In the current work, LaNiO3 perovskite was synthesized using the polymeric precursor method. The materials were thermally treated at 300°C for 2 hours, subsequently supported on alumina or zirconia and finally ca...In the current work, LaNiO3 perovskite was synthesized using the polymeric precursor method. The materials were thermally treated at 300°C for 2 hours, subsequently supported on alumina or zirconia and finally calcined at 800°C for 4 hours. The resulting samples were characterized by X-ray diffraction, thermogravimetry, BET surface area and thermo-programmed reduction. Steam reforming reactions were carried out at 750°C and 6 bar during 4 hours using a pilot reactor under a H2O:CH4 ratio of 2.5. The mass of catalysts was about 5.7 g. X-ray diffraction patterns confirmed the formation of the perovskite structure in all samples prepared. The results also showed that lanthanum nickelate was more efficient when supported on alumina than zirconia. Finally, it was observed that the methane conversion was approximately 94% and the selectivity to hydrogen was about 70%. In all cases low selectivity to CO and CO2 was verified.展开更多
This paper describes the effect of the composition of the oxide films on the properties of electrodes Ti/M<sub>x</sub>Ti<sub>y</sub>Sn<sub>z</sub>O<sub>2</sub> (M = Ir o...This paper describes the effect of the composition of the oxide films on the properties of electrodes Ti/M<sub>x</sub>Ti<sub>y</sub>Sn<sub>z</sub>O<sub>2</sub> (M = Ir or Ru) prepared by the polymeric precursor method. XRD studies showed that the anodes are formed by solid solutions. The electrodes containing IrO<sub>2</sub> exhibit lower activity for the oxygen evolution reaction. The doping of the electrode surface with SnO<sub>2</sub> improves the catalytic properties of the anodes. However, it should be held in appropriate compositions, because the change in the atomic ratio of this element shows a marked effect on the stability of the oxides. Electrode Ti/Ir<sub>0.2</sub>Ti<sub>0.3</sub>Sn<sub>0.5</sub>O<sub>2</sub> has lower lifetime, i.e. 6 hours. The 20% decrease in the stoichiometric amount of SnO<sub>2</sub> increases the time to a value above 70 hours, as observed for Ti/Ir<sub>0.3</sub>Ti<sub>0.4</sub>Sn<sub>0.3</sub>O<sub>2</sub>. Electrode Ti/Ru<sub>0.3</sub>Ti<sub>0.4</sub>Sn<sub>0.3</sub>O<sub>2</sub> shows lifetime of 11 hours;therefore IrO<sub>2</sub> is more stable than RuO<sub>2</sub> under the conditions investigated. These results suggest that electrode Ti/Ir<sub>0.3</sub>Ti<sub>0.4</sub>Sn<sub>0.3</sub>O<sub>2</sub> is promising for different applications, such as water electrolysis, capacitors and organic electrosynthesis.展开更多
基金The authors wish to acknowledge RECAT-Petrobras,Rede de Hidrogenio-MCTANP for their financial support and scholarship grants.
文摘In the current work, LaNiO3 perovskite was synthesized using the polymeric precursor method. The materials were thermally treated at 300°C for 2 hours, subsequently supported on alumina or zirconia and finally calcined at 800°C for 4 hours. The resulting samples were characterized by X-ray diffraction, thermogravimetry, BET surface area and thermo-programmed reduction. Steam reforming reactions were carried out at 750°C and 6 bar during 4 hours using a pilot reactor under a H2O:CH4 ratio of 2.5. The mass of catalysts was about 5.7 g. X-ray diffraction patterns confirmed the formation of the perovskite structure in all samples prepared. The results also showed that lanthanum nickelate was more efficient when supported on alumina than zirconia. Finally, it was observed that the methane conversion was approximately 94% and the selectivity to hydrogen was about 70%. In all cases low selectivity to CO and CO2 was verified.
文摘This paper describes the effect of the composition of the oxide films on the properties of electrodes Ti/M<sub>x</sub>Ti<sub>y</sub>Sn<sub>z</sub>O<sub>2</sub> (M = Ir or Ru) prepared by the polymeric precursor method. XRD studies showed that the anodes are formed by solid solutions. The electrodes containing IrO<sub>2</sub> exhibit lower activity for the oxygen evolution reaction. The doping of the electrode surface with SnO<sub>2</sub> improves the catalytic properties of the anodes. However, it should be held in appropriate compositions, because the change in the atomic ratio of this element shows a marked effect on the stability of the oxides. Electrode Ti/Ir<sub>0.2</sub>Ti<sub>0.3</sub>Sn<sub>0.5</sub>O<sub>2</sub> has lower lifetime, i.e. 6 hours. The 20% decrease in the stoichiometric amount of SnO<sub>2</sub> increases the time to a value above 70 hours, as observed for Ti/Ir<sub>0.3</sub>Ti<sub>0.4</sub>Sn<sub>0.3</sub>O<sub>2</sub>. Electrode Ti/Ru<sub>0.3</sub>Ti<sub>0.4</sub>Sn<sub>0.3</sub>O<sub>2</sub> shows lifetime of 11 hours;therefore IrO<sub>2</sub> is more stable than RuO<sub>2</sub> under the conditions investigated. These results suggest that electrode Ti/Ir<sub>0.3</sub>Ti<sub>0.4</sub>Sn<sub>0.3</sub>O<sub>2</sub> is promising for different applications, such as water electrolysis, capacitors and organic electrosynthesis.
