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Abstract: The manganese-promoted nickel-based catalysts were prepared via wet-incipient impregnation, and tested in auto-thermal reforming (ATR) of ethanol for hydrogen production. The Ni/Al2O3 catalyst, in which Ni existed as NiAl2O4, produced a low H2 yield near 1.85 mol H2/mol ethanol. The Ni–Mn/Al2O3 catalyst showed a better performance in a 30-h test: the conversion of ethanol reached 100%, and a higher H2 yield remained stable near 3.1–3.2 mol H2/mol ethanol. This improvement can be attributed to the promotion of Mn: With Mn, the ilmenite-type NiMnO3 was formed, the reducibility of Ni–Mn/Al2O3 was thus improved, and there were more Ni0 over the surface of catalysts. Moreover, these Ni0 species were stable in the ATR test, as indicated by XRD and XPS. [Copyright &y& Elsevier]

Abstract: Iron-doped LaNiO3 catalysts with a perovskite structure were prepared via self-combustion and tested in auto-thermal reforming (ATR) of ethanol. Characterizations of temperature-programmed surface reaction (TPSR), X-ray diffraction (XRD), physical N2 adsorption, and temperature-programmed reduction (TPR) were carried out. The results indicate that LaNiO3 perovskite structure was successfully formed via self-combustion. With iron-doping in LaNiO3, the perovskite structure still remains, in the form of solid solution La(Ni, Fe)O3, where iron is reducible and the nickel-iron alloy forms after the reduction. In addition, the surface area of the iron-doped samples increased. The TPSR results indicate that with iron-doping, the activity for adsorbed ethanol species is modified and a higher activity for methane transformation is achieved. As a result, an LNF10 sample (LaNi0.90Fe0.10O3) with both nickel and nickel-iron alloy shows better performance in ATR: the ethanol conversion is near 100%, while the selectivity to by-products, such as ethylene, ethane, acetaldehyde and methane, is decreased, and CO2 is the main carbon-containing product; consequently, a hydrogen yield near 3.0 mol H2/mol EtOH is obtained and remains stable in the 30-h test of ATR. [Copyright &y& Elsevier]

Abstract: Ni-based layered double hydroxide (LDH)-derived catalysts with Ni–Mg–Al–Fe–O were prepared via co-precipitation, and were tested in auto-thermal reforming (ATR) of ethanol for hydrogen production. The Ni0.35Mg2.65AlO4.5±δ catalyst showed poor stability and a low H2 yield, near 2.51mol H2/mol EtOH. The tetra-component catalyst of Ni0.35Mg2.65Al0.50Fe0.50O4.5±δ, in which the trivalent component consists of both aluminum and iron, showed a promising performance in ATR of ethanol: not only did the H2 yield remain stable near 3.7mol H2/mol EtOH during the 30-h test, but the CH4 reforming activity also improved and C2H4 disappeared in product gases. These improvements can be attributed to the synergic effect by both iron and nickel on the structural and electronic properties: the BET surface area was increased, the reducibility of the Ni metal and its resistance to oxidation in ATR were improved, and the acidity was constrained as well. [ABSTRACT FROM AUTHOR]

Abstract: Layered double hydroxide-derived Co0.3 Mg2.7Al1-xFexO4.5±δ catalysts were prepared via co-precipitation and tested in auto-thermal reforming of ethanol for hydrogen production. The layered double hydroxide precursors show typical hydrotalcite-like structures and form a similar MgO cubic structure after calcination. Compared with iron-free catalyst, the Co0.3 Mg2.7Al0.9Fe0.1O4.5±δ performs better in auto-thermal reforming of ethanol: the conversion of ethanol remains near 100%, and the H2 yield stays above 3.2mol H2/mol EtOH throughout the 30-h test. The improved performance can be attributed to the stable Cobalt species within Mg(Al)O matrix, the higher surface area, and the synergic effects of Co and Fe. [ABSTRACT FROM AUTHOR]

Abstract: Auto-thermal reforming (ATR) of bio-ethanol is a promising process for hydrogen production, which can lead to the possibility of directly using low concentration ethanol from fermentation plants without going through the energy-consuming distillation and dehydration processes, saving both energy and cost. Co-based catalysts are active for hydrogen production in ATR, where the hydrogen yield and stability are important factors to be considered. To address the concerns of selectivity and deactivation, iron was introduced into Co-based catalysts via wet-impregnation. The catalysts were characterized with TPR, XRD, XPS, and Raman spectra, and tested in ATR of ethanol. The XPS, XRD, and TPR results show that with iron-promotion, more Co metal is obtained over the catalyst surface, which remains stable during the oxidative atmosphere of ATR. Meanwhile, iron promotes the ethanol dehydrogenation pathway in ATR reactions. This synergic effect contributes to the higher activity and stability of Co-based catalysts in the ATR process: A higher hydrogen yield remains around 3.13mol H2/mol EtOH at 600°C and stays stable in a 30-h test. [Copyright &y& Elsevier]

Abstract: Ni-Mg-Mn-Fe-O catalysts were prepared via co-precipitation through layered double hydroxide (LDH) precursors and tested for hydrogen production from ethanol by auto-thermal reforming (ATR). With Mn and Fe in the precursor of the Ni0.35 Mg2.65Mn0.5Fe0.5O4.5±δ catalyst, an LDH structure formed via co-precipitation, and after calcination, a cubic MgO skeleton formed with spinel phases of NiMn2O4 and NiFe2O4. The H2 yield reached 4.0mol-H2/mol-EtOH and remained stable in a 30-h ATR test, which can be attributed to the improvement of reduction behavior and stability of Ni0 species. [Copyright &y& Elsevier]