Nickel-based catalysts with hierarchical structure of pores derived from layered double hydroxides for the production of hydrogen from the steam reforming of ethanol

Reference Presenter Authors
(Institution)
Abstract
06-038 Celso Valentim Santilli Gonçalves, R.G.(Instituto de Quimica/UNESP); Possato, L.G.(Instituto de Quimica/UNESP); Martins, L.(Instituto de Química/UNESP); Pulcinelli, S.H.(Instituto de Química/UNESP); Santilli, C.V.(Instituto de Química/UNESP); The aggravation of greenhouse effect and the demand for clean energy sources to replace fossil fuels has stimulated the H2 production, especially by the ethanol steam reforming (ESR) catalytic reaction, but a series of limiting factors such as the sintering of the active phase and carbon deposition limits the application of traditional catalysts supported on alumina. Materials such as layered double hydroxides (LDH) are a class of inorganic compounds with promising characteristics for various catalytic applications, since the components of the lamellar structure can act both as support and as catalyst. Therefore, the objective of this work was the production of Ni(x)Al/Cl LDH with different Ni2+ contents (x = 0.1-0.5), presenting hierarchical structure of pores to improve their performance on ESR catalytic reaction. The materials synthesized via sol-gel route conjugated with the spinodal phase separation exhibited basal peaks assigned to lamellar structure of LDH intercalated with chloride. Until now we were able to put in evidence the key role of the molar ratio (x) on the control of the growth of LDH structure, the size and the volume of mesopores of materials showing elevated specific surface area. Thanks to in situ XRD measurements it was evidenced that the increase in thermal treatment temperature and/or change in atmosphere does not alter significantly the final diffraction pattern. However, the high dispersion of M2+ cations difficult the identification by XRD of the oxides formed upon the thermal treatment. From the results of catalytic activity in the ESR reaction  it was possible to conclude that the catalysts with x = 0.3 presents the higher efficiency for ESR since the sample with lower amount 0.1 of Ni presents lower ethanol conversion. Therefore, the Ni0.3Al sample is the one that produce the higher H2 amount and is the most stable at intermediate temperatures (500°C).