Abstract: The paper presents a two-dimensional model to describe the gas flow in a propane autoth... more Abstract: The paper presents a two-dimensional model to describe the gas flow in a propane autothermal reactor, developed at the CNR-ITAE Institute, and aimed to design a βeta 5 kWe hydrogen generator, named HYGen II, to be used with Polymer Electrolyte Fuel Cells (PEFCs) for residential applications. The main aim of the mathematical model was to optimize the reactor geometrical key parameters (diameter and length of catalyst bed, diameter and shape of the catalyst, etc,) by parametric analysis. The distribution of the linear velocity in different sections of the reactor were evaluated, in order to identify the best location to place the catalyst bed. Based upon the above considerations, a mathematical model, based on momentum balances, has been developed. Keywords: Comsol Multiphysics 3.2, Porous and Free Media Flow Coupling, Reactor Design Optimization, Hydrogen Generator. 1. Introduction During the last few years, research activity on autothermal reforming for small scale applica...
The conversion of biomass to electricity has taken a role of paramount importance for both develo... more The conversion of biomass to electricity has taken a role of paramount importance for both developed and developing countries. In the present paper the technical-economical feasibility of a system for biomass conversion has been analysed; it combines the gasification process with the more advanced systems for the heat and electricity production as the fuel cells. Furthermore the two key features that will condition the development of such an integrated system has been considered.
This paper investigates the performance of 25 wt% Ni/GDC catalyst supported on ceramic monolith (... more This paper investigates the performance of 25 wt% Ni/GDC catalyst supported on ceramic monolith (MO) and open-cell foam (FO) towards the conversion of CO 2 to CH 4 at bench-scale level (CO 2 flow rate = 78-319 NL•h −1). Both structured catalysts were prepared by the In Situ-Solution Combustion Deposition (IS-SCD) method to coat thin, uniform and high-resistance catalytic layers (Ni/GDC). Catalysts were characterized by XRD, TEM, SEM, and adhesion tests. Temperature profiles in axial and radial direction were registered and discussed. The experimental results highlighted the effect of the geometry of the support on the thermal profile of the catalytic bed and, consequently, on the catalytic performance towards CO 2 methanation. For the investigated quasi-adiabatic conditions, the monolith-supported sample enabled a favourable temperature distribution, leading to higher performances (χ CO 2 = 70.3%; F CH 4 , OUT = 2.6 NL•cm −3 •h −1) compared to the foam-based catalyst (χ CO 2 = 52.0%, F CH 4 , OUT = 2.2 NL•cm −3 •h −1). Besides, Ni/GDC-MO catalyst showed high stability for 50 h of time-on-stream under daily start-up and shutdown cycles. (4) Both Eqs. (2) and (3) reduce the selectivity towards methane formation. Furthermore, the undesired Bosch and Boudouard reactions produce carbon on the catalyst surface, thus reducing the catalyst activity as well as increasing the reactor pressure drops. CO 2 methanation reaction is strongly exothermic and thermodynamically favoured at low temperatures. However, it is kinetically limited at low operating temperatures, resulting in reaction quenching due to slow reaction rates. Operating temperatures, typically around 250-400°C, are desirable for high CO 2 conversion and high CH 4 selectivity [18,19]. Besides, due to the exothermicity of the reaction, large temperature increase is
The glycerol steam reforming (GSR) reaction for hydrogen production was investigated over Rh-base... more The glycerol steam reforming (GSR) reaction for hydrogen production was investigated over Rh-based catalysts supported on g-Al 2 O3 modified with CeO 2 , MgO or La 2 O 3. High specific surface area mesoporous supports (Al 2 O 3, CeO 2 eAl 2 O 3 , MgOeAl 2 O 3 and La 2 O 3 eAl 2 O 3) were synthesized by the surfactantassisted co-precipitation method using cetyltrimethylammonium bromide (CTAB) as template. Then, highly dispersed Rh-based catalysts were prepared by the wetness impregnation technique. The physicochemical properties of the as-prepared supports and catalysts were investigated by N 2-physisorption, XRD, ICP-AES, CO-chemisorption, TEM, H 2-TPR, CO 2-TPD and NH 3-TPD measurements. Performance test experiments were carried out in a continuous flow fixed-bed reactor at water-to-glycerol feed ratio (WGFR) of 20:1 (molar), temperatures from 400 C to 750 C, weight hourly space velocity of 50,000 ml g À1 h À1 and atmospheric pressure. The stability of all catalysts was also investigated through 12 h time-on-stream (TOS) experiments at 600 C using a WGFR of 9:1. All catalysts were remarkably stable during TOS with total glycerol conversion of z90%, glycerol conversion into gaseous products of z45% and H 2 selectivity of z78%. The final H 2 yield for all catalysts was 2.4e2.9 mol H 2 /mol glycerol. TEM experiments showed that the carbon formed onto the spent catalysts was amorphous and that sintering was mostly avoided during TOS, helping explain the excellent catalytic stability observed. The unpromoted catalyst seems to be following a different reaction pathway than and the promoted ones that depends strongly on the population and kind of acid and basic sites over its surface.
