Bimetallic nanoparticle encapsulation in microporous zeolite crystals is a promising route for producing catalysts with unprecedented reaction selectivities. Herein, a novel synthetic approach was developed to produce PtZn nanoclusters encapsulated inside zeolite micropores by introducing Pt cations into a zincosilicate framework via ion exchange, and subsequent controlled demetallation and alloying with framework Zn. The resulting zeolites featured nanoclusters with sizes of approximately 1 nm, having an interatomic structure corresponding to a PtZn alloy as confirmed by pair distribution function (PDF) analysis. These materials featured simultaneous shape and substrate specificity demonstrated by the selective production of p-chloroaniline from the competitive hydrogenation of p-chloronitrobenzene and 1,3-dimethyl-5-nitrobenzene.

SnO 2 -Fe 2 O 3 nanopowders prepared by the polymeric precursor method were studied by combined conventional and high-resolution techniques. The powders treated at 500°C were analyzed by EDS local probe associated with HRTEM to directly detect surface segregation of Fe ions onto SnO 2 nanoparticles over a broad range of concentrations. The segregation of these ions controls the system microstructure by changing the surface energies and acting as nucleation sites for the formation of a Fe oxide phase (magnetite) at high Fe concentrations. A technologically interesting core-shell-type

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.

The insertion of copper into the gold lattice forming gold− copper (AuCu) nanoalloys enhances the gold catalytic performance in reactions such as CO oxidation. Here, we compared the catalytic performance of 6 nm AuCu nanoparticles (NPs) supported on SiO 2 (AuCu_SiO 2 ), a nonreducible oxide, and CeO 2 (AuCu_CeO 2 ), a reducible one, under preferential oxidation of CO (CO-PROX). Under reaction conditions, the support nature impacted on the stabilization of different species on the catalyst surface. The AuCu_CeO 2 was both more active and more stable, which was associated with the ability of CeO 2 to stabilize the AuCu alloy phase under reaction conditions.