XXXIX Cycle – Doctorate in Chemical Processes for Industry and the Environment: "Innovative technologies for the production of clean H2".
Scientific Director: Prof. Paola Russo
PhD student: Dr. Leonardo Suraniti
Today, our society relies mainly on non-renewable energy sources such as fossil fuels. The combustion of these generates sufficient heat for energy production on the one hand, and CO2 on the other. The latter, released into the atmosphere, becomes one of the main causes of so-called climate change, which is responsible for unusual natural events that make life on our planet more endangered.
The need for a switch from non-renewable to renewable sources is therefore crucial; systems such as wind and solar can generate clean energy, but due to their intermittent nature they require very efficient storage systems. Hydrogen on the other hand emerges as an alternative to fossil fuels, its combustion generates heat but not CO2 presenting a high calorific value of 142 MJ/kg, while its oxidation can be exploited, in systems such as fuel cells, for the production of electricity.
Hydrogen is the most abundant element on earth but is not found free in nature, hence its production is necessary. Industrially, this is obtained from hydrocarbon reforming processes or from iron production processes.
The reforming of hydrocarbons, however, releases not only hydrogen but also CO2, effectively making the process ‘non-carbon-neutral’.
From the growing need to reduce CO2 emissions, recent studies have focused on processes and technologies that lead to ‘carbon-neutral’ hydrogen. For this reason, the use of biomass or technologies that promote water splitting are being widely investigated. To the previously mentioned techniques one can add the pyrolysis of hydrocarbons such as methane; at high temperatures (approx. 1000 °C) and in the absence of oxygen, it is indeed possible to decompose methane in an endothermic process, eventually obtaining hydrogen, heavier carbon black hydrocarbons of high quality. While the main advantage is the absence of CO2 as a side product of the reaction, on the other hand, in the absence of suitable catalysts, the temperatures required for the breaking of the C-H bonds are very high, with a not inconsiderable expenditure of energy. In the presence of catalysts, on the other hand, the operating temperatures are lower (600-1000 °C), the speed of the reaction and the final product yield increase.
Methane cracking can therefore be achieved thermally, catalytically or by a combination of these. An alternative to thermal cracking is plasma cracking. In this situation, the energy supplied to the gas molecules does not only come from the high temperatures, but from collisions with the electrons generated in the plasma state.
The aim of this research is to develop and optimise new technologies that exploit plasma in order to obtain, through cracking processes, the best yield in terms of products of interest such as hydrogen and coal with a high commercial value, and in terms of energy. The development of these technologies will be accompanied by the development of new catalysts with a lower environmental impact that can improve the yield, selectivity and morphology of reaction products.
XXXVII Cycle – Doctorate in Chemical Engineering : "Development of methodologies for the remediation of contaminated sites following accidents, including significant ones, relating to lithium batteries".
Scientific Director: Prof. Paola Russo
PhD student: Eng. Davide Palma
The development policies of Smart, Green and Integrated Transport provide for the increasingly massive use of lithium batteries and accumulators, as they are used in electric vehicles, in energy storage systems - ESS, in consumer electronics, with repercussions on management of the supply chain of batteries and vehicles or of the logistics chain and the management of the collection of unstable or end-of-life batteries and WEEE waste.
All this poses serious problems in the prevention and management of the risk of fire and explosion associated with these batteries, due to their chemistry, such as fire extinguishing operations (choice of extinguishing and extinguishing techniques) and the subsequent restoration of areas in which accidents have been occurred. The extreme variability of the chemical composition of these batteries and the scarce information on the characterization of the chemical products that can develop in the event of an accident, added to the management of unstable residues of the batteries and with risks also of an electrical nature, entail the need to deepen the topic and develop specific remediation methodologies.
The reclamation of the areas affected by accidents is provided for by international legislation on environmental protection (in Italy: Part IV, Title V of the Legislative Decree 3 April 2006, n. 152, and subsequent amendments). The chemical-physical characterization of wastewater (liquid and solid, but also airborne) from batteries, utilities and extinguishing agents (if used) is the basis of every remediation intervention. Some studies highlight the release of substances harmful to humans and the environment, such as: nanomaterials; breathable SiO2 fibers; organofluorophosphate compounds such as dimethyl fluorophosphate (DMFO) and diethyl fluorophosphate (DEFP) which appear to have acute toxicity properties comparable to Sarin; heavy metals such as: nickel, cobalt, lead, chromium and thallium.
