Thursday, 21 September 2017

Spanish researchers propose a new system of efficient production, storage and safe transportation of hydrogen

Source: Asociación RUVID, 18th September 2017

A group of researchers from the Universitat Jaume I de Castelló, the University of Zaragoza and the Institute of Chemical Technology of the Universitat Politècnica de València-CSIC, coordinated by Professor José Antonio Mata of the UJI, have developed and patented a new procedure of efficient production, storage and safe transport of hydrogen for their use in fuel cells through the use of chemical reagents. The technology is based on the use of so-called liquid hydrogen organic carriers (LOHC).

Hydrogen is an excellent fuel because of its high energy density and zero emission of greenhouse gases. Its combination with atmospheric oxygen produces energy and water as the only by-product, making it one of the main candidates to replace fossil fuels as a source of energy for the transport sector.

Despite this, there are still some drawbacks that have prevented the implementation of the so-called "hydrogen economy". The first is that this gas is not found in the earth's crust and must be produced in a process that is not usually sustainable, and the second is its flammable nature and the need to transport it in a compressed way, with the dangers they derive.

The main advantage of these liquids is that they can store hydrogen for long periods and can be transported using the current infrastructure. The research team has studied different hydrogen-bearing organic liquids to arrive at a new hydrogen storage system based on a chemical coupling reaction between a hydrosilane and an alcohol catalysed by a ruthenium compound supported in graphene.

The contributions of this process are multiple with respect to the already established systems. First, it is a chemically versatile process because there are many combinations of hydrosilanes and alcohols that can be employed. Secondly, the process can be performed very fast and no elevated temperatures are required, as the team has also developed ruthenium catalysts that are highly efficient for this reaction. Thirdly, the process is reversible because the product formed in the coupling between a hydrosilane and alcohol is a silyl ether that can be further transformed into the original product by a reductant.

Among its main advantages, it constitutes an energy system whose only by-product is water and, at the same time, it is reversible, by allowing to store-generate hydrogen according to demand. It can be easily adapted to non-static energy generation and use systems, such as automobiles; the use of silane-alcohol as LOHC allows working at low temperatures in obtaining the gas and the technology circumvents the safety problems of hydrogen storage.

The overall energy generation process comprises four large blocks. Production would be the first, whose challenge would be to obtain hydrogen from alternative energies such as solar or wind, in a quasi-sustainable process; for that would be desirable that the by-products derived were obtained in an industrial centre where the generation was fully controlled. In the second (transportation) and third (distribution), which do not require any innovation in the industrial or scientific field, the proposed system could use the existing infrastructure for transportation and distribution of petroleum products. Finally, the fourth block (use) is the one that contemplates the chemical reaction for obtaining hydrogen and its use in fuel cells. The preliminary results obtained show that the reaction is very rapid and can take place even at room temperature, which corresponds to adequate kinetics for the generation and immediate use of hydrogen.

Image: The researchers Pilar Borja, José Mata and Andrés Mollar in one of the laboratories of the UJI.

This new procedure is aimed at the energy production industry, specifically at the one that exploits renewable sources of energy free of pollutant and greenhouse emissions. Specifically, it is applicable in companies dedicated to the production and commercialization of solutions for the storage and transportation of hydrogen, as energy vector, based on the use of LOHC as hydrogen carriers.

The research team, which has validated the new experimental procedure in the laboratory environment, is made up by José Mata (UJI), project manager, Miguel Baya (UZA) and Hermenegildo García (UPV-CSIC). In the research group of the UJI have also participated David Ventura-Espinosa, fellow of the Ministry of Economy and Competitiveness (FPU); Alba Carretero, student of the Master's Degree in Applied and Pharmacological Chemistry; Mapi Borja, UJI postdoctoral staff, and Andrés Mollar, a graduate student in chemistry.

Full bibliographic information

Ventura-Espinosa, D., Carretero-Cerdán, A., Baya, M., García, H. and Mata, J. A. (2017), Catalytic Dehydrogenative Coupling of Hydrosilanes with Alcohols for the Production of Hydrogen On-demand: Application of a Silane/Alcohol Pair as a Liquid Organic Hydrogen Carrier. Chem. Eur. J. doi:10.1002/chem.201700243