Basic Ionic Liquid Supported on Mesoporous SBA-15 Silica as an Efficient Heterogeneous Catalyst for Biodiesel Production

Reactive Extraction for Fatty Acid Methyl Ester Production from Castor Seeds Using a Heterogeneous Base Catalyst: Process Parameter Optimization and Characterization

Fatty acid methyl ester (FAME) from oil seeds is conventionally produced via a two/three-process-step method: extraction of oil and subsequent esterification/transesterification to fatty FAME (biodiesel). However, in the present study, we investigated the production of castor kernel oil (CKO) FAME by reactive extraction for extraction and transesterification in a single process using a heterogeneous catalyst. The content of oil that can be extracted was checked by investigating several nonreactive extraction parameters such as solvent type (polar, nonpolar, and mixture), the solvent to kernel ratio, and extraction time. Maximum oil was extracted using methanol as a solvent with a methanol-to-seed ratio of 6.25:1 for 6 h extraction time. The viscosity of CKO obtained by nonreactive extraction was reduced from 288.83 to 19.04 mm²/s by reactive extraction using a 4.09 wt % catalyst concentration (BaO) and a 330.9:1 methanol-to-oil molar ratio for 6 h reaction time at 64 °C. Reactive extraction for transesterification of CKO was performed using BaO, CaO, and ZnO heterogeneous catalysts. BaO results in the increased yield of CKO FAME compared to other catalysts. Central composite design (CCD) using the response surface methodology (RSM) was implemented to design the experimental matrix, process parameter optimization, maximize the yield of CKO FAME, and investigate interaction effects of parameters such as reactive extraction temperature (55-65 °C), catalyst concentration (3-5 wt %), and methanol-to-oil molar ratio (175:1-350:1) on the yield of CKO FAME. A second-order model equation with a p-value < 0.05 and an R ² value near 1.0 was obtained to predict the yield using the input parameters. The maximum yield CKO FAME of 96.13 wt % with 94.4% purity of produced CKO FAME was obtained at a catalyst concentration of 4.09 wt % and a methanol-to-oil molar ratio of 330.9:1 for 6 h with a reaction temperature of 64 °C. Therefore, a comparable conversion of castor seed oil triglyceride (96.13 wt %) was obtained in a single step directly from castor seeds. Furthermore, the rheological behavior investigation of castor kernel oil and castor methyl ester revealed that the dynamic viscosity of both samples was found to be dependent on triglyceride content and temperature.

A cleaner route of biodiesel production from waste frying oil using novel potassium tin oxide catalyst: A smart liquid-waste management

The valorization of waste frying oil (WFO) to biodiesel has been carried out via solid base catalyzed transesterification reaction. A novel potassium tin oxide (KSO) catalyst was synthesized via polymer precursor auto combustion method. The catalyst showed the best physicochemical properties when it was calcined at 800 °C. Using KSO 800 catalyst, the highest FAME conversion (99.5%) of WFO found at moderated reaction condition within very short time (35 min); moreover, no leaching of K-species was observed in reusability test upto 5^th cycle. Kinetics proved that the above catalytic reaction followed pseudo-first-order kinetics and the rate of the reaction was doubled with increasing 10 °C reaction temperature. The reaction activation energy, enthalpy of activation, entropy of activation, and Gibb's free energy of activation of the reaction were found to be 66.52 kJ/mol, 62.95 kJ/mol, -74.07 J/mol/K and 88 kJ/mol respectively. Evaluation of the green parameters revealed that KSO 800 catalyzed transesterification process approached a cleaner route with excellent efficacy in terms of turnover frequency and yield. KSO 800 helped to produce high quality biodiesel from WFO adopting faster and greener reaction pathway. Thus, KSO 800 was considered as a potential and green catalyst for transforming waste oil into biofuel.

Newly Designed Mesoporous Silica and Organosilica Nanostructures Based on Pentablock Copolymer Templates in Weakly Acidic Media

