Green Heterogeneous Catalyst Research Articles

Enhancing Sustainable Production of Biodiesel from Xanthoceras sorbifolia Bunge Oil Using Bio-Based Heterogeneous Catalyst

The swift exhaustion of natural oil reserves and worsening environmental issues have prompted the quest for an economical method to produce biofuels. The superiority of heterogeneous catalysis promotes the development of bio-based catalysts. Carbon materials prepared from agricultural and forestry biomass waste have good application prospects in catalysis. In the present study, Xanthoceras sorbifolia shell waste was used as the raw material, Xanthoceras sorbifolia Bunge Carbon (XC) was used as the catalyst carrier, and K2CO3 was used as the activator to prepare a heterogeneous catalyst (KXC). The heterogeneous catalyst was characterized by scanning electron microscopy-energy dispersion X-ray spectroscopy (SEM-EDS), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) and X-ray photoelectron spectroscopy (XPS) analysis techniques to evaluate its chemical composition, structure, and physical morphology. EDS and XPS revealed the presence of K metal, which provided an alkaline site for the transesterification reaction to produce biodiesel. The biodiesel yield was observed by gas chromatography−mass spectrometry (GCMS). Under the reaction conditions of a methanol-to-oil molar ratio of 12:1, a reaction time of 90 min, a temperature of 65 °C, and a catalyst loading of 4 wt.% using 25KXC-600-4, the yield of biodiesel can reach 95.13 ± 0.82%. After being repeated five times, the yield was still 58.11 ± 3.80%. The catalyst has no waste generation, and has the characteristics of simple preparation and environmental friendliness, which make it a green heterogeneous catalyst for biodiesel production.

Promising metal-free green heterogeneous catalyst for quinoline synthesis using Brønsted acid functionalized g-C3N4

Rationally designing distinct acidic and basic sites can greatly enhance performance and deepen our understanding of reaction mechanisms. In our current investigation, we studied the utilization of Brønsted acid sites within layered graphitic carbon nitride (g-C3N4) for the first time to enhance the rate of the Friedländer synthesis. The structural and surface analyses confirm the effective integration of -COOH and -SO3H groups into the g-C3N4 lattice. The surface-functionalized g-C3N4-CO-(CH2)3-SO3H exhibits a remarkable acceleration in quinoline formation, surpassing previously mentioned catalysts, and demonstrating notable recyclability under optimized mild reaction conditions. The heightened reaction rate observed over g-C3N4-CO-(CH2)3-SO3H is attributed to its elevated surface acidity. By probing the Friedländer reaction mechanism through surface characterization, examination of reaction intermediates, and investigation of substrate scope, we elucidate the pivotal role of Brønsted acid sites. This study constitutes a comprehensive exploration of metal-free heterogeneous catalysts for the Friedländer reaction, offering a unique contribution to the field.

Two Thiophene-Functionalized Co-MOFs as Green Heterogeneous Catalysts for the Biginelli Reaction.

Two Co(II) metal-organic frameworks (Co-MOFs), namely, [Co(DMTDC)(bimb)]n (Co-MOF-1) and {[Co(DPTDC)(bimb)(H2O)]·2DMF}n (Co-MOF-2) (H2DMTDC = 3,4-dimethylthieno[2,3-b]thiophene-2,5-dicarboxylic acid, H2DPTDC = 3,4-diphenylthieno[2,3-b]thiophene-2,5-dicarboxylic acid, bimb = 1,4-bis((1H-imidazol-1-yl)methyl)benzene), were obtained by the reaction of flexible N-containing ligand bimb and two structurally related thiophene-containing ligands H2DMTDC and H2DPTDC, respectively. These Co-MOFs displayed a 3D framework and porous structure, respectively. Co-MOF-1 and the activated sample Co-MOF-2' could act as green heterogeneous catalysts for the one-pot multicomponent Biginelli reaction, specifically the dehydration condensation process involving aldehydes, acetoacetates, and urea to yield dihydropyrimidin-2(1H)-ones. The reaction has advantages such as solvent-free conditions, water as only byproduct, readily accessible starting materials, excellent functional group compatibility, and simple operation. Both catalysts exhibited a wide substrate scope and maintained significant catalytic activity over five cycles. The special catalytic performance may be ascribed to functional groups within the ligand.