Today biogas produced from anaerobic digestion is used mainly for thermic and electric energy pro... more Today biogas produced from anaerobic digestion is used mainly for thermic and electric energy production. Its use as raw material for syngas production and further upgrading to chemical products like methanol (MeOH), dimethyl ether (DME) or acetic acid could be an interesting option as process intensification. In this work the sustainability of a Biogas-to-MeOH (BtoMeOH) or Biogas-to-DME (BtoDME) process was studied. The biogas feedstock of the Combined Heat, Power and Chemicals (CHPC) is equivalent to the production of 1 MWe in a Combined Heat and Power Plant (CHP). Biogas is converted using a reformer into syngas to produce methanol. The plant was designed considering mild conditions for chemical production and the energy necessary to reactors was generated using a fraction of the inlet biogas. This process was studied using the Simulation Suite PRO/II® by Schneider-Electric Simulation Science. The reformer and the methanol reactorproductivity were evaluated with the experimental ...
As is well known, the most acknowledged process for generation of hydrogen for fuel cells is base... more As is well known, the most acknowledged process for generation of hydrogen for fuel cells is based upon the steam reforming of methane or natural gas. A valid alternative could be a process based on partial oxidation of methane, since the process is mildly exothermic and therefore not energy intensive. Consequently, great interest is expected from conversion of methane into syngas, if an autothermal, low energy intensive, compact and reliable process could be developed. This paper covers the activities, performed by CNR Institute Transformation and Storage of Energy, Messina, Italy, on theoretical and experimental studies for a compact hydrogen generator, via catalytic selective partial oxidation of methane, integrated with a PEFC (Polymer Electrolyte Fuel Cell). In particular, the project focuses the attention on methane partial oxidation via heterogeneous selective catalysts, in order to: demonstrate the basic Catalytic Selective Partial Oxidation of Methane (CSPOM) technology in ...
Abstract Liquid hydrocarbons conversion into hydrogen rich gas is a central process step in fuel ... more Abstract Liquid hydrocarbons conversion into hydrogen rich gas is a central process step in fuel processors for auxiliary power units (APUs) for naval applications. Diesel, together with gasoline, is the preferred fuel for these applications. The CNR-ITAE has developed an hydrogen generator based on steam reforming (SR) of n-dodecane (n-C 12 H 26 ) as surrogate of diesel, designed for a maximum hydrogen production of 1.5 Nm 3 /h. The prototype consists of an integrated catalytic reactor coupled with heat exchanger, static mixer, water–dodecane and recycle reservoirs, manual/automatic valves, pressure regulators/transducers, flow meters, and ancillaries. The unit has been engineered, focusing every single component and the system integration, to meet the requirements of small size and volume, improving thermal/mass transfer and system efficiency. This study reports the performance of the hydrogen generator with a commercial Rh-based catalyst, packed on the steam reforming reactor. Experimental tests were carried out at a molar ratio steam to carbon (S/C) of 2.5, under a gas hourly space velocity (GHSV) of 3500 h −1 , as derived from preliminary investigations in laboratory scale. Total conversion of n-dodecane and absence of carbon deposition phenomena, were observed. The syngas produced (H 2 /CO = 4.7) was adequate to feed a Solid Oxide Fuel Cell (SOFC).
