Matteo D'Amore

Catalytic oxidation of an amorphous carbon black

Abstract The oxidation of an amorphous carbon black in the presence of a potassium-copper-vanadium catalyst supported on α-alumina has been studied. Burnoff temperatures in the presence of catalyst were lowered by about 300 K with respect to those for uncatalyzed combustion. Cycles of temperature-programmed reduction and oxidation, along with TG-MS analyses demonstrated that a redox mechanism is at the basis of the catalyst strong activity. A differential flow reactor was employed to perform kinetic tests. The progress of the catalytic combustion process was followed measuring the concentrations of carbon oxides in the product stream at the reactor outlet with on-line NDIR analyzers. The dependence of the reaction rate on the relevant variables was investigated. In particular, the apparent activation energy for the catalytic oxidation was found to be less than half that of the corresponding uncatalyzed process, while the carbon reactivity showed a linear dependence upon the amount of catalyst and a square root dependence upon the oxygen partial pressure. The results allowed the formulation of a mechanism for the catalytic oxidation of carbon black and suggest that the limiting step of the overall process is that of catalyst reduction. On the basis of such findings a kinetic equation for catalytic carbon black oxidation is proposed.

Some issues in modelling bubbling and circulating fluidized-bed coal combustors

Abstract Fundamental aspects of coal combustion in the two types of atmospheric fluidized combustors, i.e. those based on bubbling and on circulating technologies, have been studied in order to determine those variables which play a dominant role in the reactor performance. The analysis is based on two relatively simple models, which take into account carbon surface reaction, intraparticle and external diffusion as well as phenomena of comminution of coal and its char. Performances of the two types of fluidized-bed combustors are discussed with reference to coal combustion only, without taking into consideration the emission issues. Sensitivities of main output variables to changes in fuel properties, design and operating variables are evaluated.

On the Behavior of HPMC/Theophylline Matrices for Controlled Drug Delivery

Design of systems for oral controlled release of drug could take advantages from the knowledge of which phenomena take place. In this work matrices obtained by powders compression (50:50, hydroxypropyl methylcellulose, a swelling hydrogel, and theophylline, a model drug) were immersed in water at 37 degrees C, allowing the water uptake and the drug release by lateral surface, confining the cylindrical matrices between glass slides. The tablets, after given immersion times, were withdrawn, cut in several annuli, and subsequently analyzed for the drug and the water concentration radial profiles. The data confirmed the pseudo-diffusive nature of the process, allowing to give a deep insight into the drug release process from swellable hydrogel matrices. In particular, it was confirmed the presence of nonhomogeneous gel layer, rich in water and poor in drug, with a profile of drug concentration which agrees well with a pseudo-diffusion phenomenon.

The influence of temperature on the properties of the particulate phase at incipient fluidization

Abstract An experimental study is reported which demonstrates that the influence of the operating temperature on bed voidage at incipient fluidization cannot be explained on a hydrodynamic basis, as currently accepted. Because the increase in bed porosity also occurs in the settled state, this is shown to be a consequence of the enhancement, at medium and high temperature, of the attractive forces acting in the particulate phase. The analogy with the fluidization behaviour of beds affected by other types of interparticle forces is examined.

Catalytic Combustion of Methane Soot

Abstract The performances of a Cu-V-K catalyst in the oxidation of soot collected in a methane-rich flame have been studied in a tubular flow reactor. Burn-off temperatures were lowered by about 300 K with respect to uncatalyzed combustion. The dependence of the reaction rate on the relevant variables was investigated. The apparent activation energy for the catalytic oxidation was found to be about a half of the one of the uncatalyzed process, while the carbon reactivity showed a linear dependence on the initial soot to catalyst mass ratio. A square root dependence on the oxygen partial pressure was found. The results of soot combustion confirm previous findings obtained with other carbon materials. Moreover, kinetic data follow a model proposed for the catalytic combustion of amorphous carbon black (Ciambelli et al, 1994a). An extension of this model, incorporating the influence of carbon-catalyst contact on the catalyst performances, has been presented.

