Enhancement of Alkyne Semi-Hydrogenation Selectivity by Electronic Modification of Platinum
Zhenshu Wang, Aaron Garg, Linxi Wang, Haoran He, Anish Dasgupta, Daniela Zanchet, Michael J. Janik, Robert M. Rioux, Yuriy Román‐Leshkov
Abstract
We demonstrate that atomically thin Pt shells deposited on transition metal carbide or nitride cores induce up to a 4-fold enhancement in C2H4 selectivity during the partial hydrogenation of acetylene compared with commercial carbon-supported Pt (Ptcomm) nanoparticles. While Pt typically catalyzes the complete hydrogenation of alkynes to alkanes, a catalyst comprising a nominal one monolayer (ML) Pt shell on titanium tungsten nitride cores (Pt/TiWN) is capable of net C2H4 generation under industrial front-end reaction conditions featuring a large excess of C2H4 and H2. Microcalorimetry measurements are consistent with a change in the Pt electronic structure that decreases C2H4 binding strength, thus increasing partial hydrogenation selectivity. Density functional theory (DFT) calculations and X-ray absorption near edge structure (XANES) both indicate broadening of the Pt d-band and concomitant down-shifting of the d-band center. The ability to control shell coverage and core composition opens up extensive opportunities to modulate the electronic and catalytic properties of noble metal-based catalysts.