giuseppina carotenuto - Academia.edu (original) (raw)

Papers by giuseppina carotenuto

Biomass Conversion and Biorefinery, 2012

In the present paper, the development of new heterogeneous catalytic processes to produce high co... more In the present paper, the development of new heterogeneous catalytic processes to produce high commodity chemicals of industrial interest such as acetaldehyde, ethyl acetate, and pure hydrogen by bioethanol has been discussed. All the reactions were performed in a conventional packed bed tubular reactor and in a wide range of temperature 50-500°C, pressure 1-30 bar, and space time W/F00.1-100 gh mol −1. The aim of this research is to demonstrate that by varying properly the operative range of residence time and pressure, it is possible to obtain with high selectivity acetaldehyde or ethyl acetate from ethanol in a single reaction step. The performances of a series of commercial copper-based catalysts have been studied in the ethanol dehydrogenation/oxidative reforming reactions. In particular, very promising results have been obtained by using a commercial catalyst of copper/copper chromite containing barium chromite as a promoter. In a low range of residence time 0.1-1 gh mol −1 and at low pressure, very high performances in terms of ethanol conversion (60 %) and acetaldehyde selectivity (90 %) have been obtained. On the contrary, by operating at high residence time, at a pressure higher than 10 bar, and by feeding 25 cm 3 /min of a mixture of 6 %H 2 in N 2 , a very high selectivity to ethyl acetate (98.9 %) was observed. The examined catalysts were characterized by using ex situ methods such as X-ray photoelectron spectroscopy and in situ EXAFS and FTIR with the aim to evaluate their physical properties and to correlate them with the catalysts' performances.

Catalysis for Sustainable Energy, 2015

The activity and stability of niobia supported on silica catalyst have been tested in continuous ... more The activity and stability of niobia supported on silica catalyst have been tested in continuous micro-pilot reactors, for biodiesel production starting from acid vegetable oils. A catalyst was prepared by the impregnation of silica pellets with a loading of 12% of Nb and was extensively characterized. The activity of this catalyst in both esterification and transesterification was tested in a continuous micro-pilot laboratory plant in which acid oil was fed (FFA 10% w/w) at a temperature of 220°C and at a pressure of 60 bar. The niobia based catalyst resulted in a very active catalyst in both esterification (FFA conversion = 95-90%) and transesterification reactions (FAME yield = 80-90%), and the activity remained quite constant for more than 100 h on stream. Notwithstanding this stability, a non-negligible leaching phenomena has been detected, in the case of long-time continuous runs, as the Nb concentration on the spent catalyst resulted lower than that on the fresh one. The obta...

ABSTRACT Waste raw materials obtained by several sources of food and by agro industries could be ... more ABSTRACT Waste raw materials obtained by several sources of food and by agro industries could be used for biofuel production. In the last years, these topics have growing in interest according to the last EU legislation on biofuels sustainability. Our research, related to AGROPROM national project of the Italian Ministry of Agriculture, is focusing on the development of new technologies to obtain biodiesel from agro-industrial wastes, in particular from oleins, that is mixtures of free fatty acids (FFAs) and triglycerides. A preliminary study on the sources of oleins in Europe will be reported. These raw materials cannot be processed in the classical biodiesel plant, because, the usual basic catalyst cannot be employed for promoting transesterification reaction. At this purpose, we are studying an innovative way to produce biodiesel by using these waste feedstock performing, before the esterification, a reaction of FFAs with glycerol and submitting then the whole mixture to transesterification with methanol. The esterification of FFAs with glycerol provided the possibility to operate at relatively high temperature and atmospheric pressure removing, by stripping, the water formed during the esterification reaction, shifting the chemical equilibrium to the right. The mixture of monoglycerides, diglycerides and triglycerides, that can be obtained by esterification with glycerol, can be subsequently submitted to transesterification with methanol to produce biodiesel in the usual way. As reported in the literature, the most employed catalysts to perform the esterification reaction, are homogeneous mineral acids and acid ion exchange resins [1-3]. Although a heterogeneous catalyst is more convenient, because, can be more easily separated and recycled, commercially available acid ion exchange resins are limited in the use because cannot be used at temperature greater than about 120°C. Therefore, other more temperature-resistant sulphonic resins, Nafion, and H2WO4/SiO2, have been tested in the described esterification reaction and their performances have been compared with the ones of sulphuric acid. At last, different heterogeneous catalysts for transesterification have also been studied in a continuous micropilot plant reactor with encouraging results. [1] Y. Pouilloux , S. Abro, C. Vanhove, J. Barrault Journal of Molecular Catalysis A: Chemical 149 _1999. 243–254 [2] Franz J. Luxem, US 6,822,105 B1 [3]Parodi, Augusto, WO 2008/007231 A1