The research is aimed at the development of one or more remediation methodologies through experimental activities carried out starting from the laboratory scale up to the real scale. On the basis of the chemical-physical characterization of the effluents, absorbent products for hazardous chemicals generally used in these contexts will be tested. The issue of collection, transport and subsequent disposal in landfills as hazardous waste will also be addressed, taking into account that the current practice of using water as a fire extinguisher or washing liquid following the reclamation with absorbents, provides for the quantitative collection and disposal in landfills as it is just as dangerous to waste.
XXXVI Cycle – Doctorate in Chemical Engineering “Fire risk management in solid waste management plants”
Scientific Director: Prof. Paola Russo
PhD student: Dr. Sofia Ubaldi
Fire is an ever-present possibility at most waste management sites, if only because many wastes are readily combustible. In recent years, numerous fires have occurred in the treatment and storage facilities of wastes whose causes are various: from involuntary triggers, such as short circuits in machinery or reactions uncontrolled chemicals among industrial waste, to cases of malicious origin, confirmed by the vision of footage captured by security cameras in the factories. Fires involving wastes can cause significant harm to people, property, and the environment. The main risk is that of death and/or serious injury and health damage from high thermal energy and smoke inhalation. Moreover, combustion products, even those from non-toxic materials, release airborne pollutants which can cause short- and long-term effects on human health and the environment. From an environmental point of view, firewater run-off can transport pollutants into drainage systems, rivers and lakes, groundwater and soil, threatening water supplies, public health, wildlife, and recreational use. Finally, explosions, sparks and projectiles can harm people and spread any fire. Consequently, property damage can be significant and costly. Operators should therefore ensure they have adequate controls in place to prevent fires and, should a fire occur, that the risks to human health, property and the environment are minimized. This research aims to develop a methodology for fire safety management on solid waste treatment and storage sites. The methodology will be developed in collaboration with the National Fire Corps and to support them in development of fire management guidance and technical regulations.
XXXIV Cycle - Doctorate in Chemical Engineering "Study of safety issues of Lithium-ion batteries for their application in the automotive sector"
Scientific Director: Prof. Paola Russo
PhD candidate: Eng. Maria Luisa Mele
Li-ion batteries are characterised by high energy and high power density, making this technology the most suitable choice for feeding portable electronics, power tools, and hybrid/full electric vehicles. In normal use conditions, electrons flow through the terminals and lithium ions pass from the anode to the cathode through the electrolyte in a process that is quasi-reversible and no significant changes appear in the chemical structure of the cell components. During failure conditions, for example an internal short circuit, the power generated rapidly surpasses the external heat losses cell capability, and Li-ion battery cells can undergo into a process called thermal runaway, which has resulted in numerous fire accidents. Thermal runaway implies a rapid increase in battery cells temperature accompanied by the release of flammable gases. These flammable gases could be easily ignited by the battery’s high temperature, resulting in a fire. In addition, the combustion of these gases as they vent from the battery poses another safety concern: the accumulation and potential explosion of the gases themselves. Thermal runaway may also be responsible for mechanical effects such as the projection of fragments as well as the release of toxic gases and vapours. This project wants analyse the safety aspectsrelevant to Li-ion battery application,especially in the automotive sector. The main purpose is to predict the possible accidents, to evaluate their effects and to develop the appropriate fire prevention and protection measures. Since the appropriate measures have not yet been developed, the results of the reasearch will be also utilised to develop safe instructions and procedures for a rescue team that is called to respond to accidents involving hybrid/full electric vehicles. The research activity will be conducted in collaboration with ENEA and the National Fire Corps.