The production of hydrogen via steam reforming (SR) of simulated bio-oil (glycerol, syringol, n-b... more The production of hydrogen via steam reforming (SR) of simulated bio-oil (glycerol, syringol, n-butanol, m-xylene, m-cresol, and furfural) was investigated over Ni/CeO 2-Al 2 O 3 and Me-Ni/CeO 2-Al 2 O 3 (Me ¼ Rh, Ru) catalysts. Monometallic (Ni) and bimetallic (Rh-Ni and Ru-Ni) catalysts were prepared by the wetness impregnation technique of the CeO 2-Al 2 O 3 support previously synthesized by the surfactant-assisted co-precipitation method. The as-prepared powders were systematically characterized by N 2-physisorption, XRD, H 2-TPR, and TEM measurements to analyze their structure, morphology, and reducibility properties. Experiments were performed in a continuous fixed-bed reactor at atmospheric pressure, temperature of 800 C, steam to carbon (S/C) ratio of 5, and WHSV of 21.15 h À1. Then, the temperature was decreased to 700 C and increased afterwards to 800 C. After the experiments TPO and TEM analysis were performed on the spent catalysts to check any evidence of catalyst deactivation. The results showed that the incorporation of noble metal (Ru or Rh) promoter positively affected the activity of the Ni/CeO 2-Al 2 O 3 catalysts by enhancing the reducibility of Ni 2þ species. Ni-based catalyst deactivated under the studied conditions, whereas Ru-and mainly Rh-promoted systems showed increased resistance to carbon deposition by favouring the gasification of adsorbed carbon species. Between all tested catalysts, the Rh-Ni/CeO 2-Al 2 O 3 provided the highest H 2 yield and coking-resistance in SR of simulated bio-oil.
A series of high specific surface area mesoporous supports (CeO 2 , CeO 2-Al 2 O 3 , and Al 2 O 3... more A series of high specific surface area mesoporous supports (CeO 2 , CeO 2-Al 2 O 3 , and Al 2 O 3) were synthesized by the surfactant-assisted precipitation method using cetyltrimethylammonium bromide (CTAB) as template. Highly dispersed Rh-based catalysts were prepared by the wetness impregnation technique. The physico-chemical properties of the as-prepared supports and catalysts were investigated by N 2-physisorption, CO-chemisorption, XRD, and H 2-TPR measurements. Catalytic performance was evaluated towards the methane steam reforming (MSR) reaction up to 300 h of time-on-stream varying temperature (700e800 C), steam-to-carbon (S/C ¼ 2e3), and space velocity (88e200 SL$g cat À1 $h À1); turnover frequencies were calculated at each reaction condition. All catalysts exhibited high activity strictly connected with high specific surface area (105e325 m 2 g À1) and metal dispersion (34.3e84.0%). Significant enhanced stability was observed for Al 2 O 3-containing catalysts towards the MSR reaction at high space velocity.
A new approach for the direct conversion of syngas into methanol has been proposed as alternative... more A new approach for the direct conversion of syngas into methanol has been proposed as alternative to the conventional process requiring WGS and/or PSA clean-up steps for syngas upgrading. A comparative thermodynamic equilibrium analysis of biogas reforming processes (dry reforming, steam reforming and oxy-steam reforming) has been performed using the Gibbs free energy minimization method. The calculations have been carried out under different biogas composition (CH 4 /CO 2 =1-2.3), reaction temperature (400-900°C), S/CH 4 (0.0-3.0) and O 2 /CH 4 (0.0-0.2) molar ratios. The effects of process variables on the reforming performances as well as on the syngas quality, in term of CH 4 and CO 2 conversion, H 2 /CO and H 2 /CO 2 ratios, coke deposition and energetic consumption, has been examined. Subsequently, methanol synthesis has been studied using the same mathematical approach, with the aim to identify the most adequate operating conditions for the direct conversion of the syngas obtained from reforming process into methanol. The simulations suggested that steam reforming of biogas, with high methane content, is the most appropriate route to produce a syngas quality suitable for the new proposed approach.
The effect of acid/base functional‐groups associated with platinized‐carbon electrodes on their c... more The effect of acid/base functional‐groups associated with platinized‐carbon electrodes on their catalytic activitytoward electro‐oxidation of methanol in sulfuric acid electrolyte at 60°C is studied. Platinized‐carbon electrodes with smallamounts of functional groups exhibit ...
