Biochar-Based Graphitic Carbon Nitride Adorned with Ionic Liquid Containing Acidic Polymer: A Versatile, Non-Metallic Catalyst for Acid Catalyzed Reaction

A novel biochar-based graphitic carbon nitride was prepared through calcination of Zinnia grandiflora petals and urea. To provide acidic and ionic-liquid functionalities on the prepared carbon, the resultant biochar-based graphitic carbon nitride was vinyl functionalized and polymerized with 2-acrylamido-2-methyl-1-propanesulfonic acid, acrylic acid and the as-prepared 1-vinyl-3-butylimidazolium chloride. The final catalytic system that benefits from both acidic (–COOH and –SO3H) and ionic-liquid functionalities was applied as a versatile, metal-free catalyst for promoting some model acid catalyzed reactions such as Knoevenagel condensation and Biginelli reaction in aqueous media under a very mild reaction condition. The results confirmed high activity of the catalyst. Broad substrate scope and recyclability and stability of the catalyst were other merits of the developed protocols. Comparative experiments also indicated that both acidic and ionic-liquid functionalities on the catalyst participated in the catalysis

k-carrageenan nanocomposite as an efficient acidic bio-based catalyst for the synthesis of 5-hydroxymethylfurfural from fructose

International audienceA 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

Pd on poly(1-vinylimidazole) decorated magnetic S-doped grafitic carbon nitride: an efficient catalyst for catalytic reduction of organic dyes

Abstract A novel magnetic catalyst, (SGCN/Fe3O4/PVIs/Pd) was synthesized by growing of poly(1-vinylimidazole) on the surface of ionic liquid decorated magnetic S-doped graphitic carbon nitride, followed by stabilization of palladium nanoparticles. Catalytic activity of the prepared heterogeneous catalyst was explored for the catalytic reduction of hazardous dyes, methyl orange and Rhodamine B, in the presence of NaBH4. Besides, the effects of the reaction variables on the catalytic activity were investigated in detail. The kinetics study established that dye reduction was the first order reaction and the apparent activation energy was calculated to be 72.63 kJ/mol and 68.35 kJ/mol1 for methyl orange and Rhodamine B dyes, respectively. Moreover, ΔS# and ΔH# values for methyl orange were found to be − 33.67 J/mol K and 68.39 kJ/mol respectively. These values for Rhodamine B were − 45.62 J/mol K and 65.92 kJ/mol. The recycling test verified that the catalyst possessed good stability and reusability, thereby making it a good candidate for the catalytic purposes. Furthermore, a possible catalytic mechanism for dye catalytic reduction over SGCN/Fe3O4/PVIs/Pd was proposed

Sulfonic acid-functionalized chitosan–metal–organic framework composite for efficient and rapid conversion of fructose to 5-hydroxymethylfurfural

Abstract In pursuit of designing a bio-based catalyst for the dehydration of biomass (i.e., fructose) to 5-hydroxymethylfurfural, a novel catalytic composite was prepared by in-situ formation of an Al-based metal–organic framework in the presence of chitosan. To enhance the acidity of the as-prepared catalyst, it was sulfonated with chlorosulfonic acid. Various characterization techniques, including XRD, XPS, FTIR, SEM/EDX, TGA, and elemental mapping analysis were applied to validate the formation of the acidic composite. Fructose dehydration conditions were also optimized using Response Surface Method (RSM) and it was found that reaction in the presence of catalyst (23 wt%) in DMSO, at 110 °C for 40 min led to the formation of HMF in 97.1%. Noteworthy, the catalyst was recyclable and stable up to five runs with a minor reduction in its activity

Heteropolyacid supported on ionic liquid decorated hierarchical faujasite zeolite as an efficient catalyst for glycerol acetalization to solketal

Abstract 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

Palladated cyclodextrin and halloysite containing polymer and its carbonized form as efficient hydrogenation catalysts

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Ag Nanoparticles Stabilized on Cyclodextrin Polymer Decorated with Multi-Nitrogen Atom Containing Polymer: An Efficient Catalyst for the Synthesis of Xanthenes

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

Research in green chemistry has recently focussed on designing reactions in water as a safe solvent, calling for catalysts that operate in aqueous solutions. In particular, supramolecular metal nanoparticles have been synthesized by associating macrocyclic compounds with transition metal nanoparticles, to produce water-dispersible catalytic systems of high performance and molecular recognition ability. Here we review methods for stabilizing catalytically active metal nanoparticles in cyclodextrin-based systems. Indeed, cyclodextrins form inclusion complexes with molecules of appropriate size and shape, and the presence of hydroxyl groups enables coordination with metal ions. Representative examples show increasing stability, recyclability and catalytic activity. We present 1) the synthesis, characterization and catalytic behaviors with focus on the development of metal nanoparticles in solvent-dispersed form or immobilized onto supports in the presence of cyclodextrins or their derivatives; 2) the multi-functional role of cyclodextrins capable of acting as reducing agents, stabilizing/dispersing agents or mass transfer promoters; and 3) the design of more sophisticated catalytic systems, in which the cyclodextrin is a supramolecular host with dynamic equilibrium.

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