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To handle huge amount of glycerol produced in biodiesel industry, glycerol is transformed to value-added products. In this regard, glycerol acetalization to solketal is industrially attractive. As in this process various by-products can be formed, designing highly selective catalysts is of great importance. In this line, we wish to report a novel catalyst that benefits from strong acidity, high specific surface area and thermal stability, which can selectively form solketal in glycerol acetalization. To prepare the catalyst, hierarchical zeolite was prepared via a novel method, in which partially dealuminated NaY was treated with PluronicF-127 and then reacted with NH4NO3 to furnish the H-form zeolite. Hierarchical faujasite was then achieved through calcination and template removal. Subsequently, it was functionalized with ionic liquid and used for the immobilization of heteropolyacid. The results indicated the importance of the mesoprosity of zeolite and the presense of ionic liquid functionality for achiveing high solketal yield. Moreover, among three investigated heteropolyacids, phosphomolybdic acid exhibited the highest catalytic activity. In fact, using 10 wt% catalyst at 55 °C and glycerol to acetone molar ratio of 1:20, solketal with yield of 98% was furnished under solvent-less condition. Besides, the catalyst was recyclable with low leaching of heteropolyacid. [ABSTRACT FROM AUTHOR]

[Display omitted] • Halloysite and histidine were combined as a bio-based heterogeneous acidic catalyst for converting fructose to HMF. • DFT calculations revealed that histidine-based ionic liquid with halloysite outperform other amino acids catalytically. • NCI plots highlighted the crucial role of hydrogen bonds, favoring histidine over tryptophan due to its higher contribution. • Chemical functionalization of Halloysite with IL significantly improved the catalyst's acidity and catalytic performance. • The catalyst demonstrated high activity under mild conditions and was highly recyclable. In an effort to design a bio-based catalyst with enough acidic strength to promote the conversion of fructose to 5-hydroxymethylfurfural, a series of halloysite clay-supported acidic ionic liquids were considered as potential candidates. The catalysts could be synthesized from reaction of Cl-functionalized halloysite with histidine, histamine, adenine and tryptophan, followed by treatment with chlorosulfuric acid. Predictive computational studies were performed and approved the superior activity of the histidine-based catalyst. In addition, the computational studies aimed to identify the optimal catalyst using Density Functional Theory (DFT) calculations and other characterization techniques, particularly non covalent interactions plots. Aknowledged by computational results, histidine based catalyst was prepared, characterized and its catalytic activity and recyclability were appraised for the synthesis of 5-hydroxymethylfurfural from fructose as a bio-based starting material. The reaction conditions were optimized and it was revealed that using 30 wt% catalyst, the desired product could be achieved at 100 °C within 1 h. Notably, the catalyst exhibited high recyclability and efficiently promoted the reaction of other mono-saccharides as well. [ABSTRACT FROM AUTHOR]

In the world of chemical catalysis and with the importance of being especially in the petrochemical industry, hydrogenation reactions play a central role. Within this framework, the hydrogenation of polyalphaolefins (PAOs) is receiving increasing attention. In this work, for the sake of efficiency and to furnish an efficient support for the immobilization of Pd nanoparticles, a new catalyst containing the 1,3‐diaminopropane (DAP) diamine for the decoration of the halloysite (HNT) outer surface is used. The resulting catalytic system exhibited high activity in the hydrogenation of PAOs and high catalyst recyclability since it could be used for several reaction runs, with no appreciable loss of the catalytic activity and Pd leaching. In addition, the nature of the heterogeneous catalysis was demonstrated by a hot filtration test. Density functional theory (DFT) calculations not only unveil the reaction mechanism, in which the rate determining step was determined mechanistically, but also confirm the best location of the palladium nanoparticles, placed between the diamino ligands in the halloysite surface. Furthermore, the computational simulations rationalize why experimentally the catalytic process requires hydrogen pressure of 7 bar and temperature of 130°C to reach high yield. [ABSTRACT FROM AUTHOR]

Polyalphaolefins (PAOs) are synthetic oils with wide industrial applications. Synthesis of PAOs is fulfilled through oligomerization of α-olefin monomers and hydrogenation of the resultant oil. Oligomerization catalyst is AlCl3 that is toxic and corrosive. To reduce the content of AlCl3, ionic liquid/AlCl3 systems are recently suggested. Hydrogenation is also a catalytic process catalyzed by precious metals. To reduce the required amount of this costly catalyst, precious metals need to be immobilized on a suitable support that can provide uniform dispersion. In this study, a dual-task composite of halloysite clay and ionic liquid is reported that can be used for both oligomerization and hydrogenation processes. In fact, this composite played the role of supported ionic liquid to be applied along with AlCl3 in the 1-octene oligomerization. On the other hand, it was utilized as a support for the immobilization of Pd nanoparticles to give hydrogenation catalyst. The results indicated that the PAO obtained from this catalytic system exhibited extremely uniform microstructure with high long chain branching (74.5%) and VI (147) values. Moreover, examining the catalytic activity of palladated halloysite-ionic liquid composite confirmed that it could assure formation of fine Pd particles with homogeneous metal dispersion. Notably, the catalyst showed high activity under optimized conditions (temperature = 130 °C, hydrogen pressure = 7 bar and catalyst loading = 5 wt%) and rendered the hydrogenated PAO in 98% yield with bromine index of 49 Br/100. Furthermore, the catalyst exhibited high recyclability and slight Pd leaching. [ABSTRACT FROM AUTHOR]

• MOF-encapsulated Keggin catalyst was prepared and then 3D-printed via DLP technique. • The printed catalyst exhibited high catalytic activity and recyclability in Knoevenagel reaction. • Double encapsulation of Keggin in MOF and printed system suppress its leaching dramatically. • Hot filtration test approved heterogeneous nature of catalysis. To address the limitations of metal-organic frameworks for large-scale applications and the challenges associated with the heterogenization of heteropolyacids, we developed a catalytic monolith leveraging the encapsulation concept and 3D-printing technology. In this approach, a Keggin-type heteropolyacid was encapsulated within a Fe-based metal-organic framework through an in-situ method and subsequently incorporated into a 3D printing ink for the fabrication of a catalytic monolith. The monolith underwent comprehensive characterization, elucidating its morphological, structural, and mechanical features. Moreover, the catalytic performance of the 3D-printed monolith was thoroughly evaluated in Knoevenagel condensation reaction, highlighting its remarkable catalytic activity and exceptional recyclability. Characterization of the recycled catalyst, along with a hot filtration test, further confirmed the stability of the catalyst, the suppression of heteropolyacid leaching, and the manifestation of true heterogeneous catalysis. [Display omitted] [ABSTRACT FROM AUTHOR]

5-Hydroxymethylfurfural is a key compound, which is obtained through acid-catalyzed conversion of saccharides. To devise a bio-based catalyst, halloysite nanoclay was utilized and its acidity was improved through a dual approach. More precisely, halloysite was first acid-treated for three distinct periods to give dealuminated samples. It was revealed that acid-treatment affected both acidity and textural features of halloysites based on the reaction time and treatment for 48 h led to sample with the highest acidity and specific surface area. To further increase the acidity of halloysite, chemical modification with bio-based acidic ionic liquid, containing tryptophan and vitamin B7 was conducted. Examination of the catalytic activity of the catalyst for conversion of fructose to 5-hydroxymethylfurfural and optimization of reaction conditions via Response Surface Method confirmed that use of catalyst (21 wt%) at 100 °C led to the formation of the product in 98.8% in 60 min. Noteworthy, the catalyst was highly recyclable up to eight runs and the catalyst could also promote reaction of glucose and galactose efficiently. Kinetic study also affirmed that activation energy was 23.22 kJ/mol. Furthermore, the thermodynamic parameters of enthalpy, entropy and Gibbs free energy values were 22.16 kJ/mol, − 0.17 kJ/mol and 86.32 kJ/mol respectively. • Acid-treatment and chemical modification were combined to improve the acidity of halloysite. • For chemical modification, an acidic ionic liquid containing vitamin B7 and tryptophan was used. • The modified halloysite was applied as an efficient catalyst for conversion of fructose to 5-hydroxymethylfurfural. • According to the RSM results use of catalyst (21 wt%) at 100 °C led to formation of 5-hydroxymethylfurfural in 98.8%. • The catalyst was recyclable and could also promote reaction of glucose efficiently. [ABSTRACT FROM AUTHOR]