Green heterogeneous catalyst based on cross-linked carrageenans for direct conversion of fructose to ethyl levulinate

Ethyl levulinate (EL) is a biomass-derived compound, capable of being converted to an array of costly compounds and therefore is attracted by many researchers. In the present study, κ and ι-carrageenan grafted methylenebisacrylamide (MBA) catalysts (κC-g-MBA and ιC-g-MBA) were prepared and applied to convert fructose to EL. FT-IR spectroscopy, XRD of both low-angle and wide-angle, N2 adsorption-and-desorption, FESEM, and TGA were used to identify the catalysts. From the catalysts, κC-g-MBA and ιC-g-MBA revealed the desirable results for EL with 80 and 82 % yields, respectively. The various parameters like reaction temperature, time, catalyst quantity, and the original fructose quantity were studied. Furthermore, experimental design was employed to create the ideal conditions for the reaction temperature 180 °C for the reaction, 5 h for the duration of the reaction, and 50 mg of catalyst for EL chosen. In addition, the catalyst's capability for reuse was explored and the catalyst was used repeatedly without a significant change in the catalyst activity.

Green hetero-alkali catalyst in optimized waste lard oil transesterification for biodiesel synthesis

Climate change in addition to the imminent depletion of the fossil fuel reserve has necessitated the search for a sustainable alternative fuel. In this research, the catalytic capability of a green heterogeneous alkali catalyst, thermally activated banana-plantain-peel-ash catalyst was examined in optimized waste lard oil (WLO) transesterification process in lard-oil-methyl-ester (LOME) synthesis. The catalyst was derived from a banana-plantain-peel-ash mixture and subjected to a calcination process while the catalyst properties were described via Scanning electron microscope-Energy dispersive atomic-x-ray-spectroscopy (SEM-EDX), X-ray diffraction-(XRD), Fourier Transform Infra-Red (FTIR) as well as Brunauer-Emmett-Teller (BET). Optimization of the waste lard oil transesterification process was conducted with the Desirability Explore Algorithm (DEA) in Central Composite Design (CCD) of Response Surface Methodology (RSM). A 99.9 % conversion of WLO to LOME was attained at the optimum reaction settings of 57 °C temperature, catalyst amount-2.5 wt%, time-1.5 h, and methanol to WLO molar ratio of 10.5:1 with a total desirability of 0.99 which was evaluated experimentally as 99 %. In the LOME synthesis procedure, the resulting empirical model demonstrated statistical significance and suitability based on its high F-value of 35.59 and infinitesimal p-value of less than 0.0001. The determined LOME fuel qualities met the applicable standard specifications (ASTM-D6751 and EN-14241) hence, have the potential to function as a diesel fuel substitute. The fused influence of WLO and the thermally activated bio-mixture catalyst was highly effective in biodiesel synthesis. Thus; a promising cheap feedstock source for green and sustainable biodiesel production was achieved.

Exploring the peel ash of musa acuminate as a heterogeneous green catalyst for producing biodiesel from Niger oil: A sustainable and circular bio economic approach

Currently, biodiesel stands as a sustainable and renewable alternative to depleting fossil fuels like petro-diesel. The widespread adoption of biodiesel production holds promise for enhancing environmental quality by reducing greenhouse gas emissions and promoting societal-economic development. In line with this, our research has focused on synthesizing biodiesel from the novel and edible seed oil of Niger oil, utilizing a green catalyst derived from the calcination of banana peel ash at 600 °C for 4 h. Advanced characterization techniques, including X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Diffraction X-Ray (EDX), Thermogravimetric Analysis (TGA), X-ray Photoelectron Spectroscopy (XPS), and Fourier-transform Infrared Spectroscopy (FT-IR), were employed to assess the catalytic activity of the catalyst. Under optimized reaction conditions a methanol-to-oil molar ratio of 15:1, catalyst loading of 1% (wt.%), reaction time of 4 h, and temperature of 70 °C we achieved a commendable biodiesel yield of 92.30%. Gas Chromatography (GC) analysis of the biodiesel revealed four distinctive peaks corresponding to methyl esters. Results from Fourier-transform Infrared Spectroscopy (FTIR) and Nuclear Magnetic Resonance (NMR) confirmed the presence of methyl esters in the biodiesel sample. Additionally, the fuel properties of the biodiesel, including density (0.904 kg/m3), kinematic viscosity (4.56 cst), cloud point (3 °C), pour point (2.8 °C), and flash point (149 °C), complied with international ASTM D standards. In conclusion, Niger biodiesel emerges as a highly promising, eco-friendly, reusable, and cost-effective feedstock for biodiesel production, thereby holding significant potential for advancing sustainable energy solutions.

