Heterogeneous Solid Acid Catalyst Research Articles

Halloysite Nanotube Modified (CuO@HNTs-SO3H) Novel Heterogeneous Catalyst for One-Pot Synthesis of Tetrahydrobenzo[ɑ]Xanthen-11-One

In this study, CuO@HNTs-SO3H was investigated as a novel eco-friendly heterogeneous solid acid catalyst prepared by straightforward co-precipitation method. Thus, the cost-effective CuO NPs was used to modify halloysite nanotubes initially, which were subsequently further functionalized with sulfonic acid. The prepared catalyst was analyzed by means of FT-IR, XRD, EDX, SEM and TGA methods. Its catalytic activity is investigated in the solvent-free one-pot condensation of various aromatic aldehydes, dimedone, and β-naphthol to produce tetrahydrobenzo[a]xanthen-11-one derivatives. A few benefits of the discovered method are its simple process, quick reaction time, high yields (96%), affordable cost, and the catalyst ability to be reused without losing its activity.

Clay based heterogeneous catalysts for carbon-nitrogen bond formation: a review.

Clay and modified clay-based catalysts are widely used in organic transformation. Owing to the interlayer ions and good ion exchange capacity of clay, replacement with another ion and incorporation of different nanomaterials can be done. Due to these significant properties of clay, it can be utilized in the synthesis of various organic compounds. Carbon-nitrogen bonded compounds possess diverse applications in different fields. These compounds are prepared using different solid acid heterogeneous catalysts. This review presents a detailed discussion on clay used for the carbon-nitrogen bond formation reaction, such as the Biginelli reaction and A3 and KA2 coupling reactions. Additionally, other C-N bond formation reactions using various clay-based catalysts such as bentonite, montmorillonite, hydrotalcite and halloysite clay with various metals, metal oxides, Kegging type heteropoly acid and various nanomaterial incorporated clay heterogeneous catalysts are discussed.

High-efficiency recyclable reduced graphene oxide-tin oxide nanocomposite catalyst for esterification

Graphene oxide (GO) possesses 2D nanostructures and was synthesized indigenously via the enhanced Hummer method. It is well-accepted that the redox approach is a distinctive technique to fabricate GO on an expanded scale. Here, reduced graphene oxide-tin oxide (SnO2-rGO) nanocomposite material was produced for application as an efficient heterogeneous solid acid catalyst esterification reaction. Fourier transform infrared analysis was carried out to validate the incidence of oxygen functional groups in GO and SnO2-rGO nanocomposite. The Raman spectra of GO and SnO2-rGO nanocomposite have been simulated to get stable structure and functional groups. To get surface morphological and structural features, powder X-ray diffraction, scanning electron microscope-energy dispersive X-ray spectra, transmission electron microscope and high resolution-TEM analysis, and thermogravimetric analysis were delineated during this experimental study. It is seen that the catalyst has high efficiency for esterification reaction. The maximum efficiency (96% yield) was obtained when a 1:3 (acetic acid to benzyl alcohol) molar ratio, catalyst (25 mg), temperature (60 0C), and time (4 h) were maintained. The SnO2-rGO nanocomposite was recycled several times with a minimal loss of its efficiency.

Simultaneous Dehydration of Glucose and Xylose Present in a Process-Relevant Biorefinery Hydrolysate to Furfurals Using Heterogeneous Solid Acid Catalysts

Simultaneous Dehydration of Glucose and Xylose Present in a Process-Relevant Biorefinery Hydrolysate to Furfurals Using Heterogeneous Solid Acid Catalysts

Development of phosphotungstic acid immobilized amine-grafted graphene oxide as heterogeneous catalyst for synthesis of bis(indolyl)methane derivatives

Phosphotungstic acid was immobilized hydrothermally on the surface of 3-aminopropyltriethoxysilane-grafted graphene oxide (GO-N-PTA) and used as a heterogeneous solid acid catalyst for the synthesis of bis(indolyl)methane derivatives. X-ray diffraction (XRD), fourier transform infrared (FTIR) spectroscopy, BET isotherm, FESEM with EDS and elemental mapping, FETEM, X-Ray photoelectron spectroscopy (XPS), Raman spectroscopy techniques were used to characterize the synthesized catalyst. The catalyst was found to be highly effective for the synthesis of bis(indolyl)methane derivative compounds with yields in the ranges of 94–96.5 % under the optimized reaction conditions. The catalyst was recycled upto 3rd cycle for a specific reaction, that produced 94.5% yield with marginal loss in yield compared to the fresh catalyst (96.5%) depicting the hetreogneiety and sustainability of the present GO-N-PTA catalyst. This study provides the development of sustainable heterogeneous GO-N-PTA catalyst towards the synthesis of highly pharmaceutically important bis(indolyl)methanes derivative compounds.

