1,721,067 research outputs found
Hydrogen Production by Steam Reforming of Bioethanol: Catalytic Tests and Process Design
No full textAbstract
2nd generation bioethanol was considered as raw material for the sustainable hydrogen production by catalytic steam reforming. An experimental kinetic investigation has been carried out selecting different catalysts synthesized by Flame Spray Pyrolysis, a one step high temperature synthesis able to impart strong metal-support interaction, besides high thermal resistance [1]. Ethanol conversion, selectivity to the main possible byproducts and the CO/CO2 ratio, as a measure of the contribution of the water gas shift reaction, were correlated to the temperature, water/ethanol ratio and space velocity in a central composite experimental design [2]. Two different bioethanol samples, 50 and 90 vol%, produced and supplied by a company (Mossi&Ghisolfi), have been used for at each temperature. Attention was paid to the catalyst resistance towards deactivation by coking.
The kinetic expression was implemented in a software simulation (Aspen Plus), designing a high pressure reactor. A successive process design was investigated considering the hydrogen purification section as well and evaluating the economic feasibility of different plant configurations and operative conditions. Net plant efficiencies and total capital investment will be estimated as well as internal rate of return and payback period.
[1] M. Compagnoni, J. Lasso, A. Di Michele, I Rossetti*, Cat. Sci. & Tech, 6 (2016) 6247
[1] M. Compagnoni, A. Tripodi, I. Rossetti*, App. Cat. B:Environ., 203 (2017) 899–90
Flame Spray Pyrolysis: catalysts for the Steam Reforming of bio-ethanol
No full textFlame Spray Pyrolysis (FSP) is a one step high temperature synthesis able to impart strong metal-support interaction [1], besides high thermal resistance. A set of Ni catalysts supported over ZrO2 doped with different basic oxide (CaO, MgO) were prepared by this innovative technique. Steam Reforming catalytic test were carried out for the production of hydrogen using bio-ethanol. The catalytic activity was compared with catalysts of the same composition, but prepared with a traditional precipitation/impregnation method (multistep synthesis). Very high activity has been observed at high reaction temperature (>600°C), but further kinetic studies were done under milder conditions (500-300°C), in order to lower the energy input to the process and to improve H2 productivity favoring the water gas shift reaction [2]. Two different bioethanol samples, 50 and 90 vol%, produced and supplied by Mossi&Ghisolfi, have been used for 8 h-on-stream at each temperature. Attention was paid to the catalyst resistance towards deactivation by coking, besides its activity and selectivity. The acidity of the support was tuned by doping ZrO2 with basic oxides, helping to prevent ethanol dehydration and coking by ethylene polymerization. Fresh and spent samples were characterized by XRD, TPR, TPO, TEM, FE-SEM and Raman analysis.
Figure: scheme and image of Flame Spray Pyrolysis
[1] G. Ramis, I. Rossetti, E. Finocchio, M. Compagnoni, M. Signoretto, A. Di Michele, Progress in Clean Energy, I. Dincer, Ed. Springer, in press.
[2] I. Rossetti, J. Lasso, E. Finocchio, G. Ramis, V. Nichele, M. Signoretto, A. Di Michele, Appl. Catal. B: Environmental, 150-151 (2014) 257-267
Metal modified TiO2 for CO2 photoreduction in unconventional conditions
No full textCO2 photoreduction, a growing field in green catalysis, shows great potentialities to avoid fossil fuels exploitation and to obtain C-based solar fuels through a sustainable process using water as a reductant and light irradiation as only energy input [1]. However, many efforts need to be made to have a substantial breakthrough to increase the efficiency of the whole process. To pursue this aim, different strategies can be followed, such as reaction conditions implementation and photocatalyst formulation.
Process efficiency is strictly dependent on chosen photocatalytic materials. In particular titanium dioxide, the most commonly used material, needs to be modified in order to boost light harvesting and increase photoactivity [2]. In this work, TiO2 was modified in order to increase electron mobility on photocatalytic surface. In particular, copper oxide was introduced as a co-catalyst and gold nanoparticles as surface plasmonic agents.
