Catalisadores de Cu e Ni suportados em γ-Al2O3 e SiO2 comerciais foram estudados frente a reforma a vapor de glicerol. Os catalisadores foram preparados pelo método da impregnação e caracterizados por espectrometria de emissão atômica por plasma acoplado indutivamente, fisissorção de nitrogênio, redução a temperatura programada com H2 e difração de raios X. A caracterização mostrou a presença de espécies com diferentes interações com os suportes: CuO, NiO e NiAl2O4. Os testes catalíticos foram realizados a 600 °C e, para o catalisador que apresentou o melhor desempenho, foram realizadas reações a 500 °C e a 700 °C. Os testes mostraram que a presença de NiAl2O4 desfavorece a deposição de carbono, provavelmente devido à maior dispersão do Ni na superfície do catalisador. Observou-se também que o catalisador NiSi foi o que apresentou a maior atividade para a formação de H2, porém este apresentou a maior deposição de carbono ao longo da reação.

Cu and Ni catalysts supported on commercial γ-Al2O3 and SiO2 were tested in the glycerol steam reforming. The catalysts were prepared by the impregnation method and characterized by inductively-coupled plasma atomic emission spectrometry, nitrogen physisorption, temperature programmed reduction with H2 and X-ray diffraction. The characterization indicated several catalytic species in the samples interacting differently with the supports: NiO, CuO and NiAl2O4. The catalytic tests were performed at 600 °C, and the best catalyst was also tested at 500 °C and 700 °C. The results showed that the presence of NiAl2O4 did not favor the deposition of carbon during the reaction, probably due to the greater dispersion of Ni on the catalyst surface. It was also observed that, although NiSi was the most active catalyst for H2 production, it also showed the highest carbon deposit during the reaction.

Catalisadores Ni/La2O3-SiO2 foram preparados por diferentes métodos: impregnação sequencial, impregnação simultânea (I-sim), precipitação do suporte seguida da impregnação do metal e co-precipitação. As amostras foram caracterizadas por espectroscopia de energia dispersiva de raios X, fisissorção de nitrogênio, difração de raios X (XRD), espectroscopia de infravermelho, redução a temperatura programada (TPR), quimissorção de H2, microscopia eletrônica de varredura e análise termogravimétrica. As análises de XRD e TPR indicaram duas espécies de Ni nas amostras: NiO (I-sim) e La2NiO4 (outras amostras). Foram realizados testes catalíticos na reação de reforma a vapor de glicerol a 600 ºC. O melhor resultado foi observado com o catalisador I-sim, que apresentou o maior grau de redução, maior dispersão metálica e maior área metálica (TPR e TPD). Foram realizados testes a 500 e 700 ºC com esse catalisador, que apresentou melhores resultados a 600 ºC.

Ni/La2O3-SiO2 catalysts were obtained by different methods of preparation: sequential impregnation, simultaneous impregnation (I-sim), precipitation of support followed by Ni impregnation and co-precipitation. The samples were characterized by energy-dispersive X-ray spectroscopy, nitrogen physisorption, X-ray diffraction (XRD), infrared spectroscopy, temperature programmed reduction (TPR), H2 chemisorption, scanning electron microscopy and thermogravimetric analysis. XRD and TPR results indicated two Ni species in the samples: NiO (I-sim) and La2NiO4 (other samples). Catalytic tests were performed in glycerol steam reforming at 600 ºC. The best result was observed with I-sim catalyst, which presented the higher reduction degree, metallic dispersion and metallic area (TPR and TPD). This catalyst was also tested at 500 ºC and 700 ºC and performed best at 600 ºC.

In this work, the perovskite-type oxides LaNiO3, LaMnO3, La0,7Sr0,3NiO3 and La0,7Sr0,3MnO3 were prepared by co-precipitation and tested in the NO reduction with CO at 400 and 500 ºC for 10 h. The catalysts were characterized by X-ray diffraction, temperature programmed reduction with hydrogen, nitrogen adsorption and chemical analysis. The nonstoichiometric oxygen was quantified by temperature programmed reduction, and the catalytic tests showed that the La0,7Sr0,3MnO3 catalyst presented the higher performance for the reduction reaction of NO with CO. The partial substitution of lanthanum by strontium increased the NO conversion and the N2 yield.

Cu/Ni/gamma-Al2O3 catalysts were prepared by an impregnation method with 2.5 or 5% wt of copper and 5 or 15% wt of nickel and applied in ethanol steam reforming. The catalysts were characterized by atomic absorption spectrophotometry, X-ray diffraction, temperature programmed reduction with hydrogen and nitrogen adsorption. The samples showed low crystallinity, with the presence of CuO and NiO, both as crystallites and in dispersed phase, as well as of NiO-Al2O3. The catalytic tests carried out at 400 ºC, with a 3:1 water/ethanol molar ratio, indicated the 5Cu/5Ni/Al2O3 catalyst as the most active for hydrogen production, with a hydrogen yield of 77% and ethanol conversion of 98%.

The development of cobalt catalysts to produce hydrogen from ethanol is the goal of this investigation. Co/Al2O3 catalysts were prepared by impregnation and characterized by atomic absorption, nitrogen adsorption, X-ray diffraction, Raman spectroscopy, temperature programmed reduction and carbon analysis. The catalysts contained Co3O4 oxide and Co3+ and Co2+ species interacting with alumina. The cobalt load affects the crystal size and the crystalline structure and higher Co loads influence the reaction mechanism, changing the selectivity of the catalysts, decreasing the amount of CO produced and avoiding the formation of products catalyzed by the support. The ethanol conversion was 50-70% with 10-<1% of CO in the hydrogen.