scholarly journals Rational design of single-site heterogeneous catalysts: towards high chemo-, regio- and stereoselectivity

2012 ◽  
Vol 468 (2143) ◽  
pp. 1904-1926 ◽  
Author(s):  
Vladimiro Dal Santo ◽  
Matteo Guidotti ◽  
Rinaldo Psaro ◽  
Leonardo Marchese ◽  
Fabio Carniato ◽  
...  
Keyword(s):  
Rational Design ◽  
Heterogeneous Catalysts ◽  
Direct Synthesis ◽  
Single Site ◽  
Added Value ◽  
Catalytic Systems ◽  
Oxide Supports ◽  
Key Factor ◽  
Catalytically Active ◽  
Post Synthesis

The main methods for the design and preparation of single-site heterogeneous catalysts on inorganic oxide supports are described and reviewed. Catalytically active metal sites can be either introduced into the framework of porous materials via direct synthesis or added to a pre-existing support by post-synthesis techniques. Particular attention is paid to selected examples where the geometry, the nature and the chemical surroundings of the active single site is a key factor to obtain catalytic systems with enhanced chemo-, regio- and stereoselectivity. The ever-increasing capabilities of ‘nanoarchitecture’ at molecular level enable chemists to build ideal catalysts for the sustainable transformation of bulky and high added-value molecules.

scholarly journals Exploiting the Potential of Biosilica from Rice Husk as Porous Support for Catalytically Active Iron Oxide Nanoparticles

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1259
Author(s):  
Ana Franco ◽  
Rafael Luque ◽  
Carolina Carrillo-Carrión
Keyword(s):  
Iron Oxide ◽  
Iron Oxide Nanoparticles ◽  
Rice Husk ◽  
Heterogeneous Catalysts ◽  
Catalytic Performance ◽  
Added Value ◽  
Oxide Nanoparticles ◽  
Porous Support ◽  
Green Materials ◽  
Catalytically Active

Biomass-derived materials are put forward as eco-friendly alternatives to design heterogeneous catalysts. To contribute in this field, we explored the potential of mesoporous biogenic silica (RH-Silica) obtained from lignocellulosic waste, in particular from rice husk, as an inorganic support to prepare heterogenized iron oxide-based catalysts. Mechanochemistry, considered as a green and sustainable technique, was employed to synthetize iron oxide nanoparticles in pure hematite phase onto the biosilica (α-Fe2O3/RH-Silica), making this material a good candidate to perform catalyzed organic reactions. The obtained material was characterized by different techniques, and its catalytic activity was tested in the selective oxidation of styrene under microwave irradiation. α-Fe2O3/RH-Silica displayed a good catalytic performance, achieving a conversion of 45% under optimized conditions, and more importantly, with a total selectivity to benzaldehyde. Furthermore, a good reusability was achieved without decreasing its activity after multiple catalytic cycles. This work represents a good example of using sustainable approaches and green materials as alternatives to conventional methods in the production of high-added value products.

ChemInform Abstract: Rational Design of Single-Site Heterogeneous Catalysts: Towards High Chemo-, Regio- and Stereoselectivity

ChemInform ◽  
2012 ◽  
Vol 43 (48) ◽  
pp. no-no
Author(s):  
Vladimiro Dal Santo ◽  
Matteo Guidotti ◽  
Rinaldo Psaro ◽  
Leonardo Marchese ◽  
Fabio Carniato ◽  
...  
Keyword(s):  
Rational Design ◽  
Heterogeneous Catalysts ◽  
Single Site

scholarly journals Heterogeneous catalysis for green chemistry based on nanocrystals

2015 ◽  
Vol 2 (2) ◽  
pp. 150-166 ◽  
Author(s):  
Yuxi Liu ◽  
Guofeng Zhao ◽  
Dingsheng Wang ◽  
Yadong Li
Keyword(s):  
Green Chemistry ◽  
Rational Design ◽  
Heterogeneous Catalysts ◽  
Modern Society ◽  
Active Species ◽  
Catalytic Systems ◽  
Practical Applications ◽  
Precise Control ◽  
Effective Strategies ◽  
Increasing Demand

Abstract Modern society has an ever-increasing demand for environmentally friendly catalytic processes. Catalysis research is working towards a solution through the development of effective heterogeneous catalysts for environment-related applications. Nanotechnologies have provided effective strategies for the preparation of nanocrystals (NCs) with well-defined sizes, shapes and compositions. Precise control of these NCs provides an important foundation for the studies of structure-performance relationships in catalysis, which is critical to the design of NCs with optimized catalytic performances for practical applications. We focus on recent advances in the development of bottom-up strategies to control NCs structures for some key catalytic applications, including CO oxidation, selective oxidation of alcohols, semihydrogenation of alkynes, and selective hydrogenation of unsaturated aldehydes and nitrobenzene. These key applications have been a popular research focus because of their significance in green chemistry. Herein we also discuss the scientific understandings of the active species and active structures of these systems to gain an insight for rational design of efficient catalytic systems for these catalytic reactions.