Some of the authors reported that unconventional conditions are able to increase solar fuels production from CO2 photoreduction in liquid phase, enhancing in particular CO2 absorption in aqueous media and tuning selectivity to desired products [3]. A novel pressurized liquid phase reactor was employed to study photocatalytic activity of these materials in liquid phase and reaction conditions were chosen in order to enhance CO2 absorption in liquid phase. In photocatalytic tests it was observed the formation of different liquid and gaseous products such as formic acid, formaldehyde, methanol, methane and hydrogen. The different materials provide a significant difference in both activity and product distribution. Photocatalytic behaviours were correlated to different physicochemical properties that were investigated though several techniques.
References
[1] O. Ola, M. Maroto-Valer, Journal of Photochemistry and Photobiology C: Photochemistry Reviews 24 (2015) 16-42
[2] A. Olivo, V. Trevisan, E. Ghedini, F. Pinna, C.L. Bianchi, A. Naldoni, M. Signoretto, Journal of CO2 Utilization 12 (2015) 86-94
[3] I. Rossetti, A. Villa, M. Compagnoni, L. Prati, G. Ramis, C. Pirola, C.L. Bianchi, W: Wang, D. Wang, Catalysis Science and Technology 5 (2015) 4481 - 448
Electric and thermal energy from bioethanol : process intensification by using diluted feeds
No full textBioethanol attracted growing interest as raw material for the production of hydrogen. The latter can be successfully used to feed fuel cells with the aim of combined heat and power (CHP) cogeneration. A demonstrative project has been carried out c/o our Dept. [1] by running an integrated CHP unit with residential size, i.e. 5 kWel + 5 kWth. It was constituted by 6 integrated reactors, connected in series, fed with bioethanol and water, to produce reformate gas (prereformer and steam reformer) and to accomplish gas purification from CO (high- and low-temperature water gas shift reactors and two methanators). The purified reformate is suitable to feed a PEM fuel cell with the above mentioned power output.
The aim of this work was to focus on process intensification, to achieve an economically sustainable solution. This was done at first by identifying the effect of bioethanol concentration on process output and proposing suitable means to achieve bioethanol purification. This is particularly straightforward because second generation bioethanol is nowadays proposed as fuel or as blending agent for gasoline, thus requiring deep dehydration. However, if used as feed for steam reforming, much lower concentration is needed, allowing to limit distillation/dehydration cost, which account for 50-80% of bioethanol production expenses [2,3].
Process layout has been revised by comparing different possible schemes, compared as for heat and power duty (input) and output. Different solutions to account for energy input to the reformer have been also compared.
Accordingly, different options for the purification of raw bioethanol beer have been compared, in order to meet the required specifications and to limit the cost of the reformer feed.
The effect of the purity of the resulting bioethanol stream on reformer performance has been also experimentally addressed. As well, the effect of reactor temperature was considered, and this was set at the minimum level to guarantee optimal product yield, suitable catalyst durability and minimum heat input to the reactor.
Process simulation has been carried out by using the Aspen Plus software and economic assessment of the solutions proposed has been carried out by using the Aspen ONE cost evaluation tool.
References
[1] Rossetti, I.; Biffi, C.; Tantardini, G.F.; Raimondi, M.; Vitto, E.; Alberti, D. Int. J. Hydrogen Energy, 2012, 37, 8499.
[2] Rossetti, I.; Compagnoni, M.; Torli, M. Chem Eng. J., 2015, 281, 1024.
