Development of Magnetizable, Nickel-Ferrite-Decorated Carbon Nanocomposites as Hydrogenation Catalyst for Aniline Synthesis

Catalysts with magnetic properties can be easily recovered from the reaction medium without loss by using a magnetic field, which highly improves their applicability. To design such systems, we have successfully combined the magnetic properties of nickel ferrite nanoparticles with the positive properties of carbon-based catalyst supports. Amine-functionalized NiFe2O4 nanoparticles were deposited on the surfaces of nitrogen-doped bamboo-like carbon nanotubes (N-BCNT) and carbon nanolayers (CNL) by using a coprecipitation process. The magnetizable catalyst supports were decorated by Pd nanoparticles, and their catalytic activity was tested through the hydrogenation of nitrobenzene (NB). By using the prepared catalysts, high nitrobenzene conversion (100% for 120 min at 333 K) and a high aniline yield (99%) were achieved. The Pd/NiFe2O4-CNL catalyst was remarkable in terms of stability during the reuse tests due to the strong interaction formed between the catalytically active metal and its support (the activity was retained during four cycles of 120 min at 333 K). Furthermore, despite the long-lasting mechanical stress, no significant palladium loss (only 0.08 wt%) was detected.

Exploring Hydrogen Sources in Catalytic Transfer Hydrogenation: A Review of Unsaturated Compound Reduction

Catalytic transfer hydrogenation has emerged as a pivotal chemical process with transformative potential in various industries. This review highlights the significance of catalytic transfer hydrogenation, a reaction that facilitates the transfer of hydrogen from one molecule to another, using a distinct molecule as the hydrogen source in the presence of a catalyst. Unlike conventional direct hydrogenation, catalytic transfer hydrogenation offers numerous advantages, such as enhanced safety, cost-effective hydrogen donors, byproduct recyclability, catalyst accessibility, and the potential for catalytic asymmetric transfer hydrogenation, particularly with chiral ligands. Moreover, the diverse range of hydrogen donor molecules utilized in this reaction have been explored, shedding light on their unique properties and their impact on catalytic systems and the mechanism elucidation of some reactions. Alcohols such as methanol and isopropanol are prominent hydrogen donors, demonstrating remarkable efficacy in various reductions. Formic acid offers irreversible hydrogenation, preventing the occurrence of reverse reactions, and is extensively utilized in chiral compound synthesis. Unconventional donors such as 1,4-cyclohexadiene and glycerol have shown a good efficiency in reducing unsaturated compounds, with glycerol additionally serving as a green solvent in some transformations. The compatibility of these donors with various catalysts, substrates, and reaction conditions were all discussed. Furthermore, this paper outlines future trends which include the utilization of biomass-derived hydrogen donors, the exploration of hydrogen storage materials such as metal-organic frameworks (MOFs), catalyst development for enhanced activity and recyclability, and the utilization of eco-friendly solvents such as glycerol and ionic liquids. Innovative heating methods, diverse base materials, and continued research into catalyst-hydrogen donor interactions are aimed to shape the future of catalytic transfer hydrogenation, enhancing its selectivity and efficiency across various industries and applications.

Amberlyst-15 supported zirconium sulfonate as an efficient catalyst for Meerwein-Ponndorf-Verley reductions

The Meerwein-Ponndorf-Verley (MPV) reaction is an important chemoselective route for carbonyl group hydrogenation, and thus designing new and effective catalysts for this transformation remains important and challenging. In this work, a new sulfonate coordinated Zr(IV) catalyst was prepared by the coordination of Zr(IV) onto the sulfonate groups of Amberlyst-15, which can effectively catalyze the MPV reaction and quantitatively convert carbonyl compounds to the corresponding alcohols with high reactivity and stability. Detailed mechanistic investigations reveal that the catalytic performance of Zr-AIER can be attributed to the synergetic effect between Zr⁴⁺ and the sulfonate group, and the porous structure with high surface area.

Gamma radiation-induced synthesis of a novel chitosan/silver/Mn-Mg ferrite nanocomposite and its impact on cadmium accumulation and translocation in brassica plant growth