Synthesis of Guanidine and Its Deposition on Bacterial Cellulose as Green Heterogeneous Catalyst for Transesterification to Methyl Esters

Green catalysts used in the transesterification reaction of biodiesel must have biodegradability and non-toxicity as their main characteristics, being thus friendly to the environment, since they perform in processes in which the content of CO2, which is increasing from year to year, should be reduced. As a consequence, their manufacture can be extremely rigorous. This work presents the two-step construction, synthesis, and deposition of such a green heterogeneous catalyst and its testing in the catalysis of the transesterification of triglycerides with methanol, resulting in methyl esters. A CSTR-type reactor was used to perform transesterification, and the biodiesel yields obtained had values in the range of 91.7–95.7%, using 2, 3, and 4 g/g catalyst to oil, under conditions like those for obtaining commercial biodiesel in homogeneous catalysis, i.e., a 65 °C process temperature and a 4:1, 5:1 or 6:1 methanol-to-oil molar ratio.

Immobilized SbCl3@Chitosan as a green heterogeneous catalyst for the synthesis of 1,2,4,5-tetrasubstituted imidazoles

Immobilized SbCl3@Chitosan as a green heterogeneous catalyst for the synthesis of 1,2,4,5-tetrasubstituted imidazoles

Agro-industrial residue of Pouteria sapota peels as a green heterogeneous catalyst to produce biodiesel from soybean and sunflower oils

We report the use of ash from the agro-industrial waste of Pouteria sapota peels as a reusable heterogeneous catalyst to produce biodiesel from soybean and sunflower oils. The heterogeneous catalyst was prepared by activating raw Pouteria sapota peel powder at 500 °C for 2 h. The physicochemical and structural properties of the ash were evaluated by SEM-EDS, XRD, FTIR, BET analyses, and its basicity was determined through acid-base titration. The good activity of the ash-based catalyst was attributed mainly to the presence of potassium chloride (KCl), a specific surface area of 1.432 m2 g−1, and its high basicity of 9.069 mmol g−1. A maximum conversion yield of 92% was achieved for both the oils under optimized reaction conditions. For the soybean and sunflower oils, the optimum parameters were 3 wt% and 5 wt% of catalyst charge, methanol to oil molar ratio of 6:1 and 9:1, and a reaction time of 240 min, respectively. The reactions were performed at 65 °C under stirring at 400 rpm. The physicochemical properties of soybean and sunflower biodiesel satisfactorily complied with the International Standard of the American Society for Testing and Materials (ASTM-D6751) and the European Standardization (EN-14214).

Biomass substrate-derived graphene-like N-doped porous carbon nanosheet-supported PtCo nanocatalyst for efficient and selective hydrogenation of unsaturated furanic aldehydes

Unsaturated furanic aldehydes are derived from lignocellulosic biomass resources and subsequently used to produce valuable chemicals. However, the highly efficient, selective hydrogenation of the biomass-derived unsaturated furan CO bond remains challenging. Here we report that graphene-like nitrogen doped porous carbon (GNPC) nanosheets are synthesized from carbon-rich, sustainable, and renewable biomass precursors (glucose, fructose and 5-hydroxymethylfurfural, HMF) with high surface areas, large pore volumes and narrow mesopores. GNPC derived from HMF is an excellent catalyst support for PtCo nanoparticles with ultrafine nanoparticles size and homogeneous distributions. This catalyst is highly efficient for hydrogenation of biomass-derived furan-based unsaturated aldehydes, with high yields, to the corresponding unsaturated alcohols under mild conditions. This design strategy should further allow the development of selective, simple, green heterogeneous catalysts for challenging chemical transformations.

Green heterogeneous catalysts derived from fermented kola nut pod husk for sustainable biodiesel production

ABSTRACT The use of green heterogeneous catalysts that are obtained from waste agricultural biomass can make the production of biodiesel more economical. In this research, three solid base heterogeneous catalysts (Catalyst A, B, and C) were synthesized from kola nut pod husks, and the synergistic effects of the elemental composition on catalytic activities for biodiesel production were studied. The results revealed a high surface area of Catalysts A, B, and C at 419.90 m2/g, 430.54 m2/g, and 432.57 m2/g, respectively. Their corresponding pore diameters are 3.53 nm, 3.48 nm, and 3.32 nm, showing that the catalysts are mesoporous in nature. The X-ray Fluorescence (XRF) results revealed the presence of a variety of alkaline earth metals and their corresponding metal oxides in substantial amounts. Catalyst A was produced with the highest concentration of calcium at 40.84 wt.% and calcium oxide at 68.02 mole%. The substantial concentration of other elements, such as potassium, magnesium, and aluminum, and their corresponding metal oxides are the proof of high catalytic activity of the produced green catalysts. The high CaO contents of all three produced catalysts and their high surface areas indicate their strong potential for good catalytic activities applied to the synthesis of biodiesel.

