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Intermetallic nanoparticles (NPs) possess significant potentials for catalytic applications, yet their production presents challenges as achieving the disorder-to-order transition during the atom ordering process involves overcoming a kinetic energy barrier. Here, we demonstrate a robust approach utilizing atomic gas-migration for the in-situ synthesis of stable and homogeneous intermetallic alloys for propane dehydrogenation (PDH). This approach relies on the physical mixture of two separately supported metal species in one reactor. The synthesized platinum-zinc intermetallic catalysts demonstrate exceptional stability for 1300 h in continuous propane dehydrogenation under industrially relevant industrial conditions, with extending 95% propylene selectivity and propane conversions approaching thermodynamic equilibrium values at 550–600 oC. In situ characterizations and density functional theory/molecular dynamics simulation reveal Zn atoms adsorb on the particle surface and then diffuse inward, aiding in the formation of ultrasmall and highly ordered intermetallic alloys. This in-situ gas-migration strategy is applicable to a wide range of intermetallic systems. Intermetallic alloys (IMAs) hold significant potential for catalysis. Here, the authors present a robust gas-migration method for synthesizing stable and uniform IMAs, which exhibit exceptional stability over 1300 h in propane dehydrogenation. [ABSTRACT FROM AUTHOR]

The catalytic partial oxidation of methane (POM) presents a promising technology for synthesizing syngas. However, it faces severe over-oxidation over catalyst surface. Attempts to modify metal surfaces by incorporating a secondary metal towards C–H bond activation of CH4 with moderate O* adsorption have remained the subject of intense research yet challenging. Herein, we report that high catalytic performance for POM can be achieved by the regulation of O* occupation in the atomically dispersed (AD) MoNi alloy, with over 95% CH4 conversion and 97% syngas selectivity at 800 °C. The combination of ex-situ/in-situ characterizations, kinetic analysis and DFT (density functional theory) calculations reveal that Mo-Ni dual sites in AD MoNi alloy afford the declined O2 poisoning on Ni sites with rarely weaken CH4 activation for partial oxidation pathway following the combustion reforming reaction (CRR) mechanism. These results underscore the effectiveness of CH4 turnovers by the design of atomically dispersed alloys with tunable O* adsorption. The catalytic partial oxidation of methane (POM) is a promising technology for synthesizing syngas but suffers from severe over-oxidation on the catalyst surface. Here the authors demonstrate that regulating O* occupation in an atomically dispersed MoNi alloy can achieve high catalytic performance for POM. [ABSTRACT FROM AUTHOR]

The article discusses the importance of catalyst stability in chemical processes and the challenges faced by catalysts in the production of propylene. It highlights the recent development of a new catalyst, In/Rh@Silicalite-1, which has demonstrated superior stability and high catalytic efficiency in producing propylene for 5500 hours. The catalyst's coking-resistant nature enables hydrogen-free propylene production, simplifying the process and reducing costs. The article suggests that further research is needed to explore the catalyst's structural performance and potential for coupling with selective hydrogen combustion materials. [Extracted from the article]

The capture of low concentration CO2 presents numerous challenges. Here, we report that zinc containing chabazite (CHA) zeolites can realize high capacity, fast adsorption kinetics, and low desorption energy when capturing ca. 400 ppm CO2. Control of the state and location of the zinc ions in the CHA cage is critical to the performance. Zn2+ loaded onto paired anionic sites in the six‐membered rings (6MRs) in the CHA cage are the primary sites to adsorb ca. 0.51 mmol CO2/g‐zeolite with Si/Al=ca. 7, a 17‐fold increase compared to the parent H‐form. The capacity is increased further to ca. 0.67 mmol CO2/g‐zeolite with Si/Al=ca. 2 due to more paired sites for zinc exchange. Zeolites with double six‐membered rings (D6MRs) that orient 6MRs into the cages give enhanced uptakes for CO2 adsorption with zinc exchange. The results reveal that zinc exchanged CHA and several other small pore, cage containing zeolites merit further investigation for the capture of low concentration CO2. [ABSTRACT FROM AUTHOR]

Back Cover: Unravelling Channel Structure-Diffusivity Relationships in Zeolite ZSM-5 at the Single-Molecule Level (Angew. In their Communication (e202114388), Bert M. Weckhuysen and co-workers compare the molecules' motion behavior in different zeolite channel geometries at the single-molecule level. Keywords: Diffusion; Single-molecule studies; Thin films; Zeolites; ZSM-5 EN Diffusion Single-molecule studies Thin films Zeolites ZSM-5 1 1 1 01/20/22 20220126 NES 220126 B Single-molecule tracking b is used to follow the motion of individual molecules. [Extracted from the article]

Dieser Ansatz bietet mechanistische Einblicke in die Beziehungen zwischen Kanalgeometrie und Diffusionsfähigkeit und liefert die Grundlage für die Verbesserung der Diffusion in hierarchischen Zeolithen. Rücktitelbild: Unravelling Channel Structure-Diffusivity Relationships in Zeolite ZSM-5 at the Single-Molecule Level (Angew. Keywords: Diffusion; Single-molecule studies; Thin films; Zeolites; ZSM-5 EN Diffusion Single-molecule studies Thin films Zeolites ZSM-5 1 1 1 01/20/22 20220126 NES 220126 B Einzelmolekül-Tracking b wird eingesetzt, um die Bewegung einzelner Moleküle zu verfolgen. [Extracted from the article]

