Efficient Catalyst Support Research Articles

Unveiling the potential of desert sand-derived mesoporous silica supported nickel-based catalysts for co-production of H2 and carbon nanomaterials via methane cracking

This study investigates the replacement of a costly commercial silicate source with locally abundant desert sand in the United Arab Emirates (UAE), for synthesizing mesoporous silica. Hydrothermal synthesis methods were employed to develop various mesoporous materials having different pore geometries, namely MCM41-S, SBA15-S and MCF-S, using desert sand as a silica source. These materials were then impregnated with 15 wt% NiO (∼13 wt% Ni) by sono-wet impregnation technique. All Ni-based silica supported catalyst demonstrated enhanced stability at 550 °C during the reaction. It was observed that the synthesized MCF-S proves to be a highly efficient catalyst support, as Ni/MCF-S, for the catalytic decomposition of methane (CDM), exhibiting the highest methane conversion (60 %), which is 1.4–2.1 times higher than the Ni-based classic-structured mesoporous siliceous supported catalysts, such as SBA15-S and MCM41-S. In particular, the H2 yield (62 %) of the Ni/MCF-S catalyst was 1.40 and 2.38 times higher than that of the Ni/SBA15-S and Ni/MCM41-S catalysts, respectively. To understand the observed differences, a detailed characterization of the physicochemical properties of these materials was conducted. The results revealed that the macro/mesopores size (4–60 nm) and bimodal sinusoidal pore geometry of MCF-S, played a critical role in enhancing Ni particle dispersion, resulting in the highest active Ni metal surface area (7.66 m2/gcat) and contributing to the improved catalytic activity of Ni catalysts in methane cracking.

Hybrid 1D titanium oxide nanowire – Reduced graphene oxide nanocomposites as efficient catalyst support for PEMFC

With hydrogen being projected as the fuel of the future, proton exchange membrane fuel cells (PEMFC) have regained prominence as a zero-emission power source. Researchers are focusing on replacing the conventional carbon support used for the platinum catalysts with alternative materials to improve the durability of the electrocatalysts. Despite being a potential candidate, graphene-based materials have been limited by their lower limiting current density, possibly due to restacking of the graphene sheets. On this note, we introduced varying quantities of metal-oxide based 1D TiO2 nanowires to reduced graphene oxide (rGO) support and analysed their impact on the performance of the electrocatalyst. The optimized support with an initial content of 60 wt.% GO and 40 wt.% TiO2 exhibited higher mass transfer limiting current density, after Pt incorporation (Pt/TiO2-rGO), in comparison to the other composites. The catalyst showed higher retention in electrochemical surface area (1.42 times) and mass activity (1.48 times) compared to the commercial Pt/C after an accelerated durability test. Polarization studies carried out in a 25 cm2 fuel cell fixture exhibited a peak power density close to 720 mW cm−2 and almost two times higher current density (at 0.6 V) than the catalyst without TiO2. These results reaffirm the role of TiO2 in overcoming the limitations of graphene-based support.

3D-printed Al2O3 framework supported carbon-bridged tri-s-triazine of g-C3N4 for photocatalytic tetracycline oxidation

Powder-like g-C3N4 has been widely used as a photocatalyst but exhibits several drawbacks, including unrecyclable, high charge recombination, and limited light absorption. In this study, carbon-bridged g-C3N4 was successfully prepared and coated on a 3D-printed Al2O3 substrate for the photocatalytic oxidation of tetracycline. Oxamide (OD), malonamide (MD), and succinamide (SD) were used as carbon-containing linkers to react with precursors (melamine and urea) and produce carbon-bridged g-C3N4. Carbon substitution at the bridged N atoms of g-C3N4 improved light absorption, reduced charge recombination, and resulted in high photocatalytic tetracycline removal efficiency. Computational calculations were also employed, and Bader charge analysis supported the charge redistribution and charge transfer of the carbon-bridged g-C3N4 samples. Our results indicated that the degradation of tetracycline followed step-by-step oxidation, deamination, and mineralization to form CO2 and H2O. The 3D-printed Al2O3-supported carbon-bridged g-C3N4 exhibited a high removal rate of 85–90 % and stability for photocatalytic reactions and can be reused for at least 10 cycles. This study demonstrates that the 3D-printed Al2O3-supported carbon-bridged g-C3N4 catalyst is an efficient and effective catalyst support system for photocatalytic reactions.

