Periodic Reporting for period 1 - PLASMACAT (Understanding the material structure-activity correlation in plasma catalytic CO2 conversion)
Berichtszeitraum: 2019-04-01 bis 2021-03-31
Plasma catalysis is seen as a promising and emerging conversion technology that can be part of the solution in the transition to circular, carbon-neutral chemical production. Plasma catalysis is of particular interest in the conversion of relatively stable gases such as CO2 to basic chemical building blocks by the use of (renewable) electrical energy. In a dielectric barrier discharge (DBD) plasma reactor, the electrical energy is mainly transferred to highly energetic, accelerated electrons producing a cocktail of activated species such as ions, radicals, and excited species. Nevertheless, although the alternative reaction paths of DBD plasma reactors show high potential in CO2 conversion, their current Achilles heel is the lack of product selectivity and limited energy efficiency. To solve this, packing materials and catalysts are being introduced in the plasma. Although it is well accepted that there is a mutual interaction of the materials on the plasma properties and vice versa, the underlying mechanisms and even more, the specific material properties influencing plasma conversion, selectivity, and energy efficiency are still largely unknown (A. Bogaerts et. al. J. Phys. D: Appl. Phys. 53, 2020, 443001).
Therefore, this project’s objective is a systematic study, applying the know-how of the applicant and supervisor in controlled material synthesis to identify key material aspects in plasma catalytic studies. Moreover, secondments to VITO specialized in materials shaping technology, aim to explore the impact of material architecture on plasma catalysis. This will permit a systematic structure-activity correlation, identifying the impact of yet unrevealed material properties on the plasma characteristics and performance (conversion, selectivity and energy efficiency).
The project focuses on studying the impact of metal dispersion and metal support interactions of Cu, Fe, and Mg species on the plasma characteristics and plasma catalytic performance in dry reforming of methane as well as its stability and that of the packing material. Furthermore, based on the identified importance of packing and reactor configurations on plasma performance, the role of packing geometry on plasma catalysis is a particular aspect of this MSCA. In order to study the role of the architecture of the packing material on the plasma properties and performance, 3D printed packing materials have been developed and manufactured in collaboration with the CAST research team at VITO.
Therefore, this project’s objective is a systematic study, applying the know-how of the applicant and supervisor in controlled material synthesis to identify key material aspects in plasma catalytic studies. Moreover, secondments to VITO specialized in materials shaping technology, aim to explore the impact of material architecture on plasma catalysis. This will permit a systematic structure-activity correlation, identifying the impact of yet unrevealed material properties on the plasma characteristics and performance (conversion, selectivity and energy efficiency).
The project focuses on studying the impact of metal dispersion and metal support interactions of Cu, Fe, and Mg species on the plasma characteristics and plasma catalytic performance in dry reforming of methane as well as its stability and that of the packing material. Furthermore, based on the identified importance of packing and reactor configurations on plasma performance, the role of packing geometry on plasma catalysis is a particular aspect of this MSCA. In order to study the role of the architecture of the packing material on the plasma properties and performance, 3D printed packing materials have been developed and manufactured in collaboration with the CAST research team at VITO.
Different types of commercial -alumina support materials have been evaluated in the plasma as well as the impact of calcination of the -alumina support material at various temperatures. The results showed a clear effect of the packing material and properties on the plasma-assisted dry reforming of methane (DRM) reaction with respect to selectivity and conversion in function of the Al2O3 properties and the space time applied.
In addition, we activated commercial -alumina powder with 10 wt% of CuO by different methods such as Wet impregnation (WI), the Molecular designed dispersion method (MDD), and an Ammonia driven deposition precipitation method (ADP). This allows changing the metal-support interaction and dispersion degree of the catalysts. These powders were spray-coated on silica and zirconia spherical packing materials, creating core-shell packing materials. Next to the impact of the core material, a clear influence of the activation method could be observed in activity and selectivity.
Besides studying the influence of dispersion, we also changed the wt% of the active element directly loaded on a commercial Al2O3 spherical support material. Different percentages between 1 and 15% of Cu and Mg were deposited as oxides on the support via direct metal loading using an adsorption technique followed by filtration. All materials were characterized pre- and post-plasma by various techniques such as XRD, TPR, UV-Vis DRS, Raman, TGA, SEM, and N2 sorption. All the synthesized materials were used for the plasma-assisted DRM reaction in a DBD reactor. For the MgO activated material, no significant impact of the MgO wt% could be observed in conversion, in contrast to the CuO and FeO activated samples.
