Enhanced catalytic performance of La2O3 promoted Co/CeO2 and Ni/CeO2 catalysts for effective hydrogen production by ethanol steam reforming

Abstract

Cobaltand nickel-based catalysts were synthesized by the co-impregnation method of the ceria support with aqueous solution of the active phase and promoter precursors and evaluated in steam reforming of ethanol (SRE) reaction. The stability of Co/CeO2 and Ni/CeO2 catalysts was effectively improved by the addition of ∼2 wt% of La2O3 promoter as the carbon deposition rate was reduced which results from an increase in an active phase dispersion and from strengthening of a metal-support interactions. Whereas the La2O3 promoter influences on the rate of carbon deposit formation, its type and a degree of graphitization depends on the metal active phase. Highly ordered carbon deposit encapsulating the active sites was mainly formed on the surface of cobalt-based catalysts. Whereas SRE reaction over nickel-based catalysts leads to formation of long filaments carbon with a lower degree graphitization. Temperature of 460 °C was sufficient to obtain complete ethanol conversion for 21 h of SRE process over Ni-0.1La/CeO2 sample and to maintain high selectivity to H2 (88%) and CO2 (68%) over this time. For Co-0.1La/CeO2 catalyst, the higher temperature of 500 °C was required to sustain its stable operation but selectivity to H2 and CO2 was even higher, 94% and 88%, respectively.