Journal of Molecular Catalysis A: Chemical, 2012

ABSTRACT Times Cited: 0

Chemical Engineering Journal, 2012

In the recent years, the interest in the ethanol production from renewable natural sources, as a ... more In the recent years, the interest in the ethanol production from renewable natural sources, as a possible alternative energy vector, has strongly grown in the world. The low-cost ethanol availability has also favored the study of the production of different chemicals such as ethylene, ethyl ether, acetaldehyde and ethyl acetate starting from ethanol as raw material. In this paper, ethanol dehydrogenation to ethyl acetate, in one step reaction, has been studied by using three different commercial copper based catalysts. The reaction has been conducted in a conventional packed bed tubular reactor, by exploring a temperature range of 200-260 • C and a pressure range of 10-30 bars. The best results have been found by using a commercial copper/copper chromite catalyst, supported on alumina and containing barium chromite as promoter, operating at 220-240 • C, 20 bars and 98 g h mol −1 of ethanol contact time. In these conditions, a conversion of 65% with a selectivity to ethyl acetate of 98-99% has been obtained. However, the effect of temperature, pressure and ethanol contact time on both conversion and selectivity to ethyl acetate has been investigated. Moreover, the best catalyst has also shown a good stability to deactivation. For these reasons, the behavior of this catalyst has been subjected to a deeper investigation. The obtained results have been discussed on the basis of a reliable reaction scheme and mechanism. At last, a simplified scheme of a possible process is reported.

Catalysis Today, 2012

The performances of a commercial Mg/Al hydrotalcite (Pural © MG76) in biodiesel production have b... more The performances of a commercial Mg/Al hydrotalcite (Pural © MG76) in biodiesel production have been tested in an autoclave and in a continuous packed bed reactor. The obtained results have shown that calcined Mg/Al hydrotalcite (Pural © MG76) is a promising heterogeneous catalyst for biodiesel production because is sufficiently active, deactivates slowly and can easily be regenerated.

Catalysis Today, 2013

In this work gas phase photocatalytic selective oxidation of ethanol to acetaldehyde was studied ... more In this work gas phase photocatalytic selective oxidation of ethanol to acetaldehyde was studied with directly fluidizable photocatalysts made of grafted VO x on titania/silica in presence of phosphors as light carriers to test their performances in the photocatalytic system. The presence of VO x species anchored on TiO 2 /SiO 2 enhanced ethanol conversion up to 66%, with acetaldehyde selectivity higher than 99%. The performances of V-based sample at 11 wt% of TiO 2 supported on fluidizable support were higher than those evaluated when nano-TiO 2 powder is used as support. Moreover, the photocatalytic conversion of ethanol was further increased in presence of phosphors as light carriers. From the obtained results, it is concluded that by preparing VO x based catalyst through grafting method allows a dramatic enhance in the productivity of acetaldehyde, even when the concentration level of alcohol at photoreactor inlet is increased.

Catalysis Today, 2013

A kinetic study of the ethanol dehydrogenation to ethyl acetate on a copper/copper-chromite catal... more A kinetic study of the ethanol dehydrogenation to ethyl acetate on a copper/copper-chromite catalyst has been performed. The used catalyst, in cylindrical pellets, contained also alumina as a support and barium chromate as a promoter. Support and promoter have the effect of increasing the activity, the selectivity and the stability of the catalyst, as shown in a previous work. The kinetic runs were carried out in a packed bed tubular reactor, alternatively filled with 2 or 50 g of catalyst, approximately isothermal, by feeding pure ethanol together with a mixture of nitrogen and hydrogen as carrier gas. Kinetic runs have been made by changing the temperature, in the range of 200-260 • C, the pressure between 10 and 30 bar and the space time from 1 to 100 g h mol −1. We have verified, at first, that inter-phase and intra-phase mass transfer limitations were negligible in the adopted conditions. Then, a Langmuir-Hinshelwood-Hougen-Watson kinetic model has been used for interpreting all the experimental data collected. This model corresponds to a mechanism in which the first step is the dissociative adsorption of ethanol on the surface, giving an adsorbed ethoxy group. Then, two other consecutive steps give place to respectively acetaldehyde as intermediate and ethyl acetate. This kinetic model allows a satisfactory fitting of all the performed experimental runs with a standard error below 15% for the runs performed with 2 g of catalyst and less than 12% for the runs made with 50 g of catalyst.

