Monodispersed mesoporous silica nanospheres based on pyridinium ionic liquids

In the past decades, ionic liquids (ILs) have garnered a lot of attention especially in the field of green chemistry due to their unique properties which help to solve the problems posed by organic solvents. Interestingly, their applications are not limited to that only as ILs have the potential to become alternative templates in the development of mesoporous silica nanoparticles (MSNs). This work reported the usage of a series of pyridinium ILs as template in the synthesis of monodispersed mesoporous silica nanosphere (MNSs) via two methods. Both syntheses utilize triethanolamine (TEA) as the base catalyst where in one method the TEA undergoes pre-treatment process while the other did not. Besides that, the effects of pyridinium ILs alkyl chain length were also investigated. MNSs generated via both methods exhibit spherical morphology and decreasing average particles size with increasing alkyl chain length of pyridinium ILs. The MNSs porosity were further analyzed through nitrogen sorption analysis where the surface area were in between 71.85 and 525.02 m² g^?1 and the pore volume was up to 1 cm³ g^?1.     

Ethylene polymerization using vanadium catalyst supported on silica modified by pyridinium ionic liquid

Vanadium catalyst systems (SIL_1–3A(B)/V) for ethylene polymerization were obtained by immobilization of the Cp₂VCl₂ precursor (V) in the ionic liquid 1‐[3‐(triethoxysilyl)propyl]pyridinium chloride (IL), modified by AlCl₃ and AlEtCl₂ (A) or AlEt₂Cl (B), and supported on three types of silica carrier S_1–3. The properties of the ionic liquid supports were determined using Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller measurements, scanning electron microscopy and elemental analysis. The best results (above 2 tons PE (mol V)^?1 (0.5 h)^?1) were obtained using the catalyst system SIL₃B/V. Addition of ethyl trichloroacetate is possible in the ionic liquid medium and it further increases the activity up to 7 tons PE (mol V)^?1 (0.5 h)^?1. In contrast, application of the imidazolium ionic liquid to the SIL system or application the analogous catalyst system without the ionic liquid results in lower activities. The obtained polyethylene (PE) is a linear polymer, with molecular weight (M_w) of over 10⁶ g mol^?1 and molecular weight distribution (M_w/M_n) in the range 1.6–1.9, and has a characteristic fluffy or fibrous shape. In contrast, the PE samples obtained using the systems without ionic liquid reveal broader M_w/M_n (2.5–3.7) and replicate the support morphology. © 2016 Society of Chemical Industry     

Synthesis of ordered cerium-doped cubic mesoporous silica using long-chain ionic liquid as template

The long-chain ionic liquid 1-hexadecyl-3-methylimidazolium chloride (C₁₆mimCl) was used as a template to prepare cerium-doped MCM-48 materials in basic medium by a hydrothermal synthesis procedure. The effect of the amount of Ce salt and C₁₆mimCl/Si on the synthesis were discussed in detail. This mesoporous material exhibits a pore architecture which is cubic Ia3d gyroid and possesses a large surface area and a narrow pore distribution. Cerium in calcined porous framework exists in the form of well-dispersed tetrahedral coordination. The C₁₆mimCl shows a high tendency toward self-aggregation that allows the formation of the cerium-doped gyroid mesostructure by using the appropriate amount of Ce salt.     

Synthesis of ordered cerium-doped cubic mesoporous silica using long-chain ionic liquid as template

The long-chain ionic liquid 1-hexadecyl-3-methylimidazolium chloride (C₁₆mimCl) was used as a template to prepare cerium-doped MCM-48 materials in basic medium by a hydrothermal synthesis procedure. The effect of the amount of Ce salt and C₁₆mimCl/Si on the synthesis were discussed in detail. This mesoporous material exhibits a pore architecture which is cubic Ia3d gyroid and possesses a large surface area and a narrow pore distribution. Cerium in calcined porous framework exists in the form of well-dispersed tetrahedral coordination. The C₁₆mimCl shows a high tendency toward self-aggregation that allows the formation of the cerium-doped gyroid mesostructure by using the appropriate amount of Ce salt.     

