Assessment of acid catalytic properties of ferrosilicate MFI zeolite by methanol-to-hydrocarbon conversion.

Four representative synthetic methods were employed to prepare Fe-containing siliceous MFI zeolites. The obtained Fe-MFI zeolites exhibited markedly different catalytic performances in the methanol-to-hydrocarbon (MTH) conversion reaction depending on the type of Fe incorporation within the siliceous framework. The catalytically active Brønsted acid sites were analyzed using pyridine adsorption experiments combined with Fourier transform infrared spectroscopy, providing characteristic signal intensities according to the acid-base interactions.

Low-Temperature controlled synthesis of nanocast mixed metal oxide spinels for enhanced OER activity.

The controlled cation substitution is an effective strategy for optimizing the density of states and enhancing the electrocatalytic activity of transition metal oxide catalysts for water splitting. However, achieving tailored mesoporosity while maintaining elemental homogeneity and phase purity remains a significant challenge, especially when aiming for complex multi-metal oxides. In this study, we utilized a one-step impregnation nanocasting method for synthesizing mesoporous Mn-, Fe-, and Ni-substituted cobalt spinel oxide (MnFeNiCoO, MFNCO) and demonstrate the benefits of low-temperature calcination within a semi-sealed container at 150-200 °C.

Morphology-Dependent Interaction of Silica Nanoparticles with Intestinal Cells: Connecting Shape to Barrier Function.

The intestinal compartment ensures nutrient absorption and barrier function against pathogens. Despite decades of research on the complexity of the gut, the adaptive potential to physical cues, such as those derived from interaction with particles of different shapes, remains less understood. Taking advantage of the technological versatility of silica nanoparticles, spherical, rod-shaped, and virus-like materials were synthesized.

Tuning CO Hydrogenation Selectivity through Reaction-Driven Restructuring on Cu-Ni Bimetal Catalysts.

Tuning the selectivity of CO hydrogenation is of significant scientific interest, especially using nickel-based catalysts. Fundamental insights into CO hydrogenation on Ni-based catalysts demonstrate that CO is a primary intermediate, and product selectivity is strongly dependent on the oxidation state of Ni. Therefore, modifying the electronic structure of the nickel surface is a compelling strategy for tuning product selectivity.

Confining Gold Nanoparticles in Preformed Zeolites by Post-Synthetic Modification Enhances Stability and Catalytic Reactivity and Selectivity.

Confining Au nanoparticles (NPs) in a restricted space (., zeolite micropores) is a promising way of overcoming their inherent thermal instability and susceptibility to aggregation, which limit catalytic applications. However, such approaches involve complex, multistep encapsulation processes.

The facet effect of ceria nanoparticles on platinum dispersion and catalytic activity of methanol partial oxidation.

The effect of platinum-supported nano-shaped ceria catalysts on methanol partial oxidation and methyl formate product selectivity has been investigated. A Pt-supported CeO2 nanocube catalyst had a higher turnover frequency than nanosphere catalysts; however, nanosphere catalysts showed higher selectivity towards methyl formate. The observed ceria shape effect in catalysis was associated with the shape-dependent Pt dispersion and its oxidation states.

Cascade reaction engineering on zirconia-supported mesoporous MFI zeolites with tunable Lewis-Brønsted acid sites: a case of the one-pot conversion of furfural to γ-valerolactone.

Catalytic cascade reactions are strongly desired as a potential means of combining multistep reactions into a single catalytic reactor. Appropriate catalysts composed of multi-reactive sites to catalyze cascade reactions in a sequential fashion are central to such efforts. Here, we demonstrate a bifunctional zeolite catalyst with close proximity of Brønsted and Lewis acid sites through the synthesis of a mesoporous ZrO[Al]MFI nanosponge (NS).

Rare-earth-platinum alloy nanoparticles in mesoporous zeolite for catalysis.

Platinum is a much used catalyst that, in petrochemical processes, is often alloyed with other metals to improve catalytic activity, selectivity and longevity. Such catalysts are usually prepared in the form of metallic nanoparticles supported on porous solids, and their production involves reducing metal precursor compounds under a H flow at high temperatures. The method works well when using easily reducible late transition metals, but Pt alloy formation with rare-earth elements through the H reduction route is almost impossible owing to the low chemical potential of rare-earth element oxides.