scholarly journals Boosting the Characterization of Heterogeneous Catalysts for H2O2 Direct Synthesis by Infrared Spectroscopy

Catalysts ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 30 ◽  
Author(s):  
Maela Manzoli
Keyword(s):  
Ir Spectroscopy ◽  
Heterogeneous Catalysts ◽  
Direct Synthesis ◽  
Chemical Characterization ◽  
Ir Absorption ◽  
Spectroscopic Techniques ◽  
Catalytic Systems ◽  
Spectroscopy Studies ◽  
H2o2 Direct Synthesis

Infrared (IR) spectroscopy is among the most powerful spectroscopic techniques available for the morphological and physico-chemical characterization of catalytic systems, since it provides information on (i) the surface sites at an atomic level, (ii) the nature and structure of the surface or adsorbed species, as well as (iii) the strength of the chemical bonds and (iv) the reaction mechanism. In this review, an overview of the main contributions that have been determined, starting from IR absorption spectroscopy studies of catalytic systems for H2O2 direct synthesis, is given. Which kind of information can be extracted from IR data? IR spectroscopy detects the vibrational transitions induced in a material by interaction with an electromagnetic field in the IR range. To be IR active, a change in the dipole moment of the species must occur, according to well-defined selection rules. The discussion will be focused on the advancing research in the use of probe molecules to identify (and possibly, quantify) specific catalytic sites. The experiments that will be presented and discussed have been carried out mainly in the mid-IR frequency range, between approximately 700 and 4000 cm−1, in which most of the molecular vibrations absorb light. Some challenging possibilities of utilizing IR spectroscopy for future characterization have also been envisaged.

scholarly journals Rational design and synthesis of noble-metal nanoframes for catalytic and photonic applications

2016 ◽  
Vol 3 (4) ◽  
pp. 520-533 ◽  
Author(s):  
Xue Wang ◽  
Aleksey Ruditskiy ◽  
Younan Xia
Keyword(s):  
Noble Metal ◽  
Active Sites ◽  
Noble Metals ◽  
Rational Design ◽  
Heterogeneous Catalysts ◽  
Open Architecture ◽  
Design Synthesis ◽  
Design And Synthesis ◽  
Surface Areas ◽  
Catalytically Active

Abstract Nanoframes are unique for their 3D, highly open architecture. When made of noble metals, they are attractive for use as heterogeneous catalysts because of their large specific surface areas, high densities of catalytically active sites and low vulnerability toward sintering. They promise to enhance the catalytic activity and durability while reducing the material loading and cost. For nanoframes composed of Au and/or Ag, they also exhibit highly tunable plasmonic properties similar to those of nanorods. This article presents a brief account of recent progress in the design, synthesis and utilization of noble-metal nanoframes. We start with a discussion of the synthetic strategies, including those involving site-selected deposition and etching, as well as dealloying of both hollow and solid nanocrystals. We then highlight some of the applications enabled by noble-metal nanoframes. Finally, we discuss the challenges and trends with regard to future development.

scholarly journals A one-step rapid synthesis of TS-1 zeolites with highly catalytically active mononuclear TiO6 species

2020 ◽  
Vol 8 (19) ◽  
pp. 9677-9683 ◽  
Author(s):  
Wenjing Xu ◽  
Tianjun Zhang ◽  
Risheng Bai ◽  
Peng Zhang ◽  
Jihong Yu
Keyword(s):  
Active Sites ◽  
High Performance ◽  
Rational Design ◽  
Heterogeneous Catalysts ◽  
Rapid Synthesis ◽  
Catalytically Active ◽  
One Step

The modulation and determination of the coordination environments of Ti active sites in titanosilicate zeolites are key challenges in the rational design of high-performance heterogeneous catalysts.

scholarly journals The societal significance of catalysis and the growing practical importance of single-site heterogeneous catalysts

2012 ◽  
Vol 468 (2143) ◽  
pp. 1884-1903 ◽  
Author(s):  
John Meurig Thomas
Keyword(s):  
Heterogeneous Catalysts ◽  
Practical Importance ◽  
Single Site ◽  
Chemical Production ◽  
Solid Catalysts ◽  
Wide Range ◽  
Mesoporous Solids ◽  
Catalytically Active ◽  
Shape Selective ◽  
Enantioselective Catalysts

