Conversion of Limonene over Heterogeneous Catalysis: An Overview

2021 ◽  
Vol 18 ◽  
Author(s):  
Ravi Tomar ◽  
Swati Jain ◽  
Purnima yadav ◽  
Tanima Bajaj ◽  
Fatemeh Mohajer ◽  
...  
Keyword(s):  
Heterogeneous Catalysis ◽  
Essential Oils ◽  
Heterogeneous Catalysts ◽  
Low Cost ◽  
Citrus Fruits ◽  
Catalytic Systems ◽  
Low Toxicity ◽  
The Subject ◽  
Valuable Compounds ◽  
Intense Research

: The natural terpene limonene is widely found in nature. The (R)-limonene (the most abundant enantiomer) is present in the essential oils of lemon, orange, and other citrus fruits, while the (S)-limonene is found in peppermint and the racemate in turpentine oil. Limonene is a low-cost, low toxicity biodegradable terpene present in agricultural wastes derived from citrus peels. The products obtained from the conversion of limonene are valuable compounds widely used as additives for food, cosmetics, or pharmaceuticals. The conversion of limonene to produce different products has been the subject of intense research, mainly with the objective to improve catalytic systems. This review focused on the application of heterogeneous catalysts in the catalytic conversion of limonene.

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.

scholarly journals Evaluation of Nitroxide Radical Catalyst Activity in C-H Activation Step of the Oxidative Coupling between 9,10-Dihydroacridine and Nitromethane

2019 ◽  
Vol 31 (9) ◽  
pp. 2107-2110 ◽  
Author(s):  
Kousuke Iwasaki ◽  
Yamazaki Yudai ◽  
Hiroaki Gotoh
Keyword(s):  
Oxidative Coupling ◽  
Research Effort ◽  
Catalyst Activity ◽  
Coupling Reaction ◽  
Nitroxide Radical ◽  
Activation Reaction ◽  
Low Toxicity ◽  
The Subject ◽  
Stable Radicals ◽  
Intense Research

Organocatalysts have been the subject of intense research effort because of their low toxicity, facile handling, and eco-friendly characteristics. Recently, the development of C-H activation reaction using organocatalysts has also been studied. Herein, we report the studies on the oxidative coupling of 9,10-dihydroacridine and nitromethane using a series of stable radicals. tert-Butyl(10-phenyl-9-anthryl)nitroxide was found to be an optimal catalyst for the coupling reaction.

Carbon Nanocomposites: The Potential Heterogeneous Catalysts for Organic Transformations

2020 ◽  
Vol 24 ◽  
Author(s):  
Ambika ◽  
Pradeep Pratap Singh
Keyword(s):  
Heterogeneous Catalysis ◽  
Environmental Remediation ◽  
High Stability ◽  
Heterogeneous Catalysts ◽  
Low Cost ◽  
Chemical Properties ◽  
Organic Transformations ◽  
Wide Availability ◽  
Physical And Chemical ◽  
Carbon Based

: One of the major challenges in chemistry confronted by the chemists is the replacement of conventional homogeneous catalysts by heterogeneous catalysts for the development of green, sustainable and economical chemical processes. Recently, carbon based nanocomposites have attracted the attention of scientists due to their unique physical and chemical properties such as large surface area and pore volume, chemical inertness, high stability and high electrical conductivity. These NCs have been employed in energy storage, electronic devices, sensors, environmental remediation etc. Owing to the wide availability and low cost, carbon‐based‐materials have been utilized as supports for transition metals and other materials. The carbon based NCs offers a number of advantages such as high stability, easy recovery, reusability with often minimal leaching of metal ions, and green and sustainable approaches to heterogeneous catalysis for various organic transformations. Hence, they can be used as the substitute of the existing catalyst used for heterogeneous catalysis in industries. In this review, various processing methods for carbon based nanocomposites and their applications as heterogeneous catalyst for organic transformations like hydrogenation, oxidation, coupling, and multi‐component reactions, have been discussed.