1-Butyl-3-vinylimidazolium chloride was synthesized and polymerized with acrylamide to furnish an ionic liquid-containing polymer, which was then used for the formation of a composite with iron-based metal–organic framework. The resultant composite was characterized with XRD, TGA, FE-SEM, FTIR, EDS and elemental mapping analyses and its catalytic activity was appraised for ultrasonic-assisted Knoevenagel condensation. The results confirmed that the prepared composite could promote the reaction efficiently to furnish the corresponding products in high yields in very short reaction times. Moreover, the composite exhibited high recyclability up to six runs. It was also established that the activity of the composite was higher compared to pristine metal–organic framework or polymer. [ABSTRACT FROM AUTHOR]

In this research, a new heterogeneous catalyst is fabricated through covalent modification of iron-based metal–organic framework with ionic liquid. In more detail, using 2-aminoterephthalic acid and iron (III) chloride hexahydrate, amino-functionalized metal–organic framework has been synthesized and then reacted with 2,4,6-trichloro-1,3,5-triazine and 1,4-diazabicyclo[2.2.2]octane successively to furnish ionic liquid on metal–organic framework. The as-prepared catalyst was characterized by FTIR, TGA, BET, SEM/EDS, XRD and elemental mapping analysis and then employed for catalyzing synthesis of pyrano [2,3‐d]pyrimidines (with yields of 80–100%) from one-pot three-component reaction of aldehydes, barbituric acid and malononitrile in aqueous media. The catalytic test inferred high catalytic activity of the catalyst, superior to that of IL and metal–organic framework. Furthermore, the catalyst could be recovered and recycled for five reaction runs with preserving its morphology. [ABSTRACT FROM AUTHOR]

A novel composite has been fabricated by using MOF and chitin as a natural and biocompatible compound. To this purpose, MOF was synthesized by using 2-aminoterephthalic acid and iron (III) chloride hexahydrate and then reacted with Cl-functionalized chitin. The resulting composite was characterized and utilized as a catalyst for degradation of methylene blue both in dark condition and under visible light irradiation. The results indicated superior catalytic activity under visible light irradiation. Furthermore, study of the reaction variables, including basicity, dye concentration and catalyst loading showed that the highest catalytic activity was achieved at basic condition. It was also found that both initial dye concentration and catalyst loading can affect the catalytic activity. To disclose the merits of the composite compared to its individual components, kinetic studies of the photo-degradation process in the presence of the composite, chitin and MOF have been performed. The results confirmed superior activity the composite compared to its components. The study of the mechanism of the reaction using scavengers confirmed that the created holes (h+) are the most effective species in the process of photocatalytic degradation of MB. Notably, the catalyst was recyclable and could be used for degradation of other dyes. [Display omitted] • A novel covalent composite of MOF and chitin is reported. • The composite exhibited high photocatalytic activity for dye degradation. • Chitin plays role in photocatalysis by improving dye adsorption • The activity of the composite was superior to each component. • The kinetic and mechanism of photocatalytic process are investigated. [ABSTRACT FROM AUTHOR]

A novel catalytic nanocomposite, MNPs/Hal‐POSS‐HEMA‐Pd, composed of halloysite nanoclay and polyhedral oligomeric silsesquioxane is reported. To synthesize the catalyst, magnetic halloysite was vinyl functionalized and then polymerized with 2‐hydroxyethyl methacrylate and methacrylate polyhedral oligomeric silsesquioxane. Afterwards, the latter was palladated to furnish a heterogeneous catalyst with use for catalyzing the reductive degradation of organic dyes, Rhodamine B, and methyl orange with NaBH4. The kinetic and thermodynamic parameters of both reactions were estimated. The results asserted that low content of the catalyst could catalyze the dye reduction reactions to furnish hydrogenated product in quantitative conversion in a very short reaction times (1 min). It is assumed that both halloysite and polyhedral oligomeric silsesquioxane can contribute to the anchoring of Pd nanoparticles. On the other hand, the polymeric network around halloysite can furnish a microenvironment for bringing dyes in the vicinity of active sites. Moreover, unique tubular morphology of halloysite can effectively improve dye adsorption and consequently enhance dye reduction. Additionally, the study of the recyclability of the catalyst approved that it could be magnetically recovered and reused for ten successive reaction runs with trivial leach of Pd (2 wt.%) and decrement of the catalytic activity. [ABSTRACT FROM AUTHOR]

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. Unlabelled Image • A novel magnetic catalyst benefiting from carbohydrates and carbon quantum dots has been reported. • Cyclodextrin decorated chitosan was applied as a catalyst support. • The catalyst exhibited high catalytic activity for hydrogenation of nitroarenes in aqueous media. • The catalyst was highly recyclable up to ten reaction runs. [ABSTRACT FROM AUTHOR]

• Using halloysite and k -carrageenan as natural compounds, a novel acidic catalyst is developed. • The catalyst showed excellent catalytic activity for the conversion of fructose to 5-Hydroxymethylfurfural. • Optimization of the reaction variables showed that using 10 wt% catalyst at 100 °C gave the product in 99 % yield in 35 min. • The catalyst was reusable and could be reused for five consecutive runs. • The catalytic composite exhibited superior activity compared to each component. A novel bio-based nanocomposite was designed based on a modification of halloysite with k -carrageenan via precipitation polymerization with acrylic acid in aqueous media. Various techniques such as X-ray diffraction (XRD), infrared spectroscopy (FT-IR), thermo gravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM) were conducted to verify the formation of the catalyst. Afterward, it was tested as a solid acid catalyst for the dehydration of fructose, resulting in the production of 5-hydroxymethylfurfural (HMF). Effective parameters, such as catalyst amount, temperature, and reaction time were optimized and it was revealed that 10 wt% catalysts at 100 °C gave the desired product (HMF, 97.9 % yield) in 35 min. The catalyst was also reusable and could be reused for up to four runs. k -carrageenan as a carbohydrate-containing acidic functionality in the backbone of prepared nanocomposite was successfully applied for improving the catalytic activity of halloysite. Thus, the present protocol can open up an innovative opportunity for the preparation of a bio-based catalytic system from naturally occurring components for the conversion of fructose to 5-hydroxymethylfurfural. [Display omitted] [ABSTRACT FROM AUTHOR]

With the aim of benefiting from the advantage of magnetic catalysts, chemistry of cyclodextrin, i. e. the capability of formation of inclusion complex and acting as phase transferring agent, as well as biochars as biocompatible, cost‐effective and efficient catalyst support, for the first time a ternary hybrid system composed of cyclodextrin nanosponges (CDNS), palladated magnetic carbon quantum dot (Pd@CQDs@Fe) and Bell‐pepper‐derived biochar (Biochar) was designed and prepared through functionalization of CDNS and Biochar and their covalent conjugation followed by immobilization of Pd@CQDs@Fe. The hybrid system was characterized and then applied as a magnetic heterogeneous catalyst for promoting hydrogenation of nitroarenes. The results confirmed high catalytic activity, selectivity and recyclability of the catalyst (up to ten reaction runs) as well as low Pd leaching. Comparing the catalytic activity of the catalyst with some control samples, the contribution of CDNS, Biochar and CQDs@Fe to the catalysis was confirmed. [ABSTRACT FROM AUTHOR]