Catalysis Today, 2013

ABSTRACT The catalytic generation by ethanol decomposition and partial oxidation over copper-chro... more ABSTRACT The catalytic generation by ethanol decomposition and partial oxidation over copper-chromite and copper-zinc catalyst supported on alumina has been investigated. The catalysts have been prepared by the method of combustion synthesis, characterized by a fast heating rate and a short reaction time, leading to increase catalyst porosity and total surface area. The catalytic activity and selectivity have been investigated without O2 and under various O2 and C2H5OH molar ratio in the temperature range up to 500 °C. It was found that copper chromite supported on alumina shows the best activity and hydrogen selectivity during ethanol decomposition. The selectivity decreased during partial oxidation but with a low O2/EtOH = 0.6 molar ratio at 300 °C, a hydrogen rich mixture (35–40%) was obtained. The use of relatively low amount of oxygen is necessary to reduce coke formation, which causes catalyst deactivation. The catalysts were characterized by ex situ methods such as XRD, BET, XPS, and in situ EXAFS and FTIR with the aim to evaluate their physico-chemical properties and to correlate them with the catalysts performance.

The Canadian Journal of Chemical Engineering, 2010

Polymeric ion-exchange resins are widely used in important industrial processes for both separati... more Polymeric ion-exchange resins are widely used in important industrial processes for both separation and reaction applications. Due to their particular cross-linked structure, these materials are subjected to a remarkable swelling phenomena when are contacted with polar solvents like methanol or water. The high liquid volume retained and the selectivity towards the absorption of particular substances can results in a significant alteration of the liquid reactive mixture composition when polymeric resins are used as catalysts. In this situation the bulk liquid phase and the absorbed phase are different in composition and the kinetics could be strongly affected as the chemical reaction occurs mainly on the internal surface of the resin particles. The correct description of the kinetics for such systems requires additional information regarding the phase partitioning of the various components between the liquid and the absorbed phase. In this work, experimental absorption data, concerning the binary system methanol-water partitioned in the presence of Amberlyst 15 and Relite CFS, two sulphonic ion-exchange resins, typically used as esterification catalysts, are presented. This mixture is of great interest in the esterification reaction of free fatty acids (FFAs) that is nowadays considered a suitable pre-treatment of cheap feedstock for biodiesel production. The data collected on binary systems water-methanol, at different temperatures, have then been successfully correlated by a multicomponent competitive absorption model that could be useful, in the future, in a wider kinetic study. The same model has also been tested on data taken from the literature. Les résineséchangeuses d'ions polymériques sont largement utilisées lors de processus industriels importantsà la fois pour les applications de séparation et de réaction. En raison de leur structure réticulée particulière, ces matériaux sont soumisà un remarquable phénomène de gonflement lorsqu'ils sont en contact avec des solvants polaires comme le méthanol ou l'eau. Le volume liquideélevé retenu et la sélectivité vers l'absorption de substances particulières peuvent menerà une modification considérable de la composition du mélange réagissant liquide lorsque des résines polymériques sont utilisées comme catalyseurs. Dans cette situation, la phase liquide volumique et la phase absorbée sont différentes sur le plan de la composition et la cinétique pourraitêtre fortement touchée alors que la réaction chimique se produit principalement sur la surface interne des particules de résine. La bonne description de la cinétique pour de tels systèmes exige des renseignements supplémentaires sur la séparation des phases des divers composants entre la phase liquide et la phase absorbée. Dans ce travail, les données d'absorption expérimentales sont présentéesà propos du système méthanol-eau séparé, en présence d'Amberlyst 15 et de Relite CFS, deux résineséchangeuses d'ions sulphoniques typiquement utilisées comme catalyseurs d'estérification. Ce mélange est d'un grand intérêt pour la réaction d'estérification des acides gras libres (AGL) qui est maintenant considérée comme un prétraitement approprié de la matière biologique bon marché pour la production de biodiésel. Les données recueillies sur les systèmes binaires eau-méthanol,à différentes températures, ontété corrélées avec succès par un modèle d'absorption compétitiveà composants multiples qui pourraitêtre utile,à l'avenir, dans uneétude cinétique plus approfondie. Le même modèle aégalement eté misà l'essai avec des données prises dans la littérature.

Biomass Conversion and Biorefinery, 2012

Catalysis for Sustainable Energy, 2015

Journal of Molecular Catalysis A: Chemical, 2012

ABSTRACT Times Cited: 0

Chemical Engineering Journal, 2012

Catalysis Today, 2012

Catalysis Today, 2013

The Canadian Journal of Chemical Engineering, 2010