Maria da Graça Carneiro da Rocha (original) (raw)
Papers by Maria da Graça Carneiro da Rocha
Chemical Engineering Science, Dec 1, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Materials Chemistry and Physics, Mar 1, 2011
Journal of the Brazilian Chemical Society, 2022
The development of efficient, stable, and non-precious metal water oxidation catalysts (WOCs) is ... more The development of efficient, stable, and non-precious metal water oxidation catalysts (WOCs) is a matter of importance for sustainable energy research. In this work, iron cobaltite (FeCo2O4) nanoparticles were prepared by the coprecipitation method, and we present the effect of heat treatment (250, 350, 450, 650 and 900 °C) on the catalytic properties. Catalytic activity tests of FeCo2O4 nanocatalysts were performed in the presence of ammonium cerium(IV) nitrate (CAN), and the formation of oxygen was followed using a Clark-type oxygen electrode. The samples were characterized by infrared (IR), thermogravimetric analysis (TGA), powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), and their surface areas were determined by the Brunauer, Emmett, and Teller (BET) method. Fourier transform infrared (FTIR) data confirm a metal-oxygen bond at the octahedral and tetrahedral sites. XRDs data were characteristic of spinel-like cubic materials. The XPS results confirmed ...
Langmuir, 2021
In this paper, two biosystems based on filamentous fungi and Pd nanoparticles (NPs) were synthesi... more In this paper, two biosystems based on filamentous fungi and Pd nanoparticles (NPs) were synthesized and structurally characterized. In the first case, results concerning the integration and distribution of Pd-NPs on Phialomyces macrosporus revealed that nanoparticles are accumulated on the cell wall, keeping the cytoplasm isolated from abiotic particles. However, the Penicillium sp. species showed an unexpected internalization of Pd-NPs in the fungal cytosol, becoming a promising biosystem to further studies of in vivo catalytic reactions. Next, we report a new solution-based strategy to prepare palladized biohybrids through sequential reduction of Pd2+ ions over previously harvested fungus/Au-NP composites. The chemical composition and the morphology of the biohybrid surface were characterized using a combination of scanning electron microscopy, transmission electron microscopy, and photoelectron spectroscopy. The deposition of Pd0 over the fungal surface produced biohybrids with a combination of Au and Pd in the NPs. Interestingly, other chemical species such as Au+ and Pd2+ are also observed on the outermost wall of microorganisms. Finally, the application of A. niger/AuPd-NP biohybrids in the 3-methyl-2-buten-1-ol hydrogenation reaction is presented for the first time. Biohybrids with a high fraction of Pd0 are active for this catalytic reaction.
Chemical Engineering Science, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Materials Chemistry and Physics, 2020
Fe-doped TiO 2 supports show decreased band gap (2.95-1.90 eV) compared to pure TiO 2. � Pt nanos... more Fe-doped TiO 2 supports show decreased band gap (2.95-1.90 eV) compared to pure TiO 2. � Pt nanostructures deposited on Pt/Fe-TiO 2 support present sized around 3.5 nm. � Fe-doping enhanced metal-support interactions and oxygen species on surfaces. � Fe doping improved the activity of the Pt/TiO 2 electrocatalysts toward EOR.
Studies in Surface Science and Catalysis, 1997
3rd World Congress on Oxidation Catalysis RK Grasselli, ST Oyama, AM Gaffney and JE Lyons (Editor... more 3rd World Congress on Oxidation Catalysis RK Grasselli, ST Oyama, AM Gaffney and JE Lyons (Editors) 1997 Elsevier Science BV All rights reserved. 767 Catalytic Combustion of Methane: Activation and Characterization of Pd/AI203 Maria GraCa Carneiro da Rochaa ...
Materials Chemistry and Physics, 2011
1D nanostructured sodium trititanate was synthesized by alkali hydrothermal treatment of TiO 2 an... more 1D nanostructured sodium trititanate was synthesized by alkali hydrothermal treatment of TiO 2 anatase, coexisting with incompletely converted precursors like nanosheets and poorly crystalline aggregates. This product easily exchanged with Fe 3+ at room temperature to saturation at approximately 8 wt% Fe, following the Langmuir adsorption model. Iron exchange caused changes on the structural (interlayer shrinkage) and optical properties of the nanomaterial without affecting significantly its original morphology and mesoporous structure. According to consistent XRD and TEM/EDS data, iron was saturated within the interlayers of the 1D nanostructured particles at a lower content as compared to the coexisting poorly crystalline aggregates. Based on XPS results iron was found to be also in a lower oxidation state Fe 2+ , likely on the layered surface of the 1D nanostructured particles, through a mechanism tentatively explained by formation of structural iron defects promoted by the acidic medium. The iron modified trititanate nanostructure (Fe/TTNS) is stable up to 400 • C and at high temperatures it is eventually transformed into rutile (TiO 2) and pseudobrookite (Fe 2 TiO 5), whereas some freudenbergite phase (Na 2 Fe 2 Ti 6 O 16) is generated due to residual sodium.