Abstract For the first time a novel magnetic catalyst was prepared through hybridization of functionalized cyclodextrin nanosponges and octakis(3-chloropropyl)octasilsesquioxane followed by incorporation of Pd and magnetic nanoparticles. The resulting composite, was utilized as an efficient heterogeneous catalyst for promoting Sonogashira and Heck reactions in the absence of any ligand and co-catalyst under mild reaction condition. Comparison of the catalytic activities of the control catalysts and the catalyst confirmed that cyclodextrin nanosponges was more efficient support that cyclodextrin. Moreover, the hybrid catalyst showed superior catalytic activity compared to those obtained from the individual components, indicating the contribution of both hybrid components to the catalysis. Furthermore, it was found that incorporation of magnetic nanoparticles could improve the catalytic performance. The Study of the recyclability of the catalyst showed high recyclability of the catalyst as well as low Pd leaching. Graphical abstract Unlabelled Image Highlights • A hybrid of CDNS and POSS is applied for immobilization of Pd NPs. • The hybrid exhibited high catalytic activity. • The contribution of hybrid components to the catalysis is confirmed. • CDNS contributed to the catalysis via formation of inclusion complex. [ABSTRACT FROM AUTHOR]

Considering the importance of oxidation of allylic C-H bonds in olefins and the unresolved challenging issues, such as long reaction time and the large quantity of catalyst required, and encouraged by the excellent performance of halloysite as a catalyst support, a novel catalytic system was developed to promote this reaction efficiently. To prepare the catalyst, halloysite was first functionalized with ionic liquid then reacted with 2-aminopyrimidine to afford a potential support, Hal-P. The latter was then used for in situ immobilization of Cu(CH3CN)4PF6 and applied to promote the reaction of cycloolefin and tert-butyl p-nitrobenzoperoxoate under mild reaction condition. The results showed that the nature of copper could play an important role in the catalytic activity. Moreover, the presence of ionic liquid and 2-aminopyrimidine in the structure could improve the activity of the final catalyst. Notably, low amounts of catalyst could catalyze the reaction to afford corresponding allylic esters in good yield. It was also found that the reaction was size selective and that cyclic olefins with lower strain could undergo this reaction more effectively. Study of the recyclability of the catalyst confirmed that it was recyclable and could be recovered and recycled for five consecutive reaction runs. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Pd immobilized on magnetic covalent hybrid of GO and g-C 3 N 4 is prepared. • The hybrid was applied as recyclable catalyst for promoting coupling reactions. • It was proved that all the hybrid components contributed to the catalysis. • The hybridization of GO and g-C 3 N 4 could improve the catalytic activity. • The covalent conjugation was significantly more effective than physical mixture. Abstract For the first time a magnetic carbon based hybrid catalyst, Pd@g-C 3 N 4 -Fe-GO, is prepared through covalent conjugation of magnetic graphitic carbon nitride and graphene oxide followed by incorporation of Pd nanoparticles. First, the formation of the catalyst was confirmed via XRD, TG, BET, TEM, FTIR, ICP and VSM analyses and then its catalytic activity for promoting Suzuki and Sonogashira coupling reactions under mild reaction condition was investigated. To elucidate whether hybridization of two carbon materials could improve the catalytic activity, the catalytic activity of the catalyst was compared with the control catalysts (Pd@g-C 3 N 4 -GO, Pd@g-C 3 N 4 -Fe, Pd@ Fe-GO, Pd@g-C 3 N 4 , Pd@GO and the GO/g-C 3 N 4 physical hybrid). Moreover, the role of magnetic nanoparticles in the catalytic performance was confirmed. Notably, the catalytic activities of the catalyst and the control sample prepared via physical hybridization of two carbon materials were compared to confirm the effect of covalent conjugation on the catalytic activity. Moreover, the study of the substituent effect of p -substituted phenyl iodides was considered by Hammett plot, which revealed a beneficial effect of electron-withdrawing side groups for the C C coupling reaction. Finally, the recyclability of Pd@g-C 3 N 4 -Fe-GO as well as leaching of Pd and magnetic nanoparticles was studied. [ABSTRACT FROM AUTHOR]

Halloysite nanoclay, Hal, was amine-functionalized and subsequently reacted with 2,4,6-trichloro-1,3,5-triazine, TCT, and ethylenediamine, EDA, to provide multinitrogen containing functionality on the surface of Hal. The resulting surface-modified Hal, Hal-2N-TCT-EDA, was then used for immobilization of Pd nanoparticles and affording a heterogeneous catalyst, Pd@Hal-2N-TCT-EDA, with utility for copper and ligand-free Sonogashira coupling of alkynes and aryl halides. The results established the efficiency of this protocol in terms of product yield, ecofriendly nature, and reaction time. Study of the reusability of the catalyst confirmed that the catalyst could be recovered and recycled up to seven times with slight loss of catalytic activity and Pd leaching, indicating the efficiency of Hal-2N-TCT-EDA for embedding Pd nanoparticles. To elucidate the role of the number of surface nitrogens on the catalytic performance, the catalytic activity, and recyclability of the catalyst was compared with those of Hal-2N and Hal-2N-TCT. It was found that more surface nitrogen atoms gave higher loading of Pd and lower Pd leaching. This result confirms the contribution of surface nitrogens to anchor the Pd species and suppress leaching. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A novel catalyst, Pd@Hal-CS-SFIL, containing Pd NPs, chitosan, halloysite and ionic liquid is prepared. • The catalyst exhibited high catalytic activity for promoting C C coupling reaction. • The catalyst was highly recyclable with low Pd leaching. • The synergism between chitosan and halloysite is confirmed. • The contribution chitosan, halloysite and ionic liquid to the catalysis is proved. Abstract Taking advantage of biocompatible chitosan (CS), halloysite (Hal) and ionic liquid (IL), a triple hybrid system, Hal-CS-SFIL was designed and prepared via covalent bonding of Cl-functionalized Hal and CS-SFIL. The hybrid system was successfully utilized as a heterogeneous catalyst support for immobilizing Pd nanoparticles. The resulting hybrid catalyst, Pd@Hal-CS-SFIL was used as a heterogeneous catalyst for catalyzing Sonogashira reaction under mild reaction condition. The results showed that this catalyst was efficient. Studying the recyclability of the catalyst confirmed that the catalyst could be recycled for seven reaction runs with slight loss of the catalytic activity and Pd leaching. The role of each hybrid component in the catalysis was confirmed by comparing the catalytic activity of Pd@Hal, Pd@CS, Pd@Hal-CS and Pd@Hal-CS-SFIL. Moreover, the synergism between the components was established by observing the superior catalytic activity of the catalyst with those of Pd@Hal-CS + SFIL, Pd@CS-SFIL+Hal and Pd@Hal + CS-SFIL. [ABSTRACT FROM AUTHOR]

A novel heterogeneous catalyst, CuI supported on sulfur functionalized halloysite (CuI@HNTs-S), was designed and synthesized through functionalization of the halloysite nanoclay surface with 3-mercaptopropyl trimethoxysilane and subsequent immobilization of CuI. The catalyst was characterized by using various characterization techniques such as FTIR, SEM/EDS, XRD, ICP and TGA. The catalytic activity of CuI@HNTs-S for the synthesis of propargylamines through ultrasonic-assisted multi-component A3 coupling reaction of aldehydes, phenyl acetylene and amines was also studied. The results established that CuI@HNTs-S could efficiently catalyze the reaction to furnish the desired products in excellent yield and in short reaction time. Notably the catalyst was recyclable and could be recycled with slight loss of the catalytic activity for five reaction runs. Then, the ability of pristine HNTs and sulfur functionalized HNTs toward CuI grabbing was compared quantitatively using molecular simulation. Calculated energies confirmed better performance of HNTs-S toward CuI physisorption, which decreases its leaching during catalytic reaction. This result was experimentally confirmed by observing the superior recyclability and low copper leaching of CuI@HNTs-S compared to CuI@HNTs. [ABSTRACT FROM AUTHOR]

