Chitosan Catalyst Research Articles

Heterogeneous catalytic oxidation regeneration of desulfurization-rich liquor with Fe3+ modified chitosan

To solve the problem of pipeline blockage caused by sulfur deposition in industrial gas wet oxidative desulfurization operations, this study developed an iron-modified chitosan catalyst for the catalytic oxidation regeneration of conventional wet oxidative desulfurization-rich liquids. Detailed characterization results show that Fe3+ species are successfully coordinated with the chitosan substrate. The results of desulfurization and regeneration experiments showed that the Fe3+-modified chitosan could effectively regenerate the desulfurization waste stream and remain stable in the acidic desulfurization stream. The powdered iron-based modified chitosan catalyst prepared with a mass ratio of chitosan to FeCl3 of 1:5 and glutaraldehyde of 12.5% by mass has better catalytic performance than the microbead counterpart. The regeneration performance of the catalyst was evaluated by the desulfurization performance of the regenerated desulfurization solution. The iron-based modified chitosan shows a good regeneration performance, and the loss of Fe content is less than 1.5% after five runs. This study provides an efficient way to develop cost-effective catalysts for the regeneration of wet oxidative desulfurization-rich liquids.

Efficient and Eco-Friendly Perspectives for C-H Arylation of Benzothiazole Utilizing Pd Nanoparticle-Decorated Chitosan

In this contribution, an eco-friendly, sustainable, and efficient palladium nanoparticle-decorated chitosan (Pd@Chitosan) catalyst was synthesized by a simple impregnation method. The synthesized material was utilized as a heterogeneous catalyst for the C-H arylation of benzothiazole under ultrasonic irradiation. The Pd@Chitosan catalyst efficiently catalyzed the conversion of aryl iodides and bromides to 1-(4-(benzothiazol-2-yl)phenyl)ethan-1-one selectively. A single product of 83–93% yield was obtained in N,N-dimethylformamide solvent at 80 °C for 2.5h. This study reveals that Pd@Chitosan is an efficient catalyst, which catalyzes the C-H arylation with good reaction yields. The activity of the Pd@Chitosan is due to the presence of highly dispersed Pd(0) nanoparticles on the surface of the chitosan and Pd2+; a tentative mechanism was proposed based on the XPS results of the fresh catalyst and spent catalyst.

Ionic Liquid Functionalized Chitosan Catalyst with Optimized Hydrophilic/Hydrophobic Structural Balance for Efficient CO2 Fixation

AbstractIn this work a series of chitosan‐based catalysts with ranging hydrophobic/hydrophilic balance are successfully prepared by varying the ionic liquid and hydrocarbon chain length attached to chitosan. The chitosan modified with eight carbon units displayed efficient catalytic activity for the conversion of a wide range of epoxides to their corresponding cyclic carbonates under 1 atmosphere pressure of carbon dioxide without cocatalyst and solvent. The optimized catalyst was able to convert even diepoxides and sterically bulky epoxides like t‐butyl glycidyl ether to their corresponding cyclic carbonates. This study provides an insight into catalyst designing based on possible molecular interaction between reactants and active sites of the catalyst.

Synthesis of long chain alkanes via aldol condensation over modified chitosan catalyst and subsequent hydrodeoxygenation

In this paper, jet fuel range alkanes were produced by aldol condensation of furfural and levulinic acid over modified chitosan catalyst and subsequent hydrodeoxygenation. NaOH modified chitosan was developed and used as a solid catalyst in the aldol condensation of furfural and levulinic acid to produce long carbon chain compounds. At room temperature, the total yield of condensation products reached 94.4% over NaOH/CT-4 catalyst. The amine of chitosan plays an important role in the aldol condensation, which reacted with the aldehyde group of the furfural, producing an intermediate Schiff base and promoting the formation of condensation products. This new route avoided the occurrence of side reactions caused by NaOH. Therefore, the yield of the products was greatly increased. Moreover, kinetic analysis of the condensation reaction and the test of catalyst repeatability were also conducted with NaOH/CT-4. The condensation products were further converted to long-chain branched alkanes by hydrodeoxygenation over the 5 wt% Pd/NbOPO4 catalyst. As a potential application, these alkanes could be mixed with and used as the components of jet fuels.