Herein, a novel chitosan/silver/Mn_0.5Mg_0.5Fe₂O₄ (Cs/Ag/MnMgFe₂O₄) nanocomposite was synthesized with gamma irradiation assistant. The prepared Cs/Ag/MnMgFe₂O₄ nanocomposite was characterized via EDX, XRD, SEM, UV-vis spectroscopy. To evaluate the effects of soak low and high-dose nanocomposite on physiological parameters, photosynthetic pigments, antioxidant and non-antioxidant enzymes of cabbage under Cd stress, a factorial experiment was conducted based on CRD with five replications. The Cd stress decreased the morphological characteristics and photosynthetic pigments while increasing cabbage's antioxidant and non-antioxidant enzymes. The application of low and high-dose of nanocomposite decreased Cd content in leaves by about 42.86%, 60.48%, and the root by approximately 18.72%, 28.72%, respectively, and translocation factors and tolerance index, H₂O₂, O₂, and malondialdehyde. In contrast, the application of high of the nanocomposite increased the values of SPAD chlorophyll about 27.50%, stomatal conductance about 87.18%, net photosynthetic rate about 44.90%, intercellular CO₂ concentration about 32.00%, and transpiration rate about 85.20%, as compared to Cd stress. Furthermore, the application of low and high-dose Cs/Ag/MnMgFe₂O₄ nanocomposite enhances the antioxidant and non-antioxidant enzymes of the cabbage plant compared to Cd stress. Generally, it was conducted that Cs/Ag/MnMgFe₂O₄ nanocomposite can be used as a proper tool for increasing cabbage plants under Cd stress.

Recent catalytic routes for the preparation and the upgrading of biomass derived furfural and 5-hydroxymethylfurfural

Furans represent one of the most important classes of intermediates in the conversion of non-edible lignocellulosic biomass into bio-based chemicals and fuels. At present, bio-furan derivatives are generally obtained from cellulose and hemicellulose fractions of biomass via the acid-catalyzed dehydration of their relative C6-C5 sugars and then converted into a wide range of products. Furfural (FUR) and 5-hydroxymethylfurfural (HMF) are surely the most used furan-based feedstocks since their chemical structure allows the preparation of various high-value-added chemicals. Among several well-established catalytic approaches, hydrogenation and oxygenation processes have been efficiently adopted for upgrading furans; however, harsh reaction conditions are generally required. In this review, we aim to discuss the conversion of biomass derived FUR and HMF through unconventional (transfer hydrogenation, photocatalytic and electrocatalytic) catalytic processes promoted by heterogeneous catalytic systems. The reaction conditions adopted, the chemical nature and the physico-chemical properties of the most employed heterogeneous systems in enhancing the catalytic activity and in driving the selectivity to desired products are presented and compared. At the same time, the latest results in the production of FUR and HMF through novel environmental friendly processes starting from lignocellulose as well as from wastes and by-products obtained in the processing of biomass are also overviewed.

Catalytic transfer hydrogenation of furfural to furfuryl alcohol using easy-to-separate core–shell magnetic zirconium hydroxide

A core–shell magnetic catalyst is applied for the hydrogenation of furfural and other carbonyl compounds using isopropanol as H-donor.

High Performance and Sustainable Copper-Modified Hydroxyapatite Catalysts for Catalytic Transfer Hydrogenation of Furfural

Designing and developing non-noble metal-based heterogeneous catalysts have a substantial importance in biomass conversion. Meerwein-Ponndorf-Verley (MPV) reaction is a significant pathway for eco-friendly catalytic transfer hydrogenation (CTH) of biomass derived furfural into furfuryl alcohol. In this work, a series of copper-supported hydroxyapatite (HAp) catalysts with different copper loadings (2–20 wt.%) were prepared by a facile impregnation method and tested in the reduction of furfural to furfuryl alcohol using 2-propanol as a hydrogen donor. The structural and chemical properties of the synthesised catalysts were analysed by using various techniques (XRD, N2 sorption, SEM, TEM, UV-DRS, ICP, FTIR, TPR, TPD-CO2 and N2O titration). The effect of copper loading was found to be significant on the total performance of the catalysts. The results demonstrate that 5CuHAp catalyst possess highly dispersed copper particles and high basicity compared to all other catalysts. Overall, 5CuHAp exhibited highest conversion (96%) and selectivity (100%) at 140 °C at 4 h time on stream. The optimised reaction conditions were also determined to gain the high activity.

Highly Efficient Cleavage of Ether Bonds in Lignin Models by Transfer Hydrogenolysis over Dual-Functional Ruthenium/Montmorillonite

Cleavage of ether bonds is a crucial but challenging step for lignin valorization. To efficiently realize this transformation, the development of robust catalysts or catalytic systems is required. In this study, montmorillonite (MMT)-supported Ru (denoted as Ru/MMT) is fabricated as a dual-functional heterogeneous catalyst to cleave various types of ether bonds through transfer hydrogenolysis without using any additional acids or bases. The prepared Ru/MMT material is found to efficiently catalyze the cleavage of various lignin models and lignin-derived phenols; cyclohexanes (fuels) and cyclohexanols (key intermediates) are the main products. The synergistic effect between electron-enriched Ru and the acidic sites on MMT contributes to the excellent performance of Ru/MMT. Systematic studies reveal that the reaction proceeds through two possible reaction pathways, including the direct cleavage of ether bonds and the formation of intermediates with one hydrogenated benzene ring, for all examined types of ether bonds, namely, 4-O-5, α-O-4, and β-O-4.