Biodiesel Production from Waste Cooking Oil via β-Zeolite-Supported Sulfated Metal Oxide Catalyst Systems.

Waste cooking oil (WCO) is a readily available and cheap feedstock for biodiesel production. However, WCO contains high levels of free fatty acids (FFAs), which negatively impact the biodiesel yield if homogeneous catalysts are used. Heterogeneous solid acid catalysts are preferred for low-cost feedstocks because the catalysts are highly insensitive to high levels of FFA in the feedstock. Therefore, in the present study, we synthesized and evaluated different solid catalysts, pure β-zeolite, ZnO-β-zeolite, and SO42-/ZnO-β-zeolite for the production of biodiesel using WCO as feedstock. The synthesized catalysts were characterized by Fourier transform infrared spectroscopy (FTIR), pyridine-FTIR, N2 adsorption-desorption, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy, while the biodiesel product was analyzed using nuclear magnetic resonance (1H and 13C NMR) and gas chromatography-mass spectroscopy. The results revealed that the SO42-/ZnO-β-zeolite catalyst showed excellent catalytic performance for simultaneous transesterification and esterification of WCO, with a higher percentage conversion than the ZnO-β-zeolite and pure β-zeolite catalyst, due to the large pore size and high acidity. The SO42-/ZnO-β-zeolite catalyst exhibits 6.5 nm pore size, a total pore volume of 0.17 cm3/g, and high surface area of 250.26 m2/g. Experimental parameters such as catalyst loading, methanol:oil molar ratio, temperature, and reaction time were varied in order to establish the optimal parameters. The highest WCO conversion of 96.9% was obtained using the SO42-/ZnO-β-zeolite catalyst under an optimum reaction condition of 3.0 wt % catalyst loading, 200 °C reaction temperature, and 15:1 molar ratio of methanol to oil in 8 h reaction time. The WCO-derived biodiesel properties conform to the ASTM6751 standard specification. Our investigation of its kinetics revealed that the reaction follows a pseudo first-order kinetic model, with an activation energy (Ea) of 38.58 kJ/mol. Moreover, the stability and reusability of the catalysts were evaluated, and it was found that the SO42-/ZnO-β-zeolite catalyst exhibited good stability, giving a biodiesel conversion of over 80% after three synthesis cycles.

Modeling and optimization of transesterification of rubber seed oil using sulfonated CaO derived from giant African land snail (Achatina fulica) catalyst by response surface methodology

Rubber seed oil (RSO) is an abundance of low-cost non-edible vegetable oil and an attractive resource for biodiesel production through transesterification. The study aims to model and optimize the transesterification of RSO to biodiesel using sulfonated CaO derived from snail shells as a bifunctional heterogeneous catalyst. We prepared the raw snail shell (RSS) catalyst by calcination and sulfonated it to produce an acid-activated snail shell (AASS) catalyst. We used the central composite design (CCD) of the response surface methodology (RSM) to model and optimize the transesterification process. The X-ray fluorescence (XRF), Scanning Electron Microscopy (SEM), Fourier-Transform Infrared Spectroscopy (FTIR), and Brunauer-Emmett-Teller method (BET) were used to characterize RSS and AASS catalysts.The results show that CaO (95.6%) is the major component of RSS. The maximum biodiesel yield of 97.6% was obtained at a 12:1 methanol to oil molar ratio, 80 °C reaction temperature, 2.5 h reaction time, and 2.5 wt% catalyst loading with a quadratic regression model. The recyclability of the catalyst shows six runs without an appreciable decrease in biodiesel yield. The AASS catalyst can perform excellently as a bifunctional solid acid heterogeneous catalyst, and the fuel properties of the biodiesel produced compare favorably with American society for testing and materials (ASTM D6751) and European standard methods (EN 14214) standards.

KIT-5 Structural and Textural Changes in Response to Different Methods of Functionalization with Sulfonic Groups.