[3] Rossetti, I.; Compagnoni, M.; Torli, M. Chem Eng. J., 2015, 281, 1036
Chemical reaction engineering, process design and scale up issues at the frontier of synthesis: flow chemistry
Full text linkFlow chemistry has been proposed in modern organic chemistry as a mean for process intensification, to improve the control over reaction performance and to achieve higher yield. However, many open issues can be evidenced regarding the true possibility of scale-up, as well as currently lacking information for process design and economical evaluation. This review proposes some recent examples of flow synthesis deepening in particular the scale-up and engineering issues
Catalytic and photocatalytic processes for the production of alternative fuels and chemicals from renewable sources
No full textCatalytic and photocatalytic processes for the production of alternative fuels and chemicals from renewable sources
M. Compagnonia, I. Rossettia
a Dip. Chimica, Università degli Studi di Milano, via C. Golgi 19, 20133 Milan, Italy
This work presents the PhD research project of Matteo Compagnoni. In particular, the presentation focuses on the valorization of bioethanol through the heterogeneously catalysed production of H2 and ethylene. The whole thesis was based on innovative heterogeneous catalytic processes, addressed from an industrial chemistry point of view. Besides the screening of different catalyst formulations, the attention was predominantly focused on process design, including the optimisation of process conditions, the use of less purified (less expensive) raw materials, less demanding conditions, etc. A preliminary economic assessment was also carried out for the centralised production of hydrogen from diluted bioethanol.
References
1. Rossetti, I. et al. Chem. Eng. J. 2015, 281, 1036–1044.
2. Compagnoni, M. et al. Catal. Sci. Technol. 2016, 6, 6247–6256.
3. Compagnoni, M. et al. Appl. Catal. B Environ. 2017, 203, 899–909
4. Rossetti, I. et al. Appl. Catal. B Environ. 2017, 210, 407–420.
5. Compagnoni, M. et al. Energy & Fuels 2017, 31, 12988–12996.
Acknowledgements: This work was funded by Università degli Studi di Milan
Energia e ambiente. Introduzione generale alle tecniche di miglioramento dell’efficienza nella conversione dell’energia, alle tecniche di abbattimento di emissioni inquinanti, alla valorizzazione delle materie prime di scarto e all’impiego di biocombustibili
No full textEnergia e ambiente. Introduzione generale alle tecniche di miglioramento dell’efficienza nella conversione dell’energia, alle tecniche di abbattimento di emissioni inquinanti, alla valorizzazione delle materie prime di scarto e all’impiego di biocombustibili
Matteo Compagnoni, Ilenia Rossetti
Università degli Studi di Milano, Dipartimento di Chimica, via Golgi 19, 20133 Milano
[email protected]
Uno dei principali obiettivi della politica ambientale ed energetica Europea è lo sviluppo di tecnologie altamente innovative per la conversione dell’energia a ridotto impatto ambientale. La visione spazia da soluzioni a breve termine (obiettivi decennali o ventennali) per migliorare la sostenibilità ambientale rispetto ai metodi canonici di conversione dell’energia basati sulla combustione di combustibili primari fossili, alla ricerca di base di nuove tecnologie altamente innovative, in grado di rivoluzionare il panorama energetico mondiale (tipicamente si individuano obiettivi al 2050).
L’inversione di rotta nell’approvvigionamento energetico deve rispondere ad alcuni requisiti. In primo luogo si basa su drivers ambientali, è necessario cioè individuare soluzioni che siano in grado di migliorare sensibilmente l’impatto ambientale delle attuali tecnologie. Particolare attenzione deve essere rivolta alla quantificazione dell’impatto (ad esempio mediante tecniche di Life Cycle Assessment, LCA), che se svolta in modo non corretto può portare a risultati fuorvianti. Inoltre, un secondo punto chiave è la disponibilità locale delle risorse, particolarmente sensibile in Italia. Pertanto la diversificazione e la contestualizzazione dei metodi di conversione dell’energia sono parametri da prendere in considerazione per garantire un reale beneficio a livello locale. Infine, è necessario considerare la sostenibilità economica delle soluzioni proposte. Quest’ultimo aspetto è particolarmente importante e viene di norma posto come prioritario nelle critiche diffuse al “mondo delle rinnovabili”, che spesso non sono sostenibili senza meccanismi di sostegno pubblico. Da un lato la non sostenibilità è legata alla maturità delle tecnologie, molto più recenti rispetto alle “rivali” fossili, quindi non ancora ottimizzate in termini di efficienza. Dall’altro lato ci sono problemi di vantaggio di scala e di mercato. La domanda chiave da questo punto di vista è: esiste una scala critica per le rinnovabili?