Abstract: The paper presents a two-dimensional model to describe the gas flow in a propane autoth... more Abstract: The paper presents a two-dimensional model to describe the gas flow in a propane autothermal reactor, developed at the CNR-ITAE Institute, and aimed to design a βeta 5 kWe hydrogen generator, named HYGen II, to be used with Polymer Electrolyte Fuel Cells (PEFCs) for residential applications. The main aim of the mathematical model was to optimize the reactor geometrical key parameters (diameter and length of catalyst bed, diameter and shape of the catalyst, etc,) by parametric analysis. The distribution of the linear velocity in different sections of the reactor were evaluated, in order to identify the best location to place the catalyst bed. Based upon the above considerations, a mathematical model, based on momentum balances, has been developed. Keywords: Comsol Multiphysics 3.2, Porous and Free Media Flow Coupling, Reactor Design Optimization, Hydrogen Generator. 1. Introduction During the last few years, research activity on autothermal reforming for small scale applica...
The conversion of biomass to electricity has taken a role of paramount importance for both develo... more The conversion of biomass to electricity has taken a role of paramount importance for both developed and developing countries. In the present paper the technical-economical feasibility of a system for biomass conversion has been analysed; it combines the gasification process with the more advanced systems for the heat and electricity production as the fuel cells. Furthermore the two key features that will condition the development of such an integrated system has been considered.
This paper investigates the performance of 25 wt% Ni/GDC catalyst supported on ceramic monolith (... more This paper investigates the performance of 25 wt% Ni/GDC catalyst supported on ceramic monolith (MO) and open-cell foam (FO) towards the conversion of CO 2 to CH 4 at bench-scale level (CO 2 flow rate = 78-319 NL•h −1). Both structured catalysts were prepared by the In Situ-Solution Combustion Deposition (IS-SCD) method to coat thin, uniform and high-resistance catalytic layers (Ni/GDC). Catalysts were characterized by XRD, TEM, SEM, and adhesion tests. Temperature profiles in axial and radial direction were registered and discussed. The experimental results highlighted the effect of the geometry of the support on the thermal profile of the catalytic bed and, consequently, on the catalytic performance towards CO 2 methanation. For the investigated quasi-adiabatic conditions, the monolith-supported sample enabled a favourable temperature distribution, leading to higher performances (χ CO 2 = 70.3%; F CH 4 , OUT = 2.6 NL•cm −3 •h −1) compared to the foam-based catalyst (χ CO 2 = 52.0%, F CH 4 , OUT = 2.2 NL•cm −3 •h −1). Besides, Ni/GDC-MO catalyst showed high stability for 50 h of time-on-stream under daily start-up and shutdown cycles. (4) Both Eqs. (2) and (3) reduce the selectivity towards methane formation. Furthermore, the undesired Bosch and Boudouard reactions produce carbon on the catalyst surface, thus reducing the catalyst activity as well as increasing the reactor pressure drops. CO 2 methanation reaction is strongly exothermic and thermodynamically favoured at low temperatures. However, it is kinetically limited at low operating temperatures, resulting in reaction quenching due to slow reaction rates. Operating temperatures, typically around 250-400°C, are desirable for high CO 2 conversion and high CH 4 selectivity [18,19]. Besides, due to the exothermicity of the reaction, large temperature increase is
The glycerol steam reforming (GSR) reaction for hydrogen production was investigated over Rh-base... more The glycerol steam reforming (GSR) reaction for hydrogen production was investigated over Rh-based catalysts supported on g-Al 2 O3 modified with CeO 2 , MgO or La 2 O 3. High specific surface area mesoporous supports (Al 2 O 3, CeO 2 eAl 2 O 3 , MgOeAl 2 O 3 and La 2 O 3 eAl 2 O 3) were synthesized by the surfactantassisted co-precipitation method using cetyltrimethylammonium bromide (CTAB) as template. Then, highly dispersed Rh-based catalysts were prepared by the wetness impregnation technique. The physicochemical properties of the as-prepared supports and catalysts were investigated by N 2-physisorption, XRD, ICP-AES, CO-chemisorption, TEM, H 2-TPR, CO 2-TPD and NH 3-TPD measurements. Performance test experiments were carried out in a continuous flow fixed-bed reactor at water-to-glycerol feed ratio (WGFR) of 20:1 (molar), temperatures from 400 C to 750 C, weight hourly space velocity of 50,000 ml g À1 h À1 and atmospheric pressure. The stability of all catalysts was also investigated through 12 h time-on-stream (TOS) experiments at 600 C using a WGFR of 9:1. All catalysts were remarkably stable during TOS with total glycerol conversion of z90%, glycerol conversion into gaseous products of z45% and H 2 selectivity of z78%. The final H 2 yield for all catalysts was 2.4e2.9 mol H 2 /mol glycerol. TEM experiments showed that the carbon formed onto the spent catalysts was amorphous and that sintering was mostly avoided during TOS, helping explain the excellent catalytic stability observed. The unpromoted catalyst seems to be following a different reaction pathway than and the promoted ones that depends strongly on the population and kind of acid and basic sites over its surface.