One-phase preparation of palladium nanoparticles using thiol-functionalized ionic liquid

Thiol-functionalized ionic liquid (TFIL: 1,3-di(2’,3’-dimercaptoacetoxypropyl) imidazolium, 3′’-mercapto1 ″-propanesulfonic acid) as a stabilizer for preparing palladium (Pd) nanoparticles was synthesized. The suggested TFIL was designed to have thiol groups on both cation and anion as well as on symmetrical positions in cation. Transmission electron microscopy (TEM) shows that the average diameter of the palladium nanoparticles was 3.0 nm and that the standard deviation was 0.15 nm. The overall results strongly suggest that this potential TFIL can act as a highly effective stabilizer for the preparation of Pd nanoparticles     

双介孔二氧化硅制备研究进展

综述了双介孔二氧化硅的制备方法。溶胶-凝胶法研究较多,包括单模板法和双模板法,探讨了不同合成条件对材料的孔径大小、孔径分布及形貌的影响。微乳法、水热法和微波法均在双介孔二氧化硅的制备中有所尝试,与双模板溶胶-凝胶法相比较更加简单易行且经济性更强。未来的主要研究方向将会是介孔的孔径大小、孔径分布及形貌结构的控制。     

介孔中空二氧化硅及硅基微球制备研究进展

介孔中空材料有特定孔道结构,具有中空、密度小、比表面积大的特点,因而具有较好的渗透性、吸附性、筛分分子能力和光学性能,成为具有广泛应用前景的热点研究材料。详细地介绍了国内外新型功能材料介孔中空二氧化硅及硅基微球主要制备方法,包括表面沉积法、层层组装法、原子转移自由基聚合法、喷雾法、微乳液法。同时介绍了合成的介孔、中空二氧化硅和硅基微球的形貌特点及应用。指出不同方法、不同制备条件对材料的形貌、孔径大小、孔形状及材料晶形有很大影响,条件温和、步骤简单、环境友好的制备方法是发展趋势。     

Synthesis of mesoporous silica using a mineral silica source

Mesoporous silica has been applied in catalysis, separations, and drug delivery. It has generally been made using organosilicon precursors such as tetraethyl orthosilicate. For sustainability, it is necessary to find readily accessible mineral sources for making mesoporous silica. In this work, we demonstrate the successful synthesis of mesoporous silica with 10 nm average pore size using the mineral forsterite (Mg₂SiO₄) as a silica source, providing a potentially cheaper and more Earth-friendly route to making technologically important porous silica materials. Pure forsterite was synthesized by a solid-state chemistry route at 1000°C and underwent dissolution–reprecipitation in aqueous hydrochloric acid containing the soft template surfactant, Pluronic P123. Variations of initial reaction pH (−0.2 to 0.6), reaction time (12–24 h), reaction temperature (50 to 90°C), and silica precursor (forsterite and fumed silica) were performed. The mesoporous silica aged at 70°C for 24 h had the highest porosity, with a surface area of 735 m²/g and a pore volume of 1.4 ml/g, comparable to mesoporous silica made using conventional starting materials. This novel geomimetic synthesis route supports the possibility of analogous formation of structured (mesoporous or zeolitic) silica in nature under abiotic or prebiotic conditions.     

中空介孔氧化硅纳米颗粒的制备及应用进展

集空腔与介孔结构于一体的中空介孔氧化硅纳米材料(HMSNs)因其高比表面积、可调孔径、低密度和高渗透等特性,而在诸多领域展现了极大的潜在应用前景。该文对中空-介孔氧化硅纳米颗粒的主要制备方法及其优缺点进行了概述,着重阐述了硬核模板法、液体界面组装法和界面重组与转换法的研究进展;同时,介绍了中空介孔氧化硅纳米颗粒在生物医药、催化和光学领域方面的应用。最后,对其制备和应用目前存在的挑战以及后续突破方向进行了分析和展望。     

中空介孔氧化硅纳米颗粒的制备及应用进展

集空腔与介孔结构于一体的中空介孔氧化硅纳米颗粒因其高比表面积、可调孔径、低密度和高渗透等特性,而在诸多领域展现了极大的潜在应用前景。本文对中空-介孔氧化硅纳米颗粒的主要制备方法及其优缺点进行了概述,着重阐述了硬核模板法、液体界面组装法和界面重组与转换法;同时介绍了中空介孔氧化硅纳米颗粒在生物医药、催化和光学领域的应用情况。最后,对其制备和应用存在的挑战和研究方向进行了分析和展望。     