The industrial catalysts utilized for propane dehydrogenation (PDH) to propylene, an important alternative to petroleum-based cracking processes, either use expensive metals or metal oxides that are environmentally unbenign. We report that a typically less-active oxide, titanium oxide (TiO 2 ), can be combined with earth-abundant metallic nickel (Ni) to form an unconventional Ni@TiO x catalyst for efficient PDH. The catalyst demonstrates a 94% propylene selectivity at 40% propane conversion and superior stability under industrially relevant conditions. Complete encapsulation of Ni nanoparticles was allowed at elevated temperatures (>550°C). A mechanistic study suggested that the defective TiO x overlayer consisting of tetracoordinated Ti sites with oxygen vacancies is catalytically active. Subsurface metallic Ni acts as an electronic promoter to accelerate carbon-hydrogen bond activation and hydrogen (H 2 ) desorption on the TiO x overlayer.

The strong promotion effects of alkali/alkaline earth metals are frequently reported for heterogeneous catalytic processes such as propane dehydrogenation (PDH), but their functioning principles remain elusive. This paper describes the effect of the addition of calcium (Ca) on reducing the deactivation rate of platinum-tin (Pt-Sn) catalyzed PDH from 0.04 h -1 to 0.0098 h -1 at 873 K under a WHSV of 16.5 h -1 of propane. The Pt-Sn-Ca catalyst shows a high propylene selectivity of >96% with a propylene production rate of 41 mol C 3 H 6 (g Pt h) -1 and ∼1% activity loss after regeneration. The combination of characterization and DFT simulations reveals that Ca acts as a structural promoter favoring the transition of Sn n + in the parent catalyst to Sn 0 during reduction, and the latter is an electron donor that increases the electron density of Pt. This greatly suppresses coke formation from deep dehydrogenation. Moreover, it was found that Ca promotes the formation of a highly reactive and sintering-resistant sub-nano Pt-Sn alloy with a diameter of approximately 0.8 nm. These lead to high activity and selectivity for the Pt-Sn-Ca catalyst for PDH., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Hydrocarbon conversion catalysts suffer from deactivation by deposition or formation of carbon deposits. Carbon deposit formation is thermodynamically favored above 350 °C, even in some hydrogen-rich environments. We discuss four basic mechanisms: a carbenium-ion based mechanism taking place on acid sites of zeolites or bifunctional catalysts, a metal-induced formation of soft coke (i.e., oligomers of small olefins) on bifunctional catalysts, a radical-mediated mechanism in higher-temperature processes, and fast-growing carbon filament formation. Catalysts deactivate because carbon deposits block pores at different length scales, or directly block active sites. Some deactivated catalysts can be re-used, others can be regenerated or have to be discarded. Catalyst and process design can mitigate the effects of deactivation. New analytical tools allow for the direct observation (in some cases even under in situ or operando conditions) of the 3D-distribution of coke-type species as a function of catalyst structure and lifetime., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Close proximity usually shortens the travel distance of reaction intermediates, thus able to promote the catalytic performance of CO 2 hydrogenation by a bifunctional catalyst, such as the widely reported In 2 O 3 /H-ZSM-5. However, nanoscale proximity ( e.g. , powder mixing, PM) more likely causes the fast deactivation of the catalyst, probably due to the migration of metals ( e.g. , In) that not only neutralizes the acid sites of zeolites but also leads to the reconstruction of the In 2 O 3 surface, thus resulting in catalyst deactivation. Additionally, zeolite coking is another potential deactivation factor when dealing with this methanol-mediated CO 2 hydrogenation process. Herein, we reported a facile approach to overcome these three challenges by coating a layer of silicalite-1 (S-1) shell outside a zeolite H-ZSM-5 crystal for the In 2 O 3 /H-ZSM-5-catalyzed CO 2 hydrogenation. More specifically, the S-1 layer (1) restrains the migration of indium that preserved the acidity of H-ZSM-5 and at the same time (2) prevents the over-reduction of the In 2 O 3 phase and (3) improves the catalyst lifetime by suppressing the aromatic cycle in a methanol-to-hydrocarbon conversion step. As such, the activity for the synthesis of C 2 + hydrocarbons under nanoscale proximity (PM) was successfully obtained. Moreover, an enhanced performance was observed for the S-1-coated catalyst under microscale proximity ( e.g. , granule mixing, GM) in comparison to the S-1-coating-free counterpart. This work highlights an effective shielding strategy to secure the bifunctional nature of a CO 2 hydrogenation catalyst., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

The development of improved zeolite materials for applications in separation and catalysis requires understanding of mass transport. Herein, diffusion of single molecules is tracked in the straight and sinusoidal channels of the industrially relevant ZSM-5 zeolites using a combination of single-molecule localization microscopy and uniformly oriented zeolite thin films. Distinct motion behaviors are observed in zeolite channels with the same geometry, suggesting heterogeneous guest-host interactions. Quantification of the diffusion heterogeneities in the sinusoidal and straight channels suggests that the geometry of zeolite channels dictates the mobility and motion behavior of the guest molecules, resulting in diffusion anisotropy. The study of hierarchical zeolites shows that the addition of secondary pore networks primarily enhances the diffusivity of sinusoidal zeolite channels, and thus alleviating the diffusion limitations of microporous zeolites., (© 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)