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Purpose This paper shows the use of free web-based technology to improve English writing in academic manuscripts. This study can be used by non-native English-speaking scientists to translate their manuscripts into English removing the language barrier in publishing their scientific studies. Design/methodology/approach An internet application of free online tools was performed. Native speakers in Spanish, Russian, Portuguese, and Chinese used eight online tools to translate technical phrases into English and evaluate the results. We used five online editing tools, and ten plagiarism checkers. Feedback from peers was studied from Academia.edu, Authorea, and reviewing/feedback groups. Findings Grammarly produced better results between free online editing tools. The application of several editing tools is recommended because they give different suggestions. The best translating tools were DeepL for Spanish to English, Reverso for Portuguese to English, Yandex and Google for Russian to English, and Google for Chinese to English. Plagiarism checkers were not reproducible. Research limitations Limitations were imposed by some subscription-only sites. However, because this research aims to help researchers in low-income countries improve their manuscripts by using free online websites, this limitation was not important. Social implications We aim at helping non-native English-speaking scientists and students wishing to translate their manuscripts into English and improve their writing, eliminating the language barrier in the publication. Originality/value Not enough information is found in the scientific literature on the use of free tools to improve the presentation of scientific manuscripts.

This work deals with the comparison of the theoretical assignment of the DADP vibrational spectrum with the experimental displacements by isotopic labeling. For this, the DADP-C4 and DADP-C2 isotopomers were synthesized from acetone labeled isotopically in the methyl and the carbonyl carbon atoms, respectively. The acetone and DADP-isotopomer compounds were characterized using Raman and infrared spectroscopy. Theoretical assignments were taken from previous studies on the potential energy distribution of a vibrational mode, which provide an approach to the internal coordinates related to each band. The selective isotopic labeling allowed us to approach to the dependence of each band, because the energy of a molecular vibration also depends on the reciprocal mass of the atoms involved. In general, the results showed that some bands assigned experimentally do not coincide with the theoretical assignments by quantum mechanical simulations.

Humic acids are produced by decomposition of organic soil material and from oxidation of mineral coals. In this study, the effect of oxidation and the yield of humic acids extracted from a sample of Colombian mineral coal were studied by response surface methodology (RSM). The variables used were: particle size (0.063, 0.106 and 0.150 mm), concentration of the oxidizing agent (KMnO4: 0.010, 0.020 and 0.050 M) and oxidation time (30, 60 and 90 minutes). The degree of oxidation was verified by infrared spectroscopy. Oxidation increased oxygen groups in the carbonaceous matrix, mainly due to oxidation of aliphatic components. Extraction yields above 24% were obtained with 0.063 mm particle size and 0.020 M KMnO4. © 2017. Acad. Colomb. Cienc. Ex. Fis. Nat. Resumen Los ácidos húmicos se producen por la descomposición de la materia orgánica de los suelos y por la oxidación de carbones minerales. En este estudio se analizó mediante superficies de respuesta el efecto de la oxidación en la extracción de ácidos húmicos de un carbón colombiano. Las variables de oxidación estudiadas fueron las siguientes: tamaño de partícula (0,063, 0,106 y 0,150 mm), concentración del agente oxidante (permanganato de potasio (KMnO4): 0,010, 0,020 y 0,050 M) y tiempo de oxidación (30, 60 and 90 minutos). El grado de oxidación se verificó con espectroscopia infrarroja. La oxidación incrementó los grupos oxigenados en la matriz carbonácea debido, principalmente, a la oxidación de componentes alifáticos. Se obtuvieron porcentajes de extracción superiores a 24 % al usar partículas de 0,063 mm y KMnO4 con 0,020 M. © 2017. Acad. Colomb. Cienc. Ex. Fis. Nat.

