Acetol adsorption and reactivity on metal single crystals and oxide films: from UHV conditions to mTorr range

FREUND, HANS-JOACHIM; KARSLIOGLU, OSMAN; BLUHM, HENDRIK; STERRER, MARTIN; CALAZA, FLORENCIA C.

New Orleans, LA

Conferencia; 255th ACS National Meeting, New Orleans, LA; 2018

AMERICAN CHEMICAL SOCIETY

Using renewable materials of vegetal origin seems a promising technology to solve human dependence on fossil fuels, developing new concepts as biorefineries. During biodiesel production from biomass conversion, about10% of by-product is glycerol, in quantities higher than demand, therefore becoming waste and providing a good material to investigate possible routes for upgrading to higher value compounds. One example is the production of C3- glycols by dehydration of glycerol to acetol followed by hydrogenation of the latter to obtain diols. It is well known that precious metals are catalytic hydrogenators by excellence, but recently some oxides have been found to perform quite well for hydrogenation reactions, CeO2 showing high selectivity for the semi-hydrogenation of C2H2 to C2H4. It has been proposed that the main role of the oxide is to keep CHx surface intermediates especially well distributed to avoid their oligomerization, at the expense of a high activation barrier for H2 when compared to the reaction on metalsurfaces.In the present work we studied the adsorption of acetol on Pd(111) and Ru(0001) crystals, and CeO2(111) films, which represent our model catalytic surfaces, to further elucidate adsorption and reaction pathways. Combining surface analytical techniques which can be used in a broad range of conditions, from UHV to gas pressures close to ambient (mTorr range) we are able to observe the chemical state of the surface (by AP-XPS and NEXAFS) and the vibrational features of adsorbed species (by PEM-IRAS). We claim the different species on the metallic surfaces, are stabilized co-adsorbed carbon or oxygen atoms and for the case of CeO2, we not only studied the different species adsorbed on reduced and stoichiometric ceria but also propose some new mechanism of hydrogenation reaction of acetol based on the interaction of H2 with this oxide.