We developed a new category of porous silica and organosilicas nanostructures in a facile method based on weakly acidic aqueous-ethanol media by utilizing two different pentablock copolymer templates of type PLGA-PEO-PPO-PEO-PLGA. Pluronic block templates were used mainly to prepare these pentablock copolymers with different molecular weights and volume ratios. Silica precursor tetraethyl orthosilicate and organosilicas precursor 1,4-bis(triethoxysilyl)benzene have been used as main source for synthesizing the silica and organosilicas samples. Weak Lewis acids iron(III) chloride hexahydrate, aluminum(III) chloride hexahydrate, and boric acid were utilized as catalyst instead of any strong inorganic acids and the molar ratio of catalyst/precursor has been optimized to 1–2 for preparation of ordered mesostructures. Reaction temperatures have been optimized to 25 °C for pure silica and both 25 °C as well as 40 °C for organosilicas to get the best result for mesostructures. A detailed analysis by using various analytical techniques like synchrotron small angle X-ray scattering, nitrogen sorption, transmission electron microscopy, scanning electron microscope, solid-state ²⁹Si CP-MAS nuclear magnetic resonance (NMR), and so on has revealed well developed mesostructures with surface area of 388–836 m²/g for silica and 210–691 m²/g for organosilica samples, respectively. Furthermore, bimodal typepores have been observed from pore size distribution plot of the samples. Thermal stability of the materials was up to 400 °C as analyzed by thermogravimetric analysis.

Advances in Enzyme and Ionic Liquid Immobilization for Enhanced in MOFs for Biodiesel Production

Biodiesel is a promising candidate for sustainable and renewable energy and extensive research is being conducted worldwide to optimize its production process. The employed catalyst is an important parameter in biodiesel production. Metal-organic frameworks (MOFs), which are a set of highly porous materials comprising coordinated bonds between metals and organic ligands, have recently been proposed as catalysts. MOFs exhibit high tunability, possess high crystallinity and surface area, and their order can vary from the atomic to the microscale level. However, their catalytic sites are confined inside their porous structure, limiting their accessibility for biodiesel production. Modification of MOF structure by immobilizing enzymes or ionic liquids (ILs) could be a solution to this challenge and can lead to better performance and provide catalytic systems with higher activities. This review compiles the recent advances in catalytic transesterification for biodiesel production using enzymes or ILs. The available literature clearly indicates that MOFs are the most suitable immobilization supports, leading to higher biodiesel production without affecting the catalytic activity while increasing the catalyst stability and reusability in several cycles.

Polythiolactone-Decorated Silica Particles: A Versatile Approach for Surface Functionalization, Catalysis and Encapsulation

The surface chemistry of colloidal silica has tremendous effects on its properties and applications. Commonly the design of silica particles is based on their de novo synthesis followed by surface functionalization leading to tailormade properties for a specific purpose. Here, the design of robust "precursor" polymer-decorated silica nano- and microparticles is demonstrated, which allows for easy post-modification by polymer embedded thiolactone chemistry. To obtain this organic-inorganic hybrid material, silica particles (SiO2 P) were functionalized via surface-initiated atom transfer radical polymerization (SI-ATRP) with poly(2-hydroxyethyl acrylate) (PHEA)-poly(thiolactone acrylamide (PThlAm) co-polymer brushes. Exploiting the versatility of thiolactone post-modification, a system was developed that could be used in three exemplary applications: 1) the straightforward molecular post-functionalization to tune the surface polarity, and therefore the dispersibility in various solvents; 2) the immobilization of metal nanoparticles into the polymer brushes via the in situ formation of free thiols that preserved catalytic activity in a model reaction; 3) the formation of redox-responsive, permeable polymer capsules by crosslinking the thiolactone moieties with cystamine dihydrochloride (CDH) followed by dissolution of the silica core.

Basic ionic liquids for catalysis: the road to greater stability

Homogeneous and heterogenized basic ionic liquids as reaction catalysts have been highlighted, particularly where they are used to promote reactions that could form the basis of more sustainable energy and chemical production.

Immobilization of lipases onto the halogen & haloalkanes modified SBA-15: Enzymatic activity and glycerolysis performance study

In this study, SBA-15 was modified by halogen & haloalkanes and later used to immobilize lipases. The hydrolysis activity and the glycerolysis performance of the immobilized lipases was carefully studied. Highest activity of the immobilized Candida antarctica lipase B (CALB), Lipase from Aspergillus oryzae (AOL), Lecitase® Ultra (LU) and lipase from Rhizomucor miehei (RML) was respectively at 5577, 12000, 2822 and 11,577 U/g; in addition, the highest activity was obtained from the lowest or moderate lipase loading, at 25.73, 90.72, 89.52 and 30.56 mg/g respectively. The mechanism of lipase immobilization was studied and it was through interfacial activation. The halogen & haloalkanes modification of SBA-15 afforded considerable glycerolysis activity for diacylglycerols (DAG) preparation. CALB@SBA-15-CH₂CH₂(CF₂)₅CF₃ and CALB@SBA-15-CH₂CH₂(CF₂)₇CF₃ were suitable for DAG production, they both exhibited good reusability in glycerolysis reaction, with 117.36% and 93.06% of their initial glycerolysis activity retained respectively after ten cycles of reuse. The relationships between temperature with triacylglycerols (TAG) conversion were lnV₀ = 3.13-3.07/T and lnV₀ = 7.90-4.64/T respectively for CALB@SBA-15-CH₂CH₂(CF₂)₅CF₃ and CALB@SBA-15-CH₂CH₂(CF₂)₇CF₃; in addition, their activation energy (Ea) was respectively at 25.50 and 38.54 kJ/mol.