Hierarchically porous cellulose-based carbon aerogels with N-doped skeletons and encapsulated iron-based catalysts for efficient tetracycline catalytic degradation

Three-dimensional interpenetrating and hierarchically porous carbon material is an efficient catalyst support in water remediation and it is still a daunting challenge to establish the relationship between hierarchically porous structure and catalytic degradation performance. Herein, a highly porous silica (SiO2)/cellulose-based carbon aerogel with iron-based catalyst (FexOy) was fabricated by in-situ synthesis, freeze-drying and pyrolysis, where the addition of SiO2 induced the hierarchically porous morphology and three-dimensional interpenetrating sheet-like network with nitrogen doping. The destruction of cellulose crystalline structure by SiO2 and the iron-catalyzed breakdown of glycosidic bonds synergistically facilitated the formation of electron-rich graphite-like carbon skeleton. The unique microstructure is confirmed to be favorable for the diffusion of reactants and electron transport during catalytic process, thus boosting the catalytic degradation performance of carbon aerogels. As a result, the catalytic degradation efficiency of tetracycline under light irradiation by adding only 5 mg of FexOy/SiO2 cellulose carbon aerogels was as high as 90 % within 60 min, demonstrating the synergistic effect of photocatalysis and Fenton reaction. This ingenious structure design provides new insight into the relationship between hierarchically porous structure of carbon aerogels and their catalytic degradation performance, and opens a new avenue to develop cellulose-based carbon aerogel catalysts with efficient catalytic performance.

Investigating performance of flower-like CoCu-MOF supported on carbon felt as a binder-free anode electrode in direct ethanol fuel cell

Metal-Organic Frameworks (MOFs) have offered a new superior choice for designing the distribution of metal mixtures in carbon substrates for energy applications. Herein, the Co-MOF, Cu-MOF, and CoCu-MOF have been synthesized and characterized by Fourier transformation infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, Brunauer–Emmett–Teller (BET), and X-ray photoelectron spectroscopy (XPS) techniques. The performance of the as-prepared electrocatalysts was studied in ethanol oxidation reaction (EOR) through cyclic voltammetry (CV), chronoamperometry (CA), chronopotentiometry (CP), and electrochemical impedance spectroscopy (EIS) methods. The cyclic voltammetry results showed that CoCu-MOF has a much higher ethanol oxidation current density (9.22 mA cm−2) compared to Co-MOF (0.55 mA cm−2) and Cu-MOF (0.28 mA cm−2). As was expected, all the half-cell electrocatalytic measurement results showed that the CoCu-MOF has higher efficiency and best durability toward EOR. Based on half-cell results and the unique characteristics of carbon felt (CF), CoCu-MOF was arrayed on highly conductive three-dimensional (3D) CF (CoCu–MOF/CF) as support by the in-situ solvothermal method. The CoCu-MOF/CF used as a novel binder-free low cost anode electrode in the direct ethanol fuel cell (DEFC). The result of single-cell studies exhibited that the CoCu-MOF/CF in a DEFC operating at 60°C delivered a 0.865 V open-circuit potential and 22.85 mW cm−2 power density. The structural advantages such as 3D architecture, abundant active sites, and the synergistic effect between Co and Cu resulted in the impressive electrocatalytic activity of CoCu-MOF for EOR behavior. Therefore, this study would open a new facial approach to designing effective MOF-based electrocatalysts as efficient catalyst support for direct liquid fuel cells.

