LaMnO3-based perovskites are widely recognized as promising catalysts for several oxidation reactions, but the final physicochemical and catalytic properties can be greatly influenced by the adopted ...synthesis procedure. In this work, a series of A-site-deficient perovskites of composition La0.8MnO3 and La0.8Mn0.9B0.1O3 (B = Ni, Cu) were prepared through the citrate combustion route with variations in two synthesis parameters: a citric acid/metal cations molar ratio (CA/M) of either 1.1 or 1.5 and either acidic (given by HNO3 + citric acid) or neutral (after NH3 addition) pH of the precursor solution. The obtained samples were characterized by XRD, H2-TPR, O2-TPD, N2 physisorption, SEM-EDX and XPS. Acidic pH coupled with a CA/M ratio of 1.1 clearly emerged superior among all the other combinations of the two parameters, resulting in smaller crystallite size, higher surface area and porosity, enhanced Mn4+ reducibility and the ability to release oxygen species; these features were even further improved by B-site substitution with 10 mol% Ni and Cu cations. The synthesized catalysts were tested in CH4 oxidation to CO2 under stoichiometric O2, confirming the great superiority of samples prepared in acidic pH with a CA/M ratio of 1.1. Ni and Cu doping had a beneficial effect on catalytic activity, which, however, was more evident for less optimized perovskites (acidic pH and CA/M ratio of 1.5), without significance differences among the two dopants.
The imperative reduction of carbon dioxide into valuable fuels stands as a crucial step in the transition towards a more sustainable energy system. Perovskite oxides, with their high compositional ...and property adjustability, emerge as promising catalysts for this purpose, whether employed independently or as a supporting matrix for other active metals. In this study, an A-site-deficient La0.9FeO3 perovskite underwent surface decoration with Ni, Cu or Ni + Cu via a citric acid-templated wet impregnation method. Following extensive characterization through XRD, N2 physisorption, H2-TPR, SEM-EDX, HAADF STEM-EDX mapping, CO2-TPD and XPS, the prepared powders underwent reduction under diluted H2 to yield metallic nanoparticles (NPs). The prepared catalysts were then evaluated for CO2 reduction in a CO2/H2 = 1/4 mixture. The deposition of Ni or Cu NPs on the perovskite support significantly enhanced the conversion of CO2, achieving a 50% conversion rate at 500 °C, albeit resulting in only CO as the final product. Notably, the catalyst featuring Ni-Cu co-deposition outperformed in the intermediate temperature range, exhibiting high selectivity for CH4 production around 350 °C. For this latter catalyst, a synergistic effect of the metal–support interaction was evidenced by H2-TPR and CO2-TPD experiments as well as a better nanoparticle dispersion. A remarkable stability in a 20 h time-span was also demonstrated for all catalysts, especially the one with Ni-Cu co-deposition.
Carbon dioxide valorisation is one of the most discussed topics amongst researchers; indeed, finding a way to significantly reduce CO2 concentration in the atmosphere is crucial in order to mitigate ...climate change effects in the next decades. In this study, SrTiO3-supported Cu nanoparticles are exploited as Localised Surface Plasmon Resonance (LSPR)-mediated catalysts for CO2 reduction. The materials were prepared via sol–gel citrate route methodology, inserting Cu as a dopant in the perovskite structure; reducing treatments at different temperatures were performed to promote copper atom exsolution, thus forming nanostructures upon the surface. The perovskitic structure was confirmed via ex situ and operando XRD analysis, while compositional analysis was carried out through XPS and EDS; SEM and TEM images revealed morphological changes with different reducing treatments, and bulk reducibility was analysed with H2-TPR, revealing different Cu species in the material. Band gap analysis via DRS showed the successful incorporation of copper in the perovskite, affecting the light absorption properties. Finally, catalytic tests showed that copper nanoparticles play a role in CO2 activation with sunlight, proving that LSPR could be exploited for catalytic means.
