In this paper, we introduce formic acid as one of the most promising liquid organic hydrogen carriers, which can provide a viable method for the safe hydrogen storage and transportation. Attractive feautures of formic acid as a hydrogen carrier are (i) hydrogen production at lower temperature (< 100 °C), (ii) CO-free, and (iii) high-pressure hydrogen supply as a chemical compressor. In addition, we describe the production of formic acid from CO2 and its technoeconomic analysis. The research project with regard to formic acid as a hydrogen carrier in Europe and the United States are introduced.
This paper describes a technique for storing and releasing hydrogen by interconverting CO2/HCOOH using an iridium catalyst. It was revealed that CO2 hydrogenation to formic acid not only activates the water-soluble iridium catalyst by improving the electron donating ability of the ligand, but also activates hydrogen more effectively by biomimetics. In addition, the factors that activate hydrogen have been clarified from both experimental and theoretical calculations. In hydrogen production from formic acid dehydrogenation, the catalytic activity is also improved by increasing the electron donation from the ligand to the metal center, as in the case of formic acid synthesis. Finally, by improving the catalyst durability, we succeeded in developing a catalyst that continues to generate hydrogen for nearly 1.5 months.
Formic acid is considered as one of the promising H2 carriers for the next generation. In this topic, we introduce the potential of formic acid as well as homogenous catalyst providing a viable method for the production of H2. For the reaction, Cp* Ir complexes can produce H2 gas with a high pressure over 150 MPa. Even tough the generated gas consists of H2 and CO2 with the ratio of 1:1, H2 can be separated easily and purified under supercritical conditions by simply cooling the change the gas-liquid state of the system.
Formic acid (FA, HCOOH) is widely recognized as a convenient hydrogen carrier, which realizes an economical CO2-mediated hydrogen storage energy cycle. Thus the development of reliable heterogeneous catalysts targeted to both FA dehydrogenation and FA synthesis is an urgent yet challenging task. Herein the state of the art in the exploitation of promising nano-catalysts designed by surface and interface engineering with atomic precision for this targeted reaction are presented. The advantages of the present catalytic systems, such as facile preparation method, high durability, and superior catalytic activities compared to the previously reported systems, are particularly desirable for an ideal hydrogen vector in terms of potential industrial application for future hydrogen society.
Hydrogen has attracted attention as an alternative energy of fossil fuels due to its sustainability and no CO2 emission. In order to achieve a sustainable society based on hydrogen, safe and economic transportation and store is required. Formic acid has lots of potential as a hydrogen carrier due to its chemical and physical properties. Hydrogen is transported or stored safely as formic acid, and formic acid is decomposed into hydrogen and CO2 when energy is needed. A production of hydrogen from formic acid is achieved by using a catalyst. Pd containing catalyst has been enthusiastically studied as a high actively heterogeneous catalyst. Ir, Rh or Ru containing complexes have received attention as a sophisticated homogeneous catalyst. On the other hand, polymer dispersed noble metal catalysts are also attractive materials for production of hydrogen from formic acid. The catalytic activity of them are controlled by added water-soluble polymers. This catalyst has lots of potential since polymers can realize various properties depending on the arrangement of atoms such as C, H, N, O, etc. In this review, Pt particle catalyst dispersed by polyvinylpyrrolidone is introduced as hydrogen production catalyst from formic acid.
The recent progress in the R&D for Direct formic acid/ formate fuel cells, which can directly use formic acid / formate as a fuel of a fuel cell are summarized in this paper. Direct formic acid fuel cell, which is operated with acidic media, can generate high power density when Pd is used as an anode catalyst. However, there is a room for the improvement in its stability. Moreover, it is also important for the performance improvement to improve the mass transport in the anode electrode since the CO2 generated by electrode reaction inhibit a fuel supplying to the catalyst. Direct formate fuel cell is operated using alkaline media, such as sodium formate, potassium formate and etc. This fuel cell has a high affinity for the formate production process using CO2 reduction since the formic acid is produced in alkaline media. Although the direct formate fuel cell has a short history, various cell construction or operation mode have been already reported. There are some challenges to improve its performance and stability, however, it will be a promising energy devises for direct use of energy carrier.
Germany’s long-awaited National Hydrogen Strategy was published on June 10, 2020. Hydrogen is expected as a crucial technology which will enable Germany to decarbonize the economy and accelerate the energy transition. This report points out three issues as vital aspects of the strategy: first, blue hydrogen is allowed as a transitional technology although only green hydrogen is considered to be sustainable in the long-term; second, hydrogen import is expected to meet domestic demand in the future; and third, the State Secretaries’ Committee on Hydrogen and the National Hydrogen Council are established for effective governance to implement the strategy. Then, the goals and the action plans of the strategy are described succinctly. In addition, some essential policy measures that Germany has implemented are presented to show the country’s efforts to develop hydrogen industry/society. Lastly, several demonstration cases of Power-to-Gas (PtG) are also illustrated as Germany is the pioneer of PtG applications.