Copper supported modified magnetic carrageenan as a bio-based catalyst for the synthesis of novel scaffolds bearing the 1,2,3-triazole unit through the click reaction.

The ongoing work delineates the design of a novel library of 1,2,3-triazole-attached phenylacetamides through molecular hybridization of propargyl and phenylacetamide derivatives. Copper-supported modified magnetic carrageenan serves as a green heterogeneous catalyst, ensuring high yield, efficient reaction times, high atom economy, utilization of an environmentally friendly catalyst from a natural source, and a straightforward workup procedure. The successful synthesis of the catalyst is confirmed and evaluated using various analytical techniques, while the synthetic compounds are characterized through 1H NMR and 13C NMR.

A mild protocol for the development of an innovative green heterogeneous catalyst for the Hilbert-Johnson reaction

Ammonium iodide-coated g-C3N4 (NH4I@g-C3N4) is investigated as a new and sustainable heterogeneous catalyst for the selective N1-alkylation of pyrimidines.

SO3H‐Functionalized Carbon Materials: A Versatile and sustainable heterogeneous Catalyst for Diverse Organic Transformations

AbstractDue to their fascinating biological features, heterocyclic compounds and their derivatives have long been recognized as promising molecules with potential pharmaceutical applications. The significance of heterocyclic compounds in drug discovery and development is evident from the fact that a majority of drugs in the pharmaceutical market incorporate heterocyclic compounds as active substances or ingredients. Various synthetic methods and advancements have been devised to prepare these heterocyclic compounds using diverse catalysts under mild reaction conditions. SO3H functionalized carbon material (C‐SO3H) is heterogeneous green solid catalyst that has been employed to catalyze diverse organic reactions including construction of three‐, four‐, five‐, six‐member and fused heterocycles as well as other open chain organic transformations. The C‐SO3H catalyst works under relatively mild reaction conditions and recovered from the reaction mixtures for reuse. Various cheap carbon sources covering natural organic carbon matter and industrial waste already being used to synthesize SO3H‐functionalized acidic carbon catalyst for replacement of various homogeneous acid catalysts. The present review aims to highlight the organic reactions especially those connecting for heterocyclic synthesis catalyzed by sulfonated carbons (C‐SO3H) from 2010 to till date.

CSA@g-C3N4 as a novel, robust and efficient catalyst with excellent performance for the synthesis of 4H-chromenes derivatives

A pioneering robust and green heterogeneous acidic catalyst (CSA@g-C3N4) was rationally designed via immobilization of camphorsulfonic acid (CSA) on the g-C3N4 surface under mild conditions. Grafting CSA in the g-C3N4 lattice is distinguished as the root cause of facilitating the structure change of g-C3N4, leading to a unique morphology, accordingly the remarkable catalytic efficiency of CSA@g-C3N4. The morphology of new as-prepared nano-catalyst was specified by means of FT-IR, XRD, SEM, EDS, TEM, TGA, and BET. For the first time, it is exhibited that the efficient catalyst CSA@g-C3N4 can productively accomplish the three-component reactions with high yields and also serve as an inspiration for easily performing various sorts of MCRs based on our finding. The recommended synthesis pathway of chromenes derivatives is facile and cost-effective which applies a condensation reaction of salicylaldehyde, thiophenol, and malononitrile followed by ready purification in a benign manner. Moreover, the CSA@g-C3N4 nanocomposite can be promptly reused, illustrating no sensational decrease in the catalytic activity after ten times.

A green edge-hosted zinc single-site heterogeneous catalyst for superior Fenton-like activity

Developing green heterogeneous catalysts with excellent Fenton-like activity is critical for water remediation technologies. However, current catalysts often rely on toxic transitional metals, and their catalytic performance is far from satisfactory as alternatives of homogeneous Fenton-like catalysts. In this study, a green catalyst based on Zn single-atom was prepared in an ammonium atmosphere using ZIF-8 as a precursor. Multiple characterization analyses provided evidence that abundant intrinsic defects due to the edge sites were created, leading to the formation of a thermally stable edge-hosted Zn-N4 single-atom catalyst (ZnN4-Edge). Density functional theory calculations revealed that the edge sites equipped the single-atom Zn with a super catalytic performance, which not only promoted decomposition of peroxide molecule (HSO5-) but also greatly lowered the activation barrier for •OH generation. Consequently, the as-prepared ZnN4-Edge exhibited extremely high Fenton-like performance in oxidation and mineralization of phenol as a representative organic contaminant in a wide range of pH, realizing its quick detoxification. The atom-utilization efficiency of the ZnN4-Edge was ~104 higher than an equivalent amount of the control sample without edge sites (ZnN4), and the turnover frequency was ~103 times of the typical benchmark of homogeneous catalyst (Co2+). This study opens up a revolutionary way to rationally design and optimize heterogeneous catalysts to homogeneous catalytic performance for Fenton-like application.