Journal of the Brazilian Chemical Society, 2011
Os processos industriais mais utilizados na produção de combustíveis líquidos semelhantes ao dies... more Os processos industriais mais utilizados na produção de combustíveis líquidos semelhantes ao diesel usam catalisadores homogêneos básicos através das metanólise e etanólise de óleos tais como os de soja, canola, palma entre outros. Desse modo, se obtém o biodiesel. Por sua vez, transformações termo-catalíticas usando as facilidades existentes nas refinarias de petróleo são alternativas que merecem atenção devido a sua viabilidade econômica. De fato, três processos industriais já estão em funcionamento e novos projetos estão em fase final para comercialização. O presente trabalho analisa os experimentos já realizados por pesquisadores brasileiros nas áreas do craqueamento, do craqueamento catalítico e do hidrocraqueamento catalítico dos óleos vegetais puros ou modificados. A partir dos resultados descritos, são sugeridas novas direções destas pesquisas para os próximos anos. The most used industrial processes for the production of liquid fuels like diesel type are based on the methanolysis and ethanolysis of various oil reactants, such as palm, soybean and rapeseed oils, in the presence of homogeneous base catalysts. However, thermal and catalytic transformations of vegetable oils using available reactors and industrial processes are possible alternatives and deserve attention. In fact, three industrial processes are operating and new projects are announced. The present work analyses the experimental studies performed up to now by Brazilian researchers in the field of cracking, catalytic cracking and hydrocracking of pure or modified vegetable oils. From the published results, some research areas for the near future are suggested.
Journal of Catalysis, 2008
Water-gas shift reaction has found new purpose and challenges due to its application in clean pow... more Water-gas shift reaction has found new purpose and challenges due to its application in clean power generation systems based on fuel cells. It has been shown that the catalysts performance is dependent on both the metal phase and the nature of the support. In this contribution the modification of Pt/CeO 2 catalyst with vanadium was exploited. Spectroscopic techniques revealed that distinct dispersed VO x species were generated onto the catalysts by using different vanadium loadings. The reduction of the catalysts and CO adsorption were monitored by infrared spectroscopy. It was found that the formation/decomposition of surface carbonates is affected by vanadium. Generation of multicoordinated carbonates is inhibited due to the decrease of the exposed cerium surface cations. The catalytic activity increased up to a vanadium surface density of 6 V atoms/nm 2. Improvement in water-gas shift reaction kinetics is associated with the V-O-Ce bonds.
Catalysis Communications, 2009
Hydrogen production from the dry reforming of methane has been studied over MAl 2 O 4 (M = Cu 2+ ... more Hydrogen production from the dry reforming of methane has been studied over MAl 2 O 4 (M = Cu 2+ , Ni 2+ or both) with respect to the structure, surface properties and coke deposition of the spinel oxides. The catalysts were characterized by Raman, XPS, TEM, and N 2 adsorption isotherms methods. The Ni o /NiAl 2 O 4 system was significantly more active due to the intimated contact between Ni o specie and the NiAl 2 O 4. This system is found to give carbon filaments which easily react with CO 2 , in comparison with the Cubased spinel oxides.
Química Nova, 2001
CATALYTIC ACTIVITY. The catalytic combustion of methane on alumina supported palladium catalysts ... more CATALYTIC ACTIVITY. The catalytic combustion of methane on alumina supported palladium catalysts was studied. It has been reported that the activity of the catalyst increases with its time on line, despite of an increase of the palladium particle size. However, different preparation, pretreatment and testing conditions can be the reason for the observed different results. An experimental design, which allows to verify the influence of several parameters at the same time with a good statistical quality, was used. A Plackett-Burman design was selected for the screening of the variables which have an effect on the increase of the catalyst activity.
Journal of Materials Research and Technology
Química Nova, 2012
Palladium catalysts supported on alumina and zirconia were prepared by the impregnation method an... more Palladium catalysts supported on alumina and zirconia were prepared by the impregnation method and calcined at 600 and 1000 °C. Catalysts were characterized by BET measurements, XRD, XPS, O 2-TPD and tested in methane combustion through temperature programmed surface reaction. Alumina supported catalysts were slightly more active than zirconia supported catalysts, but after initial heat treatment at 1000 °C, zirconia supported palladium catalyst showed better performance above 500 °C A pattern between temperature interval stability of PdOx species and activity was observed, where better PdOx stability was associated with more active catalysts.
