Immobilization Of Ionic Liquid Research Articles

Immobilization of ionic liquids (ILs) on magnetic mesoporous silica nanotubes: A high throughput and reusable nanocatalyst for the green synthesis of indeno[1,2-b]indolone derivatives

The acidic ionic liquid supported on the magnetic mesoporous silica nanotubes (M-MSNTs/IL) was prepared as a new magnetic catalyst and fully characterized with FE-SEM, HR-TEM, EDS, TGA, BET, VSM, FT-IR, EDX, elemental mapping and XPS. The template of catalyst was magnetic aminated MWCNTs (M-MWCNTs/CONHBu), which removed through calcination process and magnetic mesoporous silica nanotubes (M-MSNTs) were obtained and functionalized using adenine based ionic liquid. The prepared catalyst was successfully applied as a new reusable heterogeneous catalyst for the one-pot three-component indeno[1,2-b]indole-9,10-dione derivatives in water at 75 °C. All of desired products were obtained in good to excellent yields (79–96 %) after relatively short reaction times. M-MSNTs/IL also exhibited a remarkable performance with TOF of 61.2 h-1 and TON of 86.7. The use of M-MSNTs/IL catalyst in the synthesis of indeno[1,2-b]indole-9,10-dione derivatives revealed several advantages including mild reaction conditions, high yield of pure products, clean reaction conditions, avoiding the production of toxic waste, chemical stability of the catalyst, low amount and reusability of catalyst. In addition, the applied nanocatalyst was recovered with an external magnet and reused 6 times without considerable reduction in its catalytic activity.

Immobilization of ionic liquids onto chloromethylated polystyrene as a strategy for highly efficient and selective recovery of Au(III) from gold slag and PCBs

The recovery of Au(III) has become a focal point of interest due to its significance in resource utilization and addressing environmental contamination. In this study, [C3NH2Mim]Cl-CMPS and PPh3-CMPS were successfully developed by immobilizing [C3NH2Mim]Cl and triphenylphosphine (PPh3) onto chloromethylated polystyrene beads (CMPS). The adsorbents demonstrated consistently high adsorption efficiency (>95 %) at a wide pH range. The [C3NH2Mim]Cl-CMPS and PPh3-CMPS exhibited exceptional selective adsorption ability for Au(III), and the adsorption process adhered to the PSO and Langmuir model. The adsorption efficiency of Au(III) remained constant after five consecutive cycles, highlighting outstanding reusability performance. Furthermore, as the existence of multiple coexisting metal ions, [C3NH2Mim]Cl-CMPS and PPh3-CMPS could efficiently and selectively capture Au(III) from the gold slag and PCBs lixivium, which is promising for Au recovery in practice.

Insights into the solid-liquid interface of ionic liquid-immobilized solid acid catalyst for isobutane alkylation

The hydrophobic surface modification of solid acids can modulate the interfacial behaviors for isobutane alkylation. Herein, the interfacial properties between isobutane/butene mixtures and immobilized chloroaluminate ionic liquids with different alkyl chain lengths (e.g., ethyl, butyl, hexyl, and octyl groups) on silica substrates were studied through molecular dynamics simulations. The immobilization of ILs leads to obvious aggregation of C4 reactants and improves molar ratio of isobutane to 2-butene (I/O) at the interface, e.g., SiO2-[EPIm][Al2Cl7] (I/O = 1.17) versus pure SiO2 (I/O = 0.77) systems. With the prolonged alkyl chain of cations, the interfacial thickness gradually increases, while the I/O molar ratio exhibits the opposite order. Despite the inhibited diffusion of C4 reactants by immobilized ILs, the relative diffusion of isobutane to 2-butene is improved as the alkyl chain of cations prolongs. The above information suggests that the immobilization of ionic liquids with butyl groups is a good choice for isobutane alkylation.

Covalent immobilization of di-cationic DABCO ionic liquid over graphene oxide as an efficient and recyclable nanocomposite for the synthesis of Knoevenagel and Hantzsch reactions

Covalent immobilization of di-cationic DABCO ionic liquid over graphene oxide as an efficient and recyclable nanocomposite for the synthesis of Knoevenagel and Hantzsch reactions

Ionic liquids bonded in mesoporous HAP serve as efficient catalysts for CO2 fixation

