scholarly journals Development of Covalent Triazine Frameworks as Heterogeneous Catalytic Supports

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1326 ◽  
Author(s):  
Norini Tahir ◽  
Chidharth Krishnaraj ◽  
Karen Leus ◽  
Pascal Van Der Voort
Keyword(s):  
Heterogeneous Catalysis ◽  
Surface Area ◽  
Chemical Reactions ◽  
Chemical Stability ◽  
Structural Design ◽  
Heterogeneous Catalysts ◽  
Molecular Complexes ◽  
Heterogeneous Catalytic ◽  
Catalytic Supports ◽  
Thermal And Chemical Stability

Covalent triazine frameworks (CTFs) are established as an emerging class of porous organic polymers with remarkable features such as large surface area and permanent porosity, high thermal and chemical stability, and convenient functionalization that promotes great potential in heterogeneous catalysis. In this article, we systematically present the structural design of CTFs as a versatile scaffold to develop heterogeneous catalysts for a variety of chemical reactions. We mainly focus on the functionalization of CTFs, including their use for incorporating and stabilization of nanoparticles and immobilization of molecular complexes onto the frameworks.

Metal nanoparticles: ligand free approach towards coupling reactions

2021 ◽  
Vol 01 ◽  
Author(s):  
Sharwari K. Mengane ◽  
Ronghui Wu ◽  
Liyun Ma ◽  
Chhaya S. Panse ◽  
Shailesh N. Vajekar ◽  
...  
Keyword(s):  
Heterogeneous Catalysis ◽  
Metal Nanoparticles ◽  
Surface Area ◽  
Heterogeneous Catalysts ◽  
High Surface ◽  
High Surface Area ◽  
Reaction Medium ◽  
Coupling Reactions ◽  
Research Activities ◽  
Ligand Free

: Catalysis is the multidisciplinary field involving many areas of chemistry, notably in organometallic chemistry and materials science. It has great applications in synthesis of many industrially applicable compounds such as fuels and fine chemicals. The activity and selectivity are a key issue in catalysis that generally allied to high surface area. The current research activities mainly deal with the homogeneous and heterogeneous catalysis. Homogeneous and heterogeneous catalysis have certain drawbacks which restricts their application to great extent but have their own advantages. Hence, it has a predominant concern of current research to find out an alternate to overcome their drawbacks. Therefore, it is highly desirable to find a catalytic protocol that offers high selectivity and excellent product yield with quick and easy recovery. Along with their various applications as alternatives to conventional bulk materials nanomaterial have established its great role in different industrial and scientific applications. Nanocatalysis has emerged as new alternative to the conventional homogeneous and heterogeneous catalysis. The nanomaterials are responsible to enhance surface area of the catalyst, which ultimately increases the catalyst reactants contacts. In addition, it acts as robust material and has high surface area like heterogeneous catalysts. Insolubility of such nanomaterial in reaction medium makes them easily separable, hence, catalyst can be easily separate from the product. Hence, it has been proven that nanocatalysts behave like homogeneous as well as heterogeneous catalysts which work as a bridge between the conventional catalytic systems. Considering these merits; researchers has paid their attention towards applications of nanocatalyst in several organic reactions. This review article focused on the catalytic applications of metal nanoparticles (MNPs) such as Pd, Ag, Au, Cu, Pt in ligand free coupling reactions. In addition, it covers applications of bimetallic and multimetallic nanoparticles in ligand free coupling reactions.