Chemical Engineering Science, Dec 1, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Materials Chemistry and Physics, Mar 1, 2011
Journal of the Brazilian Chemical Society, 2022
The development of efficient, stable, and non-precious metal water oxidation catalysts (WOCs) is ... more The development of efficient, stable, and non-precious metal water oxidation catalysts (WOCs) is a matter of importance for sustainable energy research. In this work, iron cobaltite (FeCo2O4) nanoparticles were prepared by the coprecipitation method, and we present the effect of heat treatment (250, 350, 450, 650 and 900 °C) on the catalytic properties. Catalytic activity tests of FeCo2O4 nanocatalysts were performed in the presence of ammonium cerium(IV) nitrate (CAN), and the formation of oxygen was followed using a Clark-type oxygen electrode. The samples were characterized by infrared (IR), thermogravimetric analysis (TGA), powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), and their surface areas were determined by the Brunauer, Emmett, and Teller (BET) method. Fourier transform infrared (FTIR) data confirm a metal-oxygen bond at the octahedral and tetrahedral sites. XRDs data were characteristic of spinel-like cubic materials. The XPS results confirmed ...
Langmuir, 2021
In this paper, two biosystems based on filamentous fungi and Pd nanoparticles (NPs) were synthesi... more In this paper, two biosystems based on filamentous fungi and Pd nanoparticles (NPs) were synthesized and structurally characterized. In the first case, results concerning the integration and distribution of Pd-NPs on Phialomyces macrosporus revealed that nanoparticles are accumulated on the cell wall, keeping the cytoplasm isolated from abiotic particles. However, the Penicillium sp. species showed an unexpected internalization of Pd-NPs in the fungal cytosol, becoming a promising biosystem to further studies of in vivo catalytic reactions. Next, we report a new solution-based strategy to prepare palladized biohybrids through sequential reduction of Pd2+ ions over previously harvested fungus/Au-NP composites. The chemical composition and the morphology of the biohybrid surface were characterized using a combination of scanning electron microscopy, transmission electron microscopy, and photoelectron spectroscopy. The deposition of Pd0 over the fungal surface produced biohybrids with a combination of Au and Pd in the NPs. Interestingly, other chemical species such as Au+ and Pd2+ are also observed on the outermost wall of microorganisms. Finally, the application of A. niger/AuPd-NP biohybrids in the 3-methyl-2-buten-1-ol hydrogenation reaction is presented for the first time. Biohybrids with a high fraction of Pd0 are active for this catalytic reaction.
Chemical Engineering Science, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Materials Chemistry and Physics, 2020
Fe-doped TiO 2 supports show decreased band gap (2.95-1.90 eV) compared to pure TiO 2. � Pt nanos... more Fe-doped TiO 2 supports show decreased band gap (2.95-1.90 eV) compared to pure TiO 2. � Pt nanostructures deposited on Pt/Fe-TiO 2 support present sized around 3.5 nm. � Fe-doping enhanced metal-support interactions and oxygen species on surfaces. � Fe doping improved the activity of the Pt/TiO 2 electrocatalysts toward EOR.
Studies in Surface Science and Catalysis, 1997
3rd World Congress on Oxidation Catalysis RK Grasselli, ST Oyama, AM Gaffney and JE Lyons (Editor... more 3rd World Congress on Oxidation Catalysis RK Grasselli, ST Oyama, AM Gaffney and JE Lyons (Editors) 1997 Elsevier Science BV All rights reserved. 767 Catalytic Combustion of Methane: Activation and Characterization of Pd/AI203 Maria GraCa Carneiro da Rochaa ...
Materials Chemistry and Physics, 2011
1D nanostructured sodium trititanate was synthesized by alkali hydrothermal treatment of TiO 2 an... more 1D nanostructured sodium trititanate was synthesized by alkali hydrothermal treatment of TiO 2 anatase, coexisting with incompletely converted precursors like nanosheets and poorly crystalline aggregates. This product easily exchanged with Fe 3+ at room temperature to saturation at approximately 8 wt% Fe, following the Langmuir adsorption model. Iron exchange caused changes on the structural (interlayer shrinkage) and optical properties of the nanomaterial without affecting significantly its original morphology and mesoporous structure. According to consistent XRD and TEM/EDS data, iron was saturated within the interlayers of the 1D nanostructured particles at a lower content as compared to the coexisting poorly crystalline aggregates. Based on XPS results iron was found to be also in a lower oxidation state Fe 2+ , likely on the layered surface of the 1D nanostructured particles, through a mechanism tentatively explained by formation of structural iron defects promoted by the acidic medium. The iron modified trititanate nanostructure (Fe/TTNS) is stable up to 400 • C and at high temperatures it is eventually transformed into rutile (TiO 2) and pseudobrookite (Fe 2 TiO 5), whereas some freudenbergite phase (Na 2 Fe 2 Ti 6 O 16) is generated due to residual sodium.