Resumen Las hidrotalcitas tienen un alto impacto en el desarrollo de nuevos materiales y en avances tecnológicos en áreas como catálisis y química ambiental. Un aspecto de vital importancia es la temperatura del colapso de la estructura HTLc, ya que de esta dependen las propiedades de los sólidos obtenidos. En este trabajo se estudió el comportamiento térmico de hidrotalcitas de níquel-aluminio y se determinó la Ea asociada al colapso y formación de NiO. Se observó que la mayor interacción entre iones carbonato y grupos OH ocurre a 250 °C, temperatura en la cual desaparece la estructura HTLc. El sólido N0,75A0,25 requirió menos energía para que ocurriese el colapso, debido a la mayor distancia entre las láminas. El material N0,66A0,33 necesito más energía para que ocurriese la formación del óxido de níquel, lo que se debe a que el mayor contenido de Al3+, desfavorece el crecimiento de las partículas iniciales de NiO. Abstract The synthesis and use of materials as hydrotalcites have a high impact on development of new materials and technological advances, applied in areas such as catalysis and environmental chemistry. An aspect of vital importance is the temperature of collapse of the HTLc structure, because from this fact depend the properties of solids obtained. In this work was studied the thermal behavior of nickel-aluminum hydrotalcite, and determined the Ea associated with the collapse and formation of NiO. It was observed that the greater interaction among carbonate ions and OH groups occurs at 250 °C, temperature at which the collapse of the HTLc structure occurs. The solid N0,75A0,25 requires less energy to collapse, which is due to the greater distances between the positive sheets. The solid N0,66A0,33 need more energy for the formation of NiO, which is due to higher content of Al3+, disfavoring the growth of the initial particles of NiO.

In this paper, two models of humic acids, the Temple-Northeastern-Birmingham (TNB) and Kolla models, were studied. Also, the complexation reaction of the structures formed by the interaction of the TNB and Kolla models with Al3+, Ca2+, Mg2+, Zn2+, K+ and NH4+ cations, common in agricultural soils, was studied. These calculations were made for the complexes, at PM6 and DFT/LANL2DZ level of theory, both in vacuum and in aqueous medium. We found a strong affinity between Kolla and TNB models, and Al3+, Ca2+, Mg2+, Zn2+, K+ and NH4+ cations, influenced by the solvent that affected the interaction sites; the solvent increased the rate of reactivity and affinity for the cations in nucleophilic regions and decreased it in electrophilic regions of the structures. Calculations of molecular electronic potential, MEP and atomic charges, the local smoothness, Fukui functions and the HSAB principle adequately described the HA/cations interactions which were affected by the number of hydrogen bonds. The most reactive sites were the hydroxyl, phenolic, carbonyls oxygens and nitrogens at both vacuum and aqueous medium, especially carbonyl oxygens. These results are consistent with the properties of HA that make them attractive as components of agricultural soils.

Low-rank coals are an important source of humic acids, which are important in retention processes of water and nutrients in plants. In this study coal samples of Montelibano, Colombia, were oxidized with air at different temperatures and subsequently with H2O2 and HNO3. The materials were characterized by FTIR, proximate and elemental analysis, and quantification of humic acids. The oxidation process led to an increased content of oxygenated groups and humic acids in the carbonaceous structure. The solid oxidized with air at 200 ºC for 12 h and re-oxidized with HNO3 for 12 h showed the highest percentage of humic acids (85.3%).

En este estudio se determinaron las propiedades interfaciales en solución acuosa del surfactante del tipo PDMS-éster que contiene polidimetilsiloxano (PDMS), polietilenglicol (PEG), anhídrido maléico y ácido fumárico. Para el estudio de las propiedades interfaciales se emplearon las técnicas tensiometría y espectroscopia en la región del UV-VIS. En solución acuosa este surfactante mostró un comportamiento complejo, que es dependiente de la concentración. En este surfactante se observó un cambio brusco en la curva de tensión superficial en función de la concentración, produciendo una reducción de la tensión superficial del agua hasta 48,9 mN/m en la CMC. La concentración del surfactante en la CMC fue de 1032 mg/L. La eficiencia del surfactante PDMS-éster se calculó como pC20 y se determinó como la concentración del surfactante necesaria para conseguir una disminución de la tensión superficial de 20 mN/m. El valor de C20 obtenido fue 213 mg/L (1,554x10-5 mol/L) (pC20=4,81). Esta concentración sirve como un indicador de la eficiencia de la adsorción del surfactante, ya que la reducción de la tensión superficial de la solución por el surfactante depende de la substitución de moléculas en la interface solución/vapor. In this work the interfacial properties in aqueous solution of surfactant of si-licon PDMS-ester type containing PEG, anhydride maleic and fumaric acid had been determined. In order to study the interfacial properties tensiometry and spectroscopy UV-VIS techniques were used. The surfactant in aqueous solution showed a complex behavior and this is dependent on the concentration. This surfactant was showed an abrupt change in surface tension curve