ANDREZZA DA SILVA RAMOS

ANDREZZA DA SILVA RAMOS

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Application of binary PdSb/C as an anode in a polymeric electrolyte reactor-fuel cell type for electrosynthesis of methanol from methane
2022 - GODOI, CAMILA M.; SANTOS, MONIQUE C.L.; NUNES, LIVIA C.; SILVA, ARACELI J.; RAMOS, ANDREZZA S.; SOUZA, RODRIGO F.B. de; NETO, ALMIR O.
PdSb catalyst prepared in different compositions were applied as an anode in a polymeric electrolyte reactor - fuel cell type (PER-FC) to convert methane into oxygenated products and energy in mild conditions. The PER-FC polarization curves for Pd90Sb10/C presented maximum current density about 0.92 mW cm-2 about 15% higher than PdSb materials. However, the material Pd50Sb50/C showed higher reaction rate for methanol generation than the other materials occurring close to the OCV (r ~ 7 mol L-1 h-1). The qualitative analyses of PER-FC effluent by FT-IR identified products as methanol, carbonate and formate ions from the partial oxidation of methane for all materials.
Methane conversion to higher value‑added product and energy co‑generation using anodes OF PdCu/C in a solid electrolyte reactor
2021 - GODOI, C.M.; SANTOS, M.C.L.; SILVA, A.J.; TAGOMORI, T.L.; RAMOS, A.S.; SOUZA, R.F.B. de; OLIVEIRA NETO, A.
PdxCuy/C catalysts combinations were employed to CH4 partial oxidation in mild condition using a solid electrolyte reactor—alkaline fuel cell type. The differential mass spectroscopy on line method was used to monitor the oxidation products obtained as methanol, dimethyl ether, methyl formate and potassium formate. It was observed that as the electrical potential of the reactor increases, the generation of products decreases. The best results for conversion of methane into methanol and energy co-generation was obtained from Pd90Cu10/ C and Pd50Cu50/ C due to better H2O activation effects and adsorption site for CH4 oxidation.
High CO tolerance of Pt nanoparticles synthesized by sodium borohydride in a time-domain NMR spectrometer
2020 - RAMOS, A.S.; SANTOS, M.C.L.; GODOI, C.M.; QUEIROZ, L.C. de; NANDENHA, J.; FONTES, E.H.; BRITO, W.R.; MACHADO, M.B.; NETO, A.O.; SOUZA, R.F.B. de
The CO poisoning effect was overcome using a novel synthesis method. This method consists of using sodium borohydride reducing agent assisted by magnetic field and radiofrequency pulses in the time-domain NMR spectrometer. This synthesis was useful to disperse the Pt nanoparticles over the carbon support and to compress the lattice strain of the Pt crystalline structure. Besides that, Pt/C MFP90° showed a multi-CO oxidation component in cyclic voltammetry, and this can avoid the poisoning effect by creating a large availability of CO species to be adsorbed, desorbed, and re-adsorbed. Pt/C MFP90° has also shown the best performance in the PEMFC regarding H2 and CO + H2 experiments.
Obtaining C2 and C3 products from methane using Pd/C as anode in a solid fuel cell-type electrolyte reactor
2020 - RAMOS, ANDREZZA S.; SANTOS, MONIQUE C.L.; GODOI, CAMILA M.; OLIVEIRA NETO, ALMIR; SOUZA, RODRIGO F.B. de
Methane was converted into C2 and C3 products under mild conditions using a single stage solid electrolyte reactor, using a proton exchange membrane fuel cell as a SER-FC and Pd/C as an electrocatalyst prepared by the reduction method of sodium borohydride. This electrocatalyst has a cubic pattern of palladium centered on the face and an average size of nanoparticles close to 6.4 nm, according to the literature. Differential mass spectrometry reveals the chemical profile of species obtained from the oxidation of methane with ionic currents (Ii) at m/z=16, 28, 30, 32, 44, 46 and 60. In many cases, Ii can be assigned to more than one species; therefore, complementary ATR-FTIR experiments were performed. The ATR-FTIR spectra confirmed the presence of C2 and C3 compounds such as ethane, ethanol, acetaldehyde, acetic acid and propane. Considering the low amount of water in the reaction medium, these results may be associated with the use of Pd/C electrocatalysts responsible for the activation of the water molecule.
Conversion of methane into methanol using the [6,6′-(2,2′-bipyridine-6,6′-diyl)bis(1,3,5-triazine-2,4-diamine)](nitrato-O)copper(II) complex in a solid electrolyte reactor fuel cell type
2020 - GARCIA, LUIS M.S.; RAJAK, SANIL; CHAIR, KHAOULA; GODOY, CAMILA M.; SILVA, ARACELI J.; GOMES, PAULO V.R.; SANCHES, EDGAR A.; RAMOS, ANDREZZA S.; SOUZA, RODRIGO F.B. de; DUONG, ADAM; NETO, ALMIR O.
The application of solid electrolyte reactors for methane oxidation to co-generation of power and chemicals could be interesting, mainly with the use of materials that could come from renewable sources and abundant metals, such as the [6,6′- (2, 2′-bipyridine-6, 6′-diyl)bis (1,3,5- triazine-2, 4-diamine)](nitrate-O)copper (II) complex. In this study, we investigated the optimal ratio between this complex and carbon to obtain a stable, conductive, and functional reagent diffusion electrode. The most active Cu-complex compositions were 2.5 and 5% carbon, which were measured with higher values of open circuit and electric current, in addition to the higher methanol production with reaction rates of 1.85 mol L−1 h−1 close to the short circuit potential and 1.65 mol L−1 h−1 close to the open circuit potential, respectively. This activity was attributed to the ability of these compositions to activate water due to better distribution of the Cu complex in the carbon matrix as observed in the rotating ring disk electrode experiments.
Effect of Ni content in PdNi/C anode catalysts on power and methanol co-generation in alkaline direct methane fuel cell type
2020 - SANTOS, M.C.L.; GODOI, C.M.; KANG, H.S.; SOUZA, R.F.B. de; RAMOS, A.S.; ANTOLINI, E.; NETO, A.O.
PdNi electrocatalysts supported on carbon were used as anode materials for methane oxidation in alkaline direct methane fuel cells (ADMEFCs). The electrocatalysts were successfully synthesized by the NaBH4 reduction method. X-ray diffraction measurements showed the formation of non-alloyed Pd in the face- centered cubic (FCC) structure for all materials and formation of NiO and Ni(OH)2 species. TEM images showed that the metal particles are well dispersed on the support with small agglomeration regions. Information about the surface structure of the catalyst were obtained by Raman spectra, mainly confirming the presence of Ni(OH)2. The species observed by DEMS, that is, methanol (m/z = 32), CO2 (m/ z = 44) and potassium formate (m/z = 84) were confirmed by FTIR, which also showed the presence of a high amount of carbonate in the methane oxidation products of the ADMEFC with Pd50Ni50/C as the anode catalyst. Tests in ADMEFCs showed that the dependence of the maximum power density on nickel content in the catalysts goes through a maximum value of 13.5 lW cm 2 at 50 at% Ni. Moreover, the amount of produced methanol decreases with increasing Ni content in the PdNi/C catalysts. Both these results can be explained by the enhanced methanol oxidation in the presence of nickel.