Ni and Fe mixed oxide anchored on CNTs, GONRs, and Ti3C2 Mxene as efficient nanocatalysts for direct power generation from methanol electro-oxidation

In the field of heterogeneous catalysis, the selection of appropriate support is an effective strategy due to metal loading reduction and enhancing electron transfer kinetic. In this work, the performance of carbon nanotubes (CNTs), reduced graphene oxide nanoribbons (rGONRs), and titanium carbide nanosheets (Ti3C2 Mxene) as support was investigated on the catalytic performance of NiFe2O4 spinel nanoparticles. The samples were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, BET surface area analysis, field emission scanning, and transmission electron microscopy. The electrochemical properties of samples as fuel cell catalysts were compared using electrochemical techniques. The electrocatalytic activity of samples in methanol oxidation reaction (MOR) was obtained to be: NiFe2O4/Ti3C2> NiFe2O4/rGONRs > NiFe2O4/CNTs > NiFe2O4. The results approve that the Ti3C2 Mxene promotes the catalytic performance of NiFe2O4 and enhances the methanol oxidation kinetics via conductive pathway creation. Therefore, Ti3C2 can lead to great opportunities as an efficient catalyst support for alcohol fuel cells in the future.

Comparison of the Anode Side Catalyst Supports with and without Incorporation of Liquid Electrolyte Layer on the Performance of a Passive Direct Methanol Fuel Cell

In the passive direct methanol fuel cell (DMFC) operation, the catalyst plays an important role in electrical energy production. Efficient catalyst support increases the power output and simultaneously decreases irreversible losses in the fuel cell (FC). Effective utilization of methanol at the anode end reduces methanol crossover by selecting good anode catalyst supports. In the present study, two types of anode catalyst support of carbon and carbon black are used. The two types of anode catalysts are Pt-Ru/C+ Pt-Ru/black and Pt-Ru/C along with a 2 mm thick liquid electrolyte (LE) layer placed in the middle of the two half MEAs. The LE layer is made of piled hydrophilic filter papers, which are soaked in a solution of 1 M H2SO4 concentration. The methanol concentration is varied from 1 M to 12 M and from 1 M to 5 M with and without LE-inserted FC, respectively. The passive DMFC with Pt-Ru/C+ Pt-Ru/black anode catalyst and the LE layer exhibit the best performance, producing an MPD of 5.328 mWcm-2 at a 5 M methanol concentration. The MPD produced by the anode catalyst of Pt-Ru/C+ Pt-Ru/black and Pt-Ru/C along with the 2 mm thickness LE layer incorporated fuel cell is 75.26% higher than conventional-based FC of anode catalyst of single-layer catalyst of Pt-Ru/C.

Comparative study of the photocatalytic degradation of tetracycline under visible light irradiation using Bi24O31Br11-anchored carbonaceous and silicates catalyst support

Abstract This study compared two hydrothermally synthesized heterojunctions composites, Bi24O31Br10 – carbonaceous (activated carbon from zinc chloride [ACZ], phosphoric acid [ACH], carbonized material [CM]), and Bi24O31Br10 – silicates (SBA-15 and MCM-41), with nanosheets structure. The photocatalytic degradation of tetracycline (TC) was used to evaluate the synergistic influence of the catalyst supports for the corresponding heterojunction composites. The X-Ray diffractometry (XRD), Fourier transform infrared spectroscopy and scanning electron microscopy (SEM) confirmed the synthesis of the Bi24O31Br10 (BOB) – composites. After 120 min of visible LED light photocatalytic reactions, the degradation trend in removal efficiency of TC was BOB-ACZ > BOB > ACH > BOB-CM > BOB-MCM-41 > BOB-SBA-15 > BOB. The study reveals that Bi24O31Br11 – carbonaceous composite exhibits much better degradation efficiency than Bi24O31Br11 – silicates. Crucially, the synergistic surface interaction of ACZ with BOB, and the efficient separation of photogenerated charge carriers, from the SEM, XRD analysis, and photocurrent response, confirmed the photocatalytic enhancement of the heterojunction formation of the BOB-ACZ composite. This study further provides convincing insights on the superiority of carbonaceous nanomaterial to silica materials as efficient catalyst support in catalytic applications.

