Mechanochemical synthesis of nanomaterials for advanced catalytic applications (original) (raw)

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. Featuring simplicity, high reproducibility, mild/short reaction conditions and often solvent-free condition (dry milling), mechanochemistry can offer remarkable possibilities in the development of advanced catalytically active materials. The proposed contribution has been aimed to provide a brief account of remarkable recent findings and advances in the mechanochemical synthesis of solid phase advanced catalysts as opposed to conventional systems. The role of mechanical energy in the synthesis of solid catalysts and their application is critically discussed as well as the influence of the synthesis procedure on the physicochemical properties and the efficiency of synthesized catalysts is studied. The main purpose of this feature article is to highlight the possibilities of mechanochemical protocols in (nano)materials engineering for catalytic applications.

Hallmarks of mechanochemistry: from nanoparticles to technology

Chemical Society Reviews, 2013

The aim of this review article on recent developments of mechanochemistry (nowadays established as a part of chemistry) is to provide a comprehensive overview of advances achieved in the field of atomistic processes, phase transformations, simple and multicomponent nanosystems and peculiarities of mechanochemical reactions. Industrial aspects with successful penetration into fields like materials engineering, heterogeneous catalysis and extractive metallurgy are also reviewed. The hallmarks of mechanochemistry include influencing reactivity of solids by the presence of solid-state defects, interphases and relaxation phenomena, enabling processes to take place under non-equilibrium conditions, creating a well-crystallized core of nanoparticles with disordered near-surface shell regions and performing simple dry time-convenient one-step syntheses. Underlying these hallmarks are technological consequences like preparing new nanomaterials with the desired properties or producing these materials in a reproducible way with high yield and under simple and easy operating conditions. The last but not least hallmark is enabling work under environmentally friendly and essentially waste-free conditions (822 references).

A Survey on Recent Developments in Catalysis Using Nanostructured Materials

This review describes that nanomaterials have received more attention by virtue of their excellent properties suited for applications in various fields such as electronic, pharmaceutical, biomedical, cosmetic, energy, and catalysis. Nanomaterial-based catalysts are usually heterogeneous catalysts. The extremely small size of the particles maximizes surface area exposed to the reactant, allowing more reactions to occur. However, thermal stability of these nanomaterials is limited by their critical sizes; the smaller the crystallite size, the lower thermal stability. The majority of industrial catalysts contain an active component in the form of nanoparticles smaller than 20nm in size that are dispersed onto high-surface-area supports. The importance of nanoparticles and nanostructure to the performance of catalysts has stimulated wide efforts to develop methods for their synthesis and characterization. Nanoparticles offer higher catalytic efficiency per gram than larger size materials due to their large surface-to-volume ratio. This makes them an attractive choice to use as catalysts. Indeed, catalysts are undoubtedly "the most successful current application of nanotechnology". In the first part of the paper, application of catalysis using nanostructured material in some reactions including alkylation, dehydrogenation, hydrogenation, Steam reforming of methane (SRM), carbon dioxide reforming (DRM), epoxidation of alkenes and oxidative coupling of methane to ethylene (OCM) are investigated. In the second part of the paper, properties of some chemical elements such as gold, silver, platinum, palladium, nickel and rhodium as nanocatalyst are studied. Our investigation shows that the metal nanoparticles can act as best catalyst for industrial application as these have large surface to volume ratio and have unique quantum size effect. Moreover, their homogeneous size distribution with the mean particle size is optimal for catalytic properties and also they increase conversion reactions. Finally, it is shown that despite some disadvantages in using nanostructured materials in catalysts such as high synthesis precise of them and also restriction in industrial usages, they have several prominent advantages which convince everyone to use nanomaterials as catalysts. In addition, this area of study is still interesting for researcher all over the world to extend application of nanostructured catalysis to all reactions which needs catalysts and also reduce synthesis price and solve other problems of using these kinds of catalysts in industrial applications.

Mechanochemical synthesis of nanoparticles

Journal of Materials Science, 2004

The results of recent investigation of the mechanochemical synthesis of inorganic nanoparticles are reviewed. It was demonstrated that, by selecting suitable chemical reaction paths, stoichiometry of starting materials and milling conditions, mechanochemical processing can be used to synthesise a wide range of nanocrystalline particles dispersed within a soluble salt matrix. Selective removal of the matrix phase by washing the resulting powder with appropriate solvents can yield nanoparticles of the desired phase. This technique has been shown to have advantages over other methods of producing nanoparticles in terms of low cost, small particle sizes, low agglomeration, narrow size distributions and uniformity of crystal structure and morphology.

Nanocomposite Catalysts Obtaining by Mechanochemical Technique for Synthesizing

In the current research reactive milling was employed to fabricate the nanocomposite precursors for the catalytic growth of carbon nanostructures. For this purpose several mixtures of iron oxide and aluminum powders along with different amounts of graphite powders were mechanically milled for different times. The adiabatic temperature and the heat released from exothermic reaction during milling were controlled by varying the percentage of graphite. Synthesized powders were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and Thermogravimetric analysis (TGA).

Creating and mastering nano-objects to design advanced catalytic materials

Coordination Chemistry Reviews, 2011

New developments in the synthesis of nano-materials have opened new possibilities for creating and mastering nano-objects in order to design novel advanced catalytic materials. This concise conceptual review will give a glimpse into this fast growing research area discussing some of the possibilities in this direction, the perspectives and the gap to reduce to develop selective catalysts for complex multistep reactions. Emphasis is given to the opportunities offered by a tailored nano-design of the catalysts, from exploiting nano-confinement effects and supramolecular active sites synergies in nano-reactors to the new possibilities offered by new concepts such as the reduction of the relaxation time between two consecutive turnover cycles on a single active site and forcing a vectorial active site sequence in complex, multistep reactions. Other aspects discussed include the development of hierarchic pore structure to maximize catalyst effectiveness, metal complexes confined with solid cavities and the concept of nano-reactors, nanostructured composites and ordered 1D-type metal oxides. It is shown how significant progress in nano-materials has still not corresponded with progress in understanding the relationship between nanostructure and catalytic performance and the development of a more general strategy on the design of next-generation nano-catalysts.

Perspectives in catalytic applications of mesostructured materials

Applied Catalysis A: General, 2003

This review paper deals with proven and potential applications of mesoporous molecular sieves in catalysis. In addition to introduction and conclusion, the text is divided into two parts, respectively, dedicated to the design of solid catalysts and catalyst supports and to some relevant examples of catalytic processes.

Recent Progress in Synthesis of Nano-and Atomic-Sized Catalysts

Advanced Heterogeneous Catalysts Volume 1: Applications at the Nano-Scale, 2020

Well-defined nano-and atomic-sized heterogeneous catalysts with extremely high catalytic activities and unique selectivities show promise in addressing the critical energy-and environment-related challenges of this century. The exceptional properties of these catalysts, such as their electronic and geometric structures and the effective interactions between metals and supports, give rise to unprecedented catalytic efficiency over that of conventional catalysts. The facile prospects for tuning the active sites of these catalysts pave the way to optimizing their activities, selectivities, and stabilities, thus offering extensive application possibilities in significant industry-related catalytic reactions. A prerequisite for synthesizing nano-and atomic-sized catalyst is to prepare extremely disperse nano-and subnanoscale atoms on suitable supports. This book chapter summarizes various synthesis methods employed to synthesize nano-and atomic-scale catalysts.