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I bitumi modificati con gomma di recupero. Parte II:caratteristiche prestazionali dei leganti modificati.
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Applicazione della reologia alla valutazione e interpretazione dell'invecchiamento del bitume
No full textThe application of rheology to the evaluation of bitumen ageing
No full textOver the past few years, rheology has been extensively used in order to classify and evaluate bituminous binders according to their performance properties. This has led to a better knowledge of bitumen behaviour that occurs when subjected to different thermal and mechanical conditions, as seen during road construction and service in the field. In the present work, rheology has been applied to evaluate the properties of three vacuum residues before and after ageing. The influence of ageing on the rheological properties and temperature susceptibility was studied on whole vacuum residues and on their respective maltene fractions. Ageing produces fundamental modifications in the colloidal structure of both the vacuum residues and their maltenes fractions. The role of maltenes is important as the role of asphaltenes in determining the residue viscoelastic response. (C) 2000 Elsevier Science Ltd. All rights reserved
Oxidative Desulfurization: Oxidation Reactivity of Sulfur Compounds in Different Organic Matrixes
No full textSulfur oxidation appears a very promising route for obtaining ultralow-sulfur fuels requested worldwide by the new regulation mandates. In this work, the oxidizing system constituted by hydrogen peroxide and formic acid was used to study the influence of the solvent on the oxidation rate of sulfur compounds in the organic phase. The experimentation was performed on organic sulfur compounds selected as representative of those contained in crude distillates. The organic solvent seems to play an important role in the reaction kinetics, indicating a strong influence of its aromaticity on the oxidation rate. A different kinetic was found for heterocyclic sulfur compounds such as benzo- and dibenzothiophene when compared with thiols and sulfides, indicating for the last ones a more complex reaction path
Functionalized hexagonal mesoporous silica as an oxidizing agent for the oxidative desulfurization of organosulfur compounds
No full textThe use of peroxycarboxylic-acid-functionalized hexagonal mesoporous silica (HMS) as an oxidizing solid agent was investigated. The experimentation was performed on organic sulfur compounds that have been selected as representative of those contained in crude distillates. The results clearly show the potentiality of this oxidizing agent for the development of oxidative desulfurization (ODS) processes for the purpose of producing ultralow-sulfur fuels and sulfoxides and sulfones as secondary products. © 2008 American Chemical Society
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