Cu dispersed ZrO2 catalyst mediated Kolbe- Schmitt carboxylation reaction to 4-hydroxybenzoic acid

The Kolbe-Schmitt reaction is one of the industrially promising route for the production of hydroxybenzoic acids. In the present manuscript, alkali metal hydroxide free, direct carboxylation reaction has been demonstrated over heterogeneous CuO/ZrO2 catalyst. Different basic oxide (ZrO2, TiO2 and Bi2O3) and corresponding Cu dispersed oxides (CuO/ZrO2, CuO/TiO2 and CuO/Bi2O3) were tested for direct carboxylation. The performance of catalysts were elucidated by comparing 4-HBA yield, phenol conversion, TON and TOF. Amongst the tested catalysts, ZrO2 showed highest catalytic activity with TON 0.1022 and TOF 0.0043, hence selected as an efficient catalyst support for Cu dispersion. The lowest value of E-factor (0.12) and PMI (0.39) was obtained for 5 wt% CuO/ZrO2 catalyst. A series of Cu dispersed ZrO2 catalyst were synthesized via simple co-precipitation method with variable Cu precursor loading. Of the tested catalysts 1.25 wt% CuO loaded ZrO2 catalyst showed highest yield (62.57%) and phenol conversion (64.55%) under non-stringent operating condition (60 bar, 170 °C). The in-depth physicochemical characteristion were also conducted by using various analytical tools which dipicted the characterstic properties of CuO/ZrO2 catalyst. The process intensification study was conducted to obtain optimum operating parameters for high yield and conversion. The catalyst recyclability performance study showed the consistency in 4-HBA yield and conversion for four consecutive recycle runs. The plausible reaction mechanism for production of 4-HBA over CuO/ZrO2 catalyst and catalytic cycle has also been proposed. Thus, the present process provides green and efficient route for alkali hydroxide free Kolbe- Schmitt reaction.

Liquid-Metal-Mediated Electrocatalyst Support Engineering toward Enhanced Water Oxidation Reaction.

Functional and robust catalyst supports are vital in the catalysis field, and the development of universal and efficient catalyst support is essential but challenging. Traditional catalyst fabrication methods include the carbonization of ordered templates and high−temperature dehydration. All these methods involve complicated meso−structural disordering and allow little control over morphology. To this end, a eutectic GaInSn alloy (EGaInSn) was proposed and employed as an intermediate to fabricate low−dimensional ordered catalyst support materials. Owing to the lower Gibbs free energy of Ga2O3 compared to certain types of metals (e.g., Al, Mn, Ce, etc.), we found that a skinny layer of metal oxides could be formed and exfoliated into a two−dimensional nanosheet at the interface of liquid metal (LM) and water. As such, EGaInSn was herein employed as a reaction matrix to synthesize a range of two−dimensional catalyst supports with large specific surface areas and structural stability. As a proof−of-concept, Al2O3 and MnO were fabricated with the assistance of LM and were used as catalyst supports for loading Ru, demonstrating enhanced structural stability and overall electrocatalytic performance in the oxygen evolution reaction. This work opens an avenue for the development of functional support materials mediated by LM, which would play a substantial role in electrocatalytic reactions and beyond.