Taking advantageous of both g‐C3N4 and magnetic core‐shell hollow spheres, for the first time a heterogeneous and magnetically separable hybrid system was prepared through a novel and simple hydrothermal procedure and used for immobilization of bio‐synthesized Ag(0) nanoparticles. The hybrid system was fully characterized by using SEM/EDS, FTIR, VSM, TEM, XRD, TGA, DTGA, ICP‐AES, BET and elemental mapping analysis. The catalytic utility of the obtained system, h‐Fe2O3@SiO2/g‐C3N4/Ag, for promoting ultrasonic‐assisted A3, KA2 coupling reactions and [3 + 2] cycloaddition has been confirmed. The results established that the catalyst could efficiently catalyze the reaction to afford the corresponding products in high yields in short reaction times. The reusability study confirmed that the catalyst could be recovered and reused for at least five reaction runs with only slight loss of the catalytic activity. The hot filtration test also proved low silver leaching, indicating the heterogeneous nature of the catalysis. [ABSTRACT FROM AUTHOR]

Taking advantage of the properties of polyacrylamide (P), the capability of cyclodextrin (CD) to form inclusion complex and outstanding features of halloysite nanoclay as catalyst support, a ternary hybrid system, Hal-P-CD, was designed and synthesized through growing polyacrylamide on the surface of functionalized halloysite nanotubes followed by introduction of β-cyclodextrin. The hybrid system was successfully used for immobilization of Pd nanoparticles and formation of a heterogeneous catalyst, Pd@Hal-P-CD. The structure of Pd@ Hal-P-CD was confirmed by using SEM/EDS, TEM, XRD, BET, ICP-AES, TGA, FTIR and elemental mapping analysis and its catalytic activity was studied for promoting ligand and copper-free Sonogashira coupling reaction in aqueous media (1:1 mixture of water and ethanol). The results established that Pd@Hal-P-CD could catalyze the coupling reaction to afford the desired products in high yields and short reaction times. Notably, the catalytic activity of Pd@Hal-P-CD was superior to those of Pd@Hal-P and Pd@Hal. The study of the reusability of the catalyst up to 7 reaction runs as well as Pd leaching confirmed the heterogeneous nature of the catalysis and the efficiency of Hal-P-CD for suppressing the Pd leaching. Additionally, this catalyst could also be successfully used for promoting Heck coupling reaction. [ABSTRACT FROM AUTHOR]

To circumvent the high solubility and low surface area of heteropolyacid and in attempt to develop a bi-functional heterogeneous catalyst for promoting organic transformations, heteropolyacid was embedded in functionalized SBA-15 and subsequently hybridized with layered double hydroxide. The catalyst could be considered as a bi-functional catalyst with both acidic and basic properties. The acidic properties emerged from the SBA-15 and heteropolyacid component while layered double hydroxide render the catalyst basic. The catalyst was characterized by using SEM/EDX, FT-IR, XRD, ICP-AES, BET and elemental mapping analysis. The catalytic activity of the catalyst was studied for promoting one-pot three-component condensation of aromatic aldehydes, malononitrile or ethyl cyanoacetate and C-H activated acidic molecules in aqueous media for the synthesis of 2-amino-4 H -pyran derivatives. The catalyst exhibited high catalytic activity, which was superior to the previously reported ones. Moreover, the reusability of the catalyst was excellent and the leaching of heteropolyacid was dramatically suppressed. High yields, short reaction times, eco-friendly conditions, simplicity of the procedure, reusability of the catalyst and broad substrate scope are the merits of this protocol. [ABSTRACT FROM AUTHOR]

• Halloysite nanoclay used as a natural support for the immobilization of an acidic ionic liquid by chlorosulfuric acid. • Catalytic conversion of various carbohydrates to 5-hydroxymethylfurfural. • Amino-functionalized halloysite o graft the ionic liquid on the halloysite. • 2,4,6-Trichloro-1,3,5-triazine and 2-aminopyrimidine to form an heterocyclic ligand on halloysite. • Catalyst working under mild reaction conditions, and of high recyclability. Halloysite nanoclay has been used as a natural support for the immobilization of an acidic ionic liquid with multiple acidic sites. To graft the ionic liquid on the halloysite, amino-functionalized halloysite was reacted with 2,4,6-trichloro-1,3,5-triazine and 2-aminopyrimidine successively to form heterocyclic ligand on halloysite, which was then converted to acidic ionic liquids through reaction with chlorosulfuric acid. The resultant catalyst was then characterized via SEM, EDS, and elemental mapping analysis, FTIR, XRD and TGA. Noteworthy, acid-base titration method confirmed that introduction of acidic ionic liquid significantly improved the Brønsted acidity of halloysite. The catalytic activity of the catalyst was investigated for conversion of various carbohydrates to 5-hydroxymethylfurfural. Gratifyingly, the results showed that the catalyst could promote the reaction of fructose, sucrose, glucose and galactose under mild reaction conditions (catalyst (0.03 g), at 85 °C in 70 min) to give the product in high to excellent yields. Computational DFT studies unveiled the reaction mechanism, pointing out the limiting steps kinetically, and in addition how important are the non-covalent interactions. Furthermore, the recycling tests confirmed high recyclability of the catalyst up to six runs. [ABSTRACT FROM AUTHOR]

Three different acidic ionic liquids were covalently grafted on halloysite to give heterogeneous catalysts. The acidity of the catalysts was higher than halloysite and differed based on the nature of ionic liquid. Investigation of the catalytic activity of the catalysts for the synthesis of 5-hydroxymethylfurfural indicates that imidazolium-based ionic liquid showed the highest activity. Using this catalyst (30 wt%), 5-hydroxymethylfurfural was achieved from dehydration of fructose in 88% yield at 85 °C in 73 min. Furthermore, the catalyst was recyclable up to six runs with slight loss of activity. Comparison of the performance of the catalyst with halloysite-free counterpart confirmed the role of halloysite in improvement of the catalytic activity and recyclability. [Display omitted] • Three halloysite-supported acidic ionic liquids have been prepared and used as acidic catalysts. • The Bronsted activity of the catalysts for conversion of carbohydrates to 5-hydroxymethylfurfural has been compared. • Using 30 wt% of the catalyst, 5-hydroxymethylfurfural could be obtained from fructose dehydration at 85 °C in 73 min. [ABSTRACT FROM AUTHOR]

An efficient hybrid catalyst was developed by immobilization of Keggin type heteropolyacid, phosphomolybdic acid, in the nanocavitis of ionic liquid-modified cyclodextrin nanosponges. This immobilized species was characterized by SEM/EDX, FTIR, TGA, ICP-AES and XRD. The catalytic activity of the hybrid catalyst was confirmed in the synthesis of benzochromeno-pyrazole derivatives via cascade reaction of hydrazine hydrate, ethyl acetoacetate, α or β-naphthol and benzaldehyde. To establish the synergetic effects of conjugation of heteropolyacid and ionic liquid, the catalytic activity of the hybrid catalyst was compared with that of bare ionic liquid-modified cyclodextrin nanosponges. The obtained results indicated the superior activity of the former, from different points of view such as product yield and reaction time. Noteworthy, the catalyst was reusable and could be recovered and reused for several reaction runs. The comparison of obtained results with previous reports was performed. Moreover, the potential utility of the catalyst under ultrasonic and microwave irradiation has been proved. [ABSTRACT FROM AUTHOR]