Preparation of mesoporous silica replica using ordered mesoporous carbon by vapor phase transport of silica source

A new vapor phase transport (VPT) technique to prepare an inverse silica replica of an ordered mesoporous carbon was developed. Tetraethyl orthosilicate (TEOS) was infiltrated in mesoporous carbon CMK-3 as the hard template at 180 °C for 48 h under an autogenous pressure in an autoclave in the presence of water. The samples obtained by removal of CMK-3 retained structural regularity of CMK-3 with little shrinkage of framework, which were characterized by SAXRD, N₂ adsorption, TG-DTA, and SEM. Influence of preparation temperature on the loading amount of silica was investigated. The multi-step replication process was monitored by characterizing the replicated materials as well as intermediate composites.     

磁性介孔硅胶负载碱性离子液体催化剂的制备与性能

用巯丙基硅氧烷对磁性介孔硅胶改性,并通过烯丙基官能化离子液体的双键与巯基之间的自由基加成反应将具有不同侧链烷基的离子液体负载到磁性介孔硅胶表面,制备了磁性介孔硅胶负载碱性离子液体催化剂.采用红外光谱分析、X射线衍射、有机元素分析、氮气物理吸附/脱附分析和样品振动磁强计对催化剂的结构和磁性能进行了表征,最后通过催化三油酸甘油酯与甲醇酯交换反应对其催化性能进行了评价.结果表明,随着离子液体侧链烷基碳个数的增多,磁性介孔硅胶负载离子液体催化剂的离子液体负载量降低,比表面积和孔体积降低.当离子液体侧链烷基为辛基、十二烷基或十六烷基时,油酸甲酯产率均高于95%,并且反应3次后油酸甲酯产率依然高于90%.     

可用于生物催化合成的离子液体的制备

以N-甲基咪唑、2-溴戊烷为原料,合成了中间体溴化1-仲戊基-3-甲基咪唑([2pentMIM]Br),与NaBF4反应制备了离子液体1-仲戊基-3-甲基咪唑四氟硼酸盐([2pentMIM]BF4)。探讨了反应时间、反应温度、料液比、溶剂等对中间体及离子液体产率的影响。结果表明,最佳制备工艺条件为:反应物料液比n(2-溴戊烷)∶n(N-甲基咪唑)=1.4∶1,反应温度80℃,反应时间20 h,转化率为92.02%,中间体使用丙酮为溶剂,等摩尔NaBF4室温下反应1.5 h,离子液体的产率为94.49%。验证了离子液体的酶生物催化合成LAP的活性。     

Ionic liquid-templated preparation of mesoporous silica embedded with nanocrystalline sulfated zirconia

A series of mesoporous silicas impregnated with nanocrystalline sulphated zirconia was prepared by a sol-gel process using an ionic liquid-templated route. The physicochemical properties of the mesoporous sulphated zirconia materials were studied using characterisation techniques such as inductively coupled optical emission spectroscopy, X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray microanalysis, elemental analysis and X-ray photoelectron spectroscopy. Analysis of the new silicas indicates isomorphous substitution of silicon with zirconium and reveals the presence of extremely small (< 10 nm) polydispersed zirconia nanoparticles in the materials with zirconium loadings from 27.77 to 41.4 wt.%.     

离子液体在纳米纤维素制备中的应用进展

纳米纤维素因其优异的性能和独特的结构在很多领域都受到了关注,其制备和应用已成为相关领域的研究热点。目前纳米纤维素的制备方法众多,但依然面临着较大的挑战。离子液体因其对木质纤维素优良的溶解性能及可回收性,在纳米纤维素制备中展现了较大的潜力。基于此,综述了离子液体在纳米纤维素制备方面的应用进展,重点介绍了离子液体作为预处理手段在纳米纤维素制备方面的应用现状,以及作为溶剂和催化剂直接水解制备纳米纤维素方面的研究进展,并对制备过程中离子液体的回收情况进行了简单概述。     

介孔硅SBA-15对水溶液中咪唑基离子液体的吸附性能研究

本文研究了介孔硅SBA-15对水中咪唑基离子液体[Bmim]Cl和[Bmim]OH的吸附行为。合成的SBA-15具有有序的二维六方介孔结构。研究发现升高温度会使SBA-15对离子液体的吸附量降低,吸附过程是放热过程。25℃下将吸附等温数据进行Langmuir和Freundlich方程线性拟合,相比之下Langmuir模型更适合用来描述SBA-15对两种离子液的吸附行为,SBA-15对[Bmim]Cl和[Bmim]OH最大吸附量分别为336.7和467.3mg·g-1。     

