Insights into the Active Species of Nanoparticle-Functionalized Hierarchical Zeolites in Alkylation Reactions

Supported Palladium Nanocatalysts: Recent Findings in Hydrogenation Reactions

Catalysis has witnessed a dramatic increase on the use of metallic nanoparticles in the last decade, opening endless opportunities in a wide range of research areas. As one of the most investigated catalysts in organic synthesis, palladium finds numerous applications being of significant relevance in industrial hydrogenation reactions. The immobilization of Pd nanoparticles in porous solid supports offers great advantages in heterogeneous catalysis, allowing control of the major factors that influence activity and selectivity. The present review deals with recent developments in the preparation and applications of immobilized Pd nanoparticles on solid supports as catalysts for hydrogenation reactions, aiming to give an insight on the key factors that contribute to enhanced activity and selectivity. The application of mesoporous silicas, carbonaceous materials, zeolites, and metal organic frameworks (MOFs) as supports for palladium nanoparticles is addressed.

Fe@Hierarchical BEA Zeolite Catalyst for MW-Assisted Alcohol Oxidation Reaction: A Greener Approach

The aim of this study was to investigate the catalytic activity of hybrid materials of iron supported on hierarchical zeolites in the oxidation reaction of 1-phenylethanol to acetophenone. A greener approach was considered for the preparation of the catalyst and performance of the oxidation reaction. Hierarchical BEA zeolite samples were obtained from an alkaline and a subsequent acid treatment. The materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and nitrogen adsorption at −196 °C. An iron salt was incorporated onto the hierarchical zeolites by mechanochemical grinding and the catalytic performance of the prepared materials was evaluated towards the microwave assisted oxidation reaction of 1-phenylethanol. The catalyst obtained by Fe immobilization on sample modified by 0.2 M NaOH followed by acid treatment (Fe@BEA0.2AT) is the most promising material with 35% yield and 56% selectivity to acetophenone, allowing five reuse cycles without significant loss of activity and selectivity.

Zeolite-Based Catalysts: A Valuable Approach toward Ester Bond Formation

Zeolite-based catalysts are versatile catalytic systems for a wide range of laboratory studies and industrial scale processes. The chemical composition, ion exchange, and pore size structure attributes of zeolites are responsible for their extensive catalytic applications. Esterification is one of the most important and routinely processes in diverse fields of organic synthesis. It has a long history in both industrial processes and laboratory work due to its versatility. This review intends to give a detailed insight into the significance of zeolite-based catalysts for ester bond formation

The recent development of efficient Earth-abundant transition-metal nanocatalysts

Whereas noble metal compounds have long been central in catalysis, Earth-abundant metal-based catalysts have in the same time remained undeveloped. Yet the efficacy of Earth-abundant metal catalysts was already shown at the very beginning of the 20th century with the Fe-catalyzed Haber-Bosch process of ammonia synthesis and later in the Fischer-Tropsch reaction. Nanoscience has revolutionized the world of catalysis since it was observed that very small Au nanoparticles (NPs) and other noble metal NPs are extraordinarily efficient. Therefore the development of Earth-abundant metals NPs is more recent, but it has appeared necessary due to their "greenness". This review highlights catalysis by NPs of Earth-abundant transition metals that include Mn, Fe, Co, Ni, Cu, early transition metals (Ti, V, Cr, Zr, Nb and W) and their nanocomposites with emphasis on basic principles and literature reported during the last 5 years. A very large spectrum of catalytic reactions has been successfully disclosed, and catalysis has been examined for each metal starting with zero-valent metal NPs followed by oxides and other nanocomposites. The last section highlights the catalytic activities of bi- and trimetallic NPs. Indeed this later family is very promising and simultaneously benefits from increased stability, efficiency and selectivity, compared to monometallic NPs, due to synergistic substrate activation.

The recent development of efficient Earth-abundant transition-metal nanocatalysts

This review presents the recent remarkable developments of efficient Earth-abundant transition-metal nanocatalysts.

MOFs vs. zeolites: carbonyl activation with M(iv) catalytic sites

Comparative review of the catalytic performance of isolated tetravalent metals as Lewis acid sites in zeolite and MOF materials.

Hierarchical ZSM-5 zeolite with uniform mesopores and improved catalytic properties

Uniform mesopores are generated in hierarchical ZSM-5 by a mesopore narrowing treatment, showing enhanced activity in the acylation of 2-methoxynaphthalene.

Mechanochemical synthesis of advanced nanomaterials for catalytic applications

Mechanochemical synthesis emerged as the most advantageous, environmentally sound alternative to traditional routes for nanomaterials preparation with outstanding properties for advanced applications.