Electrochemical surface activation of commercial tungsten carbide for enhanced electrocatalytic hydrogen evolution and methanol oxidation reactions

The chemistry of electrocatalysts deals with multiple critical factors to facilitate the electrochemical reactions. Among those, the rate limiting depends on electrons transfer for chemisorptions of molecules in redox reactions. This feature can be directly linked with efficient catalyst support material in electrocatalysis. To this end, we have developed a novel, simple and facile route to introduce commercially available material with tuned surface and interface chemistry for their potential applications in fuel cells (FCs) science and technology. Commercial tungsten carbide (WC) was activated by means of electrochemical oxygen reduction reactions (ORR) on different rotation rates to induce mild interactions of oxygen molecules with surface of WC at specified reduction potentials. The X-ray diffraction and X-ray photoelectron spectroscopy analysis before and after the activation confirmed the tuning of WC surface with incorporation of potential factors to activate them for enhanced electrocatalytic activities. In addition, the electrocatalytic methanol oxidation reactions (MOR) and hydrogen evolution reactions (HER) were carried and confirmed the exceptional boosted-up electrocatalytic behaviour of WC after the activation. The enhancement in electrocatalytic mechanism after activation was also tested and proved by means of in-situ FTIR spectroelectrochemical analysis for methanol electro-oxidation. In addition, the electrochemical depositions of Pt nanoparticles were carried out on WC surface before and after the activation to reveal the influence of surface activation for accommodating the foreign particles as support material in electrocatalysis. The results shown two fold enhancement in anodic performance of Pt-modified activated WC catalyst for methanol oxidation reactions and hydrogen evolution reactions in fuel cells.

Palladium Decorated N-Doped Carbon Foam as a Highly Active and Selective Catalyst for Nitrobenzene Hydrogenation.

Carbon foam was synthesized by the carbonization of 4-nitroaniline. The reaction is an alternative of the well-known “carbon snake” (or sugar snake) demonstration experiment, which leads to the formation of nitrogen-doped carbon foils due to its nitrogen content. The synthesized carbon foils were grinded to achieve an efficient catalyst support. Palladium nanoparticles were deposited onto the surface of the support, which showed continuous distribution. The prepared Pd nanoparticle decorated carbon foils showed high catalytic activity in nitrobenzene hydrogenation. By applying the designed catalyst, total nitrobenzene conversion, a 99.1 n/n% aniline yield, and an exceptionally high selectivity (99.8 n/n%) were reached. Furthermore, the catalyst remained active during the reuse tests (four cycles) even without regeneration.

Hexagonal BaTiO(3-x)Hx Oxyhydride as a Water-Durable Catalyst Support for Chemoselective Hydrogenation.

We present heavily H--doped BaTiO(3-x)Hx (x ≈ 1) as an efficient and water-durable catalyst support for Pd nanoparticles applicable to liquid-phase hydrogenation reactions. The BaTiO(3-x)Hx oxyhydride with a hexagonal crystal structure (P63/mmc) was synthesized by the direct reaction of BaH2 and TiO2 at 800 °C under a stream of hydrogen, and the estimated chemical composition was BaTiO2.01H0.96. Density functional theory calculations and magnetic measurements indicated that such heavy H- doping results in a metallic nature with delocalized electrons and a low work function. The potential of BaTiO(3-x)Hx as a catalyst support was examined for the selective hydrogenation of unsaturated C-C bonds by Pd nanoparticles deposited on BaTiO(3-x)Hx. We found that the turnover frequency for phenylacetylene hydrogenation per total amount of Pd in Pd/BaTiO(3-x)Hx was the highest among the supported Pd catalysts reported to date. The strong electronic charge transfer between Pd and the support, as confirmed by X-ray photoelectron spectroscopy measurements, can be attributed to be responsible for such high catalytic activity. The combination of the BaTiO(3-x)Hx support and Pd nanoparticles provides for the selective hydrogenation of unsaturated C-C bonds and highlights the validity of catalyst design that integrates H- in support materials.