Adsorption of acid dyes using polyelectrolyte impregnated mesoporous silica

Cationic polyelectrolyte, PDDA (Poly(diallyldimethylammonium chloride)), was impregnated on mesoporous silica SBA-15 (PDDA/SBA-15) and amorphous conventional silica (PDDA/CS) supports. Acid dye adsorption characteristics, such as adsorption kinetics, adsorption isotherms, maximum adsorption capacity, and breakthrough curves of the prepared PDDA/SBA-15 and PDDA/CS adsorbents, were examined by batch and column adsorption techniques where the Acid Violet 17, Acid Red 44, and Acid Blue 45 were used as target adsorbates. PDDA/SBA-15 adsorbent showed fast adsorption kinetics of less than 10 min and much higher adsorption capacities compared to PDDA/CS due to large pore sizes, ordered cylindrical pore structures, and high amount of impregnated PDDA. Results from batch and column experiments showed that practical use of PDDA/SBA-15 adsorbent for effective removal of acid dyes from aqueous solution would be possible. Polyelectrolyte impregnation method was suggested as a simple method for the development of adsorbent with large pore diameters and efficient adsorption characteristics.     

Synthesis of dimethyl carbonate from ethylene carbonate and methanol using immobilized ionic liquid on amorphous silica

Ionic liquid immobilized on mesoporous amorphous silica was prepared from the coupling of 1-(triethoxysilylpropyl)-3-n-alkyl-imidazolium halides with tetraethyl orthosilicate (TEOS) through template-free condensation under strong acidic conditions. The immobilized 1-n-butyl-3-methyl imidazolium bromide ionic liquid on amorphous silica (BMImBr-AS) was characterized by EA, N₂ adsorption, FT-IR, ¹³C NMR and ²⁹Si NMR. The immobilized amount of IL was 1.27 mmol/g-SiO₂ and surface area was 652 m²/g with bimodal distribution of pores. The average pore diameter was 3.3 and 24.6 nm, respectively. The silica-supported ionic liquids were proved to be an effective heterogeneous catalyst for the synthesis of dimethyl carbonate (DMC) from transesterification of ethylene carbonate (EC) with methanol. High temperature, high carbon dioxide pressure, and longer reaction time were favorable for the reactivity of BMImBr-AS. The catalyst can be reused for the reaction up to three consecutive runs with a slight decrease of its catalytic activity.     

Phosphotungstic acid containing ionic liquid immobilized on magnetic mesoporous silica rod catalyst for the oxidation of dibenzothiophene with H2O2

We have synthesized phosphotungstic acid (PA) containing ionic liquid 1-methyl-3-[(triethoxysilyl) propyl] imidazolium chloride (IL) immobilized on magnetic mesoporous silica rod to catalyze dibenzothiophene (DBT) for producing dibenzothiophene monoxide (DBTO) and dibenzothiophene dioxide (DBTO₂). The effects of reaction time and reaction temperature on the conversion of DBT were studied. It was demonstrated that the catalyst was extremely effective for the reaction and the catalyst could be easily separated from the reaction solution by applying an external magnetic field and recycled several times.     

Capacitive performance of mesoporous carbons derived from the citrates in ionic liquid

Mesoporous carbons with different pore structures are prepared via a simple pyrolysis process using citrate salts as precursors. BaC-T carbons derived from barium citrate possess large pore volume and typical multimodal pore size distribution (PSD), while MgC-T carbons derived from magnesium citrate possess high specific surface areas due to their dominant small mesopores and micropores. The capacitive performance of the prepared carbons is investigated in ionic liquid and high specific capacitances (maximum of 180.3 F g⁻¹ for MgC-700) are achieved. Experimental data demonstrate that porosity and surface chemistry corporately determine the capacitive performance. BaC-700 and BaC-800 present good rate performance, and exhibit energy densities of about 50 Wh kg⁻¹. The good capacitive performance of these carbons is attributed to their bimodal PSD with large pore size and appropriate surface properties. The MgC-800 and BaC-800 carbons present good durability of capacitance during three thousand of charge/discharge cycles.