[Display omitted] With the aim of benefiting from the catalytic activity of metal organic frameworks and zeolites and the possible synergistic effect between them, two novel composites, composed of MIL-101 and ZSM-5 zeolites with different SiO 2 /Al 2 O 3 ratios were synthesized via surface functionalization of ZSM-5 zeolites and their hydrothermal treatment with MIL-101 precursors. Characterization of the composites confirmed formation of MIL-101 in the presence of ZSM-5 zeolite. Moreover, it was revealed that the textural properties and acidity of the composite were influenced by SiO 2 /Al 2 O 3 ratio and the one with lower SiO 2 /Al 2 O 3 ratio showed higher acidity. The catalytic activity of the composites was then appraised for Knoevenagel condensation reaction under mild reaction conditions. Gratifying, the composites showed high catalytic activity, higher than their individual components, indicating the synergism between ZSM-5 and MIL-101. Broad substrate scope, facile recovery of the catalyst and its high recyclability were other merits of the present protocol. [ABSTRACT FROM AUTHOR]

[Display omitted] An efficient protocol for hydrofinishing of polyalphaolefins (PAO) under mild condition is developed by applying a novel catalyst. The catalyst was synthesized by successive reaction of amino-functionalized halloysite clay with trichloro-1,3,5-triazine and histidine, followed by palladation. Then, its activity for the hydrogenation of a PAO, obtained from oligomerization of 1-decene, was appraised. It was found that under optimum reaction conditions (at temperature of 130 °C, catalyst loading of 5 wt% and hydrogen pressure of 6 bar), hydrofinishing led to the saturated PAO in 94% yield. Furthermore, the catalyst was recycled up to four runs with insignificant decrement of the catalytic activity and Pd leaching. The kinetic studies indicated that the activation energy, enthalpy, and entropy for this process were as 68.59 kJ mol−1, −66.51 kJ mol−1, and −129.5 J mol−1 K−1, respectively. Hot filtration test was also conducted to approve the heterogeneous nature of the catalysis. [ABSTRACT FROM AUTHOR]

• Using Lemone verbena as bio-source, a novel Se and N-doped biochar is prepared. • 2,4,6-triselenocyanato-1,3,5-triazine was synthesized and applied as N and Se source. • The Se/N-doped biochar is applied as a metal-free catalyst for the oxidation of aldehydes. • The catalyst exhibited high catalytic activity and recyclability. In attempt to develop a metal-free and bio-based catalyst, herein we report a facile procedure for the synthesis of a novel Se and N-doped biochar. In this regard, 2,4,6-triselenocyanato-1,3,5-triazine (TSC-TA) was prepared from reaction of KSeCN and 2,4,6-trichloro-1,3,5-triazine and used as a N and Se source. Lemone verbena, that is an abundant local plant, on the other hand, was applied as bio-source. Carbonization of a mixture of Lemone verbena and TSC-TA (mass ratio of 6:1) led to the formation of Se and N co-doped biochar with graphitic nature. The as-prepared biochar was then utilized as a metal-free catalyst for the oxidation of aromatic aldehydes to their corresponding carboxylic acids under solvent-free condition. The results indicated high catalytic activity of the catalyst, which was superior to non-doped counterpart. Furthermore, the catalyst was recyclable and could be recovered and recycled for seven runs. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel bio-based bead composed of perlite and chitosan is prepared and cross-linked. • The bead was palladated to form a catalyst for decolorization of Methyl orange dye. • The catalyst exhibited high catalytic activity and recyclability up to eight runs. • Via kinetic study, E a , ΔH#, and ΔS# were obtained as 35.98 kJ/mol, 33.44 kJ/mol, −166.22 J/mol.K, respectively. • Overall results confirmed high activity of designed bio-based catalyst in pollutant dye decolorization. Perlite that is a volcanic glass was applied along with chitosan to form chitosan-perlite beads through a facile procedure. The as-prepared beads were then cross-linked with glutaraldehyde and utilized as a bio-based supporting material for the immobilization of Pd nanoparticles via wet impregnation method. The resultant catalyst was characterized via XRD, SEM, TEM, ICP, TGA, FTIR and elemental mapping analysis and its performance was then appraised for decolorization of Methyl orange dye in aqueous media at ambient temperature in the presence of sodium borohydride as a reducing agent. The results established that scant amount of the catalyst, 1.5 mg, could promote the reaction in 2 min to decolorize the dye with yield = 100 %. Using the experimental data, activation energy, enthalpy, and entropy of the decolorization reaction were calculated to be 35.98 kJ/mol, 33.44 kJ/mol, −166.22 J/mol.K, respectively. The catalyst was recyclable up to eight runs with insignificant loss of catalytic activity and Pd leaching. [ABSTRACT FROM AUTHOR]

[Display omitted] • Palladated halloysite was prepared and used for polyalphaolefins hydrogenation. • The effect of acid-treatment of halloysite on its performance was investigated. • It was found that acid treatment affected Pd loading and accessibility of Pd NPs and specific surface area. • The results indicated that non-treated halloysite was more effective than acid-treated ones. In the following of our research on the design of halloysite-based catalysts for polyalphaolefins (PAO)s hydrogenation, herein we investigate the effect of acid-treatment of halloysite on its performance as a support for the immobilization of Pd nanoparticles. To this purpose, pristine halloysite and two acid-treated counterparts, prepared through treatment with sulfuric acid for 9 and 72 h, were palladated to furnish catalysts (Pd/Hal, Pd/Hal-A9, Pd/Hal-A72) for the hydrogenation of PAO oil derived from 1-octene monomer. The characteristics and catalytic activity of the three catalyst samples were compared. The results showed that acid-treatment for long time significantly increases the specific surface area and induces formation of fine particles within the lumen of halloysite. However, it led to the slightly lower loading of Pd particles. Acid-treatment for short time, on the other hand, slightly increased the specific surface area and remarkably decreased Pd loading. The activity of the synthesized catalysts follows the order of Pd/Hal > Pd/Hal-A72 > Pd/Hal-A9, indicating the important role of Pd loading and accessibility of Pd nanoparticles in the catalysis of PAO hydrogenation containing structurally big molecules. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pd nanoparticles supported on functionalized halloysite as a catalyst for hydrofinishing of PAO. • Predictive catalysis by DFT calculations to unveil the best combination between amines and palladium. • Experimental mild conditions for the in silico catalyst choice together with excellent catalytic activity and recyclability. • Hydrogenation of organic substrates. In an attempt to move towards single metal atom catalysis, the functionalization of halloysite with amino-based ligands, where palladium atoms are complexed, is evaluated here as a pathway. The effect of the nature of the aromatic amine is first evaluated by DFT calculations to find the best one. From a series of ten aromatic amine ligands it is discernible which one has the most complexation capacity to the palladium species, analyzing the structural and electronic properties. After this small exercise of predictive catalysis, the catalyst of choice was then synthesized and characterized experimentally, in addition to conducting catalytic studies. Specifically, its efficiency for polyalphaolefin hydrogenation was investigated in different process conditions. Results demonstrate that the synthesized catalyst could promote polyalphaolefin hydrofinishing at optimum catalyst loading, reaction temperature and hydrogen pressure of 5 wt%, 130 °C and 7 bar, respectively to furnish the final product with bromine index of 55 Br/100 in 96 % yield. [ABSTRACT FROM AUTHOR]

