Control of Ni/Ce1-xMxOy Catalyst Properties Via the Selection of Dopant M = Gd, La, Mg. Part 2. Catalytic Activity

To elucidate the role of support composition in autothermal reforming of ethanol (ATR of C2H5OH), a series of Ni catalysts (Ni content 2–15 wt.%) supported on different ceria-based oxides (Ce1-xGdxOy, Ce1-xLaxOy and Ce1-xMgxOy; x = 0.1–0.9) were prepared. The synthetized materials were tested in ATR of ethanol at 200–700 °C. It was established that supports themselves show catalytic activity in ATR of C2H5OH and provide 10–15% yield of H2 at 700 °C. Upon the increase of Ni content from 2 to 15 wt.% the temperature of 100% ethanol conversion decreases from 700 tо 300 °С, hydrogen yield increases from 25 to 60%, the inhibition of С2-С3 by-products formation, as well as the promotion of decomposition of acetaldehyde occur. The enhancement of catalyst performance in ATR of C2H5OH has been observed in the next series of supports: Ce1-xMgxOy < Ce1-xGdxOy < Ce1-xLaxOy and with a decrease of x to an optimal value that correlates with the improvement of Ni active component reducibility. At 600 °C on 10Ni/Ce0.8La0.2O1.9 catalyst the H2 yield of 50% was achieved at C2H5OH conversion of 100%. Stable and high performance of developed catalysts in ATR of C2H5OH indicates the promise of their use in the production of hydrogen

Effect of preparation mode on the properties of Mn-Na-W/ Sio₂ catalysts for oxidative coupling of methane:conventional methods vs. POSS nanotechnology

Using XPS, BET, XRD, TG-DTA, HRTEM-EDX, TPR and UV-Vis Diffuse Reflectance spectroscopic methods the electronic, redox and structural properties of Mn-Na-W/ SiO2 catalysts prepared by the incipient wetness impregnation method and mixture slurry method were studied in detail. Since POSS nanotechnology (POSS = polyhedral oligomeric silsesquioxanes) has attracted attention as tooling for synthesis of catalysts with novel properties and functionalities, we expanded this method for the preparation of Mn-Na-W/ SiO2 catalyst. The physicochemical and catalytic properties of Mn-Na-W/ SiO2 catalysts prepared by conventional methods and POSS nanotechnology were examined comparatively. In all studied Mn-Na-W/ SiO2 catalysts both individual oxides (MnOx, WO3) and bimetal oxide phases (Na2WO4, MnWO4) are found in addition to oxide particles of high dispersion. The UV-Vis Diffuse Reflectance indicates that Na+ cations facilitates stabilization of octahedrally coordinated Mn3+ Oh cations in the isolated state, while Mn3+ Oh promote the disordering of W6+ cations in the supported system. The Mn-Na-W/ SiO2 prepared using metal-POSS precursors marks out presence of unglobular SiO2 particles, higher dispersion of MnOx and MnWO4 particles and more easily reducible metal-oxide species. The catalysts prepared by incipient impregnation method and mixture slurry method have practically similar catalytic performance while the catalyst prepared by POSS nanotechnology method shows lower activity and selectivity. At 800−850 °C the increase of C2 hydrocarbons yield from 4 to 15% and the rise of molar ratio C2H4/C2H6 from 0.2 to 1 are observed when impregnation or mixture slurry method are used for catalyst preparation instead of POSS nanotechnology method.</p

Effect of preparation mode on the properties of Mn-Na-W/ Sio₂ catalysts for oxidative coupling of methane:conventional methods vs. POSS nanotechnology

Using XPS, BET, XRD, TG-DTA, HRTEM-EDX, TPR and UV-Vis Diffuse Reflectance spectroscopic methods the electronic, redox and structural properties of Mn-Na-W/ SiO2 catalysts prepared by the incipient wetness impregnation method and mixture slurry method were studied in detail. Since POSS nanotechnology (POSS = polyhedral oligomeric silsesquioxanes) has attracted attention as tooling for synthesis of catalysts with novel properties and functionalities, we expanded this method for the preparation of Mn-Na-W/ SiO2 catalyst. The physicochemical and catalytic properties of Mn-Na-W/ SiO2 catalysts prepared by conventional methods and POSS nanotechnology were examined comparatively. In all studied Mn-Na-W/ SiO2 catalysts both individual oxides (MnOx, WO3) and bimetal oxide phases (Na2WO4, MnWO4) are found in addition to oxide particles of high dispersion. The UV-Vis Diffuse Reflectance indicates that Na+ cations facilitates stabilization of octahedrally coordinated Mn3+ Oh cations in the isolated state, while Mn3+ Oh promote the disordering of W6+ cations in the supported system. The Mn-Na-W/ SiO2 prepared using metal-POSS precursors marks out presence of unglobular SiO2 particles, higher dispersion of MnOx and MnWO4 particles and more easily reducible metal-oxide species. The catalysts prepared by incipient impregnation method and mixture slurry method have practically similar catalytic performance while the catalyst prepared by POSS nanotechnology method shows lower activity and selectivity. At 800−850 °C the increase of C2 hydrocarbons yield from 4 to 15% and the rise of molar ratio C2H4/C2H6 from 0.2 to 1 are observed when impregnation or mixture slurry method are used for catalyst preparation instead of POSS nanotechnology method.</p

Effect of preparation mode on the properties of Mn-Na-W/ Sio2 catalysts for oxidative coupling of methane: conventional methods vs. POSS nanotechnology

Using XPS, BET, XRD, TG-DTA, HRTEM-EDX, TPR and UV-Vis Diffuse Reflectance spectroscopic methods the electronic, redox and structural properties of Mn-Na-W/ SiO2 catalysts prepared by the incipient wetness impregnation method and mixture slurry method were studied in detail. Since POSS nanotechnology (POSS = polyhedral oligomeric silsesquioxanes) has attracted attention as tooling for synthesis of catalysts with novel properties and functionalities, we expanded this method for the preparation of Mn-Na-W/ SiO2 catalyst. The physicochemical and catalytic properties of Mn-Na-W/ SiO2 catalysts prepared by conventional methods and POSS nanotechnology were examined comparatively. In all studied Mn-Na-W/ SiO2 catalysts both individual oxides (MnOx, WO3) and bimetal oxide phases (Na2WO4, MnWO4) are found in addition to oxide particles of high dispersion. The UV-Vis Diffuse Reflectance indicates that Na+ cations facilitates stabilization of octahedrally coordinated Mn3+ Oh cations in the isolated state, while Mn3+ Oh promote the disordering of W6+ cations in the supported system. The Mn-Na-W/ SiO2 prepared using metal-POSS precursors marks out presence of unglobular SiO2 particles, higher dispersion of MnOx and MnWO4 particles and more easily reducible metal-oxide species. The catalysts prepared by incipient impregnation method and mixture slurry method have practically similar catalytic performance while the catalyst prepared by POSS nanotechnology method shows lower activity and selectivity. At 800−850 °C the increase of C2 hydrocarbons yield from 4 to 15% and the rise of molar ratio C2H4/C2H6 from 0.2 to 1 are observed when impregnation or mixture slurry method are used for catalyst preparation instead of POSS nanotechnology method