Acetol adsorption and reactivity on metal single crystals and oxide surfaces: from UHV to ambient pressure conditions

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

Deauville

Conferencia; Operando V - 5th International Conference on Operando Spectroscopy; 2015

Laboratorie catalyse et Spectrochimie (LCS)

Employing renewable sources from vegetal oil to produce chemicals and energy appears as a promising technological approach to solve human dependence on fuels from fossils. When obtaining biodiesel from biomass conversion, about 10 % of the reaction by-product is glycerol. Thus, it is accepted that glycerol will play a very important role in bio-refineries future and it is, mandatory to search for new processes to upgrade this by-product into more valuable chemicals. Glycerol is a highly functionalized compound which could be used as a starting material for a great variety of chemical products of industrial interest. It can be upgraded to produce propylene glycols by dehydration followed by hydrogenation in the presence of excess hydrogen. It is believed that the process for obtaining 1,2-PG from glycerol goes through two steps, first one being dehydration to acetol followed by its hydrogenation to the final product, and it has been proposed that the hydrogenation of the carbonyl bond is the rate limiting step. Even though commonly precious metals are used in hydrogenation reactions, it was found that some oxides perform also quite well, one of them being ceria being highly selective for the hydrogenation of acetylene to ethylene. For this specific example, it has been proposed that the main role of the oxide is to keep the surface CHx intermediates spatially well distributed to avoid oligomerization and decomposition, at the expense of a somehow higher activation barrier for the activation of H2 molecule, as compared to metals. It has also been exalted the importance of surface reduction state and hydroxyls as the species performing the hydrogenation.