A novel magnetic triple composite was synthesized through immobilization of DABCO-based ionic liquid on magnetic carbon quantum dot, followed by conjugation of the resultant compound with a copper-based metal-organic framework (CCDC no. 687690). The as-prepared composite was characterized via FESEM/EDS, XRD, TGA, FTIR, VSM and elemental mapping analysis and utilized as a magnetic catalyst for promoting three-component reaction of malononitrile, dimedone and aldehydes under mild reaction condition to furnish etrahydrobenzo[ b ]pyrans. The catalyst exhibited high catalytic activity and could promote the reaction of various aldehydes with different electronic densities. Moreover, the catalyst could be magnetically collected and successfully reused for five reaction runs with slight loss of the catalytic activity. Notably, comparison of the activity of the catalyst with that of ionic liquid, magnetic carbon quantum dot and metal-organic framework confirmed superior catalytic activity of the former. [Display omitted] • A novel triple composite of IL, MNCQD and MOF is synthesized. • The composite was used as a catalyst for synthesis of tetrahydrobenzo[ b ]pyrans. • The composite exhibited high catalytic activity and recyclability. • The activity of the composite was superior to its components. [ABSTRACT FROM AUTHOR]

Considering the synergism between chitosan and halloysite clay, herein, a novel catalytic composite is designed for promoting hydrogenation of poly alpha-olefin (PAO) oils under mild reaction condition. Briefly, naturally occurring chitosan and halloysite have been used for the formation of chitosan-halloysite beads. The beads were subsequently cross-linked and palladated. The reaction variables for the hydrogenation of PAO have been optimized. Moreover, the effect of chitosan: halloysite mass ratio on the performance of the catalyst has been investigated. It was an important factor that affects morphology, Pd average size and loading. It was also found that using 5 wt % catalyst with chitosan: halloysite mass ratio of 1:1 and hydrogen pressure of 8 bar at 130 °C, hydrogenated product was achieved in 98% yield. High recyclability and heterogeneous nature of the catalyst were also confirmed. Furthermore, comparative study confirmed positive effect of hybridization of halloysite and chitosan on the catalytic activity. [Display omitted] • Cross-linked chitosan-halloysite beads were prepared and palladated. • The palldated beads were used as catalysts for hydrogenation of poly alpha-olefin. • The catalyst exhibited high catalytic activity under relatively mild condition. • The effects of reaction variables and amount of halloysite on the catalytic activity were investigated. • The catalyst was recyclable with low Pd leaching. [ABSTRACT FROM AUTHOR]

A novel thermo-responsive catalyst for the hydrogenation of nitroarenes under mild reaction condition was devised. To prepare the catalyst, a thermo-responsive polymer was first synthesized through the co-polymerization of N-isopropylacrylamide and allylamine and then covalently grafted on the Cl-functionalized perlite. The resulting composite was subsequently utilized as a support for the stabilization of Pd nanoparticles. Investigation of the catalytic activity of the catalyst approved its high catalytic activity at a temperature above the lower critical solution temperature. More precisely, 0.03 g of the catalyst can promote the reaction of 1 mmol of nitro-compounds in H2O/EtOH (1:1) at 45 °C to furnish the corresponding products in 70–100% yields. This issue was assigned to the collapse of the polymeric component and formation of a hydrophobic environment that was beneficial for the mass-transfer of the hydrophobic nitroarenes. Notably, the catalytic activity of the catalyst was higher than that of palladated perlite and thermos-responsive polymer due to the synergistic effects between the perlite and polymeric moiety. Furthermore, the study of the substrate scope confirmed that a wide range of substrates with different steric and electronic properties could tolerate hydrogenation reaction. Moreover, the catalyst was highly selective toward hydrogenation of the nitro group and could be recycled up to seven runs with insignificant Pd leaching and loss of catalytic activity. The hot filtration test also confirmed the heterogeneous nature of the catalysis. [ABSTRACT FROM AUTHOR]

In attempt to develop a biocompatible metal-free catalyst, a dendritic moiety was grown on chitosan through successive reactions with 2,4,6-trichloro-1,3,5-triazine and ethylenediamine. Subsequently, the terminal functional groups of the dendron were decorated with 1-methylimidazolium chloride. The catalyst was characterized with SEM, EDS, TGA, FTIR, XRD and mapping analysis. Then, the catalytic activity of the resultant composite was scrutinized for catalyzing Knoevenagel condensation and synthesis of xanthene derivatives in aqueous media under mild reaction condition. The results confirmed high activity of the catalyst, superior to ionic liquid free counterpart and bare chitosan. This observation was ascribed to the instinct catalytic activity of ionic liquid. Moreover, using control catalysts, it was confirmed that the presence of the dendritic moiety that could increase the content of ionic liquid on the backbone of the catalyst enhanced the catalytic activity. [ABSTRACT FROM AUTHOR]

In this work, with the use of two natural compounds, chitin and sepiolite clay, a novel covalent hybrid is fabricated and applied as a support for the stabilization of silver nanoparticles with the aid of Kombucha extract as a natural reducing agent. The resultant catalytic system, Ag@Sep-N–CH, was characterized via XRD, TEM, FTIR, ICP, SEM, TGA, UV–Vis and BET. It was found that fine Ag(0) nanoparticles with mean diameter of 6.1 ± 1.8 nm were formed on the support and the specific surface area of the catalyst was 130 m2 g−1. The study of the catalytic performance of Ag@Sep-N–CH for catalyzing synthesis of xanthenes in aqueous media under mild reaction condition confirmed that Ag@Sep-N–CH exhibited high catalytic activity and could promote the reaction of various substrates to furnish the corresponding products in high yields. Moreover, the contribution of both chitin and sepiolite to the catalysis has been affirmed. It was found that hybridization of these two components led to synergistic effects and consequently improved the observed catalytic activity. Notably, the catalyst was recyclable up to several reaction runs. [ABSTRACT FROM AUTHOR]

In this study, the best thrichloro-and amine-compounds (i.e. 2,4,6-trichloro-1,3,5-triazine and metformin, respectively) were selected among seven possible candidates by molecular modelling tool for the synthesis of a multi-dentate nitrogen-containing ligand. Besides ligand composition, the type of solvent for Pd immobilization was studied as well. Taking advantage of simulation results, the catalyst was fabricated via amine functionalization of halloysite followed by sequential reactions with 2,4,6-trichloro-1,3,5-triazine and metformin and Pd immobilization. Then, the prepared catalyst was characterized. The results showed that small Pd nanoparticles with a mean diameter of 1.9 ± 0.4 nm were homogeneously dispersed on the functionalized halloysite. The performance of the catalyst was evaluated for the hydrogenation of nitroarenes in aqueous media. The results demonstrated high catalytic activity of the catalyst. Furthermore, the catalyst was reusable for several times with the low loss of performance and Pd leaching. It was also found out that the catalyst was selective towards nitro group reduction and could promote the reaction of steric substrates, too. Unlabelled Image • The best ligand for halloysite functionalization was determined computationally. • Halloysite was functionalized with nitrogen containing ligand and then palladated. • The activity of the catalyst was examined for the hydrogenation of nitroarenes. • The effects of the reaction variables on the yield of the reaction were studied. • The catalyst was recyclable with low Pd leaching. [ABSTRACT FROM AUTHOR]

