Support Modification of Supported Nickel Catalysts for Hydrogen Production by Auto-thermal Reforming of Ethanol

Abstract

Recent progress on support modification of supported nickel catalysts for hydrogen production by autothermal reforming of ethanol was reported in this review. Nickel catalysts supported on various materials, including metal oxides and metal oxide-stabilized mesoporous zirconias, were prepared by an incipient wetness impregnation method for use in hydrogen production by auto-thermal reforming of ethanol. Various experimental measurements such as NH 3 -TPD (temperature-programmed desorption) and TPR (temperature-programmed reduction) were carried out to elucidate the different catalytic performance of supported nickel catalysts. It was revealed that acid property of supporting materials served as one of the important factors determining the catalytic performance. Hydrogen yield over nickel catalysts supported on metal oxides showed a volcano-shaped curve with respect to acidity of the supports. Among the catalysts tested, Ni/ZrO 2 catalyst with an intermediate acidity exhibited a superior catalytic performance. It was also observed that reducibility of nickel catalysts supported on metal oxide-stabilized mesoporous zirconias played a key role in determining the catalytic performance in the auto-thermal reforming of ethanol for hydrogen production. Hydrogen yield over nickel catalysts supported on metal oxide-stabilized zirconias increased with increasing reducibility of the catalysts (with decreasing TPR peak temperature of the catalysts).

Optimizing barium promoter for nickel catalyst supported on yttria‐stabilized zirconia in dry reforming of methane

“…In recent years, ZrO 2 has been tested in methane‐reforming reactions because its high ionic conductivity and thermal stability are very useful for these reactions. The tetragonal phase of ZrO 2 is stabilized by incorporating cations, like, Mg +2 , Ca +2 , Sr +2 , La +3 , C e+4 , and Y +3 , that form solid solutions resulting in oxygen vacancies in the zirconia lattice 30 . These oxygen vacancies have a very important role in gasifying carbon deposits and in the activation of CO 2 molecules, as has been demonstrated in previous reports on the reforming reactions of methane and ethanol 31–33 .…”

“…The tetragonal phase of ZrO 2 is stabilized by incorporating cations, like, Mg +2 , Ca +2 , Sr +2 , La +3 , C e+4 , and Y +3 , that form solid solutions resulting in oxygen vacancies in the zirconia lattice. 30 These oxygen vacancies have a very important role in gasifying carbon deposits and in the activation of CO 2 molecules, as has been demonstrated in previous reports on the reforming reactions of methane and ethanol. [31][32][33] Yttrium oxide is a white solid with a high melting point.…”

Reações de reforma de biogás sobre catalisadores de NiO-MgO-ZrO2 e NiO-Y2O3-ZrO2

“…área do pico α2 nas amostras 10Ni20MZ, 20Ni20MZ e 40Ni20MZ aumentou com o aumento do teor de níquel em todos os casos, e isto sugere que o aumento do teor de níquel favoreceu a quantidade de espécies de NiO fortemente interagidas com o suporte catalítico e que estas espécies encontram-se sempre em ambientes químicos muito similares. Além disso, ZrO 2 parecem estar envolvidas no processo de redução das espécies de NiO na superfície, como encontrado em outro trabalhosYOUN et al 2010) para soluções solidas baseadas em zircônia (MOx-ZrO 2 ; onde M=Ca, Mg ou Y).Segundo a literatura as vacâncias de oxigênio podem interagir fortemente com os átomos de oxigênio terminais dos clusters de NiO e enfraquecer as ligações Ni-O, além de poderem polarizar as moléculas de H 2 (H -…H + ) para reagir mais facilmente com os oxigênios terminais dos clusters de NiO. Desta forma, é possível que as vacâncias de oxigênios tenham facilitado a redução das espécies de NiO superficiais, pois os picos α deslocaram-se para menores temperaturas em maiores teores de níquel.…”