Nano- and micro-powder of zirconia and ceria-supported cobalt catalysts for the steam reforming of bio-ethanol

The usefulness of nano- and micro-powders of ceria and zirconia as a support of the cobalt-based catalyst as well as additional modification of zirconia-supported cobalt catalysts with cerium for the production of hydrogen in the steam reforming of bio-ethanol (SRE) for fuel cell applications was studied. It was found that mainly different structural features of the nano- and micro-powder of ceria- and zirconia-supported cobalt catalysts are higher cobalt surface area and much smaller average sizes of cobalt crystallites for the catalysts with high-dispersed support. Similarly, the presence of high-dispersed ceria introduced to the zirconia-supported catalysts simultaneously with the deposition of cobalt increases their total and active surface area as well as decreases the size of cobalt crystallites, regardless of the initial dispersion of zirconia support. The results of the temperature-programmed reduction and the temperature-programmed desorption of hydrogen showed that small crystallites of the cobalt phase strongly interact with high-dispersed ceria. Ceria has a great influence on the effects of the SRE. For the nano-powder ceria-supported cobalt catalyst and for the nano-powder zirconia-supported catalysts with the cobalt–ceria active phase the yield of hydrogen formed from one molecule of ethanol supplied to the SRE process was the highest; even at the relatively low temperature of 420 °C it is close to 5.5 mol H2/mol EtOH. At the same time there were achieved: complete conversion of ethanol, very close to that of water and 92%, 81–84%, 5–6% selectivities to hydrogen, carbon dioxide and carbon monoxide, respectively.