Cu(II)-Hydrazide Coordination Compound Supported on Silica Gel as an Efficient and Recyclable Heterogeneous Catalyst for Green Click Synthesis of β-Hydroxy-1,2,3-triazoles in Water

A hydrazone ligand, (E)-6-(2-((2-hydroxynaphthalen-1-yl)methylene)hydrazinyl)nicotinohydrazide (H₂L), was synthesized and characterized by spectroscopic methods. The reaction of H₂L with CuCl₂·2H₂O in methanol gave Cu(II) coordination compound, [Cu(HL')(Cl)]·CH₃OH (1), which was characterized by elemental analysis and spectroscopic methods (Fourier transform infrared (FT-IR) and UV-vis). The structure of 1 was also determined by single-crystal X-ray analysis. Structural studies confirmed the formation of esteric group during the synthesis of 1. Compound 1 was immobilized on 3-aminopropyltriethoxysilane (APTS)-functionalized silica gel through the amidification reaction and the obtained heterogeneous coordination compound was utilized as a catalyst for the three-component azide-epoxide-alkyne cycloaddition reaction in water as a green solvent. The structural properties of the heterogeneous catalyst were characterized by a combination of FT-IR, UV-vis, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and energy-dispersive spectrometry (EDS) analyses. The effect of the amount of catalyst and temperature on the cycloaddition reaction was studied, and the obtained 1,2,3-triazoles were characterized by spectroscopic studies and single-crystal X-ray analysis. The catalytic investigations revealed that this catalytic system has high activity in the synthesis of β-hydroxy-1,2,3-triazoles. It was also found that the aromatic and aliphatic substituents on the alkyne and epoxide together with the reaction temperature have considerable effects on the activity and regioselectivity of this catalytic system.

Production of diacylglycerols through glycerolysis with SBA-15 supported Thermomyces lanuginosus lipase as catalyst

BACKGROUND

In this study, SBA-15 was functionalized by silane coupling reagents, then lipase from Thermomyces lanuginosus (TLL) was immobilized onto the parent and the organically modified SBA-15 for diacylglycerol (DAG) production through glycerolysis.

RESULTS

Diacylglycerol content of 54.77 ± 0.63%, and triacylglycerol (TAG) conversion of 77.75 ± 1.24%, were obtained from the parent SBA-15 supported TLL-mediated glycerolysis reaction in a solvent-free system. However, poor performance was unexpectedly observed when co-solvents were introduced into the reaction system. After organic modification, the functionalized SBA-15 supported TLL samples all exhibited reasonable performance, producing DAG content over 40 wt% and TAG conversion over 70 wt%. Higher DAG content, up to 59.19 ± 1.10%, was observed from the phenyl group-modified SBA-15 supported TLL. The operational stability of the immobilized TLL samples in glycerolysis was also improved after organic functionalization. The phenyl group-modified SBA-15 supported TLL showed good reusability in the present glycerolysis reaction, and 95.21 ± 4.87% of the initial glycerolysis activity remained after five cycles of reuse.

CONCLUSION

The organic modification of SBA-15 improved the catalytic performance of its supported TLL in glycerolysis, in terms of TAG conversion, DAG content, and reusability. © 2019 Society of Chemical Industry.

Recent Advances in Applications of Supported Ionic Liquids

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The supported ionic liquids have shown immense potential for numerous applications in catalysis and separation science. In the present review, the remarkable contribution of supported ionic liquids has been highlighted. The main emphasis has been laid on describing the facile separation of gas from binary gas mixtures owing to the capability of selective transport of permeable gases across supported membranes and removal of environmentally hazard sulfur compounds from fuels. The catalytic action of supported ionic liquids has been discussed in other applications such as biodiesel (biofuel) synthesis by transesterification/esterification processes, waste CO2 fixation into advantageous cyclic carbonates, and various chemical transformations in organic green synthesis. This review enclosed a maximum of the published data of the last ten years and also recently accomplished work concerning applications in various research areas like separation sciences, chemical transformations in organic green synthesis, biofuel synthesis, waste CO2 fixation, and purification of fuels by desulfurization.