Journal of the Brazilian Chemical Society, 2011
Os processos industriais mais utilizados na produção de combustíveis líquidos semelhantes ao dies... more Os processos industriais mais utilizados na produção de combustíveis líquidos semelhantes ao diesel usam catalisadores homogêneos básicos através das metanólise e etanólise de óleos tais como os de soja, canola, palma entre outros. Desse modo, se obtém o biodiesel. Por sua vez, transformações termo-catalíticas usando as facilidades existentes nas refinarias de petróleo são alternativas que merecem atenção devido a sua viabilidade econômica. De fato, três processos industriais já estão em funcionamento e novos projetos estão em fase final para comercialização. O presente trabalho analisa os experimentos já realizados por pesquisadores brasileiros nas áreas do craqueamento, do craqueamento catalítico e do hidrocraqueamento catalítico dos óleos vegetais puros ou modificados. A partir dos resultados descritos, são sugeridas novas direções destas pesquisas para os próximos anos. The most used industrial processes for the production of liquid fuels like diesel type are based on the methanolysis and ethanolysis of various oil reactants, such as palm, soybean and rapeseed oils, in the presence of homogeneous base catalysts. However, thermal and catalytic transformations of vegetable oils using available reactors and industrial processes are possible alternatives and deserve attention. In fact, three industrial processes are operating and new projects are announced. The present work analyses the experimental studies performed up to now by Brazilian researchers in the field of cracking, catalytic cracking and hydrocracking of pure or modified vegetable oils. From the published results, some research areas for the near future are suggested.
Journal of Catalysis, 2008
Water-gas shift reaction has found new purpose and challenges due to its application in clean pow... more Water-gas shift reaction has found new purpose and challenges due to its application in clean power generation systems based on fuel cells. It has been shown that the catalysts performance is dependent on both the metal phase and the nature of the support. In this contribution the modification of Pt/CeO 2 catalyst with vanadium was exploited. Spectroscopic techniques revealed that distinct dispersed VO x species were generated onto the catalysts by using different vanadium loadings. The reduction of the catalysts and CO adsorption were monitored by infrared spectroscopy. It was found that the formation/decomposition of surface carbonates is affected by vanadium. Generation of multicoordinated carbonates is inhibited due to the decrease of the exposed cerium surface cations. The catalytic activity increased up to a vanadium surface density of 6 V atoms/nm 2. Improvement in water-gas shift reaction kinetics is associated with the V-O-Ce bonds.
Catalysis Communications, 2009
Hydrogen production from the dry reforming of methane has been studied over MAl 2 O 4 (M = Cu 2+ ... more Hydrogen production from the dry reforming of methane has been studied over MAl 2 O 4 (M = Cu 2+ , Ni 2+ or both) with respect to the structure, surface properties and coke deposition of the spinel oxides. The catalysts were characterized by Raman, XPS, TEM, and N 2 adsorption isotherms methods. The Ni o /NiAl 2 O 4 system was significantly more active due to the intimated contact between Ni o specie and the NiAl 2 O 4. This system is found to give carbon filaments which easily react with CO 2 , in comparison with the Cubased spinel oxides.
Química Nova, 2001
CATALYTIC ACTIVITY. The catalytic combustion of methane on alumina supported palladium catalysts ... more CATALYTIC ACTIVITY. The catalytic combustion of methane on alumina supported palladium catalysts was studied. It has been reported that the activity of the catalyst increases with its time on line, despite of an increase of the palladium particle size. However, different preparation, pretreatment and testing conditions can be the reason for the observed different results. An experimental design, which allows to verify the influence of several parameters at the same time with a good statistical quality, was used. A Plackett-Burman design was selected for the screening of the variables which have an effect on the increase of the catalyst activity.
Journal of Materials Research and Technology
Química Nova, 2012
Palladium catalysts supported on alumina and zirconia were prepared by the impregnation method an... more Palladium catalysts supported on alumina and zirconia were prepared by the impregnation method and calcined at 600 and 1000 °C. Catalysts were characterized by BET measurements, XRD, XPS, O 2-TPD and tested in methane combustion through temperature programmed surface reaction. Alumina supported catalysts were slightly more active than zirconia supported catalysts, but after initial heat treatment at 1000 °C, zirconia supported palladium catalyst showed better performance above 500 °C A pattern between temperature interval stability of PdOx species and activity was observed, where better PdOx stability was associated with more active catalysts.