Mg(1-x)CuxFe2O4 superparamagnetic nanoparticles as nano-radiosensitizer agents in radiotherapy of MCF-7 human breast cancer cells

Magnesium-doped copper spinel ferrite superparamagnetic nanoparticles (Mg_(1-x)Cu_xFe₂O₄ SPMNPs, 0.2 ≤ x ≤ 0.8) were successfully synthesized by a hydrothermal method. The cytotoxicity effects and cell viability of MCF-7 on human breast cancer cells pre and post exposure to the Mg_1-xCu_xFe₂O₄ SPMNPs at different concentrations of 0.1, 1, 10 and 100 μg ml^-1 under radiotherapy were studied by MTT (3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide) assay. Here, x-ray diffraction, scanning electron microscopy, atomic force microscopy, UV-visible spectrophotometry, Fourier transform infrared spectroscopy and vibrating-sample magnetometry were evaluated for the crystal structure, morphology, optical and magnetic property of the Mg_(1-x)Cu_xFe₂O₄ SPMNPs. The results showed that the Mg_(1-x)Cu_xFe₂O₄ SPMNPs all at x values had no significant cytotoxicity at concentrations of 0.1,1 and 10 μg ml^-1, but were enhanced by increasing of Cu content. Furthermore, cell destruction of MCF-7 human breast cancer cells post exposure to Mg_(1-x)Cu_xFe₂O₄ SPMNPs under x-ray irradiation was enhanced by increasing the Cu content and concentration. Superparamagnetic properties of the Mg_(1-x)Cu_xFe₂O₄ SPMNPs cause their localization and elimination, by only an external magnetic field. In conclusion, the Mg_(1-x)Cu_xFe₂O₄ SPMNPs with optimum values of x = 0.2 (10 μg ml^-1) and x = 0.6 (1 μg ml^-1) can be considered as a nano-radiosensitizer because of the synergistic treatment effect without cytotoxicity on the MCF-7 cells.

Synchronous role of coupled adsorption and photocatalytic oxidation on the hybrid nanomaterials of pectin and nickel ferrite leads to the excellent removal of toxic dye effluents

Ecofriendly and robust hybrid nanomaterials of pectin and nickel ferrite were succesfully employed for the adsorptive degradation of toxic dye molecules in waste water treatment.

Recent Advances in Catalytic Hydrogenation of Furfural

Furfural has been considered as one of the most promising platform molecules directly derived from biomass. The hydrogenation of furfural is one of the most versatile reactions to upgrade furanic components to biofuels. For instance, it can lead to plenty of downstream products, such as (tetrahydro)furfuryl alcohol, 2-methyl(tetrahydro)furan, lactones, levulinates, cyclopentanone(l), or diols, etc. The aim of this review is to discuss recent advances in the catalytic hydrogenation of furfural towards (tetrahydro)furfuryl alcohol and 2-methyl(tetrahydro)furan in terms of different non-noble metal and noble metal catalytic systems. Reaction mechanisms that are related to the different catalytic materials and reaction conditions are properly discussed. Selective hydrogenation of furfural could be modified not only by varying the types of catalyst (nature of metal, support, and preparation method) and reaction conditions, but also by altering the reaction regime, namely from batch to continuous flow. In any case, furfural catalytic hydrogenation is an open research line, which represents an attractive option for biomass valorization towards valuable chemicals and fuels.

Catalytic Upgrading of Biomass-Derived Sugars with Acidic Nanoporous Materials: Structural Role in Carbon-Chain Length Variation

Shifting from petroleum-based resources to inedible biomass for the production of valuable chemicals and fuels is one of the significant aspects in sustainable chemistry for realizing the sustainable development of our society. Various renowned biobased platform molecules, such as 5-hydroxymethylfurfural, furfural, levulinic acid, and lactic acid, are successfully accessible from the transformation of biobased sugars. To achieve the specific reaction routes, heterogeneous nanoporous acidic materials have served as promising catalysts for the conversion of bio-sugars in the past decade. This Review summarizes advances in various nanoporous acidic materials for bio-sugar conversion, in which the number of carbon atoms is variable and controllable with the assistance of the switchable structure of nanoporous materials. The major focus of this Review is on possible reaction pathways/mechanisms and the relationships between catalyst structure and catalytic performance. Moreover, representative examples of catalytic upgrading of biobased platform molecules to biochemicals and fuels through selective C-C cleavage and coupling strategies over nanoporous acidic materials are also discussed.