Highly dispersed Pt nanoclusters supported on zeolite-templated carbon for the oxygen reduction reaction.

The formation of highly dispersed Pt nanoclusters supported on zeolite-templated carbon (PtNC/ZTC) by a facile electrochemical method as an electrocatalyst for the oxygen reduction reaction (ORR) is reported. The uniform micropores of ZTC serve as nanocages to stabilize the PtNCs with a sharp size distribution of 0.8-1.

Self-organization of silicates on different length scales exemplified by amorphous mesoporous silica and mesoporous zeolite beta using multiammonium surfactants.

In this study the structure directing effect of a gemini-type piperidine-based multi-ammonium surfactant during hydrothermal zeolite synthesis was investigated for two cases: with and without a source of aluminum. The absence of an aluminum source led to the formation of an amorphous mesoporous MCM-48 type silica material, while the presence of aluminum guaranteed the formation of zeolite beta with a hierarchical pore system. The two opposing cases were studied in a time and temperature-dependent manner.

Microporous 3D Graphene-like Zeolite-Templated Carbons for Preferential Adsorption of Ethane.

Microporous 3D graphene-like carbons were synthesized in Faujasite (FAU)-, EMT-, and beta-zeolite templates using the recently developed Ca ion-catalyzed synthesis method. The microporous carbons liberated from these large-pore zeolites (0.7-0.

Oxygen activation on the interface between Pt nanoparticles and mesoporous defective TiO during CO oxidation.

Platinum-based heterogeneous catalysts are mostly used in various commercial chemical processes because of their high catalytic activity, influenced by the metal/oxide interaction. To design rational catalysts with high performance, it is crucial to understand the relationship between the metal-oxide interface and the reaction pathway. Here, we investigate the role of oxygen defect sites in the reaction mechanism for CO oxidation using Pt nanoparticles supported on mesoporous TiO catalysts with oxygen defects.

Ultrafast charge transfer coupled with lattice phonons in two-dimensional covalent organic frameworks.

Covalent organic frameworks (COFs) have emerged as a promising light-harvesting module for artificial photosynthesis and photovoltaics. For efficient generation of free charge carriers, the donor-acceptor (D-A) conjugation has been adopted for two-dimensional (2D) COFs recently. In the 2D D-A COFs, photoexcitation would generate a polaron pair, which is a precursor to free charge carriers and has lower binding energy than an exciton.

Boosting hot electron flux and catalytic activity at metal-oxide interfaces of PtCo bimetallic nanoparticles.

Despite numerous studies, the origin of the enhanced catalytic performance of bimetallic nanoparticles (NPs) remains elusive because of the ever-changing surface structures, compositions, and oxidation states of NPs under reaction conditions. An effective strategy for obtaining critical clues for the phenomenon is real-time quantitative detection of hot electrons induced by a chemical reaction on the catalysts. Here, we investigate hot electrons excited on PtCo bimetallic NPs during H oxidation by measuring the chemicurrent on a catalytic nanodiode while changing the Pt composition of the NPs.

Nanocage-Confined Synthesis of Fluorescent Polycyclic Aromatic Hydrocarbons in Zeolite.

Polycyclic aromatic hydrocarbons (PAHs) attract much attention for applications to organic light-emitting diodes, field-effect transistors, and photovoltaic cells. The current synthetic approaches to PAHs involve high-temperature flash pyrolysis or complicated step-by-step organic reactions, which lead to low yields of PAHs. Herein, we report a facile and scalable synthesis of PAHs, which is carried out simply by flowing acetylene gas into zeolite under mild heating, typically at 400 °C and generates the products of 0.

Extremely high electrical conductance of microporous 3D graphene-like zeolite-templated carbon framework.

We report the remarkably high electrical conductance of microporous 3D graphene-like carbons that were formed using lanthanum (La)-catalyzed synthesis in a Y zeolite (LaY) template investigated using conductive atomic force microscopy (C-AFM) and theoretical calculations. To uncover the relation between local electrical conductance and the microporous structures, we tuned the crystallographic ordering of LaY-templated carbon systems by changing the heating temperature. The structure of the LaY-templated carbon prepared at the higher temperature has graphene-like sp hybridized bonds, which was confirmed using high-resolution transmission electron microscopy and X-ray diffraction measurements.

