Catalytic Production of Renewable Hydrogen for Use in Fuel Cells: A Review Study

Abstract

AbstractHydrogen production from renewable sources is gaining increasing importance for application as fuel, in particular with high efficiency and low impact devices such as fuel cells. In addition, the possibility to produce more sustainable hydrogen for industrial application is also of interest for fundamental industrial processes, such as ammonia and methanol synthesis. Catalytic processes are used in most options for the production of hydrogen from renewable sources. Catalysts are directly involved in the main transformation, as in the case of reforming and of electro-/photo-catalytic water splitting, or in the upgrade and refining of the main reaction products, as in the case of tar reforming. In every case, for the main processes that reached a sufficiently mature development stage, attempts of process design, economic and environmental impact assessment are presented, on one hand to finalise the demonstration of the technology, on the other hand to highlight the challenges and bottlenecks. Selected examples are described, highlighting whenever possible the role of catalysis and the open issues, e.g. for the H2 production from reforming, aqueous phase reforming, biomass pyrolysis and gasification, photo- and electro-catalytic processes, enzymatic catalysis. The case history of hydrogen production from bioethanol for use in fuel cells is detailed from the point of view of process design and techno-economic validation. Examples of steady state or dynamic simulation of a centralised or distributed H2 production unit are presented to demonstrate the feasibility of this technology, that appears as one of the nearest to market. The economic feasibility seems demonstrated when producing hydrogen starting from diluted bioethanol.