Fabrication of silver phosphate-ilmenite nanocomposites supported on glycol chitosan for visible light-driven degradation, and antimicrobial activities

Recently, photo-degradation process under ultraviolet-light irradiation is being used as a substantial treatment method for the removal of environmental pollution. In this study, a silver phosphate-ilmenite (Ag3PO4-FeTiO3) hetero structure supported on glycol chitosan catalyst was completely prepared, also, and its structural, and optical properties were characterized. Meantime, scanning electron microscopy, X-ray diffraction, X-ray photoelectron, and UV–vis spectra were applied. The Ag3PO4-FeTiO3/glycol chitosan catalyst was used to degrade metronidazole under visible-light irradiation. The degradation rate of metronidazole in 25 min by Ag3PO4-FeTiO3/glycol chitosan nanocomposites was found to be 99.2% under UV light irradiation, which was higher than that by Ag3PO4-FeTiO3 (72.24%) and FeTiO3 (35.5%), respectively. The active species trapping test of Ag3PO4-FeTiO3/glycol chitosan indicated that ·OH and ·O2− participated during the reaction. The diffusion method was evaluated to appraise the bactericidal activity of the synthesized nanomaterials when tested against both Staphylococcus aureus and Escherichia coli bacteria, with or without LED-light irradiation. The antibacterial tests show higher inhibition zones under light illumination as compared to dark conditions. The antifungal properties of the prepared nanomaterials were analyzed by fungi (Aspergillus niger, and Fusarium solani) using disc diffusion analysis. It was confirmed that the prepared nanomaterials have the best antifungal agent as compared to the standard antibiotics. When the Ag3PO4-FeTiO3/glycol chitosan was used, the amount of inhibition zone was enhanced.

Preparation of PdNPs doped chitosan-based composite hydrogels as highly efficient catalysts for reduction of 4-nitrophenol

The development of functional hydrogel materials for applications in catalysis has attracted great research interest, especially in aqueous phase catalysis. However, preparation of new structural hydrogel catalysts with enhanced catalytic activity still remains a challenge. In this study, a series of Pd nanoparticles (PdNPs) doped chitosan (CS)-based composite hydrogels were successfully prepared by adding graphene oxide (GO), carbon nanotubes (CNTs) and layered double hydrotalcites (LDHs) to CS hydrogel with glutaraldehyde as a cross-linking agent and in situ growing PdNPs. The structure and morphology analysis indicated that chitosan-based composite hydrogels could be used as carriers to load PdNPs and effectively prevent the agglomeration of PdNPs. Subsequently, 4-nitrophenol (4-NP) catalytic reaction was used as a typical model to evaluate catalytic performances of chitosan (CS)-based composite hydrogel catalysts. The obtained chitosan-based composite hydrogel catalysts exhibited better catalytic activity than that of PdNPs doped CS hydrogel catalyst (CS-PdNPs) and reusability for the reduction of 4-nitrophenol in water. The catalytic process conformed to the pseudo-first-order kinetic equation. Moreover, chitosan-based composite hydrogel catalysts containing CNTs had the best catalytic performance since the particle size of PdNPs was the smallest among three kinds of chitosan-based composite hydrogel catalysts. This work provides new ideas for the preparation of stable and efficient precious metal nanoparticle catalysts for applications in aqueous phase catalysis.

Chitosan modified Ti-PILC supported PdOx catalysts for coupling reactions of aryl halides with terminal alkynes

Biopolymer of chitosan (CS) and titanium pillared clays (Ti-PILCs) have been combined in a hybrid as advanced supports for immobilization of PdOx=0,1 species to prepare novel PdOx=0,1@Ti-PILC/CS nano-composite catalysts. The Ti-PILC materials showed high specific surface areas and abundant meso-porous structure with many irregular pore channels caused by collapses of layered structure of clay during Ti pillaring process. Both CS chains and sub-nano sized PdOx particles were successfully incorporated into the pore channels of Ti-PILC, resulting in a decrease in both the specific surface areas and uniform distribution of pore size. Besides conventional methods characterizations, the strong interactions between PdOx species and Ti-PILC/CS support were further evidenced with positron annihilation lifetime spectroscopy studies. The resultant PdOx@Ti-PILC/CS catalyst was highly active for the coupling reactions of aryl halides with phenyl acetylenes. It was recyclable and gave excellent yield up to 13 runs with low leaching of Pd species.