In this study, hydroxyapatite (HAP) with abundant surface hydroxyl and large pores was used as the ionic liquid ([DMCA]X) immobilization carrier, where the surface hydroxyl groups of HAP were used as binding sites and the n-halogen-acids were used as bonding agents. The supported ionic liquid catalysts [DMCA]X-n-HAP were characterized by XRD, TEM, TG and FTIR, proving that the ionic liquids were successfully bonded onto the surface of HAP. The utilization of hydroxyl sites on the surface of HAP was as high as 90%. The above catalysts were used to catalyze the cycloaddition reaction of CO2 and propylene oxide (PO), and the yield and selectivity of propylene carbonate (PC) were up to 98.7% and 100%, respectively. The length effect of the bonding agents on the catalyst performance was also studied, and found that n-chlorine-butyric acid was the most suitable chemical for channel structure of HAP and spatial freedom of ionic liquid. In addition, the effects of halogen anion and hydroxyl hydrogen on the performance of the reaction were also studied. Importantly, autocatalysis was discovered in the reaction. Finally, the reaction intermediates and reaction mechanism of CO2 cycloaddition were investigated by in situ-DRIFTS, revealing that ring-open of PO is rate-determining step.

Synthesis and Application of Encapsulating Metal/Sulfonic Dual‐Acid Based Phosphotungstic Acid Ionic Liquids

AbstractIn recent years, ionic liquids have been widely used for industrial acid‐catalysis. The enhancements of the acidity and immobilization of ionic liquids have been drawing increasing attention from researchers. In this study, dual‐acid based phosphotungstic acid ionic liquids (PWILs) modified by a variety of metal ions (Fe3+, Cu2+, Al3+) and sulfonic acid group (−SO3) were synthesized. They were subsequently embeded into B‐SBA‐16 mesoporous molecular sieves with acidic sites to produce a plurality of encapsulating metal/sulfonic dual‐acid based phosphotungstic acid ionic liquids (MnPWIL/B‐SBA‐16s) composite catalysts. The structural properties, thermal stability, and encapsulation of the as‐fabricated composite catalysts were systematically investigated by FT‐IR, BET, SAXD, TEM, TG‐DSC and XPS. Moreover, the catalytic performances of the composite catalysts were evaluated using the ketalization of cyclohexanone with ethylene glycol as a model reaction. Among the different composite catalysts, Al0.50PWIL/B‐SBA‐16 showed the highest cyclohexanone conversion of 94.05 % and the maximum cyclohexanone glycol ketal yield of 83.45 %. Meanwhile, this catalyst still exhibited superior catalytic properties after five cycles of the catalytic reaction. These results demonstrate the high activity and durability of the novel ionic liquid composite catalyst.

Immobilization of Ionic Liquid–Triethanolammonium Bicarbonate on Magnetic Nanoparticles as an Efficient Catalyst for Knovenegel Condensation

In this paper, a new nano-magnetic catalyst has been synthesized by immobilization of ionic liquid triethanolammonium bicarbonate with modified Fe3O4 NPs ([Fe3O4@Si-(CH2)3-TEA] [HCO3]). After, its characterization by different techniques such as FT-IR, XRD, FE-SEM, and EDX, it was used as an efficient catalyst for the knovenegel condensation. The protocol has a number of advantages which is including the ease of purification, recyclable by an external magnet, high yields (85-95% and time (15-50 min), the reusability of the catalyst (at least 5 times without reducing the catalytic activity), its high thermal and chemical stability, and its high selectivity and efficiency.

Engineered and Durable Antimicrobial Polymer via Controllable Immobilization of Ionic Liquids onto the Poly(lactic acid) Chains.

Nowadays, the development of effective modification methods for PLA has gained significant interest because of the wide application of antimicrobial PLA materials in the medical progress. Herein, the ionic liquid (IL) 1-vinyl-3-butylimidazolium bis(trifluoromethylsulfonyl)imide, has been grafted onto the PLA chains successfully in the PLA/IL blending films via electron beam (EB) radiation for the miscibility between PLA and IL. It was found that the existence of IL in the PLA matrix can significantly improve the chemical stability under EB radiation. The Mn of PLA-g-IL copolymer did not change obviously but was just decreased from 6.80 × 104 g/mol to 5.20 × 104 g/mol after radiation with 10 kGy. The obtained PLA-g-IL copolymers showed excellent filament forming property during electrospinning process. The spindle structure on the nanofibers can be completely eliminated after feeding only 0.5 wt % ILs for the improvement of ionic conductivity. Specially, the prepared PLA-g-IL nonwovens exhibited outstanding and durable antimicrobial activity for the enrichment of immobilized ILs on the nanofiber surface. This work provides a feasible strategy to realize the modification of functional ILs onto PLA chains with low EB radiation doses, which may have huge potential application in the medical and packaging industry.

