• Energy Research

Biogas, a renewable source of CH4 and CO2, is used for hydrogen generation by tri-reforming reaction; the reaction is a combination of CO2 reforming, steam reforming and partial oxidation of CH4 in a single catalytic step.Several Ni/La-Ce-O mixed oxides, prepared by combustion synthesis, were used as catalysts. The experimental tests, carried out with synthetic biogas at 800°C with a gas hourly space velocity (GHSV) of 30000 h-1, were aimed to study the influence of different parameters (amount of La doping, Ni load and feed composition) on the catalysts activity and stability. The synergic effect of nickel-lanthana-surface oxygen vacancies of ceria influences the samples activity.

Biogas, a renewable source of CH4 and CO2, is used for hydrogen generation by tri-reforming reaction; the reaction is a combination of CO2 reforming, steam reforming and partial oxidation of CH4 in a single catalytic step.Several Ni/La-Ce-O mixed oxides, prepared by combustion synthesis, were used as catalysts. The experimental tests, carried out with synthetic biogas at 800°C with a gas hourly space velocity (GHSV) of 30000 h-1, were aimed to study the influence of different parameters (amount of La doping, Ni load and feed composition) on the catalysts activity and stability. The synergic effect of nickel-lanthana-surface oxygen vacancies of ceria influences the samples activity.

This work focuses on the utilization of a two stages inorganic membrane-based system to generate and recover decarbonized hydrogen in order to meet the targets set by the European Clean Hydrogen Partnership under the Strategic Research & Innovation Agenda 2021-2027. In the first stage, a CH4:CO2 = 60:40 mixture simulating a biogas stream is used to generate a COx-free hydrogen via steam reforming reaction carried out in a tubular Pd- Ag membrane reformer, packed with a novel non-commercial 7 wt%Ni-0.5 wt%Ru/La0.3Y0.3Zr0.4Ox catalyst, prepared by solution combustion method. The catalyst was characterized by XRD, TPR and TEM techniques. The analyses reveal well-distributed active metal particles interacting differently with the support (weakly and strongly). In particular, the XRD pattern shows the formation of perovskite and nickel oxide in addition to the pyrochlore phase. This behaviour indicates a low solubility of Ni in the pyrochlore structure. Reaction measurements were carried out at a temperature of 673 K, in the total pressure range between 250 kPa ÷ 350 kPa, weight hourly space velocity (WHSV) of 0.2 h? 1, H2O/CH4 feed molar ratio between 1.5 and 2, feeding N2-sweep gas in the permeated side. As best results of Stage 1, CH4 conversion equal to 99% (@ H2O/CH4 feed molar ratio = 2 and feed pressure of 250 kPa) and a COx-free H2 recovery of 40% were reached. In the second stage, the unpermeated stream of Stage 1 rich in hydrogen was fed to a supported Pd/Al2O3 membrane separator to further recover high grade hydrogen at the same temperature and total pressure set in Stage 1. The maximum hydrogen recovery equal to 67% was reached at 673 K and 350 kPa, with a purity of the recovered stream equal to 99.9%. The total hydrogen recovered in the permeate streams of Stage 1 and Stage 2 was equal to 80% of the total hydrogen produced during the steam reforming reaction, showing an average purity equal to 99.99%, which allowed to meet the established targets. The work further analized and discussed the experimental results of the integrated system by means of performance indexes.

This work focuses on the utilization of a two stages inorganic membrane-based system to generate and recover decarbonized hydrogen in order to meet the targets set by the European Clean Hydrogen Partnership under the Strategic Research & Innovation Agenda 2021-2027. In the first stage, a CH4:CO2 = 60:40 mixture simulating a biogas stream is used to generate a COx-free hydrogen via steam reforming reaction carried out in a tubular Pd- Ag membrane reformer, packed with a novel non-commercial 7 wt%Ni-0.5 wt%Ru/La0.3Y0.3Zr0.4Ox catalyst, prepared by solution combustion method. The catalyst was characterized by XRD, TPR and TEM techniques. The analyses reveal well-distributed active metal particles interacting differently with the support (weakly and strongly). In particular, the XRD pattern shows the formation of perovskite and nickel oxide in addition to the pyrochlore phase. This behaviour indicates a low solubility of Ni in the pyrochlore structure. Reaction measurements were carried out at a temperature of 673 K, in the total pressure range between 250 kPa ÷ 350 kPa, weight hourly space velocity (WHSV) of 0.2 h? 1, H2O/CH4 feed molar ratio between 1.5 and 2, feeding N2-sweep gas in the permeated side. As best results of Stage 1, CH4 conversion equal to 99% (@ H2O/CH4 feed molar ratio = 2 and feed pressure of 250 kPa) and a COx-free H2 recovery of 40% were reached. In the second stage, the unpermeated stream of Stage 1 rich in hydrogen was fed to a supported Pd/Al2O3 membrane separator to further recover high grade hydrogen at the same temperature and total pressure set in Stage 1. The maximum hydrogen recovery equal to 67% was reached at 673 K and 350 kPa, with a purity of the recovered stream equal to 99.9%. The total hydrogen recovered in the permeate streams of Stage 1 and Stage 2 was equal to 80% of the total hydrogen produced during the steam reforming reaction, showing an average purity equal to 99.99%, which allowed to meet the established targets. The work further analized and discussed the experimental results of the integrated system by means of performance indexes.

