Benzyl alcohol is a platform molecule for production of valuable chemicals, and benzyl alcohol can be used as a probe molecule of aromatic oxygenates derived from biomass deconstruction. Benzyl alcohol can undergo reactions to a variety of products, and achieving control over selectivity is a challenge. One promising method for enhancing the selectivity to hydrodeoxygenation (HDO) over decarbonylation (DC) is to manipulate the ensembles of available surface sites, and thus restrict the adsorbed conformations of reactive intermediates. Thiol self-assembled monolayers provide a platform to control the surface coverage of site-blocking species on Pd. Catalysts coated with a sterically bulky thiol, adamantanethiol, were found to improve both overall activity and hydrodeoxygenation selectivity.  Denser octadecanethiol coatings almost completely shut down the DC pathway (with a 98% HDO selectivity at full conversion), but at the expense of activity.  Use of mixed monolayers with variable fractions of adamantanethiol and 1-octadecanethiol (C18) was found to enable tuning of the activity and selectivity.  Infrared spectroscopy studies showed that selectivity trends for the mixed monolayers strongly correlated with the availability of Pd terrace sites.  Selective occupation of those sites by C18 thiols were found to shut down DC while still allowing HDO.<br/>

Control of Pd catalyst selectivity with mixed thiolate monolayer

251st National Meeting (2016)

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