Flexible Polymer-Ionic Liquid Films for Supercapacitor Applications

Mechanically and thermally stable novel gel polymer electrolytes (GPEs) have been prepared and applied in supercapacitor cells. Quasi-solid and flexible films were prepared by solution casting technique and formulated by immobilization of ionic liquids (ILs) differing in their aggregate state. A crosslinking agent and a radical initiator were added to further stabilize them. The physicochemical characteristics of the obtained crosslinked films show that the realized cross-linked structure contributes to their improved mechanical and thermal stability, as well as an order of magnitude higher conductivity than that of the non-crosslinked ones. The obtained GPEs were electrochemically tested as separator in symmetric and hybrid supercapacitor cells and showed good and stable performance in the investigated systems. The crosslinked film is suitable for use as both separator and electrolyte and is promising for the development of high-temperature solid-state supercapacitors with improved capacitance characteristics.

Core-shell assembly of ZrO2 nanoparticles with ionic liquid: a novel and highly efficient heterogeneous catalysts for Biginelli and esterification reactions.

Imidazolium sulfonic acid chloride grafted ZrO2 nanoparticles (ZrO2-IL) were synthesized through facile post-treatment of the nanoparticles with the imidazolium-sulfonic acid chloride ionic liquid. The immobilization of the ionic liquid over the ZrO2 nanoparticles was evident from the XRD, SEM, TEM, Raman, BET, and XPS analysis. The results obtained from the XRD analysis clearly show that the catalyst has an orthorhombic structure and from the BET analysis it is evident that the surface is mesoporous with uniform pore sizes and pore distribution. Further evidence of immobilization of ionic liquid over the ZrO2 NPs was obtained from the SEM, TEM, XPS, and Raman analysis. Under mild conditions, the synthesized heterostructure was used in the acid-catalyzed esterification of different acids. The ZrO2-IL catalyst converts 99% of the acid to ester with a 98.9% yield in 1h. The material was also shown to be highly efficient as catalyst for the Biginelli reaction under solvent-free conditions, with the catalyst for dihydropyrimidin-2(1H)-one (DHPMs) in 1h with 99.2% conversion and 99% yield. The synergy between the ionic liquid catalyst and the substrates increased the catalytic efficiency and resulted in high-yield product conversion. The mechanism of both transformation reactions was investigated, as well as the synergy between ionic liquid and ZrO2 nanoparticles for better catalytic efficiency was established.

Immobilization of Ionic Liquid on a Covalent Organic Framework for Effectively Catalyzing Cycloaddition of CO2 to Epoxides.

Transforming CO2 into value-added chemicals has been an important subject in recent years. The development of a novel heterogeneous catalyst for highly effective CO2 conversion still remains a great challenge. As an emerging class of porous organic polymers, covalent organic frameworks (COFs) have exhibited superior potential as catalysts for various chemical reactions, due to their unique structure and properties. In this study, a layered two-dimensional (2D) COF, IM4F-Py-COF, was prepared through a three-component condensation reaction. Benzimidazole moiety, as an ionic liquid precursor, was integrated onto the skeleton of the COF using a benzimidazole-containing building unit. Ionization of the benzimidazole framework was then achieved through quaternization with 1-bromobutane to produce an ionic liquid-immobilized COF, i.e., BMIM4F-Py-COF. The resulting ionic COF shows excellent catalytic activity in promoting the chemical fixation of CO2 via reaction with epoxides under solvent-free and co-catalyst-free conditions. High porosity, the one-dimensional (1D) open-channel structure of the COF and the high catalytic activity of ionic liquid may contribute to the excellent catalytic performance. Moreover, the COF catalyst could be reused at least five times without significant loss of its catalytic activity.

MCM-41 supported S-alkyl/aryl-substituted 2-mercaptobenzothiazolium-based ionic liquids: synthesis, characterization, and application in the fuel desulfurization