Today biogas produced from anaerobic digestion is used mainly for thermic and electric energy pro... more Today biogas produced from anaerobic digestion is used mainly for thermic and electric energy production. Its use as raw material for syngas production and further upgrading to chemical products like methanol (MeOH), dimethyl ether (DME) or acetic acid could be an interesting option as process intensification. In this work the sustainability of a Biogas-to-MeOH (BtoMeOH) or Biogas-to-DME (BtoDME) process was studied. The biogas feedstock of the Combined Heat, Power and Chemicals (CHPC) is equivalent to the production of 1 MWe in a Combined Heat and Power Plant (CHP). Biogas is converted using a reformer into syngas to produce methanol. The plant was designed considering mild conditions for chemical production and the energy necessary to reactors was generated using a fraction of the inlet biogas. This process was studied using the Simulation Suite PRO/II® by Schneider-Electric Simulation Science. The reformer and the methanol reactorproductivity were evaluated with the experimental ...
As is well known, the most acknowledged process for generation of hydrogen for fuel cells is base... more As is well known, the most acknowledged process for generation of hydrogen for fuel cells is based upon the steam reforming of methane or natural gas. A valid alternative could be a process based on partial oxidation of methane, since the process is mildly exothermic and therefore not energy intensive. Consequently, great interest is expected from conversion of methane into syngas, if an autothermal, low energy intensive, compact and reliable process could be developed. This paper covers the activities, performed by CNR Institute Transformation and Storage of Energy, Messina, Italy, on theoretical and experimental studies for a compact hydrogen generator, via catalytic selective partial oxidation of methane, integrated with a PEFC (Polymer Electrolyte Fuel Cell). In particular, the project focuses the attention on methane partial oxidation via heterogeneous selective catalysts, in order to: demonstrate the basic Catalytic Selective Partial Oxidation of Methane (CSPOM) technology in ...
Abstract Liquid hydrocarbons conversion into hydrogen rich gas is a central process step in fuel ... more Abstract Liquid hydrocarbons conversion into hydrogen rich gas is a central process step in fuel processors for auxiliary power units (APUs) for naval applications. Diesel, together with gasoline, is the preferred fuel for these applications. The CNR-ITAE has developed an hydrogen generator based on steam reforming (SR) of n-dodecane (n-C 12 H 26 ) as surrogate of diesel, designed for a maximum hydrogen production of 1.5 Nm 3 /h. The prototype consists of an integrated catalytic reactor coupled with heat exchanger, static mixer, water–dodecane and recycle reservoirs, manual/automatic valves, pressure regulators/transducers, flow meters, and ancillaries. The unit has been engineered, focusing every single component and the system integration, to meet the requirements of small size and volume, improving thermal/mass transfer and system efficiency. This study reports the performance of the hydrogen generator with a commercial Rh-based catalyst, packed on the steam reforming reactor. Experimental tests were carried out at a molar ratio steam to carbon (S/C) of 2.5, under a gas hourly space velocity (GHSV) of 3500 h −1 , as derived from preliminary investigations in laboratory scale. Total conversion of n-dodecane and absence of carbon deposition phenomena, were observed. The syngas produced (H 2 /CO = 4.7) was adequate to feed a Solid Oxide Fuel Cell (SOFC).