The use of chitosan as a solid base catalyst for the chalcones synthesis

In the present work, chitosan was modified through the hydrogel synthesis. Chitosan catalyst was characterized for its physicochemical properties. The catalytic activity of chitosan was evaluated in chalcones synthesis via Claisen-Schmidt condensation reaction. The reaction was conducted by varying the amount of chitosan catalyst (50 mg, 100 mg, 200 mg) and temperature variations (room temperature, 40 °C, 50 °C, 60 °C). The best chalcones results were obtained in the operating conditions of 100 mg and 60 °C with the yield obtained at 45,50%.

Sustainable Membrane‐Coated Electrodes for CO2 Electroreduction to Methanol in Alkaline Media

AbstractCO2 electroreduction has high potential to combine carbon capture utilization and energy storage from renewable sources. The key challenge is the construction of highly efficient electrodes giving optimal CO2 conversion to high‐value products. In this regard, research on electrode structures remains as an important task to face. Despite the advancements in gas diffusion electrodes (GDEs) to facilitate CO2 transfer and electrode efficiency, the catalyst is still vulnerable to be swept by the gas and liquid electrolyte, reducing the stability. We report the fabrication of novel membrane‐coated electrodes (MCEs), by coating an anion exchange membrane over a copper (Cu) : chitosan (CS) catalyst layer onto the carbon paper. CS and poly(vinyl) alcohol (PVA) were chosen for membrane preparation and catalyst binder, where Cu was embedded in the polymer matrix as nanoparticles or ion‐exchanged in a layered stannosilicate or zeolite Y, to improve their hydrophilic, conductive, mechanical, and environmentally‐friendly properties considered relevant to the sustainability of the electrode fabrication and performance. The intimate connection between the CS : PVA polymer membrane over‐layer and the CS/Cu catalytic layer protects the MCEs from material losses, enhancing the CO2 conversion to methanol, even in high alkaline medium. A maximum Faraday Efficiency to methanol of 68.05 % was achieved for the 10CuY/CS : PVA membrane over‐layer.

Chitosan: A Natural and Sustainable Polymeric Organocatalyst for C-C Bond Formation During the Synthesis of 5-amino-2,3-dihydrobenzo[d] thiazole-4,6-dicarbonitriles

Background: A green, recyclable and reusable chitosan catalyst has been utilized for the synthesis of 5-amino-2,3-dihydrobenzo[d]thiazole-4,6-dicarbonitrile and its derivatives. Methods and Results: Three-component reaction protocol incorporates the reaction of aldehydes, malononitrile and rhodanine derivatives. This is examined as an efficient route for the synthesis of dicarbonitriles utilizing a green, biodegradable, environmentally benign, and easily available chitosan catalyst. In the reported protocol, catalyst can be recycled and not any substantial dropping in its catalytic activity during the recycling steps was obtained. Conclusion: A green and environmentally benign, one pot three-component protocol has been illustrated for the synthesis of 5-amino-2,3-dihydrobenzo[d]thiazole-4,6-dicarbonitrile derivatives. Adequately yield products were gained via the natural catalytic approach with the recyclability of the catalyst. The use of chitosan represents this procedure as an attractive substitute for the synthesis of biaryls complex by multicomponent reaction condition.

Chitosan-catalyzed n-butyraldehyde self-condensation reaction mechanism and kinetics

Abstract The chitosan was found to possess an excellent catalytic performance in n-butyraldehyde self-condensation to 2E2H. Under suitable conditions, the conversion of n-butyraldehyde, the yield and selectivity of 2E2H separately attained 96.0%, 86.0% and 89.6%. The chitosan catalyst could be recovered and used for 5 times without a significant deactivation after being treated with ammonium hydroxide. In order to elucidate the reaction mechanism, the adsorption and desorption of n-butyraldehyde on the surface of chitosan were studied using in situ FT-IR spectroscopy analysis. The result showed that n-butyraldehyde interacts with NH2 group of chitosan to form an intermediate species with an enamine structure. Then the reaction process of n-butyraldehyde self-condensation was monitored by React-IR technique and it was found that n-butyraldehyde self-condensation to 2-ethyl-3-hydroxyhexanal followed by a dehydration reaction to 2-ethyl-2-hexenal. On this basis, chitosan-catalyzed n-butyraldehyde self-condensation reaction mechanism was speculated and its reaction kinetics was investigated. The self-condensation reaction follows auto-catalytic reaction characteristics and then the corresponding kinetic model was established.