This paper covers the research activities performed at the CNR Institute for Advanced Energy Technologies "Nicola Giordano", aimed at developing and testing a biogas steam reforming reactor. A mathematical model has been developed in order to describe, the performance of the above-cited steam reforming reactor (packed bed). To study the effects on reaction performance, a parametric analysis was performed varying operating conditions such as inlet temperature and reagent molar ratio. The model was validated by comparing the calculated data with the experimental data obtained with a proprietary Ni/ CeO2 based catalyst in packet bed micro-scale reactor at different T ¼ 700e900 C, S/C ¼ 1e5 and GHSV ¼ 30,000 h1, showing a good agreement between the experimental and theoretical results.

This paper covers the research activities performed at the CNR Institute for Advanced Energy Technologies "Nicola Giordano", aimed at developing and testing a biogas steam reforming reactor. A mathematical model has been developed in order to describe, the performance of the above-cited steam reforming reactor (packed bed). To study the effects on reaction performance, a parametric analysis was performed varying operating conditions such as inlet temperature and reagent molar ratio. The model was validated by comparing the calculated data with the experimental data obtained with a proprietary Ni/ CeO2 based catalyst in packet bed micro-scale reactor at different T ¼ 700e900 C, S/C ¼ 1e5 and GHSV ¼ 30,000 h1, showing a good agreement between the experimental and theoretical results.

The transition toward a "Hydrogen Economy" could ensure significant advantages in terms of energetic efficiency and environmental impact, with reduced production of greenhouse gases. In the near term, considering the actual lack of infrastructure for H2 storage and distribution, equipments operating with FCs fed with H2 or H2-rich gases produced by reforming of available fossil (Natural Gas, LPG, Diesel, etc..) and renewable (biogas, bioethanol) fuels represent a valid and interesting alternative to actual energy generation systems [1,2]. Additionally, large-scale central production will depend on market volumes to evolve in order to compensate for the capital expenditures of building up capacity. Thus, distributed production of hydrogen/syngas via smaller reformer, integrated with different fuel cell systems (SOFC, PEM), is viewed as an attractive near option for stationary. Combined Heat and Power System (CHPS). Moreover, the reforming of fossil fuels could represent a practical option to create H2 filling stations realized with on-site fuel processor (FP) units fed with distribuited fuels already present on the road [3]. The key requirements for a fuel processor include rapid start-up, good dynamic-response to follow the change in hydrogen demand, high fuel conversion, small size and weight, simple design (construction and operation), stable performance for repeated start-up and shut-down cycles, maximum thermal integration, low cost and maintenance, high reliability and safety. In addition, the design of robust, low cost, highly performing and relatively fuelflexible catalysts is also required. In this regards, structured reactors, such as microchannels, ceramic or metallic monoliths and foams, show a number of advantages, like, compactness, high power densities, high mass specific powers, low catalyst request, lower pressure drop and improved heat and mass transfer, compared to conventional technology such as packet beds [4]. In this work, the performances of structured catalysts, based on 1.5wt%Rh/CeO2 coated on cordierite monoliths (400 cpsi, diameter 1 cm, length 1.5 cm) and alumina foams (20, 30, 40 ppi, diameter 1 cm, length 1.5 cm) were investigated and compared towards Steam Reforming (SR) and Oxy Steam Reforming (OSR) of different fuels (CH4, Biogas, n-dodecane). The structured supports were lined by combining the Solution Combustion Synthesis (SCS) for the deposition of ceria oxide, with the Wet Impregnation Technique (WIT) for the loading of active metal. The deposition process was repeated several times until reaching the desired and equal amount (? 0.180mg) of catalytic layer over all the supports [5]. The final structured catalysts, showed in Fig. 1, were characterized by SEM, EDX-mapping, TEM and XRD techniques; in addition, Rh/CeO2 catalyst in powder form was also prepared by the same procedure and characterized by XRD, TPR and CO chemisorption analysis. Pressure drop and catalytic layer loss tests have been evaluated. Both monolith and foam catalysts have shown comparable results in terms of uniform thin coating (thickness between 20-30 ?m), high mechanical strength (negligible weight loss ? 0.4% on total weight of the sample after ultrasonic treatment) with low pressure drop of the monolith respect the foam. The different reforming experiments were conducted in a fixed-bed quartz reactor (?i = 1 cm) at atmospheric pressure. The overall operating conditions are summarized in table 1. A first series of tests were carried out only with monolith catalysts to identify the optimum conditions in terms of S/C for SR, S/C and O/C for OSR for each fuel at fixed intermediate WSV and temperature. A second series of tests were carried out to compare the catalytic performance of foam and monolith catalysts varying the temperature and the WSV.