Nano Phytomedicine Based Delivery System for CNS Disease

2020 ◽  
Vol 21 (9) ◽  
pp. 661-673 ◽  
Author(s):  
Mohammed Asadullah Jahangir ◽  
Chettupalli Anand ◽  
Abdul Muheem ◽  
Sadaf Jamal Gilani ◽  
Mohamad Taleuzzaman ◽  
...  
Keyword(s):  
Herbal Medicine ◽  
Low Cost ◽  
Herbal Medicines ◽  
Herbal Drugs ◽  
Widespread Acceptance ◽  
The Central Nervous System ◽  
Low Toxicity ◽  
Ancient Times ◽  
Plant Sources ◽  
Herbal Formulations

Herbal medicines are being used since ancient times and are an important part of the alternative and traditional medicinal system. In recent decades, scientists are embracing herbal medicines based on the fact that a number of drugs that are currently in use are derived directly or indirectly from plant sources. Moreover, herbal drugs have lesser side effects, albeit are potentially strong therapeutic agents. The herbal medicine market is estimated to be around US $62 billion globally. Herbal medicine has gained widespread acceptance due to its low toxicity, low cost, ease of accessibility and efficacy in treating difficult diseases. Safety and efficacy are another important factors in the commercialization process of herbal medicines. Nanotechnology has been shown to be potentially effective in improving the bioactivity and bioavailability of herbal medicines. Development of nano-phytomedicines (or by reducing the size of phytomedicine), attaching polymers with phytomedicines and modifying the surface properties of herbal drugs, have increased the solubility, permeability and eventually the bioavailability of herbal formulations. Novel formulations such as niosomes, liposomes, nanospheres, phytosomes etc., can be exploited in this area. This article reviews herbal medicines, which have prominent activity in the Central Nervous System (CNS) disorders and reported nano-phytomedicines based delivery systems.

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.

scholarly journals A simple approach to prepare fluorescent molecularly imprinted nanoparticles

RSC Advances ◽  
2021 ◽  
Vol 11 (13) ◽  
pp. 7732-7737
Author(s):  
Fenying Wang ◽  
Dan Wang ◽  
Tingting Wang ◽  
Yu Jin ◽  
Baoping Ling ◽  
...  
Keyword(s):  
High Performance ◽  
Low Cost ◽  
Sol Gel ◽  
Silica Sol ◽  
Simple Approach ◽  
Imprinted Polymer ◽  
Molecularly Imprinted ◽  
Low Toxicity ◽  
Good Biocompatibility ◽  
Molecularly Imprinted Nanoparticles

Fluorescent molecularly imprinted polymer (FMIP) gains great attention in many fields due to their low cost, good biocompatibility and low toxicity. Here, a high-performance FMIP was prepared based on the autocatalytic silica sol–gel reaction.

scholarly journals The Use of Essential Oils from Thyme, Sage and Peppermint against Colletotrichum acutatum

Plants ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 114
Author(s):  
Armina Morkeliūnė ◽  
Neringa Rasiukevičiūtė ◽  
Lina Šernaitė ◽  
Alma Valiuškaitė
Keyword(s):  
Essential Oils ◽  
Fungal Pathogens ◽  
Control Plant ◽  
Antimicrobial Activities ◽  
Plant Diseases ◽  
Colletotrichum Acutatum ◽  
Low Toxicity ◽  
Colletotrichum Spp ◽  
Biological Protection

The Colletotrichum spp. is a significant strawberry pathogen causing yield losses of up to 50%. The most common method to control plant diseases is through the use of chemical fungicides. The findings of plants antimicrobial activities, low toxicity, and biodegradability of essential oils (EO), make them suitable for biological protection against fungal pathogens. The aim is to evaluate the inhibition of Colletotrichum acutatum by thyme, sage, and peppermint EO in vitro on detached strawberry leaves and determine EO chemical composition. Our results revealed that the dominant compound of thyme was thymol 41.35%, peppermint: menthone 44.56%, sage: α,β-thujone 34.45%, and camphor: 20.46%. Thyme EO inhibited C. acutatum completely above 200 μL L−1 concentration in vitro. Peppermint and sage EO reduced mycelial growth of C. acutatum. In addition, in vitro, results are promising for biological control. The detached strawberry leaves experiments showed that disease reduction 4 days after inoculation was 15.8% at 1000 μL L−1 of peppermint EO and 5.3% at 800 μL L−1 of thyme compared with control. Our findings could potentially help to manage C. acutatum; however, the detached strawberry leaves assay showed that EO efficacy was relatively low on tested concentrations and should be increased.

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.

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.

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