Cellulose-supported hyper-crosslinked l-tryptophan as an efficient chiral catalyst support for improved catalytic performance

Catalyst supports were modified using a variety of matrices, and cellulose showed the best modification effect, with an enantioselectivity up to 99% in the asymmetric Henry reaction.

Recent Trends in Graphitic Carbon Nitride-Based Binary and Ternary Heterostructured Electrodes for Photoelectrochemical Water Splitting

The graphitic carbon nitride (g-C3N4) is a class of two-dimensional layered material. The ever-growing research on this fascinating material is due to its unique visible light absorption, surface, electrocatalytic, and other physicochemical properties that can be useful to different energy conversion and storage applications. Photoelectrochemical (PEC) water splitting reaction is one of the promising applications of g-C3N4, wherein it acts as a durable catalyst support material. Very recently, the construction of g-C3N4-based binary and ternary heterostructures exhibited superior PEC water splitting performance owing to its reduced reunion of e-/h+ pairs and the fast transfer of charge carriers at the heterostructure interface. This review compiles the recent advances and challenges on g-C3N4-based heterostructured photocatalysts for the PEC water splitting reaction. After an overview of the available literature, we presume that g-C3N4-based photocatalysts showed enhanced PEC water splitting performance. Therefore, it is believed that these materials have tremendous opportunities to act as durable catalyst support for energy-related applications. However, researchers also considered several limitations and challenges for using C3N4 as an efficient catalyst support material that must be addressed. This review article provides an overview of the fundamental principles of PEC water splitting, the current PEC water splitting research trends on g-C3N4-based binary and ternary heterostructured electrodes with respect to different electrolytes, and the other key factors influencing their photoelectrochemical performance. Finally, the future research direction with several recommendations to improve the photocatalytic efficiency of these materials is also provided at the end.

Synthesis of Hollow Mesoporous TiN Nanostructures as An Efficient Catalyst Support for Methanol Electro-Oxidation

The development of efficient catalyst materials that can drive high catalytic performance is challenging. Here, we report a well-defined hollow mesoporous TiN nanostructure for use as Pt catalyst support material for methanol electro-oxidation. The hollow TiN nanostructure was synthesized by the ammonia nitridation of pre-synthesized mother hollow anatase TiO2, which was prepared by SiO2 template-assisted sol–gel synthesis followed by chemical etching, acid treatment, and sequential calcination. The variation in the ammonia nitridation temperature allowed the crystalline properties of the samples to be finely tuned. As the ammonia nitrification temperature increased, the crystallinity of the resulting hollow TiN continuously increased, and the corresponding Pt catalysts showed enhanced activity toward methanol electro-oxidation. The hollow TiN-800 sample (H-TiN-800), with a well-developed pure TiN phase, exhibited the highest electrical conductivity and the lowest resistance. The corresponding Pt/H-TiN-800 catalyst exhibited significantly enhanced catalytic activity. In this study, we systemically analyzed the physicochemical characteristics and electrochemical performance of hollow TiN samples and their corresponding Pt catalysts.

Sustainable one-pot construction of oxygen-rich nitrogen-doped carbon nanosheets stabilized ultrafine Rh nanoparticles for efficient ammonia borane hydrolysis

Heteroatom-doped porous carbons that possess large surface areas and well-defined porosity show great promise in heterogeneous catalysis, whereas their syntheses inevitably require complicated steps, hazardous activation and functional reagents, and an inert gas atmosphere. Herein, a one-pot synthetic strategy to oxygen-rich porous nitrogen-doped carbon (OPNC) is developed through pyrolysis of ethylenediamine tetra-acetic acid tetra-sodium in air without any activation and functionalization agents. The as-prepared OPNC with more surface oxygenated groups and mesopores not only benefits synthesis of well-dispersed ultrafine Rh nanoparticles (NPs) with abundant accessible active sites, but also facilitates the diffusion of reactants and avoids mass transfer limitations, thereby considerably contributes to a high performance toward AB hydrolysis. Specifically, the optimal Rh/OPNC exhibits a high activity toward AB hydrolysis with a turnover frequency (TOF) of 433 min−1. The kinetic isotope studies indicate that the cleavage of OH bond in H2O molecules is the rate-determining step (RDS). The Rh/OPNC can be reused for five repetitive cycles with approximately 62% remained activity of the first cycle. The catalytic activity of Rh/OPNC can be further improved with a very high TOF of 1201 min−1 in alkaline solution. This study proposes a simple and sustainable pathway to synthesize efficient catalyst support for depositing metal NPs toward AB hydrolysis.