In this project, KIT-5 materials were effectively functionalized with sulfonic groups introduced by grafting or the co-condensation method and tested as heterogeneous solid acid catalyst. A co-condensation procedure leading to the stable, -SO3H functionalized KIT-5 materials was successfully established. Moreover, the influence of both synthesis methods on the structural and textural parameters, as well as surface chemistry, morphology, and catalytic activity of -SO3H/KIT-5 materials was thoroughly investigated. The syntheses with 3-mepkaptopropyltrimethoxysilane (MPTMS) acting as a modifying agent resulted in samples in which functional groups were introduced into the structure and/or onto the mesoporous silica surface. The oxidation stage of -SH to -SO3H groups was carried out under mild conditions, using a "green" oxidant (H2O2). The application of different functionalization techniques and the introduction of different amounts of modifying agent allowed for an evaluation of the influence of these parameters on the ordering of the mesoporous structure of KIT-5 materials. The applied methods of assessment of the physicochemical parameters (XRD, low-temperature N2 sorption, TEM) showed that, especially when the co-condensation method was applied, as the number of functional groups increased, the ordering of structure characteristic of KIT-5 decreased. On the other hand, the samples modified by grafting had a stable structure, regardless of the amount of introduced MPTMS. Test reactions carried out on the basis of Friedel-Crafts alkylation process showed that the synthesized materials can be considered promising acid catalysts in heterogeneous catalysis reactions.

SYNTHESIS OF BIOACTIVE POLYHYDROQUINOLINES USING SULFATED TIN OXIDE AS AN EFFICIENT SOLID SUPERACID CATALYST

A novel synthetic scheme has been designed for the synthesis of polyhydroquinoline derivatives via one-pot condensation of aromatic aldehydes, EAA, dimedone, and NH4OAc by employing synthesized STO as a heterogeneous solid acid catalyst in ethanol under reflux condition. FTIR, XRD, and SEM EDX were used to confirm the sulfated tin oxide. BET plots were used to analyze the surface area of the catalyst. The reactions were assessed for diverse solvents and catalyst loading. The yields of all the polyhydroquinoline derivatives were found to range between 80 to 92%. All the synthesized polyhydroquinolines were validated by spectral data. This exercise is efficient and green as it uses an environmentally friendly catalyst, has a significant atom economy, is cost-effective and easy to work up.

A green approach for one-pot synthesis of cyclic acetals in the presence of nano-γ-alumina supported BF3 as a heterogeneous solid acid catalyst

BF3/γ-Al2O3 nanoparticles were prepared through the reaction of nano-γ-alumina with BF3.Et2O and were characterized by FT-IR, XRD, FESEM, TEM, EDS, EDS mapping and TGA. This solid acid catalyst was used for the synthesis of some cyclic acetals under thermal and solvent free conditions. The process has advantages such as short time times, easy purification technique and high yields. The work-up is easy and the catalyst is removed from the products by a simple filtration.

Nano TiCl4/γ-Al2O3: An efficient heterogeneous solid acid catalyst for rapid and solvent-less synthesis of azo dyes based on 2-naphthol at room temperature

A green heterogeneous solid acid was prepared as an extremely efficient catalyst, through the reaction of γ-alumina with titanium tetrachloride. Nano TiCl4/γ-Al2O3 was characterized by fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), Brunner–Emmet–Teller (BET) surface area analysis, X-ray fluorescence (XRF) and thermal gravimetric analysis (TGA). Nano TiCl4/γ-Al2O3 was used for the synthesis of aryl diazonium salts as the starting reactant and then, diazo coupling with 2-naphthol produced the azo dyes in a solvent-free medium at room temperature (25 °C). The work-up of the reaction is easy, and the catalyst is removed from the products by simple filtration.

Expanded Perlite-Polyphosphoric Acid (EP-PPA) as a Low-Cost Heterogeneous Solid Acid Catalyst for Green and Metal-Free Synthesis of Nitriles from Aldehydes

Expanded Perlite-Polyphosphoric Acid (EP-PPA) as a Low-Cost Heterogeneous Solid Acid Catalyst for Green and Metal-Free Synthesis of Nitriles from Aldehydes

Catalytic synthesis of 5-hydroxymethyl furfural from sorghum syrup derived fructose

5-Hydroxymethyl furfural (HMF) is regarded as a very important platform chemical with versatile application. Sucrose derived from sorghum syrup was successfully explored for the synthesis of HMF. The current study employed a chemo-catalytic approach for the conversion of hexose component of sorghum syrup to HMF. The main objective of this study was to catalytically hydrolyse the sucrose in the sorghum syrup to glucose and fructose and subsequently dehydrate the hexoses to yield HMF. Seralite SRC120 (cationic resin) was used as a heterogeneous solid acid catalyst and the reaction was conducted in water. A statistical Box-Behnken design was employed for the optimization of the reaction parameters. RSM experiments indicated a maximum of 65 % HMF yield using 0.5 % (v/v) syrup loading and 1.25 % (w/v) catalyst loading with reaction time of 1 h. Glucose remained unconsumed during the reaction. The unreacted glucose (from hydrolysed sucrose) was used as a major carbon source for microbial cell enrichment that can possibly lead to the complete utilization of carbohydrates from the sorghum plant.