The transition toward a "Hydrogen Economy" could ensure significant advantages in terms of energetic efficiency and environmental impact, with reduced production of greenhouse gases. In the near term, considering the actual lack of infrastructure for H2 storage and distribution, equipments operating with FCs fed with H2 or H2-rich gases produced by reforming of available fossil (Natural Gas, LPG, Diesel, etc..) and renewable (biogas, bioethanol) fuels represent a valid and interesting alternative to actual energy generation systems [1,2]. Additionally, large-scale central production will depend on market volumes to evolve in order to compensate for the capital expenditures of building up capacity. Thus, distributed production of hydrogen/syngas via smaller reformer, integrated with different fuel cell systems (SOFC, PEM), is viewed as an attractive near option for stationary. Combined Heat and Power System (CHPS). Moreover, the reforming of fossil fuels could represent a practical option to create H2 filling stations realized with on-site fuel processor (FP) units fed with distribuited fuels already present on the road [3]. The key requirements for a fuel processor include rapid start-up, good dynamic-response to follow the change in hydrogen demand, high fuel conversion, small size and weight, simple design (construction and operation), stable performance for repeated start-up and shut-down cycles, maximum thermal integration, low cost and maintenance, high reliability and safety. In addition, the design of robust, low cost, highly performing and relatively fuelflexible catalysts is also required. In this regards, structured reactors, such as microchannels, ceramic or metallic monoliths and foams, show a number of advantages, like, compactness, high power densities, high mass specific powers, low catalyst request, lower pressure drop and improved heat and mass transfer, compared to conventional technology such as packet beds [4]. In this work, the performances of structured catalysts, based on 1.5wt%Rh/CeO2 coated on cordierite monoliths (400 cpsi, diameter 1 cm, length 1.5 cm) and alumina foams (20, 30, 40 ppi, diameter 1 cm, length 1.5 cm) were investigated and compared towards Steam Reforming (SR) and Oxy Steam Reforming (OSR) of different fuels (CH4, Biogas, n-dodecane). The structured supports were lined by combining the Solution Combustion Synthesis (SCS) for the deposition of ceria oxide, with the Wet Impregnation Technique (WIT) for the loading of active metal. The deposition process was repeated several times until reaching the desired and equal amount (? 0.180mg) of catalytic layer over all the supports [5]. The final structured catalysts, showed in Fig. 1, were characterized by SEM, EDX-mapping, TEM and XRD techniques; in addition, Rh/CeO2 catalyst in powder form was also prepared by the same procedure and characterized by XRD, TPR and CO chemisorption analysis. Pressure drop and catalytic layer loss tests have been evaluated. Both monolith and foam catalysts have shown comparable results in terms of uniform thin coating (thickness between 20-30 ?m), high mechanical strength (negligible weight loss ? 0.4% on total weight of the sample after ultrasonic treatment) with low pressure drop of the monolith respect the foam. The different reforming experiments were conducted in a fixed-bed quartz reactor (?i = 1 cm) at atmospheric pressure. The overall operating conditions are summarized in table 1. A first series of tests were carried out only with monolith catalysts to identify the optimum conditions in terms of S/C for SR, S/C and O/C for OSR for each fuel at fixed intermediate WSV and temperature. A second series of tests were carried out to compare the catalytic performance of foam and monolith catalysts varying the temperature and the WSV.