Synthesis and characterization of nickel-based mixed oxides for ethanol steam reforming

Identifier:  TDX:2405

Handle: https://hdl.handle.net/20.500.11797/TDX2405

Authors:  Bolshak, Evgeny

Abstract:
Nickel-iron-aluminum mixed oxides derived from hydrotalcite-like precursors have been evaluated in the steam reforming of ethanol for hydrogen production. Several different parameters have been studied: the influence of the nickel-to-iron ratio (from 3 to 0.5), the calcination temperature of the hydrotalcite precursor (773K and 1073K), the effect of reaction temperature (400°C, 500°C and 600°C) and amount of aluminium in Ni-Fe-Al system with common formula Ni3Al1-xFex. It has been found that a higher amount of iron (only till Ni/Fe=1 ratio) positively affects both activity and selectivity due to a better dispersion of metallic nickel and lower carbon deposition. Lower calcination temperature induces the formation of a well-dispersed nickel-iron mixed oxide, while higher calcination temperature lead to spinel crystallization. The latter exhibits a decreased activity and fast deactivation. Compared to pure binary systems (Ni3Al and Ni3Fe), the ternary systems showed the best performance in ethanol reforming, leading to a high and stable hydrogen selectivity of up to ca. 70% in 100 h-reaction tests.