Design and Preparation of Heterogeneous Catalysts by Controlled Chemical Reactions with Oxygen and Hydrogen

1994 ◽  
Vol 368 ◽  
Author(s):  
David L. Cocke ◽  
Donald G. Naugle ◽  
Thomas R. Hess
Keyword(s):  
Chemical Reactions ◽  
Heterogeneous Catalysts ◽  
Formation Processes ◽  
Catalytic Systems ◽  
Heterogeneous Catalytic ◽  
Reduction Processes ◽  
Alloy Oxidation ◽  
Reaction Models ◽  
Catalyst Systems ◽  
Insight Into

ABSTRACTChemical reactions of metals and strongly interacting alloys such as Cu-Mn, Ni-Ti, Ni-Hf and Ni-Zr with oxygen and hydrogen play important roles in the preparation, activation, and regeneration of many important heterogeneous catalytic systems involving supported and unsupported metals and alloys. Recent advances in the understanding of metal and alloy oxidation is bringing new insight into the reactive design and activation of bi- and multi-metallic catalysts. By surface studies of oxidation, thermal annealing and reduction of selected alloys and their thin films and reaction layers and products we have been able to delineate the factors which are most important to the oxide formation processes and the oxide reduction processes. Reaction models developed from these results are permitting the design of new catalyst systems and providing long sought understanding to explain specific aspects of well established metallic catalysts.

scholarly journals Evolution of Specific Heat Capacity with Temperature for Typical Supports Used for Heterogeneous Catalysts

Processes ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 911
Author(s):  
Xiaojia Lu ◽  
Yanjun Wang ◽  
Lionel Estel ◽  
Narendra Kumar ◽  
Henrik Grénman ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Heterogeneous Catalysts ◽  
Zeolite 13X ◽  
Heterogeneous Catalytic ◽  
Different Temperatures ◽  
Catalytic Supports ◽  
Specific Heat Capacities ◽  
Calvet Calorimeter

Heterogeneous catalysts are widely used in the chemical industry. Compared with homogeneous catalysts, they can be easily separated from the reaction mixture. To design and optimize an efficient and safe chemical process one needs to calculate the energy balance, implying the need for knowledge of the catalyst’s specific heat capacity. Such values are typically not reported in the literature, especially not the temperature dependence. To fill this gap in knowledge, the specific heat capacities of commonly utilized heterogeneous catalytic supports were measured at different temperatures in a Tian–Calvet calorimeter. The following materials were tested: activated carbon, aluminum oxide, amberlite IR120 (H-form), H-Beta-25, H-Beta-38, H-Y-60, H-ZSM-5-23, H-ZSM-5-280, silicon dioxide, titanium dioxide, and zeolite 13X. Polynomial expressions were successfully fitted to the experimental data.

Nanocrystalline Mesoporous γ-Alumina Powders “UPMC1 Material” Gathers Thermal and Chemical Stability with High Surface Area

2006 ◽  
Vol 18 (22) ◽  
pp. 5238-5243 ◽  
Author(s):  
Cédric Boissière ◽  
Lionel Nicole ◽  
Christelle Gervais ◽  
Florence Babonneau ◽  
Markus Antonietti ◽  
...  
Keyword(s):  
Surface Area ◽  
Chemical Stability ◽  
High Surface ◽  
High Surface Area ◽  
Thermal And Chemical Stability

scholarly journals Microwaves and Heterogeneous Catalysis: A Review on Selected Catalytic Processes

Catalysts ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 246 ◽  
Author(s):  
Vincenzo Palma ◽  
Daniela Barba ◽  
Marta Cortese ◽  
Marco Martino ◽  
Simona Renda ◽  
...  
Keyword(s):  
Heterogeneous Catalysis ◽  
Energy Saving ◽  
Microwave Heating ◽  
Microwave Radiation ◽  
Heterogeneous Catalysts ◽  
Conventional Heating ◽  
Specific Effects ◽  
Natural Choice ◽  
Future Challenges ◽  
Catalyzed Reactions