as a function of concentration, leading to reduced sur-face tension of water to 48.9 mN/m in the CMC. The concentration of surfac-tant in the CMC was 1032 mg/L. The effciency of the PDMS-ester surfactant was calculated as pC20 and determined as the concentration of surfactant re-quired to achieve a decrease in surface tension up 20mN/m. The value of C20 obtained was 213 mg/L (1.554 x10-5 mol/L) (pC20 = 4.81). This concentra-tion serves as an indicator of the eff-ciency of adsorption of the surfactant, since the reduction of surface tension of the surfactant solution depends on the substitution of molecules at the interfa-ce solution / vapor. Neste trabalho foi feita a determinação das propriedades interfaciais do surfactante de silicone tipo PDMS-éster, con-tendo PEG, anidrido maleico e ácido fumárico. Para o estudo das propriedades interfaciais foram utilizadas as técnicas tensiometria e espectroscopia na região UV-VIS. Em solucao aquosa, este surfactante mostra um comportamento complexo e é dependente da concentracao; além disso, mostra urna mudança brusca na curva de tensão superficial em função da concentracao, produzindo urna reducao da tensão superficial da água até 48,9 (mN/m) na CMC. A concentracao do surfactante na CMC foi de 1032 mg/L. A eficiência do surfactante PDMS-éster foi calculada como pC20 determinada como a concentracao do surfactante necessá-ria para conseguir urna diminuicao da tensão superficial de 20mN/m. O valor de C20 obtido foi 213 mg/L (1,554x10"5 mol/L) (pC20=4,81). Esta concentracao serve como um indicador da eficiência da adsorcao do surfactante, já que a redução da tensão superficial da solução pelo surfactante depende da substituicao de moléculas na interface solucao/vapor.

El uso del hidrógeno para la generación de energía ha renovado el interés por la reacción WGS. Los catalizadores usados para acelerar esta reacción requieren condiciones especiales de reducción, lo que dificulta su aplicación en celdas combustibles para la producción de energía. En este trabajo se sintetizaron catalizadores de níquel soportado en óxido de cinc o aluminio usando un diseño factorial 3² en el caso de los materiales con cinc. Los resultados obtenidos se emplearon en la síntesis de sólidos trimetálicos de níquel, cinc y aluminio en las condiciones más propicias para garantizar mejor actividad y selectividad. Los sólidos fueron caracterizados por EDX, DRX, TPR y evaluados en la reacción WGS a 260 °C. Se observó la incorporación de los cationes Zn²+ yAl³+ en la red del NiO, lo que disminuye su reducibilidad con hidrógeno. Los materiales que contenían cinc fueron 100% selectivos para la reacción WGS. En la evaluación de los catalizadores con níquel y aluminio hubo formación de metano; sin embargo, este compuesto no fue observado durante la evaluación catalítica de los sólidos trimetálicos. Los catalizadores más activos fueron aquellos calcinados en temperaturas más bajas y con las menores cantidades de cinc. The use of hydrogen for power generation has again awaken the interest in the WGS reaction. The catalysts used to accelerate this reaction need special conditions of reduction. This limits their application in fuel cells for energy production. In this work, nickel catalysts-supported in zinc oxide or aluminum oxide were synthesized by using a 3² factorial design with materials containing zinc. The results were used for the synthesis of trimetallic solid containing nickel, zinc and aluminum, in the most favorable conditions to ensure high activity and selectivity. The solids were characterized by EDX, XRD, TPR and evaluated in the WGS reaction at 260 °C. The incorporation of Zn2+ and Al3+ cations was observed in the lattice of NiO. This phenomenon affects the reducibility of these materials with hydrogen. The materials containing zinc were of 100 per cent selectivity for the reaction under study. In the case of nickel and aluminum catalysts, methane formation was observed, but this species was not detected in the trimetallic catalysts. The catalytic activity of trimetallic materials is consistent with the trends in bimetallic nickel-zinc or nickel-aluminum materials. The most active catalysts were those calcined at the lowest temperatures with the smallest amounts of zinc. O uso do hidrogênio para a geração de energia tem renovado o interesse pela reação WGS. Os catalisadores usados para acelerar esta reação requerem condições especiais de redução. Isso dificulta a sua aplicação em células combustíveis para a geração de energia. Neste trabalho se sintetizaram catalisadores baseados em níquel suportado em oxido de zinco ou alumínio, usando um desenho fatorial 3² no caso dos materiais contendo zinco. Os resultados obtidos foram usados para a síntese de sólidos tri-metálicos contendo níquel, zinco e alumínio nas condições ótimas para aumentar a atividade e seletividade dos materiais. Os sólidos foram caracterizados pelas técnicas EDX, DRX, TPR e avaliados na reação WGS a 260 °C. Observou-se a incorporação dos cátions Zn2+ eAl3+ na rede do NiO, o que diminui a redução dos sólidos com hidrogênio. Os sólidos contendo zinco foram 100% seletivos para a reação em estudo. Na avaliação dos catalisadores contendo níquel e alumínio ocorreu a formação de metano, no entanto esta espécie não foi observada na avaliação catalítica dos sólidos tri-metálicos. Os catalisadores mais ativos foram os calcinados nas temperaturas mais baixas e com menores quantidades de zinco.

