Chemical looping using novel perovskite-type oxygen carriers for hydrogen production
Lead Research Organisation:
Newcastle University
Department Name: Sch of Engineering
Abstract
Previous work in our group has shown that the phases in the COCMs evolve to a complex mixture of oxides with various oxygen capacity profiles. My research will be focusing on identifying the phases responsible for the available oxygen capacity and the investigation of the profile of redox potentials as a function of cycling. To achieve that the oxygen occupancy of the material during and after each redox cycle will be studied. We aim for a better understanding of the relationship between oxygen occupancy, lattice parameter and chemical potential for a variety of oxygen partial pressures and temperatures which can then be correlated with the amount of hydrogen produced in every cycle. Moreover, investigation of the dynamic response of the change of the oxygen occupancy of the COCM under different
oxidizing/reducing environments will allow for the development of a kinetic model.
The main objective of this study is to fabricate highly active and efficient catalysts for the CLR process. Through this research, the aim is to get insight into how to tailor the COCMs in order to achieve higher hydrogen yields and overall process efficiency in view of its industrial scale implementation.
oxidizing/reducing environments will allow for the development of a kinetic model.
The main objective of this study is to fabricate highly active and efficient catalysts for the CLR process. Through this research, the aim is to get insight into how to tailor the COCMs in order to achieve higher hydrogen yields and overall process efficiency in view of its industrial scale implementation.
Organisations
People |
ORCID iD |
| Evangelos Papaioannou (Primary Supervisor) | |
| Leonidas Bekris (Student) |
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| EP/N509528/1 | 01/10/2016 | 31/03/2022 | |||
| 2267926 | Studentship | EP/N509528/1 | 01/10/2017 | 30/12/2020 | Leonidas Bekris |
| EP/R51309X/1 | 01/10/2018 | 30/09/2023 | |||
| 2267926 | Studentship | EP/R51309X/1 | 01/10/2017 | 30/12/2020 | Leonidas Bekris |
| Description | The current dominant process for large-scale syngas (a mixture of CO and H2) and hydrogen production is Steam Methane Reforming (SMR), which is based on the reforming of natural gas (methane) with steam, over transition metal catalysts at high temperatures. Despite the process being well established, highly selective conversion of methane at low temperatures remains a challenge due to the limitations of traditional catalysts. Chemical Looping (CL) is an attractive alternative technology for methane reforming that can offer syngas/ hydrogen production with high process efficiency since it allows side reactions to be eliminated leading to a process that is safer and can potentially yield higher conversions and improved selectivity. In a chemical looping process, the oxygen needed for the reactions is provided by an oxygen carrier material (OCM) which is cycled between the reacting streams with the two never coming in contact. Despite the advantages that CL offers, its implementation in industry is impeded by the limitations of current OCMs. Traditional catalytic processes for the production of syngas such as partial oxidation can be re imagined through chemical looping upon the advancement of OCMs. However, development of such OCMs is a challenge. Aiming to develop such materials, this study revolves around the design, synthesis, characterisation and testing of candidate OCMs for the activation of methane, with a focus on exsolved perovskite systems. These systems have been designed to promote the formation of well-anchored metal particles of tailorable size and population on and under their surface and are applied for the first time for the conversion of methane. The exsolved particles act both as oxygen reservoirs and active sites while the system exhibits high reactivity and selectivity with perovskite host and metal particles working synergistically. Aiming to get further insight regarding the structural and compositional changes that the material undergoes during the process, in-situ X-ray diffraction experiments were conducted at the European Synchrotron Facility (ESRF). Multiple operando experiments were carried out and samples from different stages of the process were scanned in capillaries. From the results of these experiments, is concluded that the behaviour of the system under reaction conditions seems to stem from the synergistic contribution of its components. Long term cycling of the system for chemical looping methane partial oxidation showcases its excellent stability while high product selectivity is maintained. These results provide valuable insight on the performance of exsolved systems and open new possibilities for their implementation in a plethora of applications. |
| Exploitation Route | The insight obtained from this study on exsolved systems will give new perspectives for the employment of redox exsolution for the design of active oxygen carrier materials that will allow the benefits of the chemical looping process to be exploited for selective methane activation to syngas/ hydrogen and also open new possibilities for material design for other challenging energy applications. |
| Sectors | Chemicals,Energy,Environment |
| URL | https://onlinelibrary.wiley.com/doi/full/10.1002/anie.201915140 |