Efficient reversible production of hydrogen with CO2 in a catalytic system employing Ru-PNP complexes and ionic liquids.
Brenda RABELL MONTIEL1, Anders RIISAGER1, Martin NIELSEN1
1Technical University of Denmark , Copenhagen , Denmark
Hydrogen can be used as an energy carrier for renewable energy to overcome the deficiency of its intrinsically intermittent supply. However, the lack of a safe, efficient, convenient, and low-cost storage and transportation method for hydrogen limits its application. In this regard formic acid (FA), which can reversibly be converted into hydrogen and carbon dioxide through catalysis, has significant potential for practical application as a Liquid Organic Hydrogen Carrier (LOHCs). 1,2
In this work, high catalytic activities of Ru-PNP complexes in ionic liquids (IL) were obtained for the reversible hydrogenation of CO2 and dehydrogenation of FA under exceedingly mild conditions (Figure 1). The catalytic system promotes CO2 activation already at 25°C leading to >99% FA yield, without sacrificial additives and volatile solvents. Regarding the dehydrogenation process, only CO2 and H2 are obtained by just increasing the temperature under non-inert conditions, without any CO formation in the gas stream, nor organic residues. These results demonstrate the potential of the Ru-PNP/IL system as LOHC battery, LOHC H2 releaser, and hydrogenative CO2 converter.3
In this work, high catalytic activities of Ru-PNP complexes in ionic liquids (IL) were obtained for the reversible hydrogenation of CO2 and dehydrogenation of FA under exceedingly mild conditions (Figure 1). The catalytic system promotes CO2 activation already at 25°C leading to >99% FA yield, without sacrificial additives and volatile solvents. Regarding the dehydrogenation process, only CO2 and H2 are obtained by just increasing the temperature under non-inert conditions, without any CO formation in the gas stream, nor organic residues. These results demonstrate the potential of the Ru-PNP/IL system as LOHC battery, LOHC H2 releaser, and hydrogenative CO2 converter.3
Acknowledgments: The authors gratefully acknowledge Carlsberg Foundation for financing the research project.
References
- Müller, K.; Brooks, K.; Autrey, T. Hydrogen Storage in Formic Acid: A Comparison of Process Options. Energy Fuels 2017, 31, 12603–12611.
- Guo, J.; Yin, C.K.; Zhong, D.L.; Wang, Y.L.; Qi, T.; Liu, G.H.; Shen, L.T.; Zhou, Q.S.; Peng, Z.H.; Yao, H.; et al. Formic Acid as a Potential On-Board Hydrogen Storage Method: Development of Homogeneous Noble Metal Catalysts for Dehydrogenation Reactions. ChemSusChem, 2021, 14, 2655–2681.
- Piccirilli, L.; Rabell, B.; Padilla, R.; Riisager, A.; Das, S.; Nielsen, M. ChemRxiv 2022. 10.26434/chemrxiv-2022-643jb (preprint).
