Open AccessElectrolysis Can Be Used to Resolve Hydrogenation Pathways at Palladium Surfaces in a Membrane Reactor
Author(s) -
Aoxue Huang,
Yang Cao,
Roxanna S. Delima,
Tengxiao Ji,
Ryan P. Jansonius,
Noah J. J. Johnson,
C.E.L. Hunt,
Jingfu He,
Aiko Kurimoto,
Zishuai Zhang,
Curtis P. Berlinguette
Publication year - 2021
Publication title -
jacs au
Language(s) - English
Resource type - Journals
ISSN - 2691-3704
DOI - 10.1021/jacsau.0c00051
Subject(s) - palladium , catalysis , chemistry , electrolysis , hydride , hydrogen , adsorption , membrane , membrane reactor , substrate (aquarium) , metal , palladium hydride , electrolysis of water , inorganic chemistry , chemical engineering , reaction mechanism , photochemistry , organic chemistry , electrode , biochemistry , engineering , electrolyte , oceanography , geology
For common hydrogenation chemistries that occur at high temperatures (where H 2 is adsorbed and activated at the same surface which the substrate must also adsorb for reaction), there is often little consensus on how the reactions (e.g., hydro(deoxy)genation) actually occur. We demonstrate here that an electrocatalytic palladium membrane reactor (ePMR) can be used to study hydrogenation reaction mechanisms at ambient temperatures, where the catalyst does not necessarily undergo structural reorganization. The ePMR uses electrolysis and a hydrogen-selective palladium membrane to deliver reactive hydrogen to a catalyst surface in an adjacent compartment for reaction with an organic substrate. This process forms the requisite metal-hydride surface for hydrogenation chemistry, but at ambient temperature and pressure, and without a H 2 source. We demonstrate the utility of this analytical tool by studying the hydrogenation of benzaldehyde at palladium nanocubes with dimensions of 13-24 nm. This experimental design enabled us to resolve that the alcohol product forms at the facial sites, whereas the hydrodeoxygenation step occurs at edge sites. These observations enabled us to develop the first site-specific definition of how a carbonyl species undergoes hydro(deoxy)genation.