Lignin-Derived Graphene-Like Carbon Nanosheets as an Efficient Catalyst Support for Fischer-Tropsch Synthesis

Bio-renewable lignin has been used as a precursor for the preparation of various carbon materials, such as carbon fibers, ordered mesoporous carbon and graphite carbon cages. Nevertheless, up to now, there are few studies about prepare graphene-like carbon nanosheets derived from lignin. In this study, we synthesized graphene-like carbon nanosheets, using lignin as the precursor, via one-step pyrolysis route. Fortunately, physical and chemical characterization results indicate that it has high pore volume and hierarchical pore with wrinkled sheet graphene structure. Furthermore, the capability of graphene-like carbon nanosheets was investigated as a catalyst support in Fischer-Tropsch synthesis. The results of catalytic evaluation show that Fe₂O₃/GCNs has excellent catalytic activity and the selectivity of lower olefins, compared with Fe₂O₃/AC.

Grafting of Lanthanum Complexes on a Functionalized Graphene Surface: Theoretical Investigation on Ethylene and 1,3-Butadiene Homo- and Co-Polymerization.

In this contribution, we describe the use of graphene as an efficient catalyst support and the role it plays in increasing the Lewis acidity of the supported metal complexes. By a density functional theory study, we show that the [La(N(SiMe3 )2 )3 ] complex can be easily grafted on graphene-OH and -COOH functionalized surfaces. Two stable mono-grafted compounds, (gO)-[La(N(SiMe3 )2 )2 ] and (gOO)-[La(N(SiMe3 )2 )2 ], are formed, behaving as stronger Lewis acids than the previously reported silica grafted analogues. To study the role of the graphene support in catalysis, we also computed the catalytic activity of the alkylated (gO)-[La(CH3 )2 ] and (gOO)-[La(CH3 )2 ] complexes in the ethylene and 1,3-butadiene homo- and co-polymerization reactions. Both compounds are efficient catalysts for the homo-polymerization of the ethylene and 1,3-butadiene. For the 1,3-butadiene homo-polymerization, the stereoselectivity outcome of the reaction differs according to the grafting site. The results computed for the co-polymerization reaction, finally, show that the high stability of the allylic products leads to the formation of block copolymers.

Pd immobilized on hybrid of magnetic graphene quantum dots and cyclodextrin decorated chitosan: An efficient hydrogenation catalyst

Magnetic graphene quantum dots were prepared and incorporated in cyclodextrin decorated chitosan. The resulting hybrid was then palladated and characterized using TEM, BET, TGA, XRD, VSM, ICP and FTIR spectroscopy. Next, the catalytic activity of the prepared hybrid catalyst that benefits from the chemistry of both carbohydrates and magnetic graphene quantum dots was investigated for promoting hydrogenation reaction of nitroarenes in aqueous media under mild reaction condition. The study of the catalyst performance confirmed high catalytic activity and selectivity of the catalyst towards hydrogenation of the nitro group. Moreover, the catalyst could be magnetically separated from the reaction mixture and recycled up to ten reaction runs with a slight loss of the catalytic activity and Pd leaching. These results showed that the hybrid of magnetic graphene quantum dots and carbohydrates is an efficient catalyst support that can be potentially applied for the immobilization of nanoparticles to furnish heterogeneous catalysts for promoting the chemical transformations.