SnCl4/γ-Al2O3 nanoparticles: A reusable and green heterogeneous catalyst for the one-pot synthesis of tetrahydropyridines

Nano-SnCl4/γ-Al2O3 as a reusable and green heterogeneous catalyst was prepared by the reaction of tin tetrachloride with γ-alumina. This solid acid catalyst was characterized by fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), thermal gravimetric analysis (TGA) and Brunauer-Emmett-Teller (BET) analyses. Tetrahydropyridines were synthesized via the one-pot reaction of 4-substitutd anilines, ethylacetoacetate and 4-substituted aldehydes in the presence of optimized amount (0.06 g) of nano-SnCl4/γ-Al2O3 under thermal conditions (70 °C) in ethanol as a green solvent. The process had short reaction times (5–8 h), good to excellent yields (80–93%), simple work-up and easy purification technique (recrystallization through the hot ethanol). It was found that the catalyst could be reused for three times without any considerable loss of its activity.

Parkia speciosa: A basic heterogeneous catalyst for production of soybean oil-based biodiesel

A green heterogeneous catalyst was fabricated for the biodiesel synthesis via transesterification of soybean oil. The catalyst was generated by simple calcination of the biomass Parkia speciosa (Manipuri beans) at 700 °C. Characterization techniques like TGA, FT-IR, XRD, SEM, BET, TEM, STEM, EDS, XPS, and CO2-TPD were employed to analyse the catalyst. The results showed the existence of significant amount of potassium (K) with some amount of calcium (Ca) in the form of oxides and carbonates which serves as active catalytic sites for accelerating the process of transesterification. The highest biodiesel yield of 96.4 % was achieved at 40 °C, when reaction was performed for 3 h with catalyst loading of 5 wt%, 1:15 M ratio of oil to methanol and 20 wt% of co-solvent. The catalyst has also proved to be truly heterogeneous at low temperature as its efficiency remains intact even after five successive cycles. Thus, the biomass-derived catalyst can be seen as a potentially viable alternative for the conventional homogeneous catalyst.

Cu(II)/citric acid grafted to chitosan by dendritic units of melamine as a novel and highly efficient heterogeneous catalyst for the synthesis of 2-aminobenzothiazole derivatives

In this paper, a new cross-linked chitosan by G1 dendrimer from melamine terminated by citric acid groups to support Cu(II) nanoparticles (CS@CA-Me-CA@Cu) was designed and prepared. Subsequently, the prepared nanocomposite was characterized using different spectroscopic, microscopic and analytical techniques such as FTIR, XRD, FESEM, TGA and EDX. The supramolecular CS@CA-Me-CA@Cu demonstrates higher thermal and chemical stability than its components. In addition, in order to investigate the catalytic performance of the CS@CA-Me-CA@Cu bio-based nanocomposite it was used, as a Lewis acidic and green heterogeneous catalyst, for the preparation of 2-aminobenzothiazole derivatives under green conditions. Also, other advantages of this new bio-based nanocomposite include easy preparation, high catalytic activity, recyclability, and reuse with a gradual decreasing in its catalytic activity.

Yb(OTf)3 Anchored on Crosslinked Chitosan Microsphere: A Green Heterogenized Catalyst for the Synthesis of Bispiro‐Fused Heterocycles

AbstractUsing renewable biomass chitosan as a raw material, crosslinked chitosan microsphere (CCM) was prepared by inverse suspension, which was then immersed in the ethanol solution of Yb(OTf)3 to fabricate CCM‐supported Yb(OTf)3 (Yb(OTf)3@CCM). The three‐component [3+2] cycloaddition of isatins, tetrahydroisoquinolines and 5‐alkenyl rhodanines was developed with Yb(OTf)3@CCM as a green heterogeneous catalyst, which gave access to a suite of architecturally complex bispiro‐fused heterocycles merging four pharmacophores with moderate to excellent yields (50–96 %) and diastereoselectivities (up to 99 : 1 dr). The reaction mechanism was preliminarily clarified by controlled experiments and dynamic high‐resolution mass spectrometry studies. The synthetic potential of this protocol was proved by a gram‐scale reaction which furnished the product with comparable results (85 % yield and 72 : 28 dr). Moreover, the catalyst could be recovered just through filtering, washing and drying process, and reused five times with the catalytic activity remaining in an acceptable range (from 93 % to 73 % yield).