Pt nanoparticles supported on a novel electrospun polyvinyl alcohol-CuO[sbnd]Co3O4/chitosan based on Sesbania sesban plant as an electrocatalyst for direct methanol fuel cells

Here, novel polyvinyl alcohol (PVA) nanofibers with incorporated CuO and Co3O4 nanoparticles (PVA-CuOCo3O4) were synthesized through a conventional single-nozzle electrospinning technique and characterized by atomic force microscopy (AFM), energy dispersive X-ray analysis (EDX), fourier-transform infrared spectroscopy (FT-IR), elemental analysis, transmission electron microscopy (TEM), differential thermal analysis (DTA), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Novel Pt/polyvinyl alcohol-CuOCo3O4/chitosan (Pt/PVA-CuOCo3O4/CH) catalyst was successfully prepared. EDX, TEM, and FT-IR spectroscopy techniques were used to characterize the prepared catalysts. The electrocatalytic activity of Pt/PVA-CuOCo3O4/CH catalyst was investigated for methanol electrooxidation through cyclic voltammetry, chronoamperometry, CO stripping voltammetry, and electrochemical impedance spectroscopy techniques. The effects of some experimental factors for methanol electrooxidation were studied on the prepared catalysts and the optimum conditions were determined. Pt/PVA-CuOCo3O4/CH catalyst had extraordinary electrocatalytic activity for methanol electrooxidation. It exhibited better stability, higher electrochemically active surface area, and better antipoisoning effect than Pt/PVA-CuOCo3O4 and Pt/PVA/CH catalysts indicating that Pt/PVA-CuOCo3O4/CH could be a promising catalyst for direct methanol fuel cell (DMFC) applications. A real DMFC was designed, assembled and tested with Pt/PVA-CuOCo3O4/CH as anodic catalyst.

Optimization of metal component, characterization, and stability of Cu/Mg/Al–chitosan catalyst in catalytic ozonation of a landfill leachate

Optimization of metal component, characterization, and stability of Cu/Mg/Al–chitosan catalyst in catalytic ozonation of a landfill leachate

Product distribution in hydrogenation of styrene oxide over Pd/chitosan catalyst

Palladium-decorated chitosan catalyst was synthesized by an impregnation method by varying the Pd loading in the range of 1–6 %, and was evaluated for the regioselective hydrogenation of styrene oxide. In order to correlate the chemical and textural properties with the catalytic activity, all the prepared catalysts were characterized by techniques such as Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron spectroscopy, thermo-gravimetric analysis, temperature-programmed desorption of NH3, and CO2 and N2 physisorption. The synthesized catalysts were utilized for the efficient and regioselective ring opening of styrene oxide by hydrogenation under different conditions. The complete conversion of styrene oxide with 65 % selectivity for 2-phenyl ethanol and 33 % for 1-phenyl ethanol were obtained using 4 % Pd/CS catalyst at 70 °C temperature and 3 MPa pressure. The mechanism for the regio selective ring opening of styrene oxide to 1- and 2-phenyl ethanol was also proposed on the basis of properties of the catalyst support, catalytic activity and selectivity. These results indicated that the catalytic activity and selectivity of the catalysts were affected by the nature of support. Further, the basic properties of the support play an important role in the selectivity of the styrene oxide hydrogenation reaction.

Pengaruh Pola Agitasi pada Reaksi Transesterifikasi Minyak Jelantah Warung Pecel Lele Menggunakan Katalis Kitosan

Effect of agitation on the transesterification reaction of waste cooking oil from pecel lele food stalls around UII campus using chitosan catalyst. Transesterification reaction was done by adding 46 grams of chitosan and 123 mL metanol tothe reactor. The mixture was stirred for 30 minutes to distribute methanol into chitosan. Furthermore,500 mL (460 grams) of cooking oil (= 0.916 g / mL) was add into reactor and agitated at 65oC within two hours using 30 rpm speed . Agitation was performed with several variations of the direction of stirring , one way stirring, stirring 2 ways round the turn at intervals of 5, 10 and 15 minutes. The results show that only 49,95% methyl ester yieldwas obtained (methyl palmitate, methyl-9-octadecenoate , methyl-3-oxooctadecanoate), produced by one directional rotation. Two ways agitation gives methyl ester results on average by 30.41 % . The number of methyl ester was decreased when treated with two way stirring well in intervals of 5 seconds (30.34 %) , 10 seconds (29.97 %) and 15 seconds (30.94 %). Methyl ester product was only sligtly, presumably because the raw material is very bad used cooking oil. It can be indicated from thehigh acid number 8.11 mg/L. and the number of chemical components in addition to triglycerides which may interfere with or hinder the contact between the reactants (chitosan , methanol and triglycerides). Keywords: used cooking oil, chitosan, agitation, transesterification, methyl ester