Non-Topotactic Transformation of Silicate Nanolayers into Mesostructured MFI Zeolite Frameworks During Crystallization.

Mesostructured MFI zeolite nanosheets are established to crystallize non-topotactically through a nanolayered silicate intermediate during hydrothermal synthesis. Solid-state 2D NMR analyses, with sensitivity enhanced by dynamic nuclear polarization (DNP), provide direct evidence of shared covalent Si-O- Si bonds between intermediate nanolayered silicate moieties and the crystallizing MFI zeolite nanosheet framework.

Highly monodisperse supported metal nanoparticles by basic ammonium functionalization of mesopore walls for industrially relevant catalysis.

A strategy for a high dispersion of metal/metal oxide nanoparticles in a mono-modal fashion is developed. The key is the functionalization of mesopore walls with basic -CH-N(Me)(OH) groups. The supported metal catalysts obtained in the present work exhibit high catalytic activities for CO methanation at low temperature and CO oxidation.

Lanthanum-catalysed synthesis of microporous 3D graphene-like carbons in a zeolite template.

Three-dimensional graphene architectures with periodic nanopores—reminiscent of zeolite frameworks—are of topical interest because of the possibility of combining the characteristics of graphene with a three-dimensional porous structure. Lately, the synthesis of such carbons has been approached by using zeolites as templates and small hydrocarbon molecules that can enter the narrow pore apertures. However, pyrolytic carbonization of the hydrocarbons (a necessary step in generating pure carbon) requires high temperatures and results in non-selective carbon deposition outside the pores.

Synthesis of Silicate Zeolite Analogues Using Organic Sulfonium Compounds as Structure-Directing Agents.

A microporous crystalline silica zeolite of the MEL structure type and three other zeolite analogues composed of germanosilicate frameworks were synthesized using tributylsulfonium, triphenylsulfonium, or tri(para-tolyl)sulfonium as the structure-directing agent. The germanosilicates thus obtained had ISV, ITT, or a new zeolite structure depending on the synthesis conditions. The structure of the new germanosilicate was solved using X-ray powder diffraction data with the aid of a charge-flipping method.

MFI zeolite nanosheets with post-synthetic Ti grafting for catalytic epoxidation of bulky olefins using H2O2.

The external surfaces of the surfactant-directed, 2.5 nm MFI zeolite nanosheets were grafted with Ti using titanium(IV) butoxide. The Ti/MFI nanosheets exhibited a remarkable catalytic performance for epoxidation of bulky olefins using H2O2 as an oxidant, in comparison to the mesoporous silicas with amorphous frameworks.

Direct observation of bond formation in solution with femtosecond X-ray scattering.

The making and breaking of atomic bonds are essential processes in chemical reactions. Although the ultrafast dynamics of bond breaking have been studied intensively using time-resolved techniques, it is very difficult to study the structural dynamics of bond making, mainly because of its bimolecular nature. It is especially difficult to initiate and follow diffusion-limited bond formation in solution with ultrahigh time resolution.

Co-development of crystalline and mesoscopic order in mesostructured zeolite nanosheets.

Mesoporous zeolites are a new and technologically important class of materials that exhibit improved diffusion and catalytic reaction properties compared to conventional zeolites with sub-nanometer pore dimensions. During their syntheses, the transient developments of crystalline and mesoscopic order are closely coupled and challenging to control. Correlated solid-state NMR, X-ray, and electron microscopy analyses yield new molecular-level insights on the interactions and distributions of complicated organic structure-directing agents with respect to crystallizing zeolite frameworks.

Conversion of kraft lignin over hierarchical MFI zeolite.

Catalytic pyrolysis of kraft lignin was carried out using pyrolysis gas chromatography/mass spectrometry. Hierarchical mesoporous MFI was used as the catalyst and another mesoporous material Al-SBA-15 was also used for comparison. The characteristics of mesoporous MFI were analyzed by X-ray diffraction patterns, N2 adsorption-desorption isotherms, and temperature programmed desorption of NH3.