XXXII Cycle - Doctorate in Chemical Engineering "Assessment of damage to people and buildings as consequences of Hydrogen pipeline accidents"
Scientific Director: Prof. Paola Russo
PhD candidate: Eng. Alessandra De Marco
Hydrogen is increasingly considered a valid alternative to traditional fuels, which are gradually being more and more depleted. It is defined as “the energy carrier of the future” and so, as such, it must be produced. Several hydrogen production technologies are widespread and they involve both traditional and innovative sources. After its production, the hydrogen must be made available for use and, so, it must be transported from the production site to the utilization site. One of the most common ways to transport considerable quantities of gaseous hydrogen is through pipelines. Since hydrogen is considered a “no safe” fuel due to its physical properties, the consequences of an accidental release must be investigated, to preserve the safety of people and facilities located in the surrounding area of a possible accidental event involving pipelines. Hydrogen disperses into the air very easily, being lighter than air, but if it is released in a confined space can result in an explosion. The hazards of the hydrogen-air mixture are related to the wide flammability range and the low minimum ignition energy. Furthermore, hydrogen burns with an invisible flame and so it is very difficult to suddenly identify the presence of danger. Based on these considerations, it results that a failure of pipeline conveying gaseous hydrogen can pose severe risks. The aim of this study is to evaluate damage to people and buildings involved in high-pressure hydrogen pipeline explosions and (jet) fires and, to this scope, a probabilistic risk assessment procedure is proposed. The annual probability of damage to people and to buildings exposed to an extreme event is calculated as the product of the conditional probability of damage given by a fire or an explosion and the probability of occurrence of the fire/explosion as consequence of pipeline failure. The consequences of hydrogen pipeline accidents are estimated through different tools: the SLAB integral model is used to define the gas dispersion, the TNO Multi-Energy Method to evaluate the overpressure and impulse generated from the explosions and Pressure-Impulse diagrams to evaluate damage to buildings. The flame length is calculated through the SLAB model by considering the length at which the hydrogen concentrations of 4% (lower limit flammability) is reached. The point source model is employed to estimate the radiative heat flux generated by jet fire with the radiant fraction calculated through the empirical correlation proposed by Molina et al. (2007). Finally, the Probit equations are used to calculate damage to people, both in the case of an explosion and a jet fire. The characteristic quantities of the two accidental events investigated, overpressure and impulse in the case of the explosions and radiative heat flux in the case of jet fires, are considered as causative variables. Reinforced concrete buildings and tuff stone masonry buildings are taken into consideration to estimate the effect of overpressure and impulse caused by an explosion. Direct and indirect damage on the people are investigated to define the effects of consequence of explosions and jet fires.The probabilistic procedure proposed can represent a useful tool in the design of a new hydrogen distribution network and in risks assessment for existing ones.
XXX Cycle - Doctorate in Chemical Engineering "Production of dried food quality: process optimization, recovery and improvement of waste food"
Scientific Director: Prof. Paola Russo
PhD candidate: Eng. Renato Buonocore
One of the primary goals of companies that store and process food is to convert perishable foods like fruits and vegetables in products that have a longer shelf-life and consequently a moderate loss of nutritional and sensory characteristics compared to the fresh product. One of the processes widely used for prolonging the shelf-life of food is drying. It has the aim to reduce the amount of water present in the plant to levels which inhibit the growth of microorganisms and to prevent, or minimize, the enzymatic activity and chemical degradations. The drying involves a substantial reduction in weight and volume thus minimizing the costs of packaging, storage and transport and also allowing the storage of the product at room temperature. Currently, the market demand is for quality dried food that has good texture, flavor and contain all the nutritional principles of the fresh product. To understand and optimize the drying process is therefore very important to limit thermal damage and loss of quality. The research proposal involves an experimental study and modeling of drying and rehydration of fruits and vegetables. The kinetics of dehydration, rehydration and variations of the main physico-chemical parameters and sensory properties of dried and rehydrated food will be evaluated. They will also be developed mathematical models able to estimate with sufficient accuracy the parameters of mass transport in the processes of drying and rehydration at the different temperatures used. Furthermore, as regards the waste from the agro-food production, new technologies for the extraction of substances (eg dyes, pectins, lecithins) for reuse in the food and cosmetic will be studied. The research will be conducted in collaboration with the Laboratory of Food Technology of the University of Salerno. In particular, for the study of the phenomena of diffusion of water during the drying process and the analysis of the metabolites we will rely on the cooperation of the Magnetic Resonance Laboratory "Annalaura Segre" CNR Monterotondo.