Core–shell magnetic mesoporous N-doped silica nanoparticles: solid base catalysts for the preparation of some arylpyrimido[4,5-b]quinoline diones under green conditions

Nowadays, the application of solid base catalysts as a perfect replacement for homogenous basic catalysts has attracted the attention of researchers. In this study, core–shell magnetic mesoporous N-doped silica nanoparticles N(x wt%)-MSN, as a heterogeneous base catalyst, were synthesized. The N(x wt%)-MSN composite was fabricated by adding different amounts of diethanolamine as a source of nitrogen, besides using tetraethylorthosilicate as a precursor of silica. The as-prepared catalyst was employed efficiently for the synthesis of some arylpyrimido[4,5-b]quinoline-dione derivatives under green conditions. The highly efficient catalyst N(1.3 wt%)-MSN was characterized via XRD, FESEM, HRTEM, BET and XPS techniques, and the results of these analyses proved that the nitrogen was doped into the silica structure. Also, the results demonstrated the core–shell structure of the as-synthesized composite.

Preparation of core–shell magnetic mesoporous N-doped silica nanoparticles as a new solid base catalyst was studied. obtained catalyst was used for the preparation of some arylpyrimido[4,5-b]quinoline diones under green conditions.

Palm Biochar-Based Sulphated Zirconium (Zr-AC-HSO3) Catalyst for Methyl Ester Production from Palm Fatty Acid Distillate

A palm waste kernel shell biomass was converted into bio-based sulphonated activated carbon and further used for preparation of a sulphated zirconium-doped activated catalyst (Zr-AC-HSO3) by wet impregnation method. The structural, physicochemical, morphological, textural, and thermal characteristics of the synthesized Zr-AC-HSO3 catalyst were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, temperature-programmed desorption of ammonia (TPD-NH3), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). The catalytic activity of the 20 wt% Zr-AC-HSO3 catalyst was further evaluated for esterification of palm fatty acid distillate (PFAD). This study achieved a maximum fatty acid methyl ester (FAME) yield of 94.3% and free fatty acid (FFA) conversion of 96.1% via the esterification over 20 wt% Zr-AC-HSO3 using 3 wt% catalyst concentration, 15:1 methanol:PFAD molar ratio at 75 °C for 3 h. The experiments to test for reusability showed that the spent catalyst was stable for five successive reaction cycles, with a FFA conversion of 80% in the fifth cycle, without additional treatment. The critical fuel features of the synthesized PFAD methyl ester were determined and were within the range of EN14214 and ASTM D6751 standards.

Supported ionic liquids as highly efficient and low-cost material for CO2/CH4 separation process

Physical immobilization of ionic liquids (ILs) in solid materials appears as an interesting strategy for the development of new sorbents for CO₂ separation from natural gas. In this work the effect of physical immobilization of two ionic liquids with different anions (bmim[Cl] and bmim[OAc]) on two mesoporous supports (commercial silica SBA-15 and silica extracted from rice husk) was evaluated for CO₂ separation from natural gas by experimental determination of CO₂ sorption, CO₂/CH₄ selectivity and sorption kinetics. Results showed that the pure supports present the greatest CO₂ sorption capacity when compared to immobilized ILs. However, CO₂ removal efficiency improves considerably in the CO₂/CH₄ mixture when ILs are immobilized in these supports. The best selectivity results were obtained for supports immobilized with the IL bmim[Cl] and values increased for SIL-Cl by 37% and SBA-Cl 51% when compared with their respective supports. The contribution of SIL-Cl (3.03 ± 0.12) to separation performance (CO₂/CH₄) is similar to SBA-Cl (3.29 ± 0.39). ILs supported also presented fast sorption kinetics when compared to pure ILs thus being an interesting alternative in the search for highly efficient and low-cost separation processes.

Immobilization of Candida antarctica Lipase B onto organically-modified SBA-15 for efficient production of soybean-based mono and diacylglycerols

In this study, SBA-15 was modified by a series of silane coupling reagents and later used to immobilize Candida antartica lipase B (CALB). The enzymatic properties of the immobilized CALB samples were studied. In addition, the catalytic performance in glycerolysis of soybean oil for diacylglycerols (DAG) production was also investigated. The highest enzymatic activity up to 6100.00 ± 246.41 U/g was observed from the propyl methacrylate group modified SBA-15 supported CALB. No loss of activity was observed from the propyl methacrylate group modified SBA-15 supported CALB, but a higher-than-initial activity was notably found from 3-aminopropyl group and n-octyl group modified SBA-15 supported CALB after a 4-h incubation in air at 70 °C. 1-isocyanatopropane group modified SBA-15 supported CALB exhibited selectivity for DAG production. DAG content up to 61.90 ± 2.38 wt% and a DAG/MAG ratio at 3.11 ± 0.08 was obtained after a 24-h reaction at 60 °C in a solvent-free system.

