Maximizing noble metal utilization in solid catalysts by control of nanoparticle location

Abstract

Maximizing the utilization of noble metals is crucial for applications such as catalysis. We found that the minimum loading of platinum for optimal performance in the hydroconversion of n -alkanes for industrially relevant bifunctional catalysts could be reduced by a factor of 10 or more through the rational arranging of functional sites at the nanoscale. Intentionally depositing traces of platinum nanoparticles on the alumina binder or the outer surface of zeolite crystals, instead of inside the zeolite crystals, enhanced isomer selectivity without compromising activity. Separation between platinum and zeolite acid sites preserved the metal and acid functions by limiting micropore blockage by metal clusters and enhancing access to metal sites. Reduced platinum nanoparticles were more active than platinum single atoms strongly bonded to the alumina binder.

Detecting Cage Crossing and Filling Clusters of Magnesium and Carbon Atoms in Zeolite SSZ-13 with Atom Probe Tomography

“…Additionally, the synthesis method, e.g., direct inclusion of magnesium in the synthesis gel or ion exchange, could also have a large effect on the final magnesium distribution as well on the bulk-nanoscale coking behavior. The distribution of Mg (and other metals) could have a drastic effect on the final catalytic performance, which would require further comparison studies between samples with different metal distributions …”

“…The distribution of Mg (and other metals) could have a drastic effect on the final catalytic performance, which would require further comparison studies between samples with different metal distributions. 52 ■ CONCLUSIONS Zeolite SSZ-13 was successfully modified with magnesium via an impregnation preparation step. With atom probe tomography (APT), it was discovered that magnesium is heterogeneously distributed through the sample and tends to aggregate on the nanoscale, unlike the framework elements of the zeolite.…”

One-pot synthesis of cyclohexylphenol via isopropyl alcohol-assisted phenol conversion using the tandem system RANEY® Nickel plus hierarchical Beta zeolite

“…This fact has been recently proved in the hydroconversion of n-alkanes towards branched hydrocarbons over Pt/HZSM-22/Al 2 O 3 catalysts. 38 In a previous study, we reported that the tandem catalytic system RANEY® Ni plus nanocrystalline or hierarchical ZSM-5 39 unveiled alkylation reactions in the phenol conversion alongside the expected reactions (ring saturation, dehydrogenation and dehydration). This alkylation shifted the selectivity towards bulky alkylphenolic products, cresols and cyclo-hexylphenols being the main ones obtained (36% and 17% selectivity respectively over RANEY® Nickel plus hierarchical ZSM-5 at 175 °C).…”

“…This fact has been recently proved in the hydroconversion of n -alkanes towards branched hydrocarbons over Pt/HZSM-22/Al 2 O 3 catalysts. 38…”

A novel geo-photocatalyst, an iron-containing layered clay mineral, for photocatalytic H2 evolution from water

“…The photocatalytic activity was improved further by the hybridization of Pt nanoparticles as reported for other semiconductor photocatalysts. 5,32 The intercalation of [Pt(NH 3 ) 4 ] 2+ as the Pt precursor to Fe-clay and subsequent photoreduction were performed leading to the deposition of Pt nanoparticles on Fe-clay during the photocatalytic reaction. Although the preparation of Pt nanoparticles on clay minerals has been reported by chemical/thermal reduction (Table S5, ESI †), photoreduction has not been used so far.…”