The steam reforming of methane over NiO/ZnO mixed oxides with different nickel contents was studied. Solids to x% Ni/ZnO (x = 4 and 10%) were deposited on ZnO by impregnation from nickel nitrate solution;after vaporiz...The steam reforming of methane over NiO/ZnO mixed oxides with different nickel contents was studied. Solids to x% Ni/ZnO (x = 4 and 10%) were deposited on ZnO by impregnation from nickel nitrate solution;after vaporization the solid is calcined at 500°C for 6 h. The catalysts were characterized by X-ray diffraction (XRD) and BET method, scanning electron microscopy (SEM) and temperature programmed reduction (TPR). The XRD patterns revealed the NiO phase for all calcined catalysts. The chemical analysis confirmed the theoretical values of nickel. The catalysts were pre-treated under hydrogen at 500°C in situ, overnight before testing for the steam reforming of methane reaction (CH<sub>4</sub>/H<sub>2</sub>O/Ar = 10/10/80) in the temperature range (475°C - 650°C) under atmospheric pressure. The activities of both catalysts were investigated in a fixed-bed reactor for the Methane Steam Reforming (MSR) reaction. Globally, it was shown that the catalyst 10% nickel content has an important effect on the catalytic performances of solids i.e. the better results of hydrogen production were obtained with 10% wt. Ni/ZnO (28 ′ 10-<sup>3</sup> mol/g catalyst).展开更多
MoO<sub>3</sub> and 5% MoO<sub>3</sub>/ZnO were prepared by impregnation method using (NH<sub>4</sub>)<sub>6</sub>Mo<sub>7</sub>O<sub>24</sub>, 4...MoO<sub>3</sub> and 5% MoO<sub>3</sub>/ZnO were prepared by impregnation method using (NH<sub>4</sub>)<sub>6</sub>Mo<sub>7</sub>O<sub>24</sub>, 4H<sub>2</sub>O as precursor and ZnO as support. The prepared samples were characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM), infra red (FTIR) <span style="font-family:;" "="">and</span><span style="font-family:;" "=""> UV-Vis diffuse reflectance (DRS)</span><span> </span><span style="font-family:;" "="">spectroscopies and pho<span>to-electrochemistry. The XRD pattern showed that the MoO<sub>3</sub> powder treated at 700°C is a single-phase crystallizing in an orthorhombic structure with a direct optical transition </span></span><span style="font-family:;" "="">(</span><span style="font-family:;" "="">2.70 eV</span><span style="font-family:;" "="">)</span><span style="font-family:;" "="">. The hetero-junction 5% MoO<sub>3</sub>/ZnO</span><span style="font-family:;" "=""> was photo-electrochemically characterized to assess its feasibility for H<sub>2</sub> production under visible light. The capacitance potential (<i>C<sup>-</sup></i><sup>2</sup><i> f</i>(<i>E</i>)) characteristic of MoO<sub>3</sub> plotted in Na<sub>2</sub>SO<sub>4</sub>, (0.1 M) electrolyte indicates <i>n-</i>type conduction with a flat band potential of -</span><span style="font-family:;" "=""><span>0.54 V<i><sub>SCE</sub></i>. The photocatalytic activity was performed for the photoreduction of water to hydrogen under visible light illumination. The best performance occurs at pH ~ 7 with an evolved volume of 5.9 mL.</span></span>展开更多
文摘The steam reforming of methane over NiO/ZnO mixed oxides with different nickel contents was studied. Solids to x% Ni/ZnO (x = 4 and 10%) were deposited on ZnO by impregnation from nickel nitrate solution;after vaporization the solid is calcined at 500°C for 6 h. The catalysts were characterized by X-ray diffraction (XRD) and BET method, scanning electron microscopy (SEM) and temperature programmed reduction (TPR). The XRD patterns revealed the NiO phase for all calcined catalysts. The chemical analysis confirmed the theoretical values of nickel. The catalysts were pre-treated under hydrogen at 500°C in situ, overnight before testing for the steam reforming of methane reaction (CH<sub>4</sub>/H<sub>2</sub>O/Ar = 10/10/80) in the temperature range (475°C - 650°C) under atmospheric pressure. The activities of both catalysts were investigated in a fixed-bed reactor for the Methane Steam Reforming (MSR) reaction. Globally, it was shown that the catalyst 10% nickel content has an important effect on the catalytic performances of solids i.e. the better results of hydrogen production were obtained with 10% wt. Ni/ZnO (28 ′ 10-<sup>3</sup> mol/g catalyst).
文摘MoO<sub>3</sub> and 5% MoO<sub>3</sub>/ZnO were prepared by impregnation method using (NH<sub>4</sub>)<sub>6</sub>Mo<sub>7</sub>O<sub>24</sub>, 4H<sub>2</sub>O as precursor and ZnO as support. The prepared samples were characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM), infra red (FTIR) <span style="font-family:;" "="">and</span><span style="font-family:;" "=""> UV-Vis diffuse reflectance (DRS)</span><span> </span><span style="font-family:;" "="">spectroscopies and pho<span>to-electrochemistry. The XRD pattern showed that the MoO<sub>3</sub> powder treated at 700°C is a single-phase crystallizing in an orthorhombic structure with a direct optical transition </span></span><span style="font-family:;" "="">(</span><span style="font-family:;" "="">2.70 eV</span><span style="font-family:;" "="">)</span><span style="font-family:;" "="">. The hetero-junction 5% MoO<sub>3</sub>/ZnO</span><span style="font-family:;" "=""> was photo-electrochemically characterized to assess its feasibility for H<sub>2</sub> production under visible light. The capacitance potential (<i>C<sup>-</sup></i><sup>2</sup><i> f</i>(<i>E</i>)) characteristic of MoO<sub>3</sub> plotted in Na<sub>2</sub>SO<sub>4</sub>, (0.1 M) electrolyte indicates <i>n-</i>type conduction with a flat band potential of -</span><span style="font-family:;" "=""><span>0.54 V<i><sub>SCE</sub></i>. The photocatalytic activity was performed for the photoreduction of water to hydrogen under visible light illumination. The best performance occurs at pH ~ 7 with an evolved volume of 5.9 mL.</span></span>