Chitosan: An Efficient, Reusable, and Biodegradable Catalyst for Green Synthesis of Heterocycles

A convenient and rapid method is described for the synthesis of nitrogen heterocyclic derivatives by one-pot three-component reaction of substituted aromatic aldehydes, dicarbonyl- and 2-aminobenzothiazole/3-amino-1,2,4-triazole/urea/thiourea using commercially available chitosan in 2% acetic acid in aqueous media at 60–65 °C. Chitosan was used as an efficient biodegradable and reusable green catalyst for this multicomponent reaction. The chitosan catalyst can be reused 10 times in fresh reaction. Catalytic activity has been sustained in the first five runs but slightly decreased in subsequent cycles.

Microwave assisted preparation of quaternized chitosan catalyst for the cycloaddition of CO2 and epoxides

An efficient method of utilizing microwave irradiation for the quaternization of chitosan (QCHT) has been investigated. QCHT catalysts have been characterized by various physicochemical methods such as FT-IR, XRD, XPS, TGA, EDS, SEM, EA, and BET. They exhibited excellent activity for the solvent-free cycloaddition of CO2 and allyl glycidyl ether (AGE). The influences of alkyl chain length and anion of the QCHT catalyst on the cycloaddition reactivity were studied. The effects of reaction parameters such as catalyst amount, reaction time, temperature, and CO2 pressure were also investigated. QCHT prepared by microwave irradiation exhibited higher catalytic activity than the conventional QCHT.

Application of a cross-linked Pd–chitosan catalyst in liquid-phase-hydrogenation using molecular hydrogen

Chitosan was cross-linked with hexamethylendiisocyanate and loaded with Pd which was subsequently reduced with NaBH4. The prepared catalyst was characterized by FT-IR and elemental analysis. The metal content was determined by ICP-MS measurements. Several substrates (cyclohex-2-enone, benzalacetophenone, 1,2-diphenylacetylene, and N-benzylidenaniline) were hydrogenated successfully in ethanol at mild conditions (50°C, p(H2) ∼6bar) utilizing a microwave reactor. Reaction parameters like temperature, hydrogen pressure, and the solvent were varied. It was shown that the reduction of the catalyst is crucial for catalytic activity. The catalyst was reused ten times for the hydrogenation of cyclohex-2-enone, without showing a dramatic loss in immobilized metal content. Also the polymeric support material did not show any decomposition.

Chitosan as a Renewable Heterogeneous Catalyst for the Knoevenagel Reaction in Ionic Liquid as Green Solvent

The combination of chitosan as a renewable heterogeneous catalyst and ionic liquid as a “green” solvent was employed for the Knoevenagel reaction. The chitosan catalyst was characterized by various techniques, including X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), and elemental analysis. Excellent conversions were achieved under mild conditions without the need for an inert atmosphere. There was no contribution from leached active species, and conversion was only being possible in the presence of the solid catalyst. The chitosan catalyst as well as the ionic liquid solvent could be recovered in essentially pure form after being used in the reaction, and each of them could be reused several times without a significant degradation in efficiency.

Chitosan: An efficient biodegradable and recyclable green catalyst for one-pot synthesis of 3,4-dihydropyrimidinones of curcumin in aqueous media

An efficient procedure for the synthesis of curcumin 3,4-dihydropyrimidinones has been developed by simple one-pot condensation of curcumin, aromatic aldehydes and urea/thiourea in the presence of commercially available chitosan in 2% acetic acid in aqueous media at 60 °C for 80–90 min. In the reaction, curcumin: a potential biologically active molecule has been used as a component of multi-component synthesis using chitosan as an efficient biodegradable and recyclable green catalyst. The resultant product curcumin 3,4-dihydropyrimidinone is formed in excellent yield (97%). The chitosan catalyst can be reused for without loss of catalytic activity. ► Chitosan used in the present procedure is biodegradable and reusable catalyst. ► No significant loss of catalytic activity when tested up to five catalytic cycles. ► The catalytic reaction was carried out in aqueous media. ► Yield of the desired product is excellent in the present synthesis.