In questa presentazione si proporrà una panoramica su varie tecnologie attualmente in fase di sviluppo, che verranno ordinate per classi in base alla tipologia (solare, eolico, geotermico, idroelettrico, biomasse, ecc.), alla maturità ed alla taglia d’impianto. Verranno riportati alcuni esempi di progetti dimostrativi in tal senso su scala italiana ed europea. Si discuterà anche di un possibile prospetto dei costi e della proiezione degli stessi nel breve futuro [1].
1 - RAPPORTO ENERGIA E AMBIENTE SCENARI E STRATEGIE. Verso un’Italia low carbon: sistema energetico, occupazione e investimenti, ENEA, 2013
CATALYTIC AND PHOTOCATALYTIC PROCESSES FOR THE PRODUCTION OF ALTERNATIVE FUELS AND CHEMICALS FROM RENEWABLE SOURCES
Full text linkThe research project during my three years of activity was focused on the de-velopment of innovative processes and catalytic materials for the production of sustainable chemicals and fuels. The work was mainly divided in three are-as: i) bioethanol valorization through the heterogeneous catalytic production of H2 and ethylene; ii) CO and CO2 conversion; iii) H2 usage through ammonia production
Process simulation and optimisation of H-2 production from ethanol steam reforming and its use in fuel cells. 1 : Thermodynamic and kinetic analysis
Full text linkEthanol was considered as raw material for hydrogen production by steam reforming. Reformate purification from CO to feed fuel cells may be accomplished by well established routes, such as high and low temperature water gas shift and methanation, to be integrated with the H2 production unit. A PEM fuel cell can be used for power cogeneration. Data and layout have been inspired by an existing unit Helbio, GH2-BE-5000, capable of delivering 5 kWelectrical + 5 kWthermal output. In order to size and simulate the steam reforming reactor, reliable and complete kinetic data are needed. Partial information has been only found in the literature, in spite of well detailed analysis of the reaction mechanism. In the first part of this work, alternative reaction networks and kinetic models are critically reviewed and compared. Reliable and complete models were applied to literature data to estimate sound kinetic parameters for reactor modeling and simulation, objective of the second part of this work. At first, the equilibrium composition of a reacting mixture was calculated as a function of temperature, pressure and water/ethanol ratio, to define the boundary conditions of this investigation. Then, after selection of three alternative models to represent the complex reaction scheme of bioethanol steam reforming, a full set of kinetic parameters has been estimated and checked for consistency. The latter has been successfully applied to reformer sizing and simulation, as fully described in part 2
Parametric study and kinetic testing for ethanol steam reforming
No full textAn experimental kinetic investigation has been carried out for ethanol steam reforming (ESR). The selected catalyst was a K-promoted Ni/ZrO2 sample prepared by flame pyrolysis, which revealed particularly active and stable for this application based on previous investigation. Ethanol conversion, selectivity to the main possible byproducts (methane, ethylene and acetaldehyde), hydrogen productivity and the CO/CO2 ratio, as a measure of the contribution of the water gas shift reaction, were correlated to the temperature, water/ethanol ratio and space velocity in a central composite experimental design. The parametric dependence of the reaction outcomes helped the qualitative assessment of the best operating conditions and suggested hypotheses on the reaction mechanism. A more quantitative parametric analysis was carried out by multivariate analysis.
Particularly dramatic experimental conditions have been adopted in order to highlight the formation and further evolution of possibly critical intermediates, such as ethylene and acetaldehyde. To keep ethanol and intermediates conversion below 100% at sufficiently high temperature to guarantee coke free operation, the space velocity and feed dilution were increased. This will enable drawing a kinetic model accounting for the detailed evolution of such species.
An increase of temperature did not adequately improved H-2 selectivity, whereas the water/ethanol ratio was an effective parameter to push H-2 productivity. The reforming reactions of ethanol and of acetaldehyde/ethylene byproducts were dependent on the three parameters (kinetically controlled), whereas the CO/CO2 ration was substantially independent on the space velocity, indicating that the water gas shift reaction reached an equilibrium value
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