A novel polymeric network benefiting from the chemistry of imidazolium salt (IL), cyclodextrin (CD) and carbon nanotube (CNT) is fabricated through a multi-step process, in which silica coated CNTs were vinyl functionalized and polymerized with poly (ethylene glycol) dimethacrylate and CD-IL, prepared from the reaction of vinyl imidazole and tosylated CD. The resulting hybrid system, CNT-P, was then used as a support for the immobilization of Pd nanoparticles and furnishing a heterogeneous catalyst, Pd@CNT-P, with the utility for the hydrogenation of nitroarenes in aqueous media. The catalyst exhibited high catalytic activity and selectivity towards hydrogenation of nitro group. Moreover, it was recyclable up to six reaction runs. Comparing the catalytic activity of the catalyst with that of some control catalysts, the contribution of CD-IL and silica coated CNT to the catalysis has been confirmed. It was believed that CD in the backbone of the catalyst could act as a phase transfer agent, while multiple functional groups on the polymeric moiety improved Pd anchoring and suppressed its leaching. Silica coated CNT on the other hand, allowed better dispersion of Pd nanoparticles and assured fine Pd particle size. Unlabelled Image • A functional polymer containing imidazolium salt, CNT and cyclodextrin is prepared. • Palladated polymeric system was used as a heterogeneous hydrogenation catalyst. • The catalyst was selective and recyclable. • Cyclodextrin could act as phase transfer agent to allow the reaction to proceed in water. • Imidazolium salt and CNT improved anchoring and dispersion of Pd nanoparticles. [ABSTRACT FROM AUTHOR]

In attempt to broaden the use of cyclodextrin polymer for catalytic purposes, a novel covalent hybrid system was prepared through growth of multi-nitrogen atom containing polymer (PMelamine) derived from reaction of ethylenediamine and 2,4,6-trichloro-1,3,5-triazine on the functionalized cyclodextrin polymer (CDNS). The resulting hybrid system was then utilized as a catalyst support for the immobilization of silver nanoparticles through using Cuscuta epithymum extract as a naturally-derived reducing agent. The catalytic activity of the catalyst, Ag@CDNS-N/PMelamine, for the synthesis of xanthenes through reaction of aldehydes and dimedone in aqueous media was examined. The results showed high catalytic activity and recyclability of the catalyst. It was believed that cyclodextrin in the backbone of the catalyst could act both as a capping agent for Ag nanoparticles and phase transfer agent to bring the hydrophobic substrates in the vicinity of the catalytic active sites and accelerate the reaction rate. Multi-nitrogen atoms on the polymer, on the other hand, could improve the Ag NPs anchoring and suppress their leaching. [ABSTRACT FROM AUTHOR]

• A novel nanocomposite composed of halloysite and cyclodextrin derived carbon is prepared. • The nanocomposite was palladated and applied as catalyst for hydrogenation reaction. • The catalyst showed high catalytic activity, selectivity and recyclability. • The contribution of both halloysite and carbon material to the catalysis is confirmed. Carbon nanospheres, CCDs, were fabricated using β-cyclodextrin as carbon precursor. The as prepared CCD was then hybridized with halloysite nanotubes (Hal) through hydrothermal treatment to furnish a nanocomposite, Hal-CCD that was subsequently applied as support to stabilize Pd nanoparticles. Investigation of the catalytic activity of palladated nanocomposite, Pd@Hal-CCD, for the hydrogenation reaction of nitrobenzenes confirmed that Pd@Hal-CCD could efficiently promote the hydrogenation reaction under mild reaction condition. Moreover, the catalyst was recyclable and showed slight Pd leaching upon reusing. The comparison of the catalytic activity of Pd@Hal-CCD with that of Pd@Hal and Pd@CCD indicated the superior catalytic activity of the former. The observed high catalytic activity of the catalyst was attributed to its higher Pd loading and water disperse ability. Additionally, the results confirmed that the ratio of Hal:CCD could affect the catalytic activity and the best result was obtained by using Hal:CCD ratio of 1:2. [ABSTRACT FROM AUTHOR]

In this article, a magnetic carbon-coated halloysite nanoclay (Hal) was prepared through introduction of hydrothermally carbonized glucose (Glu) on Hal followed by the immobilization of magnetic nanoparticles (MNPs) and incorporation of resorcinol-formaldehyde polymeric shell (RF) and carbonization. The resulting composite was then successfully applied for the immobilization of Pd nanoparticles to afford Pd@Hal@Glu-Fe-C that could efficiently promote hydrogenation of nitroarenes in the aqueous media at low temperature. The catalyst exhibited high selectivity toward nitro group. Moreover, it was highly recyclable with low MNPs and Pd leaching. To elucidate the contribution of each component of the support to the catalysis, a precise study was carried out by preparing several control catalysts and comparing their catalytic activities with that of Pd@Hal@Glu-Fe-C. Furthermore, the effect of carbon source used for the formation of hydrothermally derived carbon -wrapped Hal and the order of incorporation of metallic nanoparticles on the catalytic activity of the final catalyst was investigated. Unlabelled Image • A novel magnetic carbon-coated halloysite is prepared. • The nanocomposite was applied for the immobilization of Pd nanoparticles. • The palladated nanocomposite exhibited high catalytic activity and recyclability. • The effect of surface modification of halloysite on its activity is confirmed. [ABSTRACT FROM AUTHOR]

β‐Cyclodextrin (β‐CD) and glycidyl methacrylate monomer were polymerized in the presence of functionalized halloysite nanoclay (Hal) to afford a polymeric network (Hal‐P‐CD) containing Hal and CD. Hal‐P‐CD was then applied as a catalyst support for the immobilization of Pd nanoparticles. The resulting nanocomposite, Pd@Hal‐P‐CD, could serve as a catalyst for the hydrogenation of nitrobenzene. The precise study by the preparation of control samples confirmed the contribution of CD as both phase transfer and capping agent, P (polymer) and Hal to the catalysis. Moreover, the results confirmed the importance of CD: glycidyl methacrylate monomer ratio. Pd@Hal‐P‐CD was also carbonized to prepare Pd@Hal‐C. Notably, the characterization of Pd@Hal‐C showed that carbonization led to the growth of mean diameter of Pd nanoparticles, increase of Pd content and partial destruction of Hal. However, the catalytic activity of Pd@Hal‐C was superior to Pd@Hal‐P‐CD. Pd@Hal‐C was also highly recyclable and could be recovered and recycled for several reaction runs. The study of the carbonization temperature showed that this factor affected the nature of the resulting carbon and the catalyst prepared at elevated temperature showed higher catalytic activity. [ABSTRACT FROM AUTHOR]

Taking advantage of computational chemistry, the best diamine for the synthesis of a multi‐dentate ligand from the reaction with 3‐(trimethoxysilyl) propylisocyanate (TEPI) was selected. Actually, predictive Density Functional Theory (DFT) calculations provided the right diamino chain, i.e. ethylenediamine, capable to sequester a palladium atom, together with the relatively polar solvent toluene, and then undergo the experiments as a selective catalytic agent. The ligand was then prepared and applied for the decoration of the halloysite (Hal) outer surface to furnish an efficient support for the immobilization of Pd nanoparticles. The resulting catalyst exhibited high catalytic activity for hydrogenation of nitroarenes. Moreover, it showed high selectivity towards nitro functional group. The study of the catalyst recyclability confirmed that the catalyst could be recycled for several reaction runs with only slight loss of the catalytic activity and Pd leaching. Hot filtration test also proved the heterogeneous nature of the catalysis. [ABSTRACT FROM AUTHOR]