texto completo: acesso restrito. p.290– 296. Submitted by Ana Valéria de Jesus Moura (anavaleria_131@hotmail.com) on 2012-02-24T13:49:24Z No. of bitstreams: 1 nps2E.tmp.pdf: 801883 bytes, checksum: 3489d4d8beddebd4e7236304cfa8ae50 (MD5) Made available in DSpace on 2012-02-24T13:49:24Z (GMT). No. of bitstreams: 1 nps2E.tmp.pdf: 801883 bytes, checksum: 3489d4d8beddebd4e7236304cfa8ae50 (MD5) Previous issue date: 2011 Nickel or copperbased catalysts were obtained from hydrotalcitelike precursors in this work, in order to find catalysts able to work at intermediates temperatures (200–350 ◦C) in water gas shift reaction (WGSR). Samples based on nickel (or copper), aluminum and zinc were obtained by coprecipitation, characterized by several techniques and evaluated in WGSR. Zinc caused changes in the cell parameters of hydrotalcitetype structure, which determined the structural and textural properties of calcined samples. For all catalysts, zinc oxide was detected. In the case of nickelbased hydrotalcites, aluminum cations were incorporated into nickel oxide lattice, hindering reduction; however, the addition of zinc decreased this effect. For copperbased samples, aluminum entered into copper oxide lattice and the copper reduction decreased with the increase of zinc amount in solids. After calcination, copper catalysts showed lower specific surface areas than nickel ones. Zinc led to the production of smaller and more reducible nickel oxide particles, due to the decrease of their interaction with Al3+ species; under reduction, they produced small metallic nickel particles, which are supposed to be highly active and selective to carbon dioxide. Copper catalysts were less active to WGSR, as compared to the nickel ones, this can be related to their low specific surface areas. All catalysts were active in the range of 200–350 ◦C and thus are candidates to be used in a single stage of WGSR at intermediate temperatures.