From the plethora of energy-intensive synthetic processes, ammonia production has a particularly negative impact due to the high-energy consumption caused by the Haber-Bosch process and the high ...greenhouse gas (GHG) emission rate. Thus, new and effective ways to activate N
and synthesise NH
are crucial to reduce production costs and the anthropogenic footprint derived from the current harsh reaction conditions. In this study, two-dimensional materials have been employed in the photoactivation of nitrogen in an aqueous medium; M
(II)M
(III) (with M
= Cu or CuNi, and M
= Cr or Al) layered double hydroxides have been synthesised using a simple, economical and scalable co-precipitation/filtration method. The structural and functional properties were systematically investigated by XRD, SEM, TPR and BET; the results indicate that the prepared LDHs were successfully synthesised, possess high surface areas and, in the case of CuAl LDH, the material showed a nanoplate-like structure, thus confirming the two-dimensional nature of this class of catalyst. The N
fixation performances were evaluated using a scalable, cost-effective and low-energy-consuming setup; from the catalytic tests, a NH
production rate of 99 μmol g
h
was observed, demonstrating LDHs' high potential and the scalability of the overall process.
From the plethora of energy-intensive synthetic processes, ammonia production has a particularly negative impact due to the high-energy consumption caused by the Haber–Bosch process and the high ...greenhouse gas (GHG) emission rate. Thus, new and effective ways to activate N2 and synthesise NH3 are crucial to reduce production costs and the anthropogenic footprint derived from the current harsh reaction conditions. In this study, two-dimensional materials have been employed in the photoactivation of nitrogen in an aqueous medium; MI(ii)MII(iii) (with MI = Cu or CuNi, and MII = Cr or Al) layered double hydroxides have been synthesised using a simple, economical and scalable co-precipitation/filtration method. The structural and functional properties were systematically investigated by XRD, SEM, TPR and BET; the results indicate that the prepared LDHs were successfully synthesised, possess high surface areas and, in the case of CuAl LDH, the material showed a nanoplate-like structure, thus confirming the two-dimensional nature of this class of catalyst. The N2 fixation performances were evaluated using a scalable, cost-effective and low-energy-consuming setup; from the catalytic tests, a NH3 production rate of 99 μmol g−1 h−1 was observed, demonstrating LDHs’ high potential and the scalability of the overall process.
From the plethora of energy-intensive synthetic processes, ammonia production has a particularly negative impact due to the high-energy consumption caused by the Haber-Bosch process and the high ...greenhouse gas (GHG) emission rate. Thus, new and effective ways to activate N
2
and synthesise NH
3
are crucial to reduce production costs and the anthropogenic footprint derived from the current harsh reaction conditions. In this study, two-dimensional materials have been employed in the photoactivation of nitrogen in an aqueous medium; M
I
(
ii
)M
II
(
iii
) (with M
I
= Cu or CuNi, and M
II
= Cr or Al) layered double hydroxides have been synthesised using a simple, economical and scalable co-precipitation/filtration method. The structural and functional properties were systematically investigated by XRD, SEM, TPR and BET; the results indicate that the prepared LDHs were successfully synthesised, possess high surface areas and, in the case of CuAl LDH, the material showed a nanoplate-like structure, thus confirming the two-dimensional nature of this class of catalyst. The N
2
fixation performances were evaluated using a scalable, cost-effective and low-energy-consuming setup; from the catalytic tests, a NH
3
production rate of 99 μmol g
−1
h
−1
was observed, demonstrating LDHs' high potential and the scalability of the overall process.
In this work, various types of layered double hydroxides were evaluated as novel catalysts for photo-assisted dinitrogen fixation.
