Carlo Giavarini

Characterization of visbreaker bitumens by n.m.r. spectroscopy

Abstract A study was made using n.m.r. spectroscopy on visbreaker and straight-run bitumens to find structural differences. The results show that C ar and H ar contents are appreciably higher in VB bitumens, thus aiding characterization.

Active carbon from scrap tyres

Abstract The possibility of producing active carbon by activation at 850 °C of the char obtained from the pyrolysis (at 450 and 600 °C) of scrap tyres has been studied. The activated char showed good adsorbing characteristics, similar to those of typical commercial grades. The yield and the desired adsorbing capacity depend on the activation time. However, the ash content and friability are quite high; therefore the activated char is suitable for applications in powder form in which the ash does not cause problems.

FORMATION AND DISSOCIATION OF CO2 AND CO2 – THF HYDRATES COMPARED TO CH4 AND CH4 - THF HYDRATES

. This work is part of a research project sponsored by the Italian Electricity Agency for CO2 disposal in form of hydrate. The dissociation behavior of CH4 hydrate was taken as a reference for the study of the CO2 hydrate preservation. The formation and dissociation of CO2 and CO2–THF mixed hydrates, compared to CH4 and CH4 – THF mixed hydrates, has been considered. The experimental tests were performed in a 2 liter reaction calorimeter at pressures between 0.1 and 0.3 MPa. The dissociation has been followed at temperatures from -3 °C to 0 °C for CO2 and CH4 hydrates, and from -3 °C to 10 °C for THF mixed hydrates. More than pressure, which is very important for methane hydrates, temperature affects the preservation of CO2 and CO2–THF mixed hydrates. Subcooling after formation is important for methane hydrate preservation, but it does not substantially affect CO2 hydrate stability. In the studied P, T range, CO2 hydrate does not present any anomalous self-preservation effect. The mixtures containing more ice show a slower dissociation rate. Methane hydrate requires less energy to dissociate than CO2 hydrate and, therefore, is less stable. On the contrary, the mixed CO2 – THF hydrates are less stable than the mixed methane hydrates. Modulated differential scanning calorimetry (MDSC) has been used for hydrate characterization: both CH4 and CO2 hydrates include two decomposition peaks, the first due to the melting of the ice and the second to the decomposition of the hydrate. The higher temperature of the decomposition peak of CO2 hydrate confirms its higher stability respect to CH4 hydrate.

Characteristics of bitumens extracted from Italian bituminous rocks and shales

Abstract The soluble portion of representative samples from Italian bituminous rocks and shales were studied by n.m.r. spectrometry in the liquid state and by thermoanalytical techniques. The extracted bitumens have a variety of characteristics and also differ from analogous foreign material. One of the samples, from the Ragusa, Sicily area, is of considerable interest from the point of view of exploitation, as it is soluble in benzene and almost totally distillable in the 150–500 °C range.

Characterization of Gas Hydrates by Modulated Differential Scanning Calorimetry

Abstract Modulated Differential Scanning Calorimetry (MDSC) has been applied to the study of methane, ethane, and propane hydrates at different hydrate and ice concentrations. The reversing thermodynamical component of the MDSC curves, makes it possible to characterize such hydrates. Methane and ethane hydrates show the melting-decomposition peak at a temperatures higher than the ice contained in the sample, while propane hydrate melts and decomposes at a lower temperature than the ice present in the sample. The hydrate peaks tend to disappear if the hydrate is stored at atmospheric pressure. Guest size and cavity occupation fix the heat of dissociation and stability of the hydrates, as confirmed by parallel tests on tetrahydrofurane hydrates.

EVALUATION OF ASPHALT BY NON-CONVENTIONAL TECHNIQUES

ABSTRACT A number of bitumens of different origin, type, and composition (straight run, visbroken, blown, aged, rejuvenated and rock asphalts) were compared to show how non-conventional techniques may be used in solving practical problems relating to pavement performance properties, and in recognizing bitumens of different origins. Such techniques include differential scanning calorimetry (DSC) and nuclear magnetic resonance (NMR) in addition to the traditional tests. It is possible to obtain correlations which connect NMR or DSC parameters to the severity of the process by which VB bitumens were obtained.