El uso del hidrógeno para la generaciónde energía ha renovado el interés por lareacción WGS. Los catalizadores usadospara acelerar esta reacción requieren condicionesespeciales de reducción, lo quedificulta su aplicación en celdas combustiblespara la producción de energía. Eneste trabajo se sintetizaron catalizadoresde níquel soportado en óxido de cinc oaluminio usando un diseño factorial 32 enel caso de los materiales con cinc. Los resultadosobtenidos se emplearon en la síntesisde sólidos trimetálicos de níquel,cinc y aluminio en las condiciones máspropicias para garantizar mejor actividady selectividad. Los sólidos fueron caracterizadospor EDX, DRX, TPR y evaluadosen la reacción WGS a 260 °C. Se observóla incorporación de los cationesZn2+ y Al3+ en la red del NiO, lo que disminuyesu reducibilidad con hidrógeno.Los materiales que contenían cinc fueron100% selectivos para la reacción WGS.En la evaluación de los catalizadores conníquel y aluminio hubo formación de metano;sin embargo, este compuesto no fueobservado durante la evaluación catalíticade los sólidos trimetálicos. Los catalizadoresmás activos fueron aquellos calcinadosen temperaturas más bajas y conlas menores cantidades de cinc.: hidrógeno, níquel

Submitted by Ana Hilda Fonseca (anahilda@ufba.br) on 2016-09-05T18:58:35Z No. of bitstreams: 1 Tesis Final Edgardo Meza Fuentes (4).pdf: 4706850 bytes, checksum: bee3311a2964aa593f1d6a612f6eb874 (MD5) Approved for entry into archive by Vanessa Reis (vanessa.jamile@ufba.br) on 2016-09-06T12:40:55Z (GMT) No. of bitstreams: 1 Tesis Final Edgardo Meza Fuentes (4).pdf: 4706850 bytes, checksum: bee3311a2964aa593f1d6a612f6eb874 (MD5) Made available in DSpace on 2016-09-06T12:40:55Z (GMT). No. of bitstreams: 1 Tesis Final Edgardo Meza Fuentes (4).pdf: 4706850 bytes, checksum: bee3311a2964aa593f1d6a612f6eb874 (MD5) FAPESB Os problemas ambientais gerados pelo uso de combustíveis de origem fóssil e o desenvolvimento de novas tecnologias para obtenção de energia a partir do hidrogênio, têm renovado o interesse pela reação de deslocamento de deslocamento de monóxido de carbono com vapor d’água. Esta reação é usada para a eliminação do monóxido de carbono resultante da reforma de gás natural e para aumentar a produção de hidrogênio. Os catalisadores usados nesta reação estão restringidos a ser usados em condições especificas de temperatura, devido a fatores cinéticos e termodinâmicos. Isto tem motivado o estudo de sólidos que possam ser usados em diversas condições de temperatura e que apresentem atividade e seletividade elevadas. Neste trabalho foram preparados catalisadores a base de níquel e de cobre, obtidos a partir de precursores do tipo hidrotalcita; compostos que geram materiais com alta área superficial específica, homogeneidade das fases presentes e pequenas partículas de óxidos ou de metais. Os sólidos sintetizados foram caracterizados pelas técnicas de espectroscopia de absorção atômica, analise elementar de carbono, difração de raios X, espectroscopia no infravermelho, termogravimétria e analise diferencial de temperatura, espectroscopia Raman, medida da área superficial especifica e de porosidade, redução termoprogramada, medida de área metálica de cobre e avaliadas na reação de deslocamento de monóxido de carbono com vapor d’água. A estrutura do tipo hidrotalcita foi observada em todos os sólidos. A presença e o conteúdo de alumínio e do zinco nestes materiais ocasionam variações nos parâmetros de rede das estruturas do tipo hidrotalcita, as quais determinam as propriedades texturais e estruturais dos sólidos calcinados. A incorporação de cátions de alumínio na rede do óxido de níquel dificulta os processos de redução deste óxido, mas, a adição do zinco diminui esse efeito. Os catalisadores de cobre apresentaram baixas áreas superficiais específicas, não sendo observada a incorporação de alumínio na rede do óxido de cobre. Os catalisadores de níquel e alumínio apresentaram elevadas áreas superficiais especificas, enquanto que os catalisadores de cobre apresentaram as áreas superficiais especificas mais baixas. Os sólidos contendo níquel apresentam um comportamento mesoporosos, enquanto que aqueles contendo cobre apresentaram meso e macroporos em sua estrutura. Os catalisadores contendo níquel e alumínio são ativos para a reação em estudo, alcançando-se conversões do 100 %, mas também produzem metano. A adição de zinco promove a formação de partículas menores de oxido de níquel, minimizando a produção de metano. Os catalisadores de cobre são menos ativos. O solido mais promissor é aquele contendo 37% de níquel, 37 % de zinco e 25 % de alumínio, que conduz à conversão do 100 % de monóxido de carbono e 100 % de seletividade a dióxido de carbono, mostrando-se também