Catalytic Transfer Hydrogenation of Biomass-Derived Substrates to Value-Added Chemicals on Dual-Function Catalysts: Opportunities and Challenges

Aqueous-phase hydrodeoxygenation (APH) of bioderived feedstocks into useful chemical building blocks is one the most important processes for biomass conversion. However, several technological challenges, such as elevated reaction temperature (220-280 °C), high H₂ pressure (4-10 MPa), uncontrollable side reactions, and intensive capital investment, have resulted in a bottleneck for the further development of existing APH processes. Catalytic transfer hydrogenation (CTH) under much milder conditions with non-fossil-based H₂ has attracted extensive interest as a result of several advantageous features, including high atom efficiency (≈100 %), low energy intensity, and green H₂ obtained from renewable sources. Typically, CTH can be categorized as internal H₂ transfer (sacrificing small amounts of feedstocks for H₂ generation) and external H₂ transfer from H₂ donors (e.g., alcohols, formic acid). Although the last decade has witnessed a few successful applications of conventional APH technologies, CTH is still relatively new for biomass conversion. Very limited attempts have been made in both academia and industry. Understanding the fundamentals for precise control of catalyst structures is key for tunable dual functionality to combine simultaneous H₂ generation and hydrogenation. Therefore, this Review focuses on the rational design of dual-functionalized catalysts for synchronous H₂ generation and hydrogenation of bio-feedstocks into value-added chemicals through CTH technologies. Most recent studies, published from 2015 to 2018, on the transformation of selected model compounds, including glycerol, xylitol, sorbitol, levulinic acid, hydroxymethylfurfural, furfural, cresol, phenol, and guaiacol, are critically reviewed herein. The relationship between the nanostructures of heterogeneous catalysts and the catalytic activity and selectivity for C-O, C-H, C-C, and O-H bond cleavage are discussed to provide insights into future designs for the atom-economical conversion of biomass into fuels and chemicals.

Hierarchically constructed NiO with improved performance for catalytic transfer hydrogenation of biomass-derived aldehydes

A 3D nanometer-scaled NiO material with urchin-like structure was prepared via a facile route, and served as a highly efficient and durable catalyst for catalytic transfer hydrogenation of bio-based furfural to furfuryl alcohol using 2-propanol as H-donor and solvent.

Nanostructured Metal Catalysts for Selective Hydrogenation and Oxidation of Cellulosic Biomass to Chemicals

Conversion of biomass to chemicals provides essential products to human society from renewable resources. In this context, achieving atom-economical and energy-efficient conversion with high selectivity towards target products remains a key challenge. Recent developments in nanostructured catalysts address this challenge reporting remarkable performances in shape and morphology dependent catalysis by metals on nano scale in energy and environmental applications. In this review, most recent advances in synthesis of heterogeneous nanomaterials, surface characterization and catalytic performances for hydrogenation and oxidation for biorenewables with plausible mechanism have been discussed. The perspectives obtained from this review paper will provide insights into rational design of active, selective and stable catalytic materials for sustainable production of value-added chemicals from biomass resources.

Synthesis and characterization of biofunctional quaternized xylan-Fe2O3 core/shell nanocomposites and modification with polylysine and folic acid

The aims of this study are to prepare quaternized xylan-Fe₂O₃ (QX-Fe₂O₃) core/shell nanocomposites and explore their potential application in the biomedical fields. γ-Fe₂O₃ nanoparticles synthesized by a facile solvothermal process are coated with QX via reverse microemulsion method and further modified by polylysine (PLL) and folic acid (FA) to prepare PLL-QX-Fe₂O₃ and FA-QX-Fe₂O₃ nanoparticles. An obvious strong absorption of γ-Fe₂O₃ at 580 cm^-1 in the spectra of QX-Fe₂O₃ is observed, the Fe element content of QX-Fe₂O₃ is 30-75 μg/mL and the saturation magnetization of QX-Fe₂O₃ nanoparticles is 1.49 emu/g. The γ-Fe₂O₃ and QX-Fe₂O₃ nanoparticles are of regular sphericity with diameter of 50-100 nm and 60-150 nm, respectively. The highest zeta potential of QX-Fe₂O₃ nanoparticles is -41 mV, and the PLL-QX-Fe₂O₃ nanoparticles have a positive potential with a maximum value of 45.2 mV. In addition, FA-QX-Fe₂O₃ showed excellent performance in T₂-weighted Magnetic Resonance (MR) imaging with an r₂ value of 190 mM^-1S^-1. Each nanocomposite has its own inherent properties, which contributes to its versatile utilization and application potential.

Elucidating the reactivity of methoxyphenol positional isomers towards hydrogen-transfer reactions by ATR-IR spectroscopy of the liquid–solid interface of RANEY® Ni

In the presence of Raney® Ni and 2-propanol, guaiacol is orientated parallel to the catalyst surface, whereas 3- and 4-methoxyphenol forms a titled adsorption surface complex.

Functionalised heterogeneous catalysts for sustainable biomass valorisation

Functionalised heterogeneous catalysts show great potentials for efficient valorisation of renewable biomass to value-added chemicals and high-energy density fuels.