Since the late 1980s, the scientific community has been attracted to microwave energy as an alternative method of heating, due to the advantages that this technology offers over conventional heating technologies. In fact, differently from these, the microwave heating mechanism is a volumetric process in which heat is generated within the material itself, and, consequently, it can be very rapid and selective. In this way, the microwave-susceptible material can absorb the energy embodied in the microwaves. Application of the microwave heating technique to a chemical process can lead to both a reduction in processing time as well as an increase in the production rate, which is obtained by enhancing the chemical reactions and results in energy saving. The synthesis and sintering of materials by means of microwave radiation has been used for more than 20 years, while, future challenges will be, among others, the development of processes that achieve lower greenhouse gas (e.g., CO2) emissions and discover novel energy-saving catalyzed reactions. A natural choice in such efforts would be the combination of catalysis and microwave radiation. The main aim of this review is to give an overview of microwave applications in the heterogeneous catalysis, including the preparation of catalysts, as well as explore some selected microwave assisted catalytic reactions. The review is divided into three principal topics: (i) introduction to microwave chemistry and microwave materials processing; (ii) description of the loss mechanisms and microwave-specific effects in heterogeneous catalysis; and (iii) applications of microwaves in some selected chemical processes, including the preparation of heterogeneous catalysts.

In situ construction of phenanthroline-based cationic radical porous hybrid polymers for metal-free heterogeneous catalysis

2021 ◽  
Vol 9 (12) ◽  
pp. 7556-7565
Author(s):  
Guojian Chen ◽  
Yadong Zhang ◽  
Ke Liu ◽  
Xiaoqing Liu ◽  
Lei Wu ◽  
...  
Keyword(s):  
Heterogeneous Catalysis ◽  
Heterogeneous Catalysts ◽  
Hybrid Polymers ◽  
Metal Free ◽  
Oxidation Of Sulfides

Constructing phenanthroline-based cationic radical porous hybrid polymers as versatile metal-free heterogeneous catalysts for both oxidation of sulfides and CO2 conversion.

scholarly journals An Overview of Biodiesel Production via Calcium Oxide Based Catalysts: Current State and Perspective

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3950
Author(s):  
Hoora Mazaheri ◽  
Hwai Chyuan Ong ◽  
Zeynab Amini ◽  
Haji Hassan Masjuki ◽  
M. Mofijur ◽  
...  
Keyword(s):  
Heterogeneous Catalysis ◽  
Calcium Oxide ◽  
Heterogeneous Catalysts ◽  
Low Cost ◽  
Biodiesel Production ◽  
Catalyst Synthesis ◽  
Process Improvements ◽  
Current State ◽  
The Common ◽  
Activity Mechanism

Biodiesel is a clean, renewable, liquid fuel that can be used in existing diesel engines without modification as pure or blend. Transesterification (the primary process for biodiesel generation) via heterogeneous catalysis using low-cost waste feedstocks for catalyst synthesis improves the economics of biodiesel production. Heterogeneous catalysts are preferred for the industrial generation of biodiesel due to their robustness and low costs due to the easy separation and relatively higher reusability. Calcium oxides found in abundance in nature, e.g., in seashells and eggshells, are promising candidates for the synthesis of heterogeneous catalysts. However, process improvements are required to design productive calcium oxide-based catalysts at an industrial scale. The current work presents an overview of the biodiesel production advancements using calcium oxide-based catalysts (e.g., pure, supported, and mixed with metal oxides). The review discusses different factors involved in the synthesis of calcium oxide-based catalysts, and the effect of reaction parameters on the biodiesel yield of calcium oxide-based catalysis are studied. Further, the common reactor designs used for the heterogeneous catalysis using calcium oxide-based catalysts are explained. Moreover, the catalytic activity mechanism, challenges and prospects of the application of calcium oxide-based catalysts in biodiesel generation are discussed. The study of calcium oxide-based catalyst should continue to be evaluated for the potential of their application in the commercial sector as they remain the pivotal goal of these studies.

High-performance and thermostable wire supercapacitors using mesoporous activated graphene deposited on continuous multilayer graphene

2021 ◽  
Author(s):  
TaeGyeong Lim ◽  
Ba Trung Ho ◽  
Ji Won Suk
Keyword(s):  
Chemical Stability ◽  
High Performance ◽  
Multilayer Graphene ◽  
Cvd Graphene ◽  
Highly Porous ◽  
Thermal And Chemical Stability

Highly porous activated graphene coated on CVD-graphene/Cu wires enables high-performance wire supercapacitors with enhanced thermal and chemical stability.

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