Deactivation of Ceria Supported Palladium through Câ•fiC Scission during Transfer Hydrogenation of Phenol with Alcohols

The stability of palladium supported on ceria (Pd/CeO2) was studied during liquid flow transfer hydrogenation using primary and secondary alcohols as hydrogen donors. For primary alcohols, the ceria support was reduced to cerium hydroxy carbonate within 14 h and was a contributing factor toward catalyst deactivation. For secondary alcohols, cerium hydroxy carbonate was not observed during the same time period and the catalyst was stable upon prolonged reaction. Regeneration through oxidation/reduction does not restore initial activity likely due to irreversible catalyst restructuring. A deactivation mechanism involving C–C scission of acyl and carboxylate intermediates is proposed Disciplines Chemistry Comments This is an article from Nelson, Nicholas C., J. Sebastián Manzano, and Igor I. Slowing. "Deactivation of Ceria Supported Palladium through C–C Scission during Transfer Hydrogenation of Phenol with Alcohols." The Journal of Physical Chemistry C 120, no. 49 (2016): 28067-28073. doi: 10.1021/acs.jpcc.6b09828. Posted with permission. This article is available at Iowa State University Digital Repository: http://lib.dr.iastate.edu/chem_pubs/997 Deactivation of Ceria Supported Palladium through C−C Scission during Transfer Hydrogenation of Phenol with Alcohols Published as part of The Journal of Physical Chemistry virtual special issue “Mark S. Gordon Festschrift”. Nicholas C. Nelson,†,‡ J. Sebastiań Manzano,†,‡ and Igor I. Slowing*,†,‡ †U.S. Department of Energy Ames Laboratory, Ames, Iowa 50011, United States ‡Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States *S Supporting Information ABSTRACT: The stability of palladium supported on ceria (Pd/CeO2) was studied during liquid flow transfer hydrogenation using primary and secondary alcohols as hydrogen donors. For primary alcohols, the ceria support was reduced to cerium hydroxy carbonate within 14 h and was a contributing factor toward catalyst deactivation. For secondary alcohols, cerium hydroxy carbonate was not observed during the same time period and the catalyst was stable upon prolonged reaction. Regeneration through oxidation/reduction does not restore initial activity likely due to irreversible catalyst restructuring. A deactivation mechanism involving C−C scission of acyl and carboxylate intermediates is proposed. The stability of palladium supported on ceria (Pd/CeO2) was studied during liquid flow transfer hydrogenation using primary and secondary alcohols as hydrogen donors. For primary alcohols, the ceria support was reduced to cerium hydroxy carbonate within 14 h and was a contributing factor toward catalyst deactivation. For secondary alcohols, cerium hydroxy carbonate was not observed during the same time period and the catalyst was stable upon prolonged reaction. Regeneration through oxidation/reduction does not restore initial activity likely due to irreversible catalyst restructuring. A deactivation mechanism involving C−C scission of acyl and carboxylate intermediates is proposed.