ANDREZZA DA SILVA RAMOS

ANDREZZA DA SILVA RAMOS

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Effects of TiO2 in Pd-TiO2/C for glycerol oxidation in a direct alkaline fuel cell
2022 - PEREIRA, VIVIANE S.; NANDENHA, JULIO; RAMOS, ANDREZZA; OLIVEIRA NETO, ALMIR
The Pd-TiO2 electrocatalysts were synthesized via sodium borohydride reduction and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), cyclic voltammetry, chronoamperometry and attenuated total reflectance-Fourier transform infrared (ATR-FTIR). The X-ray diffraction experiments of the Pd-TiO2 showed peaks associated with Pd face-centered cubic (fcc) structure and peaks characteristics of TiO2 (anatase phase) with a tetragonal structure. The TEM images showed that the Pd and TiO2 nanoparticles were well distributed in the carbon support showing some clustered regions with nanoparticle sizes between 7 and 8 nm. Cyclic voltammograms showed an increase in current density values after the glycerol adsorption process. Experiments in alkaline direct glycerol fuel cells at 60 °C showed a higher power density for Pd-TiO2/C (70:30) in comparison to the commercial Pd/C electrocatalyst indicating that the use of the TiO2 co-catalyst with Pd nanoparticles had a beneficial behavior. This effect can be attributed to the electronic effect or to the bifunctional mechanism. Molecules with high-value added glyceraldehyde, hydroxypyruvate and formate were identified as electrochemical reaction products of glycerol on all prepared electrocatalysts.
Methanol electrosynthesis from CO2 reduction reaction in polymer electrolyte reactors - fuel cell type using [6,6′-(2,2′-bipyridine-6,6′-diyl)bis(1,3,5-triazine-2,4-diamine)] (dinitrate-O) copper (II) complex
2022 - GARCIA, L.M.S.; FILHO, N.G.P.; CHAIR, K.; KAUR, P.; RAMOS, A.S.; ZAMBIAZI, P.J.; SOUZA, R.F.B. de; OTUBO, L.; DUONG, A.; NETO, A.O.
Electrocatalytic carbon dioxide reduction reaction has been an attractive way to convert greenhouse gas into valuable chemical fuels based on carbon-neutral energy. Therefore, it serves as an effective approach to combating high concentrations of CO2 in the atmosphere as well as reducing the use of fossil fuels responsible for emitting carbon dioxide and other greenhouse gases, meeting growing energy demands. In this work, the copper(II) bis-triazine bipyridine complex supported on carbon black has been applied as a catalyst in a polymeric electrolytic reactor – fuel cell type for converting CO2 into methanol. The physical and nanostructure properties of the Cu(II) nanocomposite were previously determined by Fourier transform infrared, Raman spectroscopy, X-ray powder diffraction, and transmission electron microscopy techniques. The electrocatalytic activity of the Cu complex catalyst was monitory by differential mass spectroscopy. The results indicate that the catalyst is not selective for the preferential synthesis of a specific product, but a mixture of products (methanol, formic acid, formaldehyde, carbon monoxide, and methane) was detected. According to our results, 2.5% and 5% Cu complex on carbon black were the ideal amounts for polymeric electrolytic reactor – fuel cell type applications to produce methanol from CO2 with faradaic efficiency of ∼22% for both compositions.
cis-[6-(pyridin-2-yl)-1,3,5-triazine-2,4-diamine](dichloride) palladium(II)-based electrolyte membrane reactors for partial oxidation methane to methanol
2022 - GARCIA, LUIS M.S.; ZAMBIAZI, PRISCILLA J.; CHAIR, KHAOULA; DOAN, TUAN D.; RAMOS, ANDREZZA S.; NANDENHA, JULIO; SOUZA, RODRIGO F.B. de; OTUBO, LARISSA; DUONG, ADAM; NETO, ALMIR O.
Methane is an abundant resource and the main constituent of natural gas. It can be converted into higher value-added products and as a subproduct of electricity co-generation. The application of polymer electrolyte reactors for the partial oxidation of methane to methanol to co-generate power and chemical products is a topic of great interest for gas and petroleum industries, especially with the use of materials with a lower amount of metals, such as palladium complex. In this study, we investigate the ideal relationship between cis-[6-(pyridin-2-yl)-1,3,5-triazine-2,4-diamine(dichloride)palladium(II)] (Pd-complex) nanostructure and carbon to obtain a stable, conductive, and functional reagent diffusion electrode. The physical and structural properties of the material were analyzed by Fourier transform infrared (FT-IR) and Raman spectroscopies, transmission electron microscopy (TEM), and X-ray powder diffraction (XRD) techniques. The electrocatalytic activity studies revealed that the most active proportion was 20% of Pd-complex supported on carbon (m/m), which was measured with lower values of open-circuit and power density but with higher efficiency in methanol production with reaction rates of r = 4.2 mol L–1·h–1 at 0.05 V.
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.
Electro-oxidation of ethanol in acid medium using carbon-supported PtRh nanoparticles with (100) preferential orientation
2021 - PEREIRA FILHO, N.G.; SOUZA, R.F.B.; RAMOS, A.S.; ANTONIASSI, R.M.; OLIVEIRA NETO, A.; SPINACE, E.V.
Carbon-supported PtRh nanoparticles with preferential (100) orientation was prepared by an alcohol-reduction process using KBr as a shape directing agent. The electrocatalysts were characterized by EDX (energy-dispersive X-ray analysis), XRD (X-ray diffraction) and TEM (Transmission electron microscopy). The electro-oxidation of ethanol was studied by cyclic voltammetry and chronoamperometry at room temperature in acid medium. On-line differential mass spectrometry experiments were performed on a single cell of a direct ethanol fuel cell (DEFC) at 60 0C and the anodic effluents were analyzed by ATR-FTIR. PtRh/C (100) electrocatalyst showed cubic-like morphology and average nanoparticles size of 8 nm and provided superior DEFC performance (density power per Pt active area) and CO2 selectivity compared to polycrystalline PtRh/C and commercial Pt/C electrocatalysts.
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.