estável na temperatura de estudo The environmental problems coming from the use of fossil fuels, as well as the development of new technologies for energy generation from hydrogen, have renewed the interest for the water gas shift reaction (WGSR). This reaction is used for removing carbon monoxide produced from the stream produced during the natural gas reforming; at the same time, the production of hydrogen is increased. The catalysts used for this reaction are limited by kinetic and thermodynamic factors. This has led to the need of searching solids that can be used at various temperatures, showing high activity and selectivity towards carbon dioxide. In order to find new catalysts for this reaction, nickel and copper-based catalyst were prepared in this work, from hydrotalcite-like precursors. These compounds are expected to produce materials with high specific surface area, homogeneity of phases and small particles of oxides or metals, after the calcination and reduction processes. Samples were prepared from aluminum, zinc and nickel (or copper) nitrates and characterized by atomic absorption spectroscopy, X-ray diffraction, infrared spectroscopy, thermogravimetry, Raman spectroscopy, specific surface area and porosity measurements, temperature-programmed reduction and dispersion measurements. The catalysts were evaluated in the WGSR at 1 atm in a range of 150 to 450 oC. The production of hydrotalcite-type structure was noted for all solid. The presence and the content of aluminum and zinc caused changes in the cell parameters of hydrotalcite-type structure, which determined the structural and textural properties of solids after calcination. Aluminum cations were incorporated into the crystal lattice of nickel oxide, hindering its reduction of this oxide, but the addition of zinc decreased this effect. After calcination, the copper-containing catalysts showed low specific surface areas, and no aluminum cation was observed into the copper oxide lattice. Aluminum and nickel-based sample showed the highest specific surface area, while the copper-containing solids showed the lowest ones. The nickel-based solids were mesoporous with some macropores while the copper-based ones were macroporous. The nickel and aluminum-based catalyst was active for WGSR and achieved 100 % of conversion, but produced also methane. The addition of zinc promotes the formation of small nickel oxide particles that minimized methane production. The copper-based catalysts were less active than those of nickel. The most promising catalyst for WGSR was the sample with 37 % of nickel, 37 % of zinc and 25 % of aluminum which was 100 % selective towards hydrogen and led to 100 % of conversion, being stable in the studied temperature range.

Submitted by Ana Hilda Fonseca (anahilda@ufba.br) on 2016-09-16T14:49:44Z No. of bitstreams: 1 Dissertacion Edgardo Meza Fuentes.pdf: 2388033 bytes, checksum: d25fa353a1745c7442f4a612649af0f2 (MD5) Approved for entry into archive by Vanessa Reis (vanessa.jamile@ufba.br) on 2016-09-16T15:35:34Z (GMT) No. of bitstreams: 1 Dissertacion Edgardo Meza Fuentes.pdf: 2388033 bytes, checksum: d25fa353a1745c7442f4a612649af0f2 (MD5) Made available in DSpace on 2016-09-16T15:35:35Z (GMT). No. of bitstreams: 1 Dissertacion Edgardo Meza Fuentes.pdf: 2388033 bytes, checksum: d25fa353a1745c7442f4a612649af0f2 (MD5) A reação de deslocamento de monóxido de carbono com vapor d´água (water gas shift reaction, WGSR) é freqüentemente usada, em processos industriais,para aumentar a produção de hidrogênio, assim como para remover os óxidos de carbono das correntes produzidas pela reforma a vapor de hidrocarbonetos. Essa reação é favorecida por baixas temperaturas devido à sua exotermicidade, mas são necessárias altas temperaturas para se alcançar velocidades para fins industriais. Portanto, ela é freqüentemente conduzida em duas etapas, a primeira ocorrendo na faixa de 320-450oC (chamada high temperature shift, HTS) enquanto, na outra, monóxido de carbono é removido em condições termodinamicamente favoráveis, a 200-250oC (low temperature shift, LTS). A etapa de LTS é conduzida sobre catalisadores à base de cobre e zinco suportados em alumina, que são facilmente desativados por envenenamento e/ou sinterização do cobre e, portanto, é importante investigar novos sistemas. A fim de obter catalisadores isentos de cobre que possam ser mais resistentes à sinterização foi estudada, neste trabalho, a substituição do cobre pelo níquel em sólidos à base de alumínio e zinco. Os catalisadores foram preparados por técnicas de precipitação, a partir de nitrato de cobre, alumínio e zinco,seguida de aquecimento em diferentes temperaturas, de acordo com um planejamento fatorial de duas variáveis (temperatura