Cross-linked chitosan with a dicationic ionic liquid as a recyclable biopolymer-supported catalyst for cycloaddition of carbon dioxide with epoxides into cyclic carbonates

A dicationc ionic liquid was synthesized and immobilized on chitosan as a catalyst for cycloaddition of CO₂ with epoxides for synthesis of cyclic carbonates.

Fabrication of Core-Shell-Structured Organic-Inorganic Hybrid Nanocatalyst for the Expedient Synthesis of Polysubstituted Oxazoles via Tandem Oxidative Cyclization Pathway

The quest for designing efficient heterogeneous catalytic systems for tandem oxidative cyclization reactions has provided a great impetus to research efforts, as it enables the step-economic construction of complex heterocyclic molecules as well as confers the benefits of a facile catalytic recovery. In the present study, we disclose a new core-shell-structured organic-inorganic hybrid copper nanocatalyst fabricated via the covalent grafting of 2,2'-dipyridyl ketone ligand on amine-functionalized silica-encapsulated magnetite nanoparticles, followed by its metallation with cupric acetate for the tandem oxidative cyclization of amines and β-ketoesters, leading to the production of biologically active polysubstituted oxazole moieties. This programmed catalytic protocol proceeds via the formation of intermolecular C-C and C-N bonds by single-step synthesis and accommodates a broad combination of reaction coupling partners.

Current scenario of catalysts for biodiesel production: a critical review

Due to increasing concerns about global warming and dwindling oil supplies, the world’s attention is turning to green processes that use sustainable and environmentally friendly feedstock to produce renewable energy such as biofuels. Among them, biodiesel, which is made from nontoxic, biodegradable, renewable sources such as refined and used vegetable oils and animal fats, is a renewable substitute fuel for petroleum diesel fuel. Biodiesel is produced by transesterification in which oil or fat is reacted with short chain alcohol in the presence of a catalyst. The process of transesterification is affected by the mode of reaction, molar ratio of alcohol to oil, type of alcohol, nature and amount of catalysts, reaction time, and temperature. Various studies have been carried out using different oils as the raw material; different alcohols (methanol, ethanol, butanol); different catalysts; notably homogeneous catalysts such as sodium hydroxide, potassium hydroxide, sulfuric acid, and supercritical fluids; or, in some cases, enzymes such as lipases. This article focuses on the application of heterogeneous catalysts for biodiesel production because of their environmental and economic advantages. This review contains a detailed discussion on the advantages and feasibility of catalysts for biodiesel production, which are both environmentally and economically viable as compared to conventional homogeneous catalysts. The classification of catalysts into different categories based on a catalyst’s activity, feasibility, and lifetime is also briefly discussed. Furthermore, recommendations have been made for the most suitable catalyst (bifunctional catalyst) for low-cost oils to valuable biodiesel and the challenges faced by the biodiesel industry with some possible solutions.

An imidazolium based ionic liquid supported on Fe3O4@SiO2 nanoparticles as an efficient heterogeneous catalyst for N-formylation of amines

An ionic liquid supported on silica-coated ferrite nanoparticles as an efficient and reusable catalyst for N-formylation of amines.

Propylsulfonic and arenesulfonic functionalized SBA-15 silica as an efficient and reusable catalyst for the acidolysis of soybean oil with medium-chain fatty acids

The objective of this work was to develop a feasible ecofriendly process to produce medium-chain fatty acid (MCFA)-enriched structured lipids (SLs) in heterogeneous manners. For this purpose, the propyl-SO3H or arene-SO3H-modified SBA-15 materials were prepared through a surface functionalization of SBA-15 silica with propyl-SO3H and arene-SO3H groups. The organosulfonic acid-functionalized SBA-15 materials were characterized by Brönsted acidity determination, elemental analysis, XRD, C(13) MAS NMR, FT-IR, SEM, TG, TEM, and N2 adsorption-desorption techniques. Results showed that the propyl-SO3H and arene-SO3H groups were successfully tethered on the SBA-15 support, and the ordered mesoporous structure of SBA-15 silica was well retained after the organofunctionalization. This organic-inorganic hybrid material displayed high surface acidities and high activities in the acidolysis of soybean oil with caprylic or capric acid to produce SLs containing MCFAs. The influences of processing parameters on the reaction were investigated. The two studied catalysts showed an excellent recyclability for the reaction.

Ionic liquids and supercritical carbon dioxide: green and alternative reaction media for chemical processes

Ionic liquids (ILs) and supercritical CO