title: Silver as acrolein hydrogenation catalyst: intricate effects of catalyst nature and reactant partial pressures.
abstract: The hydrogenation of acrolein over pure and supported silver has been investigated with a focus on the influence of catalyst structure and reaction pressure (mbar to 20 bar range) on activity and selectivity. An onset of formation of allyl alcohol beyond 100 mbar reaction pressure (at 250 degrees C) is ascribed to a change in adsorption geometry upon increasing coverage. Smaller silver particles (in the nanometer range), the proximity of a reducible oxide component as well as high pressure lead to enhanced allyl alcohol formation; the selectivity to the other main product propionaldehyde is reduced. The silver dispersion changed depending on the reaction pressure. Moreover, the presence of oxygen, most likely as subsurface oxygen, and the presence of defects are of paramount importance for the catalytic behaviour. The considerable changes of the silver catalysts under reaction conditions and the pressure dependence call for in situ measurements to establish true structure-activity/selectivity relationships for this system.
authors.affiliation: Ernst-Berl-Institute of Technical and Macromolecular Chemistry, Darmstadt University of Technology, Petersenstr. 20, D-64287, Darmstadt, Germany. claus@ct.chemie.tu-darmstadt.de
authors.forename: Michael
authors.initials: M
authors.lastname: Bron
authors.forename: Detre
authors.initials: D
authors.lastname: Teschner
authors.forename: Axel
authors.initials: A
authors.lastname: Knop-Gericke
authors.forename: Friederike C
authors.initials: FC
authors.lastname: Jentoft
authors.forename: Jutta
authors.initials: J
authors.lastname: Kröhnert
authors.forename: Jens
authors.initials: J
authors.lastname: Hohmeyer
authors.forename: Claudia
authors.initials: C
authors.lastname: Volckmar
authors.forename: Bernd
authors.initials: B
authors.lastname: Steinhauer
authors.forename: Robert
authors.initials: R
authors.lastname: Schlögl
authors.forename: Peter
authors.initials: P
authors.lastname: Claus