de calcinação e razão molar Ni/Zn) em três níveis (T=300, 500 e 750 oC; Ni/Zn=0,5; 1,0 e 1,5), mantendo a razão molar Ni/Al constante (0,5). Amostras sem alumínio ou zinco também foram preparadas como referências. Os sólidos foram caracterizados por análise química, difração de raios X, termogravimetria, análise térmica diferencial, redução termoprogramada e medida de área superficial específica. Os catalisadores foram avaliados em um microreator de leito fixo, a 1 atm e 260oC, usando uma mistura gasosa (3%CO, 15%CO2, 60%H2 e 22% N2) e uma razão molar vapor/gás de 0,8. Os catalisadores usados foram caracterizados por difração de raios X e medida de área superficial específica. Foram observadas diferentes fases (óxido de alumínio,óxido de zinco,óxido de níquel, aluminato de zinco e aluminato de níquel) nos catalisadores dependendo da presença e do teor dos metais e da temperatura de calcinação. Durante a WGSR, foi produzido níquel metálico, considerado a fase ativa. Aumentando-se a temperatura de calcinação, os metais interagiram mais fortemente entre si e dificultaram a redução do níquel. A área superficial específica também mostrou dependência com a quantidade de metais e a temperatura. Os valores mais altos foram apresentados pelos sólidos contendo alumínio. De modo geral, esses catalisadores foram ativos na reação, enquanto as amostras isentas de alumínio não mostraram atividade. A adição de zinco aos catalisadores à base de alumínio aumentou a seletividade a dióxido de carbono para 100%, evitando a produção de metano. A amostra mais promissora foi aquela com Ni/Zn=1,0 e calcinada a 300oC, que possui elevada área superficial específica, sendo potencialmente mais resistente contra a sinterização, quando comparada à de cobre. The water gas shift reaction (WGSR) is often used in industrial processes for increasing the hydrogen production as well as for removing carbon oxides from the stream produced by steam reforming of hydrocarbons. This reaction is favored by low temperatures due to its exothermicity but high temperatures are required to achieve rates for industrial purposes. Therefore, it is often carried out in two steps, the first being performed in the range of 320-450oC (named high temperature shift, HTS) while, in the other stage, carbon monoxide is removed in thermodynamically favorable conditions, at 200-250oC (low temperature shift, LTS). The LTS stage is carried out over alumina- supported copper and zinc catalysts which are easily deactivated by poisoning and/or sintering of copper and thus it is important to investigate new systems. In order to find copper-free catalysts which can be more resistant against sintering, the replacement of copper by nickel in aluminum and zinc-based solids was studied in this work. The catalysts were prepared by precipitation techniques at room temperature from copper, aluminum and zinc nitrate, followed by heating at different temperatures, according to a factorial design of two variables (calcination temperature and Ni/Zn molar ratio) in three levels (T= 300, 500 and 750 oC; Ni/Zn= 0.5, 1.0 and 1.5), keeping the Ni/Al molar ratio the same (0.5). Samples without aluminum or zinc were also prepared to be used as references. The solids were characterized by chemical analysis, X-ray diffraction, thermogravimetry, differential thermal analysis, temperature programmed temperature and specific surface area measurement. The catalysts were evaluated in a fixed bed microreactor, at 1 atm and 260 oC, using a gas mixture (3% CO, 15% CO2, 60%H2 and 22% N2) and a steam to gas molar ratio of 0.8. The spent catalysts were characterized by X-ray diffraction and specific surface area measurement. Different phases (aluminum oxide, zinc oxide, nickel oxide, zinc aluminate and nickel aluminate) were found in the catalysts depending on the presence and on the amount of the metals as well as on the calcination temperature. During the WGSR, metallic nickel was produced which is supposed to be the active phase. Increasing the calcination temperature the metals interacted more strongly among themselves and made the nickel reduction more difficult. The specific surface areas also depended on the amount of metals and on the calcination temperature and the highest values were showed by the aluminum-containing solids. As a whole, these catalysts were active in the reaction while the aluminum-free samples showed no activity. The addition of zinc to the aluminum-based catalysts increased the selectivity to carbon dioxide to 100%, avoiding methane production. The most promising sample was that with Ni/Zn= 1.0 and calcined at 300 oC, which has high specific surface area being potentially more resistant against sintering as compared to copper-based one.