Rhodium Encapsulated within Silicalite‐1 Zeolite as Highly Efficient Catalyst for Nitrous Oxide Decomposition: From Single Atoms to Nanoclusters and Nanoparticles

Abstract

The size of metal species plays a pivotal role in governing catalytic performance of supported metal catalysts. In this work, a series of Rh encapsulated within silicalite-1 catalysts with different sizes were prepared by one-pot hydrothermal method and employed to catalyze the decomposition of N 2 O. Detailed structure determinations by HAADF-STEM, XPS and CO-DRIFTS demonstrate that subtle modulation of the encapsulated Rh species were achieved easily from single-atom to nanoclusters and nanoparticles by controlling the loading and reduction conditions of Rh. The turnover frequency (TOF) of N 2 O decomposition showed a typical volcano-type dependence on Rh size. Kinetic studies revealed that this structure-sensitive catalysis was related to the difference in N 2 O and O 2 adsorption/desorption for various Rh species. Furthermore, a Rh@S-1 catalyst with a proper Rh size (ca. 1.6 nm) was identified as the best-performing catalyst with a maximum TOF (ca. 95 h À 1 ), showing much superior activity than other reported Rhbased catalysts.

Encapsulation of Noble Metal Nanoclusters into Zeolites for Highly Efficient Catalytic Hydrogenation of Nitroaromatics

“…Pd@ZSM-5-SGP (Figure d, e) and Pd@SSZ-13-SGP (Figure g, h) are irregular spheres with dimensions of 200–500 nm; Pd@NaA-SGP (Figure j, k) and Pd@Beta-SGP (Figure m, n) have irregular crystals with dimensions of 30–100 nm. The ultrasmall diameters (∼ 2.0 nm) and narrow size distributions of Pd nanoparticles in these zeolites suggest that this synthesis strategy has the same confinement effect as the traditional hydrothermal method, in which zeolite matrices effectively inhibit the accumulation of metal nanoparticles. ,− …”

Metal Sites in Zeolites: Synthesis, Characterization, and Catalysis

“…C s -corrected STEM and EXAFS analyses revealed that single Rh atoms were confined within sinusoidal 5-MRs and stabilized by framework oxygen atoms of the zeolite (Figure c–e). Considering the significance of industrial propane dehydrogenation (PDH) process that can greatly meet the increasing global demand for propylene, ammonia, and EDA ligands stabilization method were also applied to the widely used Pt-based catalyst system toward solving their fast deactivation, severe sintering, and poor propylene selectivity problems. − For instance, Corma and co-workers successfully synthesized K-PtSn@ MFI catalysts via one-pot synthesis containing metal–ethylenediamine complexes in the synthesis gel . A combination of high-resolution HAADF-STEM and integrated differential phase-contrast (iDPC) imaging techniques indicated that most subnanometric bimetallic PtSn clusters were preferentially located in the sinusoidal channels of purely siliceous MFI -type zeolite, whereas a very small amount of clusters were found in the straight channels or at the intersectional voids.…”

Metal@hollow carbon sphere nanoreactors for sustainable biomass and CO2valorization

“…Notably, the single-atom catalysts can reduce the cost of catalysis via maximizing the efficiency of atom utilization, offering more active sites via adjusting the geometry and electronic configuration. 32,69 Zhang et al 70 encapsulated Au in amino-modified silica spheres, which showed excellent catalytic behavior and durability in high temperature carbon monoxide oxidation. Furthermore, the size of AuNPs was reduced from 2.3 nm to 1.5 nm by varying the number of metal precursors and showed high catalytic performance in catalytic oxidation reactions, reflecting the inherent size effect of Au nanoparticles on inert carriers.…”