The concept of single-site heterogeneous catalysis, herein defined and extensively illustrated, offers a strategy for the design of new solid catalysts. By capitalizing on the opportunities presented by nanoporous materials to assemble a wide range of new, well-defined, catalytically active centres, it is possible to bring about numerous environmentally benign processes that can replace traditional methods of chemical production. The latter often employs aggressive, corrosive or hazardous reagents. By using both microporous (less than 20 Å diameter) and mesoporous solids (20–500 Å diameter), abundant scope exists for the construction and application of shape-selective, regio-selective and enantioselective catalysts.

scholarly journals Elaboration, characterization and properties of silica-based single-site heterogeneous photocatalysts

2012 ◽  
Vol 468 (2143) ◽  
pp. 2113-2128 ◽  
Author(s):  
Michel Che ◽  
Kohsuke Mori ◽  
Hiromi Yamashita
Keyword(s):  
Heterogeneous Catalysts ◽  
Synthesis Method ◽  
Active Phase ◽  
Single Site ◽  
Preparation Methods ◽  
Counter Ions ◽  
Catalytically Active ◽  
Photocatalytic Reactions ◽  
Definition Of ◽  
Catalytically Active Phase

This study concerns single-site heterogeneous photocatalysts, composed of isolated transition metals ions (single-sites) dispersed on silica-based supports, which can be used as photocatalysts. The first part gives the definition of single-site heterogeneous catalysts. The main difficulty to prepare the latter resides in the speciation of the key elements (metal of the catalytically active phase and oxygen of the solid support) and other species (notably counter ions and ligands) the presence of which depends on the synthesis method adopted. The best preparation methods as well as the ideal features of single-site heterogeneous photocatalysts are discussed before the study focuses on single-site heterogeneous photocatalysts. Case studies are presented with photocatalysts involving titanium and chromium, and their photocatalytic reactions such as CO 2 reduction with H 2 O, degradation of organic pollutants diluted in water, NO decomposition and selective oxidation of propane are also described.

Hydrogen peroxide decomposition on a two-component CuO-Cr2O3 catalyst

1988 ◽  
Vol 53 (8) ◽  
pp. 1636-1646 ◽  
Author(s):  
Viliam Múčka ◽  
Kamil Lang
Keyword(s):  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Extreme Values ◽  
Catalytic Properties ◽  
Active Components ◽  
Catalytic Systems ◽  
Heterogeneous Catalytic ◽  
Peroxide Decomposition ◽  
Two Component ◽  
Catalytically Active

Some physical and catalytic properties of the two-component copper(II)oxide-chromium(III)oxide catalyst with different content of both components were studied using the decomposition of the aqueous solution of hydrogen peroxide as a testing reaction. It has been found that along to both basic components, the system under study contains also the spinel structure CuCr2O4, chromate washable by water and hexavalent ions of chromium unwashable by water. The soluble chromate is catalytically active. During the first period of the reaction the equilibrium is being established in both homogeneous and heterogeneous catalytic systems. The catalytic activity as well as the specific surface area of the washed solid is a non-monotonous function of its composition. It seems highly probable that the extreme values of both these quantities are not connected with the detected admixtures in the catalytic system. The system under study is very insensitive with regard to the applied doses of gamma radiation. Its catalytic properties are changed rather significantly after the thermal treatment and particularly after the partial reduction to low degree by hydrogen. The observed changes of the catalytic activity of the system under study are very probably in connection with the changes of the valence state of the catalytically active components of the catalyst.

scholarly journals Selective Styrene Oxidation to Benzaldehyde over Recently Developed Heterogeneous Catalysts

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1680
Author(s):  
Marta A. Andrade ◽  
Luísa M. D. R. S. Martins
Keyword(s):  
Heterogeneous Catalysts ◽  
Carbon Materials ◽  
Oxygen Species ◽  
Styrene Oxidation ◽  
Reaction Conditions ◽  
Reactive Metal ◽  
Catalytic Systems ◽  
Tert Butyl Hydroperoxide ◽  
Metal Organic ◽  
Important Intermediate

The selective oxidation of styrene under heterogeneous catalyzed conditions delivers environmentally friendly paths for the production of benzaldehyde, an important intermediate for the synthesis of several products. The present review explores heterogeneous catalysts for styrene oxidation using a variety of metal catalysts over the last decade. The use of several classes of supports is discussed, including metal–organic frameworks, zeolites, carbon materials and silicas, among others. The studied catalytic systems propose as most used oxidants tert-butyl hydroperoxide, and hydrogen peroxide and mild reaction conditions. The reaction mechanism proceeds through the generation of an intermediate reactive metal–oxygen species by catalyst-oxidant interactions. Overall, most of the studies highlight the synergetic effects among the metal and support for the activity and selectivity enhancement.

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