Supported ionic liquids (SILs), synthesized by immobilization of ionic liquids (ILs) onto solid support materials, have played an effective role in several applications like fuel desulfurization, organic catalysis, gas separations, biofuel synthesis, etc., in comparison to pure ILs which suffer from many drawbacks like difficult recovery, high cost, mass transfer issue owing to large viscosity, toxic nature, complications in product purifications and fixed bed reactor technology. In this study, a series of new SILs (MCM-41@[S-RBTh][Cl]; R = aryl/alkyl groups) were synthesized via immobilization of different S-alkyl/aryl-substituted 2-mercaptobenzothiazolium-based ILs onto MCM-41 silica support. Structure elucidation of SILs was achieved through SEM, EDS, SAXS, NMR, BET, and FT-IR spectroscopy. Further, the synthesized SILs and MCM-41 were investigated for the removal of sulfur-containing aromatic species from model gasoline and real gasoline. MCM-41@[S-BzBTh][Cl] (0.5 g) removed maximum sulfur content with the percentage of 57.5 % (at 35 °C), 58.7 % (at 40 °C), and 63.4 % (at 45 °C) of TS, TN, and DBT respectively, from model gasoline (5 g) of sulfur concentration of 200 ppm under shaking conditions for 140 min. The impact of the aryl group and different lengths of alkyl groups of supported benzothiazolium-based ILs on their adsorption performance was also studied.

Facile Ionization of the Nanochannels of Lamellar Membranes for Stable Ionic Liquid Immobilization and Efficient CO2 Separation.

Two-dimensional (2D) lamellar membranes, with highly ordered nanochannels between the adjacent layers, have revealed potential application prospects in various fields. To separate gases with similar kinetic diameters, intercalation of a functional liquid, especially an ionic liquid (IL), into 2D lamellar membranes is proved to be an efficient method due to the capacity of imparting solubility-based separation and sealing undesired defects. Stable immobilization of a high content of liquid is challenging but extremely required to achieve and maintain high separation performance. Herein, we describe the intercalation of a typical IL, 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]), into the ionized nanochannels of sulfonated MXene lamellar membranes, where the sulfonate groups are anchored onto MXene nanosheets through a facile method based on metal-catechol chelating chemistry. Thanks to the intrinsic benefits of MXene as building blocks and the decorated sulfonate groups, the optimal membrane possesses adequate interlayer spacing (∼1.8 nm) and high IL uptake (∼47 wt %) and therefore presents a CO2 permeance of 519 GPU and a CO2/N2 selectivity of 210, outperforming the previously reported liquid-immobilized lamellar membranes. Moreover, the IL loss rate of the membrane within 7 days at elevated pressure (5 bar) is measured to be significantly decreased (from 43.2 to 9.0 wt %) after growing sulfonate groups on the nanochannel walls, demonstrating the excellent IL storage stability.

Silica-Based Supported Ionic Liquid-like Phases as Heterogeneous Catalysts.

Supported ionic liquid phases offer several advantages related with catalysis. Immobilization of ionic liquid on the solid support provides catalytic activity or efficient matrix for active phases, as enzymes or metal compounds. Ionic liquid can be physically adsorbed on the carrier (supported ionic liquid phase) or chemically grafted to the material surface (supported ionic liquid-like phase). The use of supported ionic liquid phases improves mass transport, reduces ionic amount in the process and, most importantly, enables effortless catalyst separation and recycling. Moreover, chemical modification of the surface material with ionic liquid prevents its leaching, enhancing length of catalyst life. Silica-based materials have become an effective and powerful matrix for supported ionic liquid-like phase due to its cost-efficiency, presence of hydroxyl groups on the surface enabling its functionalization, and specific material properties, such as the size and shapes of the pores. For these reasons, supported ionic liquid-like phase silica-based materials are successfully used in the organic catalysis.

Solvate ionic liquid-based ionogels for lithium metal batteries over a wide temperature range

Ionogels for lithium metal batteries are usually obtained by immobilization of lithium salt-containing ionic liquids using linear polymers as gelator, which are thermally unstable and lack of adhesion. Meanwhile, the two-cation (ionic liquid cation and lithium ion) competition results in low lithium-ion transference number. In this work, we designed novel ionogels by in situ UV radiation-induced chemically crosslinked polymerization of butyl acrylate in a solvate ionic liquid ([Li(G4)][TFSI]) without additional lithium salt. The obtained ionogels (IG-m/n, m/n is the weight ratio between butyl acrylate and solvate ionic liquid) exhibit nonflammability, favorable thermal and mechanical features, high ionic conductivity, wide electrochemical window, and interestingly adhesive ability that provides an intimate contact with the Li anode. Consequently, one of the ionogels, IG-1/2, owing to its optimized adhesion, ionic conductivity, and mechanical property, could endow the as-fabricated Li|IG-1/2|LiFePO4 cells with high cyclability and Coulombic efficiency at room temperature, 90 °C, and 150 °C.

