatment methods of the residual gas from the low-temperature process. The latter is critical for optimal design of the hybrid system with a high H2 recovery rate as the PMR retentate gas may contain considerable amounts of hydrogen and CO if the PMR is not operated at high conversion. The detailed process flow diagram of the hybrid process with the liquefaction system is illustrated in the figure below. In the selected hybrid process, a mixed refrigerant liquefaction system is used for the carbon capture part, and a water gas shift reactor for the retentate gas is included to reduce the CO content in the feed and achieve a high CO2 capture rate and high H2 recovery rate by recycling the residual gas. Based on the performance analysis of the hybrid process, the configuration of the liquefaction process will be further modified to minimize the overall cost of the system. The heat recovery method of the warm hydrogen product and retentate gas from the PMR will also be further developed in the MACH-2 project to improve the energy efficiency of the hybrid system for hydrogen production with low carbon footprint. 

Detailed process flow diagram of hybrid PMR and CO2-liquefaction process with off-gas recycle and WGS reactor after PMR.
Detailed process flow diagram of hybrid PMR and CO2-liquefaction process with off-gas recycle and WGS reactor after PMR.

In 2020, results originating from the MACH-2 project were presented at the 30th European Virtual Symposium on Computer Aided Process Engineering (ESCAPE-30) in September, and during the NCCS-organized webinar in October. A scientific article detailing the low temperature process was published in the Elsevier journal Computer Aided Chemical Engineering.

Main results 2019

PMR experiments at lower temperatures for the first time

In 2019, we managed to perform catalytic PMR experiments at lower temperatures (750 and 700°C) for the first time, for comparison with the standard operation at 800°C (left figure). Methane conversion of 98.7% was achieved and the catalytic data corresponds well with thermodynamic equilibrium at the highest hydrogen recoveries (>95%). These results are important for further optimization of the PMR operating conditions. Specifically, lower operating temperature may translate to improved lifetime and reduced cost of materials and components in the PMR modules.

Improvements to experimental setup

The task-team has made several upgrades to the setup for detailed characterization of PMR membranes. We achieved high quality electrical measurements which provides the main input for further development of membrane cells with improved electrochemical performance. This work also benefits the long-term PMR testing that is planned within KPN MACH-2.

Modelling of membranes and modules

Simulations of PMR membranes and thermally integrated modules are being pursued to benchmark and improve the PMR hydrogen production process. Single-tube PMR simulations were performed for detailed temperature and gas composition profiles along membrane length, and for the role of gas inlet temperature. The results demonstrated the importance of thermal integration of PMR modules, and a simulation framework for a thermally integrated SEU – containing 36 membrane segments – was established for isothermal conditions.

Left: PMR test of single membrane at 700 °C showing CH4 conversion and CO/CO2 yield as a function of hydrogen recovery, as well as Faradaic efficiency (FE) and the difference in temperature at the center and outlet of the membrane relative to the process temperature (700 °C). Right: Module containing 36 membrane segments.

Results 2018

Main Results

  • Performance targets defined for a single PMR membrane for testing in NCCS, and for commercial deployment of the PMR technology.
  • Several modification and improvements to the experimental setup have been performed amid significant challenges with the experimental setup.
  • Simulation model for CoorsTek membranes was developed for modelling of PMR membrane and reactor.
  • Paper on theoretical studies of CO2 and H2O co-adsorption on membrane surface accepted for publication.


Impact and innovations

  • Knowledge of possible critical role of coke deposition in membrane anode.

 

Single tubular PMR membrane (dark grey) with electrode (light grey) and Cu-wire as current collector. PMR test could not be completed due failure of the membrane (cracked at the top), ascribed to unstable steam supply and coke deposition in the inner electrode.
Schematic of the various components of the membrane described in the simulation model.

Results 2017

The task deals with development of the Protonic Membrane Reformer (PMR) technology by CoorsTek Membrane Sciences which allows hydrogen production with CO2 capture in a modular steam methane reformer.

The work aims to identify and improve material stability and performance issues of the ceramic membrane and seals under PMR operating conditions and thermal cycling.

A membrane unit at SINTEF was upgraded for testing of electrochemical membranes provided by CoorsTek and commissioned for PMR test conditions (800 °C and 10 bar pressure with a steam to carbon ratio of 2.5). A single-segment tubular membrane was tested under PMR conditions and further improvements were made to the setup.

A paper was submitted on atomistic studies of CO2 adsorption on the BaZrO3-based membrane material in connection with a research visit at MIT supported by CLIMIT and other RCN projects.

Publications

See also other NCCS Publications registered in Cristin, the Norwegian Research Information system.

Journal Publications

2019: 

2018: 

Task leader

Belma Talic

Belma Talic

Research Scientist
41 38 62 91
Name
Belma Talic
Title
Research Scientist
Phone
41 38 62 91
Department
Sustainable Energy Technology
Office
Oslo
Company
SINTEF AS