The imperative reduction of carbon dioxide into valuable fuels stands as a crucial step in the transition towards a more sustainable energy system. Perovskite oxides, with their high compositional ...and property adjustability, emerge as promising catalysts for this purpose, whether employed independently or as a supporting matrix for other active metals. In this study, an A-site-deficient Lasub.0.9 FeOsub.3 perovskite underwent surface decoration with Ni, Cu or Ni + Cu via a citric acid-templated wet impregnation method. Following extensive characterization through XRD, Nsub.2 physisorption, Hsub.2 -TPR, SEM-EDX, HAADF STEM-EDX mapping, COsub.2 -TPD and XPS, the prepared powders underwent reduction under diluted Hsub.2 to yield metallic nanoparticles (NPs). The prepared catalysts were then evaluated for COsub.2 reduction in a COsub.2 /Hsub.2 = 1/4 mixture. The deposition of Ni or Cu NPs on the perovskite support significantly enhanced the conversion of COsub.2 , achieving a 50% conversion rate at 500 °C, albeit resulting in only CO as the final product. Notably, the catalyst featuring Ni-Cu co-deposition outperformed in the intermediate temperature range, exhibiting high selectivity for CHsub.4 production around 350 °C. For this latter catalyst, a synergistic effect of the metal–support interaction was evidenced by Hsub.2 -TPR and COsub.2 -TPD experiments as well as a better nanoparticle dispersion. A remarkable stability in a 20 h time-span was also demonstrated for all catalysts, especially the one with Ni-Cu co-deposition.
Carbon dioxide valorisation is one of the most discussed topics amongst researchers; indeed, finding a way to significantly reduce COsub.2 concentration in the atmosphere is crucial in order to ...mitigate climate change effects in the next decades. In this study, SrTiOsub.3-supported Cu nanoparticles are exploited as Localised Surface Plasmon Resonance (LSPR)-mediated catalysts for COsub.2 reduction. The materials were prepared via sol–gel citrate route methodology, inserting Cu as a dopant in the perovskite structure; reducing treatments at different temperatures were performed to promote copper atom exsolution, thus forming nanostructures upon the surface. The perovskitic structure was confirmed via ex situ and operando XRD analysis, while compositional analysis was carried out through XPS and EDS; SEM and TEM images revealed morphological changes with different reducing treatments, and bulk reducibility was analysed with Hsub.2-TPR, revealing different Cu species in the material. Band gap analysis via DRS showed the successful incorporation of copper in the perovskite, affecting the light absorption properties. Finally, catalytic tests showed that copper nanoparticles play a role in COsub.2 activation with sunlight, proving that LSPR could be exploited for catalytic means.
LaMnOsub.3-based perovskites are widely recognized as promising catalysts for several oxidation reactions, but the final physicochemical and catalytic properties can be greatly influenced by the ...adopted synthesis procedure. In this work, a series of A-site-deficient perovskites of composition Lasub.0.8MnOsub.3 and Lasub.0.8Mnsub.0.9Bsub.0.1Osub.3 (B = Ni, Cu) were prepared through the citrate combustion route with variations in two synthesis parameters: a citric acid/metal cations molar ratio (CA/M) of either 1.1 or 1.5 and either acidic (given by HNOsub.3 + citric acid) or neutral (after NHsub.3 addition) pH of the precursor solution. The obtained samples were characterized by XRD, Hsub.2-TPR, Osub.2-TPD, Nsub.2 physisorption, SEM-EDX and XPS. Acidic pH coupled with a CA/M ratio of 1.1 clearly emerged superior among all the other combinations of the two parameters, resulting in smaller crystallite size, higher surface area and porosity, enhanced Mnsup.4+ reducibility and the ability to release oxygen species; these features were even further improved by B-site substitution with 10 mol% Ni and Cu cations. The synthesized catalysts were tested in CHsub.4 oxidation to COsub.2 under stoichiometric Osub.2, confirming the great superiority of samples prepared in acidic pH with a CA/M ratio of 1.1. Ni and Cu doping had a beneficial effect on catalytic activity, which, however, was more evident for less optimized perovskites (acidic pH and CA/M ratio of 1.5), without significance differences among the two dopants.
TuSoW: Tuple Spaces for Edge Computing Ciatto, Giovanni; Rizzato, Lorenzo; Omicini, Andrea ...
2019 28th International Conference on Computer Communication and Networks (ICCCN),
2019-July
Conference Proceeding
Edge Computing is rapidly gaining traction in scenarios such as Cyber-Physical Systems and Web of Things. Whereas the Cloud hides heterogeneity of devices behind its standard interfaces and ...protocols, the Edge should deal with it, as well as with embracing openness and governing interactions. In this paper we propose TuSoW as a model and technology for bringing tuple-based coordination to the Edge.