Furthermore, in collaboration with the University of Ghent, we evaluate the impact of bimetallic Fe-Cu species on plasma catalysis. We screened different ratios of Fe-Cu -alumina materials with DRM reaction. Both the conversion (CO2 and total conversion) and energy efficiency were affected by the Fe-Cu packing material. These results show that there is an impact of the Fe: Cu ratio on the plasma catalytic conversion, mainly influencing the CO2 conversion while having limited to no impact on the methane conversion. This also resulted in a clear impact on selectivity.
Finally, in collaboration with VITO, 3D printed support materials have been developed and manufactured with differences in their architecture. To allow a good fit for the reactor, an innovative printing process has been successfully developed.
During my project I attended and presented my work at several scientific workshops as well as to the broad public, introducing them to the potential of new technologies using electrical energy rather than the currently applied thermal processes. One such event was the Interreg “Funding The Future” science exhibition. Also, 2 bachelor and master students were mentored and introduced to the topic of materials chemistry and plasma catalysis.
The results obtained in this MSCA have opened important opportunities to further material development to unlock the full potential of plasma catalysis. Intriguing material structure-performance correlations have been identified that will be further explored in follow-up projects including the collaborations that have been established in this project. Therefore, also after the project end, further dissemination and exploitation of the results obtained within this MSCA are expected.
In addition, we activated commercial -alumina powder with 10 wt% of CuO by different methods such as Wet impregnation (WI), the Molecular designed dispersion method (MDD), and an Ammonia driven deposition precipitation method (ADP). This allows changing the metal-support interaction and dispersion degree of the catalysts. These powders were spray-coated on silica and zirconia spherical packing materials, creating core-shell packing materials. Next to the impact of the core material, a clear influence of the activation method could be observed in activity and selectivity.
Besides studying the influence of dispersion, we also changed the wt% of the active element directly loaded on a commercial Al2O3 spherical support material. Different percentages between 1 and 15% of Cu and Mg were deposited as oxides on the support via direct metal loading using an adsorption technique followed by filtration. All materials were characterized pre- and post-plasma by various techniques such as XRD, TPR, UV-Vis DRS, Raman, TGA, SEM, and N2 sorption. All the synthesized materials were used for the plasma-assisted DRM reaction in a DBD reactor. For the MgO activated material, no significant impact of the MgO wt% could be observed in conversion, in contrast to the CuO and FeO activated samples.
Furthermore, in collaboration with the University of Ghent, we evaluate the impact of bimetallic Fe-Cu species on plasma catalysis. We screened different ratios of Fe-Cu -alumina materials with DRM reaction. Both the conversion (CO2 and total conversion) and energy efficiency were affected by the Fe-Cu packing material. These results show that there is an impact of the Fe: Cu ratio on the plasma catalytic conversion, mainly influencing the CO2 conversion while having limited to no impact on the methane conversion. This also resulted in a clear impact on selectivity.
Finally, in collaboration with VITO, 3D printed support materials have been developed and manufactured with differences in their architecture. To allow a good fit for the reactor, an innovative printing process has been successfully developed.
During my project I attended and presented my work at several scientific workshops as well as to the broad public, introducing them to the potential of new technologies using electrical energy rather than the currently applied thermal processes. One such event was the Interreg “Funding The Future” science exhibition. Also, 2 bachelor and master students were mentored and introduced to the topic of materials chemistry and plasma catalysis.
The results obtained in this MSCA have opened important opportunities to further material development to unlock the full potential of plasma catalysis. Intriguing material structure-performance correlations have been identified that will be further explored in follow-up projects including the collaborations that have been established in this project. Therefore, also after the project end, further dissemination and exploitation of the results obtained within this MSCA are expected.
The major point of progress beyond the state of the art: (I) is an improved method to directly load the metal oxides on the support via an easier synthesis approach. (II) A clear impact of the support properties (e.g. type of alumina support, calcination temperature), the method to deposit the active element (e.g. differences in dispersion degree and/or metal support interaction), type of active element, and metal loading have been identified with respect to conversion, product selectivity and energy efficiency in plasma-assisted DRM in a DBD reactor. This confirms the potential and the need for further research on the material-performance correlation in packed bed plasma-based CO2 conversion. (III) Finally, to develop better fit 3D architectures as packing for DBD reactors, an improved 3D printing process was established.
Overall, our work within the PLASMACAT project provides new insights that bring the development of plasma-adjusted catalysts for CO2 conversion a step closer to a solution in the transition to a more sustainable circular chemical production, reducing CO2 in our atmosphere. Our work provided insights into the material-performance relation of non-thermal DBD plasma and catalyst in dry reforming of methane.
Overall, our work within the PLASMACAT project provides new insights that bring the development of plasma-adjusted catalysts for CO2 conversion a step closer to a solution in the transition to a more sustainable circular chemical production, reducing CO2 in our atmosphere. Our work provided insights into the material-performance relation of non-thermal DBD plasma and catalyst in dry reforming of methane.