Solvent free one pot syntheses of highly substituted propargyl ethers and propargyl amines from propargyl alcohols catalyzed by recyclable alumina-sulfuric acid

A study to develop an efficient protocol for the solvent-free synthesis of a wide variety of highly substituted propargyl ethers and amines using alumina-sulfuric acid as a recyclable heterogeneous solid acid catalyst has been presented. This mild protocol tolerates a good number of acid-sensitive moieties and can be applicable to a diverse range of alcohols and amines accommodating a variety of substitution patterns. Moreover, the entire process is highly atom-efficient leaving the most innocuous material, namely water, as the sole by-product.

A New Procedure for the Preparation of 3,4-dihydropyrimidin-2(1H)-one and Octahydroquinazolinone Derivatives catalyzed by SCMNPs@CA-EASO3H under Solvent-free Conditions

Abstract: 3,4-dihydropyrimidin-2(1H)-one and octahydroquinazolinone derivatives were obtained in high-to-excellent yields and short reaction times using SCMNPs@CA-EA-SO3H as a green and heterogeneous solid acid catalyst in a one-pot multi-component condensation of ethyl acetoacetate or dimedone, urea, and aldehyde compounds under solvent-free conditions. More importantly, the green catalytic system could be easily collected from the reaction solution utilizing an external magnet and reused for five runs with a negligible decrease in yields and reaction rate.

A straightforward preparation of levulinic esters from biorenewable levulinic acid using methanesulfonic acid supported on silica gel (MSA-SG) as an efficient heterogeneous catalyst

The present work reports methanesulfonic acid supported on silica gel (MSA-SG) as an inexpensive heterogeneous solid acid catalyst for the high-yielding production of various alkyl levulinates from biomass-derived levulinic acid. The catalyst was characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDX). The reactions were conducted in a batch-type glass pressure reactor under conventional heating. The esterification reaction was optimized on temperature, duration, and catalyst loading. The optimized reaction conditions (120 °C, 8 h, 8 wt% MSA-SG) afforded methyl- to butyl levulinate in excellent isolated yields (≥90 %). The catalyst was filtered, and the products were purified by simply evaporating the excess alcohol reagent.

Ionic liquid grafted NH2-UiO-66 as heterogeneous solid acid catalyst for biodiesel production

In this work, acidic ionic liquid (AIL) was grafted into NH2-UiO-66 through acid-base interaction. And the novel heterogeneous catalyst xAIL@NH2-UiO-66 (x means the mass ratio of AIL to NH2-UiO-66) was first applied in the field of biodiesel production. The optimal catalyst 3AIL@NH2-UiO-66 with good wettability (with reactants) and high acidity was prepared successfully. Accordingly, the 3AIL@NH2-UiO-66 can be widely applied in biodiesel production from different raw materials. The conversion of free fatty acids (FFAs) in esterification was above 90%, as well as the biodiesel yield in transesterification was above 80%, showing excellent catalytic activities of 3AIL@NH2-UiO-66. And the 3AIL@NH2-UiO-66 also revealed excellent reusability, with the conversion of oleic acid decreases from 96.86% to 90.42% after 6 runs. In addition, the interaction between any two of the three factors (catalyst dosage, reaction time and molar ratio) on the oleic acid conversion was revealed with 3D response surface technology. By the mechanism investigation, the good wettability with reactants and high acidity of the catalysts are identified as key factors for biodiesel production. The method of anchoring ionic liquids with organic linkers for the application of MOFs in biodiesel production offers abundant possibilities.