Regeneration of a soot-trap ceramic foam by a single-mode microwave cavity

The regeneration of a ceramic foam used as a filter for soot trapping in the exhausts of a gas-oil burner has been performed in a specially designed single-mode microwave cavity. The microwave applicator, of a cylindrical shape, has been designed to be a TM 010 resonant cavity, with a parabolic-like profile of the electromagnetic field that identically repeats itself along the axis. CO, CO 2 , and O 2 concentrations in the flue gas and surface temperature of the filter have been measured online. The effectiveness of regeneration has been followed through a mass balance of the carbon. All the runs have been performed in cold gas. Results in terms of time and completeness of the regeneration under the various experimental conditions are reported and discussed.

Studying the influence of cognitive load on driver's performances by a Fuzzy analysis of Lane Keeping in a drive simulation.

Abstract The psycho-physical state of a driver has been widely recognized as the crucial point in any issue concerning the development of models headed to improve the vehicle safety, either inherent and active, so much so that almost all the new in-vehicle technology, currently developing at a rapid rate, introduces devices to continuously monitor the driver. This paper describes the architecture of a real time, performance-based, driver monitoring system able to detect the decrease in driver performances due to driver distraction, fatigue, sleepiness and alcohol or drugs ingestion. The system processes the instantaneous lateral position of the vehicle on the road. This allows to work out an index of the lane keeping precision by means of the lateral position standard deviation (SDLP). This latter and the road environment complexity has been processed by a fuzzy inference system that has, as an output, a score reflecting the drivers ability to maintain adequate lane-tracking movements for a given road scenario. Fuzzy membership functions and inference rules has been based and optimized on data obtained on 12 subjects performing driving simulation under both baseline condition and two different cognitive overload situations induced by different secondary tasks, one with visual distraction, the other characterized by a pure cognitive load, respectively. Aim of the work is to attain to a black-box type devices that could both provide warnings or reminding in case of risky driving and encourage the driver to improve his behavior. Advantages would also come for parents of novice drivers promptly alerted for improper driving and even for the car insurance companies that could reward safe drivers.

Microencapsulation effectiveness of small active molecules in biopolymer by ultrasonic atomization technique

A method to produce biopolymeric (alginate) microparticles by ultrasonic assisted atomization, previously developed, has been applied to the production of microparticles loaded with a small active molecule (theophylline). Fine loaded alginate droplets have been cross-linked with divalent ions to produce microparticles. Once produced, the particles have been separated by centrifugation or filtration and then they have been dried. Drug release has been evaluated by dissolution tests, dissolving the dried particles in acidic solution at pH 1 for a given time and then at pH 7 to simulate the stomach and intestinal environment, respectively. The encapsulation efficiency and the drug loading have been investigated and the operating conditions have been changed to clarify the role of the transport phenomena on the overall process. To increase the drug loading, shorter separation time and better network’s structure were identified as the key operating parameters to allow the process to gain interest from a practical point of view.

Carbon attrition in the fluidized combustion of a metallurgical coke

The multiplication of carbon particles inside the bed of a fluidised coal combustor can be related to fragmentation and attrition. Attrition generates finer carbon which is rapidly elutriated from the bed. Previous work on attrition was carried out on a non-swelling coal. The present paper reports an extension of this work to a metallurgical coke during fluidised bed combustion. In comparison with the coal, metallurgical coal is not subject to fragmentation and is less reactive. This enabled attrition to be examined separately and at higher bed carbon content for a given fluidising velocity and excess air.

79 Microwaves assisted regeneration of catalytic filter for soot particulate

Abstract In this work a microwave source has been employed for the regeneration of a ceramic foam used as a filter for soot trapping in the exhaust of a gas-oil burner. A specially designed single mode microwave cavity with a parabolic-like profile of the electromagnetic field has been constructed. We have found that a combined system of catalytic filter and microwave heating is able to perform filter regeneration at the temperature typical of diesel exhaust. In particular, the presence of catalyst assures lower soot ignition temperature, higher selectivity to CO2, higher soot combustion rate and higher microwave energy saving.