The production of hydrogen via steam reforming (SR) of simulated bio-oil (glycerol, syringol, n-b... more The production of hydrogen via steam reforming (SR) of simulated bio-oil (glycerol, syringol, n-butanol, m-xylene, m-cresol, and furfural) was investigated over Ni/CeO 2-Al 2 O 3 and Me-Ni/CeO 2-Al 2 O 3 (Me ¼ Rh, Ru) catalysts. Monometallic (Ni) and bimetallic (Rh-Ni and Ru-Ni) catalysts were prepared by the wetness impregnation technique of the CeO 2-Al 2 O 3 support previously synthesized by the surfactant-assisted co-precipitation method. The as-prepared powders were systematically characterized by N 2-physisorption, XRD, H 2-TPR, and TEM measurements to analyze their structure, morphology, and reducibility properties. Experiments were performed in a continuous fixed-bed reactor at atmospheric pressure, temperature of 800 C, steam to carbon (S/C) ratio of 5, and WHSV of 21.15 h À1. Then, the temperature was decreased to 700 C and increased afterwards to 800 C. After the experiments TPO and TEM analysis were performed on the spent catalysts to check any evidence of catalyst deactivation. The results showed that the incorporation of noble metal (Ru or Rh) promoter positively affected the activity of the Ni/CeO 2-Al 2 O 3 catalysts by enhancing the reducibility of Ni 2þ species. Ni-based catalyst deactivated under the studied conditions, whereas Ru-and mainly Rh-promoted systems showed increased resistance to carbon deposition by favouring the gasification of adsorbed carbon species. Between all tested catalysts, the Rh-Ni/CeO 2-Al 2 O 3 provided the highest H 2 yield and coking-resistance in SR of simulated bio-oil.
A series of high specific surface area mesoporous supports (CeO 2 , CeO 2-Al 2 O 3 , and Al 2 O 3... more A series of high specific surface area mesoporous supports (CeO 2 , CeO 2-Al 2 O 3 , and Al 2 O 3) were synthesized by the surfactant-assisted precipitation method using cetyltrimethylammonium bromide (CTAB) as template. Highly dispersed Rh-based catalysts were prepared by the wetness impregnation technique. The physico-chemical properties of the as-prepared supports and catalysts were investigated by N 2-physisorption, CO-chemisorption, XRD, and H 2-TPR measurements. Catalytic performance was evaluated towards the methane steam reforming (MSR) reaction up to 300 h of time-on-stream varying temperature (700e800 C), steam-to-carbon (S/C ¼ 2e3), and space velocity (88e200 SL$g cat À1 $h À1); turnover frequencies were calculated at each reaction condition. All catalysts exhibited high activity strictly connected with high specific surface area (105e325 m 2 g À1) and metal dispersion (34.3e84.0%). Significant enhanced stability was observed for Al 2 O 3-containing catalysts towards the MSR reaction at high space velocity.
A new approach for the direct conversion of syngas into methanol has been proposed as alternative... more A new approach for the direct conversion of syngas into methanol has been proposed as alternative to the conventional process requiring WGS and/or PSA clean-up steps for syngas upgrading. A comparative thermodynamic equilibrium analysis of biogas reforming processes (dry reforming, steam reforming and oxy-steam reforming) has been performed using the Gibbs free energy minimization method. The calculations have been carried out under different biogas composition (CH 4 /CO 2 =1-2.3), reaction temperature (400-900°C), S/CH 4 (0.0-3.0) and O 2 /CH 4 (0.0-0.2) molar ratios. The effects of process variables on the reforming performances as well as on the syngas quality, in term of CH 4 and CO 2 conversion, H 2 /CO and H 2 /CO 2 ratios, coke deposition and energetic consumption, has been examined. Subsequently, methanol synthesis has been studied using the same mathematical approach, with the aim to identify the most adequate operating conditions for the direct conversion of the syngas obtained from reforming process into methanol. The simulations suggested that steam reforming of biogas, with high methane content, is the most appropriate route to produce a syngas quality suitable for the new proposed approach.
The effect of acid/base functional‐groups associated with platinized‐carbon electrodes on their c... more The effect of acid/base functional‐groups associated with platinized‐carbon electrodes on their catalytic activitytoward electro‐oxidation of methanol in sulfuric acid electrolyte at 60°C is studied. Platinized‐carbon electrodes with smallamounts of functional groups exhibit ...
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