• HNTs are successfully functionalized with APTES, TCT, and l -arginine. • F-HNTs resulted in an increased deposition of HSiW and a marked reduction in leaching. • Depositing HSiW onto F-HNTs resulted in high catalytic activity in fructose-to-5-HMF. • HSiW@F-HNTs showed exceptional recyclability, achieving a 5-HMF yield exceeding 90 %. 5-Hydroxymethylfurfural (5-HMF) is a valuable organic compound commonly derived from sugars such as fructose and glucose. Silicotungstic acid (HSiW), a unique Keggin-type heteropolyacid, is a typical catalyst for organic compound production. To synthesize 5-HMF from fructose, we developed a novel catalyst, HSiW@F-HNTs, by combining HSiW and functionalized halloysite nanotubes (F-HNTs) modified with (3-amino-propyl) triethoxysilane (APTES), 2,4,6-trichloro-1,3,5-triazine (TCT), and l -arginine. We analyzed the physicochemical properties of HSiW@F-HNTs using the FT-IR, XRD, BET, FESEM, EDS, and XPS characterization techniques, confirming their suitability for fructose-to-5-HMF conversion. Through response surface methodology (RSM), we investigated and optimized the effects of reaction conditions on 5-HMF production yield. Optimal conditions were found to be a 102 °C reaction temperature, a 65 min reaction time, and an 8.5 wt.% catalyst loading, resulting in a 95 % yield of fructose-to-5-HMF conversion. We also conducted the kinetic and thermodynamic analyses to determine the reaction rate and activation energy (Ea) and estimate the changes in Gibbs free energy (Δ G), enthalpy (Δ H), and entropy (Δ S) of the catalytic conversion reaction. Additionally, the prepared HSiW@F-HNTs catalyst could be recycled up to 9 times without a significant loss in activity, demonstrating its high stability for real-world applications. [Display omitted] [ABSTRACT FROM AUTHOR]

This study investigated the feasibility of using calcined Salmon fish bone wastes as an inexpensive and reusable catalyst-support for the biodiesel production via transesterification of sunflower oil. In this venue, a series of catalysts were synthesized by impregnating potassium hydroxide (KOH) onto the calcined Salmon fish bones. The as-prepared catalysts were characterized through several techniques, including the FESEM, BET-BJH, TGA, FT-IR, and XRD. In this regard, the effects of the calcination temperature of the waste Salmon fish bone, KOH loading amount, and the calcination temperature of KOH-impregnated support upon the catalytic activity of the final catalyst were understudied. Results displayed that the calcination temperature of fish bones at 1273 K with 40 wt% of KOH loading, which was calcined at 873 K, led to the highest catalytic performance. For this optimum material, the effects of the parameters, such as the catalyst loading, the methanol: oil molar ratio, and the reaction time and temperature upon the biodiesel production yield were examined. It was determined that the optimum operating conditions for the reaction included the catalyst loading of 10 wt%, the methanol: oil molar ratio of 10:1, and the reaction temperature of 338 K for 3 h. The gas chromatography and 1HNMR analyses revealed an optimum biodiesel production yield of 99.13 %. This result is attributed in part to a rather high basicity of the aforementioned optimum material. Moreover, this optimum species was shown to endure four consecutive reaction cycles, whereas its activity dropped by about 10 %. Furthermore, the chemical kinetic parameters of the reaction using this catalyst were determined to be; the reaction rate constant of 0.45 h−1 and its respective activation energy of 67.01 kJ/mol. Ultimately, it was demonstrated that neither internal nor external mass transfer limitations existed in the heterogeneous system considered in this research hence, all observed behaviors were solely due to chemical kinetics. [Display omitted] • Using waste Salmon fish bone as effective catalyst support for biodiesel synthesis. • Optimized support's calcination T, catalyst wt.%, MeOH:oil ratio and Rxn. t and T. • Optimized KOH of catalyst to 40 wt% at Calcination T of 873 K to get 99.13 % yield. • Rxn. kinetics, with rate constant of 0.45 h−1 and E act of 67.01 kJ/mol determined. [ABSTRACT FROM AUTHOR]

The oxidation of 5-hydroxymethylfurfural (HMF) to 2, 5-diformylfuran (DFF) is an important reaction for the conversion of renewable biomass into feedstock chemicals. In this work, palygorskite (Pal)-supported ruthenium (Ru) catalysts were developed for the efficient selective oxidation of HMF to DFF. Using natural clay mineral palygorskite as the support enabled the immobilization and dispersion of Ru nanoparticles. A 100% HMF conversion, 98% DFF yield, and 98% DFF selectivity were obtained over Ru(III)/Pal catalyst after 4.5 h under the optimal reaction conditions at 110 °C and 10 bar of O 2 in toluene. Ru nanoparticles and palygorskite synergistically achieve the excellent catalytic performance of the catalyst. The Ru metal active sites facilitate the activation of the reactants or intermediates, accelerating the formation of DFF. Furthermore, due to their different particle sizes and Ru species, the Ru(III)/Pal catalyst exhibits higher catalytic activity than the Ru(0)/Pal catalyst for the oxidation of HMF to DFF. The palygorskite-enhanced dispersion effect on Ru nanoparticles augments the catalytic activity. Moreover, the palygorskite-supported Ru catalyst showed good stability and was reused for at least five times consecutive cycles without significant loss of its catalytic activity. • Natural palygorskite (Pal)-supported ruthenium (Ru) catalysts are synthesized. • Ru(III)/Pal exhibits higher activity with 98% 2,5-diformylfuran yield than Ru(0)/Pal. • Palygorskite enables high dispersion of Ru particles, enhancing catalytic activity. [ABSTRACT FROM AUTHOR]

Aerobic oxidation of biomass-derived 5-hydroxymethylfurfural (HMF) to 2, 5-furandicarboxylic acid (FDCA) is an important reaction for producing green and sustainable chemicals. Herein, natural clay mineral palygorskite (Pal)-supported bimetallic Pt–Pd catalyst for the oxidation of HMF to FDCA in water without the addition of any bases was developed. The 1Pt 9 Pd 1 /Pal catalyst with Pt/Pd molar ratio of 9/1 exhibited excellent catalytic performance, and 100% HMF conversion and 99% FDCA yield were obtained under optimum reaction conditions after 12 h, which was mainly attributed to the synergy between palygorskite and bimetallic Pt–Pd nanoparticles. Palygorskite used as support realized the immobilization and dispersion of bimetallic nanoparticles, increasing the catalytic activity. The basicity of palygorskite and alloying effects between Pt and Pd facilitated the formation of FDCA by synergistically catalyzing the oxidation of alcohol and aldehyde groups in the reactants and intermediates. Furthermore, this catalyst showed good stability and reusability. The present work provides a highly efficient, cost-effective, and environmentally benign catalyst for the base-free oxidation of HMF to FDCA in practical industrial applications. • Efficient palygorskite-supported bimetallic Pt–Pd catalyst is synthesized. • The catalyst exhibits high activity for the base-free oxidation of 5-hydroxymethylfurfural to 2, 5-furandicarboxylic acid. • The basicity of palygorskite and the alloying effect facilitate the formation of 2, 5-furandicarboxylic acid. [ABSTRACT FROM AUTHOR]

[Display omitted] • AlCl 3 supported on functionalized halloysite with a ionic liquid as a catalyst. • Synthesis of ionic liquids to support AlCl 3 and experimental and DFT calculations characterization. • Synthesis of polyisobutylene. • Experimental mild conditions together with excellent catalytic activity. Ionic liquid based systems are used to facilitate the cationic polymerization of isobutylene to conventional grade polyisobutylene (PIB) using AlCl 3 as an initiator. Specifically, the compound 1-butyl-3-methylimidazolium chloride (IL) is employed as a reference system due to its simplicity, as well as the polyionic liquid (PIL), prepared via radical polymerization of 1-butyl-3-vinylimidazolium chloride, and the halloysite clay (Hal) supported ionic liquid (S-IL). The overall results stated that the designed AlCl 3 /S-IL initiator system can be used as a safer and greener alternative to the industrially used BF 3 system, in the development of isobutylene polymerizations under mild reaction conditions to conventional grade PIB for viscosity improvement applications. The microstructure and final properties of the as-synthesized PIB was unraveled and compared to Indopole 2100, as a commercial PIB. DFT calculations were performed to understand the different performance of IL and PIL with respect to the S-IL system, and also to show why the catalyst loading for the latter system is lower, as well as to understand how each of the three systems sequesters the catalyst AlCl 3. Since the interaction is non-covalent or ionic, in addition to NBO charges, NCI plots were also used. [ABSTRACT FROM AUTHOR]