PNNL

Abstract

Promoters are ubiquitous in industrial heterogeneous catalysts. The wider roles of promoters in accelerating catalysis and/or controlling selectivity are, however, not well understood. A model system has been developed where a heterobimetallic active site comprising an active metal (Rh) and a promoter metal (Ga) are preassembled and delivered into a metal-organic framework (MOF) support. The Rh-Ga sites in the MOF selectively catalyze the hydrogenation of acyclic alkynes to E-alkenes, which is complementary to Lindlar’s catalyst, which generates only Z-alkenes. The role of the Ga in promoting this unusual selectivity is underscored by the lack of semi-hydrogenation selectivity when Ga is absent and only Rh is present in the active site. We acknowledge Dr. Camille Malonzo May (UMN), Dr. David Kaphan (Argonne), Dr. Tata Gopinath (UMN), and Dr. Zhanyong Li (NW) for experimental assistance, and Dr. Dale Pahls for preliminary theoretical calculations. This work was supported as part of the Inorganometallic Catalyst Design Center, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award No. DE-SC0012702. This research used resources of: (1) the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility; and, (2) the University of Minnesota Characterization Facility, which is supported by the NSF through the MRSEC, ERC, MRI, and NNIN programs. X-ray crystallographic data have been deposited in the Cambridge Crystallographic Data Centre database (CCDC 1842577 to 1842581).