An efficient heterogeneous solid acid catalyst derived from sewage sludge for the catalytic transformation of sludge into biodiesel: Preparation, characterization, and arylation process modeling

Homogeneous and heterogeneous catalysts for biodiesel production are facing challenges such as corrosion, leaching of active sites, and separation difficulties. Herein, a safe, chemically stable, and high-recoverable heterogeneous solid acid catalyst was fabricated and successfully evaluated in the catalytic transesterification of sludge-derived lipids. To this end, sludge-based granular activated carbon (SBGAC) was prepared and arylated with 4-sulfobenzenediazonium chloride in a reducing agent-free reaction. Hybrid models of the adaptive neuro-fuzzy inference system (ANFIS) with evolutionary algorithms such as the genetic algorithm (GA-FIS), particle swarm optimization (PSO-FIS), and ant colony optimization (ACO-FIS) were developed to model and optimize the empirical relationship between arylation parameters. The highest PhSO3H density (1.36 mmol/g) was obtained at 70 °C, 7.6 min arylation time, and a mass ratio of acid to SBGAC of 9.83 using the PSO-FIS model, which was ∼26% more than the value obtained without optimization. Loading 20 wt% of this catalyst in the transesterification of sludge-originated lipid at 70 °C yielded 17.34% (w/w dry sludge) biodiesel after 14 h. Coating the catalyst granules on the polystyrene grains was significantly enhanced its recoverability from the reaction mixture. Moreover, the spent catalyst exhibited good chemical stability and reusability after the ninth transesterification cycle.

Biodiesel Synthesis from High Free-Fatty-Acid Chicken Fat using a Scrap-Tire Derived Solid Acid Catalyst and KOH.

A heterogeneous solid acid catalyst was synthesized using tire polymer waste (TPW) for the esterification of waste chicken fat (CF) enriched with fatty acids. The TPW was carbonized and functionalized with concentrated sulfuric acid under various sulfonation conditions to obtain a sulfonated tire polymer char (TPC-SO3H) catalyst. The TPC-SO3H catalyst was further characterized via acid-base titration (to ascertain the total concentration of acid), X-ray diffraction, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), and Brunauer–Emmett–Teller (BET) analysis. The esterification reaction conditions of extracted chicken fat with methanol and the viability of catalyst reuse were also investigated. The composition of the free fatty acid (FFA) decreased to below 1% under optimum reaction conditions of 5% TPC-SO3H catalyst, the methanol-to-CF molar-ratio of 15:1, and a reaction time of 120 min at 70 °C. The catalyst preserved its conversion efficiency above 90%, even after three cycles. The results demonstrate that the catalyst is applicable and efficient in the esterification of raw materials containing various fatty acid compositions since different carbonized materials have distinct abilities to combine acid groups. Furthermore, after de-acidification of CF-FFA by the as-prepared TPC-SO3H catalyst, the neutral CF was transesterified completely to biodiesel and characterized via Fourier Transform Infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (1H NMR) spectroscopy and physicochemical analysis. This work unveils a promising technique for utilizing tire waste generated in large quantities for the development of a novel heterogeneous acid catalyst for biodiesel production.

Heteropoly acids as supported solid acid catalysts for sustainable biodiesel production using vegetable oils: A review

Biodiesel is a promising renewable energy source with environmentally friendly properties such as non-toxicity, sulfur-free, and low emission of carbon dioxide. However, the higher cost of biodiesel production relative to petroleum diesel is the major challenge for the commercialization of biodiesel. The utilization of suitable feedstocks and an appropriate catalyst are two dominant factors, which play a crucial role in the determination of reaction conditions, biodiesel yield, and cost of biodiesel production. Heterogeneous catalysts were found to be promising relative to homogeneous catalysts owing to their high selectivity, reusability, and stability. Among several heterogeneous catalysts, heteropoly acids (HPAs) are efficient catalysts that have recently stimulated many scientists to investigate their application as solid acid catalysts using different support materials and functionalization techniques during transesterification. This review presents a comprehensive overview of the employment of various types of plant oils (edible and non-edible) as feedstocks, several heterogeneous catalysts, their properties, benefits, and drawbacks for biodiesel production. The primary objective of this review is to indicate the advances of supported heteropoly acid catalysts as efficient heterogeneous solid acid catalysts over other types of catalysts. This goal is thoroughly addressed by discussing the performance of different HPA catalysts by providing catalyst features. Further, the influence of critical factors on the properties of solid acid catalysts, different structures of HPAs, their advantages and challenges, suitable support materials for HPAs, modification of supported HPAs through the post, and direct functionalization and their mechanism is highlighted. This review is also addressed overcoming the leaching problem of HPAs to improve the activity and reusability of the HPA catalysts; further, economic challenges are discussed in detail to produce high-quality bio-diesel via HPA catalysts.