Composite of magnetic carbon quantum dot-supported ionic liquid and Cu-BDC (CCDC no. 687690) MOF: A triple catalytic composite for chemical transformations

A novel magnetic triple composite was synthesized through immobilization of DABCO-based ionic liquid on magnetic carbon quantum dot, followed by conjugation of the resultant compound with a copper-based metal-organic framework (CCDC no. 687690). The as-prepared composite was characterized via FESEM/EDS, XRD, TGA, FTIR, VSM and elemental mapping analysis and utilized as a magnetic catalyst for promoting three-component reaction of malononitrile, dimedone and aldehydes under mild reaction condition to furnish etrahydrobenzo[b]pyrans. The catalyst exhibited high catalytic activity and could promote the reaction of various aldehydes with different electronic densities. Moreover, the catalyst could be magnetically collected and successfully reused for five reaction runs with slight loss of the catalytic activity. Notably, comparison of the activity of the catalyst with that of ionic liquid, magnetic carbon quantum dot and metal-organic framework confirmed superior catalytic activity of the former.

Immobilization of molecule-based ionic liquids: a promising approach to improve elecrocatalyst performance towards the hydrogen evolution reaction

Ionic liquids (ILs) have received continuous attention owing to their unique chemical and physical properties and to their successful integration in several applications.

Electrostatic immobilization of ionic liquids onto SBA-15 as heterogenized catalysts for esterification of oleic acid with trimethylolpropane

To overcome the drawbacks of homogeneous catalysts in the synthesis of trimethylolpropane trioleate (TMPTO), ionic liquids with different acidity were electrostatically immobilized onto SBA-15 to obtain heterogenized catalysts. The catalytic performance of the as-prepared two catalysts (IL1/SBA-15 and IL2/SBA-15) was investigated at different temperatures (100–140 °C) and molar ratio of oleic acid (OA) to trimethylolpropane (TMP) (3:1 to 5:1) at fixed catalyst dosage of 3 wt% and reaction time of 20 h; where the catalyst IL1/SBA-15 with higher acidity exhibits higher activity. The optimum temperature (at OA:TMP = 3:1) was obtained at 130 °C, where the total conversion was 86.1% and 70% with selectivity towards TMPTO of 95.6% and 92.96% for IL1/SBA-15 and IL2/SBA-15, respectively. Above this temperature, the selectivity began to decrease. The effect of OA: TMP molar ratio showed the increase of conversion (92.7% and 79.1%) with the increase of OA: TMP molar ratio up to 4.5. Further increase in OA concentration results in a damping of the catalytic efficiency of the two catalysts. Through six consecutive runs, the periodicity test refers to the relative stability of the employed catalysts with a slight decrease in activity. All results were interpreted and discussed in detail.

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.

Research progress in application of immobilized ionic liquid materials to separation by solid-phase extraction

离子液体是由阴、阳离子组成的低温熔融盐,几乎没有蒸汽压,具有稳定性好、溶解能力强、结构可设计、导电性好等优良性能。离子液体作为一种广受关注的新型“绿色溶剂”,具有代替传统有机溶剂的潜力,其制备方法和应用范围研究日趋完善和多样,已广泛应用于催化化学、光电化学、材料化学和分析化学等领域。离子液体通过功能化导向设计后,可以将羟基、氨基、羧基、氰基等活性基团键合在离子液体结构上,促使其更加易于与目标分子通过生成π-π键、氢键、离子键和范德华力等而产生相互作用,更加易于发生固定化反应。将离子液体负载到固体载体材料进行固定化后,新型材料既可以减少离子液体的流失,同时保留了离子液体和固体载体的独特性能,具有富集效率高、吸附容量高、稳定性好、识别位点多、萃取选择性强、离子液体利用率高等特点,近年来,在有机小分子固相萃取分离研究中应用广泛。该文从离子液体与硅胶、分子筛、分子印迹聚合物、氧化石墨烯、磁性材料等固体载体的固定化研究情况入手,综述了离子液体固定化材料在固相萃取分离中的应用情况,涉及的目标分离物质包括生物碱类、黄酮类、多酚类等天然活性成分,以及常见药物分子、有机农药等有机小分子化合物,系统地介绍了离子液体与多种载体固定化的性质、应用和分离机制。离子液体的引入,增加了复合材料的活性位点分布和吸附容量,离子液体固定化材料的吸附效率与离子液体种类、吸附材料用量、样品溶液浓度、吸附温度、pH值、洗脱溶剂类型、用量及流速等因素有关。该文探讨了离子液体结构相对单一、相关基础理论研究相对薄弱、复杂基质萃取程度不理想等问题,并提出相应的解决思路,以期为离子液体固定化材料在复杂基质中目标分子分离分析方面的应用提供借鉴和参考。