Hydrogen production with photocatalysts prepared by mechanochemical methods

The objective of this thesis is to study the hydrogen production according to the preparation of photocatalysts with mechanochemical methods from semiconductors such as titanium dioxide. The preparation of the photocatalysts and their assay were performed in a laboratory with a photoreactor. In this way it was possible to determine by the different techniques and chemical compositions, which formulation was the most effective. The mechanochemical methods are simple and environmentally friendly because no solvents are used; they are faster and easily reproducible. The technique by which the experiments were performed is called ball milling. This method is a is a mechanical technique widely used to grind powders into fine particles and blend materials. The samples used for this study were a mixture of titanium dioxide (TiO2) with different chemical compositions of another semiconductor. These were tin (IV) oxide (SnO2), zinc oxide (ZnO), copper (II) oxide (CuO), cadmium sulphide (CdS) and zinc sulphide (ZnS). Once the sample was obtained by ball milling from different compositions of 90% TiO2 plus 10% from another semiconductor mentioned before, its reactivity was analysed in a laboratory photoreactor to determine how much hydrogen produces each photocatalyst. This analysis has determined that the photocatalyst that achieves the best results in terms of hydrogen production is the combination of 90% TiO2 and 10% CuO, since CuO semiconductor has a smaller band gap than the other semiconductors analysed. Therefore, the semiconductors that had a higher band gap, such as ZnO or ZnS, were the ones that obtained the worst results, except for the SnO2 photocatalyst, as it was the second photocatalyst that worked best. Therefore, according to the results obtained, it has been determined that not only the semiconductor band gap must be considered when preparing a photocatalyst, but also the position of the CB and VB of each semiconductor, to be able to determine which combination of elements is most suitable

Planning and operation objectives of public electric vehicle charging infrastructures: a review

Planning public electric vehicle (EV) charging infrastructure has gradually become a key factor in the electrification of mobility and decarbonization of the transport sector. In order to achieve a high level of electrification in mobility, in recent years, different studies have been presented, proposing novel practices and methodologies for the planning and operation of electric vehicles charging infrastructure. In this paper, the authors present an up-to-date analysis of the existing literature in this research field, organized by considering the perspectives and objectives of the principal actors/operators of the EV public charging infrastructure value chain. Among these actors, the electric vehicle, the charging operators and service providers, and the power system infrastructure (transmission and distribution system) are analyzed in depth. By classifying the reviewed literature based on this manifold viewpoints approach, this paper aims to facilitate researchers and technology developers in exploring the state-of-the-art methodologies for each actor’s perspective, and identify conflicting interests and synergies in charging infrastructure operation and planning.The authors would like to thank the Research Council of Norway and industry partners for the support in writing this paper under project 295133/E20FuChar—Grid and Charging Infrastructure of the Future https://prosjektbanken.forskningsradet.no/en/project/FORISS/295133?Kilde=F ORISS&distribution=Ar&chart=bar&calcType=funding&Sprak=no&sortBy=score&sortOrder=desc& resultCount=30&offset=0&Fritekst=fuchar&source=FORISS&projectId=295133 (accessed on 23 June 2023). The authors gratefully acknowledge Michele Garau, Bendik Nybakk Torsæter, and Daniel Mota from SINTEF Energy Research for their contribution to the conceptualization and review of the article. The work of Andreas Sumper was supported by the Catalan Institution for Research and Advanced Studies (ICREA) Academia Program.Postprint (published version

Investigation on the influence of char properties on its oxidation reactivity under different atmospheres

The objective of this thesis is the study of the influence of char properties on its reactivity of oxidation and gasification under different atmospheres, including air, carbon dioxide and water vapor. To modify the properties of the chars, the conditions of the pyrolysis process were varied: initial material used, final temperature of the pyrolysis process and composition of the atmosphere in the pyrolysis process. As for the initial material, we used: oak wood, beech wood, oak wood doped with iron (II) sulphate (FeSO4), oak wood doped with potassium hydroxide (KOH) and almond shell. The chars were produced by pyrolysis at temperatures of 450 and 500 °C in atmospheres of N2, H2O y H2O+N2. This thesis focused on the study of the reactivity of these chars, which was carried out by thermogravimetry. The first step was to determine the experimental conditions that would ensure a kinetic regime in thermogravimetric experiments, that is, the absence of transport limitations both external and internal. This is a fundamental step since if there are transport limitations the reactivity studied will not correspond to the thermochemical process investigated (oxidation and gasification), but to physical transport processes. For this, two types of experiments were carried out: oxidation up to 600 °C with a char of known reactivity at a constant heating rate, varying the air flow and the amount of initial mass used; and gasification experiments at 900 °C (isothermal) in an atmosphere of carbon dioxide (CO2). Next, the reactivity of the different chars was characterized using the experimental conditions previously defined. The oxidation reactivity was measured in an air atmosphere up to a temperature of 600 °C under a constant heating rate. The gasification reactivity was determined in a CO2 atmosphere at 900 °C (isothermal experiments). In some cases, it was necessary to vary these conditions to analyse more complex chars. This will be presented and discussed in more detail throughout the thesis. This work was carried out in the context of a major research project in the Multi-phase reactive flows group, part of the Chair for Energy Process Engineering and Conversion Technologies for Renewable Energies of the Technische Universität Berlin.Outgoin

