Ricerc@Sapienza

In the energy transition from fossil to clean fuels, hydrogen plays a key role. Proton-exchange membrane fuel cells (PEMFCs) represent the most promising hydrogen application, but they require a pure hydrogen stream (CO < 10 ppm). The steam iron process represents a technology for the production of pure H2, exploiting iron redox cycles. If renewable reducing agents are used, the process can be considered completely green. In this context, bio-ethanol can be an interesting solution that is still not thoroughly explored.

Hydrogen is becoming an attractive alternative for energy storage and transportation, because of the elevated energy content per unit of mass and possibility to have zero carbon-emission vehicles. For these reasons, hydrogen's share in global market is expected to grow substantially in the coming years. Today, hydrogenfueled buses and cars are already available, and several refueling stations are operating in different countries around the world.

Membrane-electrode assemblies based on chemically stabilised short-side-chain proton exchange Aquivion ® membranes, prepared by extrusion or recast methods, have been investigated for operation at high current density (3–4 A cm −2 ) in water electrolysis cells. A thickness of 90 μm was selected for these perfluorosulfonic acid membranes in order to provide proper resilience to hydrogen crossover under differential pressure operation while allowing operation at high currents.

The share of electrical energy hailing from renewable sources in the European electricity mix is increasing. The match between renewable power supply and demand has become the greatest challenge to cope with. Gas infrastructure can accommodate large volumes of electricity converted into gas whenever this supply of renewable power is larger than the grid capacity or than the electricity demand. The Power-to-Gas (P2G) process chain could play a significant role in the future energy system.

Hydrogen leakage and fire ignition and propagation are safety concerns in several industrial plants. In a nuclear fusion power plants the separation of hydrogen and tritium takes place in different steps, among which one or more electrolyzers are foreseen. A fire scenario could take place in case of leakage of hydrogen. In such cases, it is important to prevent the spreading of the fire to adjacent rooms and, at the same time, to withstand the pressure load on walls, to avoid radioactivity release in the surrounding environment.

Membrane reactors for hydrogen production have been extensively studied in the past years due to the interest in developing systems that are adequate for the decentralized production of high-purity hydrogen. Research in this field has been both experimental and theoretical. The aim of this work is two-fold. On the one hand, modeling work on membrane reactors that has been carried out in the past is presented and discussed, along with the constitutive equations used to describe the different phenomena characterizing the behavior of the system.

Membrane reactors for low-temperature hydrogen production are receiving significant attention. The main design challenges include the choice of appropriate membranes, catalysts, and catalyst supports. Research on the mechanical supports has been addressed towards the use of solid foams; however, information regarding mass dispersion within these foams is still lacking, even though the resistance to mass transport in the packed bed may become relevant when using a good catalyst and a high-permeability membrane.

Membrane reactors for the production of pure hydrogen are complex systems whose performance is determined by the interplay between transport by convection and dispersion within the packed bed, hydrogen permeation across the membrane, and the reaction kinetics. Much effort has been devoted to the development of simplified models that combine an adequate description of the system, while maintaining a low computational cost.

Global warming and climate change are indisputable theories. Since the Industrial
Revolution, the mean temperature of the planet has increased by 1°C. Now, temperatures
are approaching a higher stage of +1.5°C and the attention is on both CO2 emissions and
energy consumption. Transportation is a major component of the environmental impact,
accounting for approximately 30% of air pollution and energy consumption. Due to the
rapid urbanization in the EU, with an estimated 74.3% of the population living in cities,