Investigation on the influence of char properties on its oxidation reactivity under different atmospheres

The objective of this thesis is the study of the influence of char properties on its reactivity of oxidation and gasification under different atmospheres, including air, carbon dioxide and water vapor. To modify the properties of the chars, the conditions of the pyrolysis process were varied: initial material used, final temperature of the pyrolysis process and composition of the atmosphere in the pyrolysis process. As for the initial material, we used: oak wood, beech wood, oak wood doped with iron (II) sulphate (FeSO4), oak wood doped with potassium hydroxide (KOH) and almond shell. The chars were produced by pyrolysis at temperatures of 450 and 500 °C in atmospheres of N2, H2O y H2O+N2. This thesis focused on the study of the reactivity of these chars, which was carried out by thermogravimetry. The first step was to determine the experimental conditions that would ensure a kinetic regime in thermogravimetric experiments, that is, the absence of transport limitations both external and internal. This is a fundamental step since if there are transport limitations the reactivity studied will not correspond to the thermochemical process investigated (oxidation and gasification), but to physical transport processes. For this, two types of experiments were carried out: oxidation up to 600 °C with a char of known reactivity at a constant heating rate, varying the air flow and the amount of initial mass used; and gasification experiments at 900 °C (isothermal) in an atmosphere of carbon dioxide (CO2). Next, the reactivity of the different chars was characterized using the experimental conditions previously defined. The oxidation reactivity was measured in an air atmosphere up to a temperature of 600 °C under a constant heating rate. The gasification reactivity was determined in a CO2 atmosphere at 900 °C (isothermal experiments). In some cases, it was necessary to vary these conditions to analyse more complex chars. This will be presented and discussed in more detail throughout the thesis. This work was carried out in the context of a major research project in the Multi-phase reactive flows group, part of the Chair for Energy Process Engineering and Conversion Technologies for Renewable Energies of the Technische Universität Berlin.Outgoin

Investigation on the influence of char properties on its oxidation reactivity under different atmospheres

The objective of this thesis is the study of the influence of char properties on its reactivity of oxidation and gasification under different atmospheres, including air, carbon dioxide and water vapor. To modify the properties of the chars, the conditions of the pyrolysis process were varied: initial material used, final temperature of the pyrolysis process and composition of the atmosphere in the pyrolysis process. As for the initial material, we used: oak wood, beech wood, oak wood doped with iron (II) sulphate (FeSO4), oak wood doped with potassium hydroxide (KOH) and almond shell. The chars were produced by pyrolysis at temperatures of 450 and 500 °C in atmospheres of N2, H2O y H2O+N2. This thesis focused on the study of the reactivity of these chars, which was carried out by thermogravimetry. The first step was to determine the experimental conditions that would ensure a kinetic regime in thermogravimetric experiments, that is, the absence of transport limitations both external and internal. This is a fundamental step since if there are transport limitations the reactivity studied will not correspond to the thermochemical process investigated (oxidation and gasification), but to physical transport processes. For this, two types of experiments were carried out: oxidation up to 600 °C with a char of known reactivity at a constant heating rate, varying the air flow and the amount of initial mass used; and gasification experiments at 900 °C (isothermal) in an atmosphere of carbon dioxide (CO2). Next, the reactivity of the different chars was characterized using the experimental conditions previously defined. The oxidation reactivity was measured in an air atmosphere up to a temperature of 600 °C under a constant heating rate. The gasification reactivity was determined in a CO2 atmosphere at 900 °C (isothermal experiments). In some cases, it was necessary to vary these conditions to analyse more complex chars. This will be presented and discussed in more detail throughout the thesis. This work was carried out in the context of a major research project in the Multi-phase reactive flows group, part of the Chair for Energy Process Engineering and Conversion Technologies for Renewable Energies of the Technische Universität Berlin.Outgoin