Amine-functionalized ordered mesoporous silicas as model materials for liquid phase acid capture

Uptake of dilute aqueous acetic acid was compared using primary, secondary, tertiary amines, and quaternary ammonium grafted ordered mesoporous silica. Primary amine and quaternary ammonium grafted samples showed the highest uptake, 0.21 mmol acetic acid/g SBA-15, with secondary and tertiary amines showing nominally lower, 0.18 mmol/g, at 0.5 mmol aminosilane loaded per gram SBA-15. Solution conditions during uptake were varied to conclude that only associated acetic acid could be bound and that the mechanism relied heavily on electrostatic interactions. The aminosilane packing density was found to be crucial to performance with variation depending on the ligand bulk as well as the silica support's pore size. Relevant solution conditions for cellulose depolymerization were also explored by comparing uptake of multiple organic acids and with dextrose added. Here, it was shown that the most hydrophobic organic acid was preferentially extracted, and the uptake was enhanced in the presence of dextrose.     

Inorganic–organic hybrid materials based on functionalized silica and carbon: A comprehensive understanding toward the structural property and catalytic activity difference over mesoporous silica and carbon supports

Inorganic–organic hybrid materials based on functionalized silica and carbon were synthesized by anchoring molybdovanadophosphoric acid (H₅[PMo₁₀V₂O₄₀] · 32.5H₂O) onto amine-functionalized SBA-15, ethane-bridged SBA-15 and mesoporous carbon, respectively. Small angle X-ray diffraction, N₂ sorption analysis, HRTEM, SEM, FT-IR, CP-MAS NMR were used to diagnose the mesoporous structure of inorganic–organic hybrid materials. The structural integrity of molybdovanadophosphoric acid has been found to be retained after immobilization over mesoporous materials. These inorganic–organic hybrid materials were tested in the environmentally friendly oxidation of 2-methylnaphthalene (2MN) with 30% aqueous hydrogen peroxide. Molybdovanadophosphoric acid containing mesoporous organosilica hybrid material (ethane-bridged SBA-15) exhibited higher catalytic activities in the oxidation of 2MN to give a clean product 2-methy-1,4-naphthoquinone (menadione vitamin K3 precursor), because of the improved hydrophobicity of the material. The correlation between structural properties and catalytic activities of these hybrid materials has been well addressed in our present studies.     

Synthesis and characteristics of Ce modified HY/SBA-15 and its desulfurization performance for simulated oil

A composite zeolite HY/SBA-15 has been synthesized by an overgrowth approach, and then doped with Ce by a liquid phase ion exchange process to form the Ce modified HY/SBA-15 catalyst. The synthesized materials were examined by X-ray diffraction (XRD), nitrogen adsorption–desorption, transmission electron microscopy (TEM), BJH analysis and pyridine adsorption Fourier-transform infrared spectroscopy (Py-FTIR). The results showed the existence of two different pores sizes of 1.8 and 6 nm. Thus, the HY/SBA-15 composite includes both microporous and mesoporous structures. Desulfurization activity of the composite materials was evaluated using as simulated oil gas. The results showed that the SO_x adsorption capacity of Ce-HY/SBA-15 was enhanced by 1.97 mg/g compared to HY/SBA-15, which suggested that the Ce plays an important role in the desulfurization of simulated oil over composite zeolite. Furthermore, the Py-FTIR results revealed the relationship between the surface acids and the desulfurization performance. It was found that the weak Lewis acids were important for the improved desulfurization performance, while the Brönsted acids inhibited the desulfurization performance.     

Trypsin immobilization on mesoporous silica with or without thiol functionalization

The effects of pore size, structure, and surface functionalization of mesoporous silica on the catalytic activity of the supported enzyme, trypsin, were investigated. For this purpose, SBA-15 with 1-dimensional pore arrangement and cubic Ia3d mesoporous silica with 3-dimensional pores were prepared and tested as a support. Materials with varying pore diameters in the range 5–10 nm were synthesized using a non-ionic block copolymer by controlling the synthesis temperature. Thiol-group was introduced to the porous materials via siloxypropane tethering either by post synthesis grafting or by direct synthesis. These materials were characterized using XRD, SEM, TEM, N₂ adsorption, and elemental analysis. Trypsin-supported on the solids prepared was active and stable for hydrolysis of N-α-benzoyl-DL-arginine-4-nitroanilide (BAPNA). Without applying thiol-functionalization, cubic Ia3d mesoporous silica with ca. 5.4 nm average pore diameter was found to be superior to SBA-15 for trypsin immobilization and showed a better catalytic performance. However, enzyme immobilized on the 5% thiol-functionalized SBA-15 prepared by directly synthesis was found to be the most promising and was also found recyclable.     

Ethylene polymerization catalyzed by metallocene supported on mesoporous materials

Summary  In this work, different mesoporous materials were employed for the preparation of supported metallocene catalysts to be evaluated in ethylene polymerization and their performance was related to the chemistry of the materials surface used as support. The supports employed were MCM-41, SBA-15 and mesoporous TiO₂. The performance of the prepared catalysts was compared with the homogeneous catalyst precursor system. Those mesoporous materials, as well as the prepared metallocene catalysts, were analyzed by infrared absorption spectrometry (FTIR). Polymers were also characterized by FTIR, for the determination of the number-average molecular weight, and by differential scanning calorimetry (DSC) to determine thermal characteristics of the produced polyethylene. Among the studied metallocene supported catalysts, the one based on the mesoporous support SBA-15 achieved the highest activities, almost as high as that observed for the homogeneous system.     

对甲苯磺酸改性SBA-15的合成及催化合成乙酸正丁酯

采用浸渍法将含有磺酸基的对甲苯磺酸负载在SBA-15表面上,合成含有一定酸性的固体酸催化剂TsOH-SBA-15。催化剂的制备条件为:对甲苯磺酸的浸渍浓度为0.5 mol/L,焙烧温度为300℃,焙烧时间为4 h。用XRD,IR,DTA/TGA,氮吸附-脱附等方法对改性后的样品进行表征。结果表明,改性后的SBA-15分子筛的结构未发生变化,仍具有有序孔道结构。TsOH-SBA-15催化剂对冰乙酸和正丁醇的酯化反应具有较高的活性,正交实验结果为:反应时间80 m in,n(冰乙酸)∶n(正丁醇)=1∶1.2,催化剂用量为冰乙酸质量的5%,此时酯化率可达到95%。     

Trypsin immobilization on mesoporous silica with or without thiol functionalization

The effects of pore size, structure, and surface functionalization of mesoporous silica on the catalytic activity of the supported enzyme, trypsin, were investigated. For this purpose, SBA-15 with 1-dimensional pore arrangement and cubic Ia3d mesoporous silica with 3-dimensional pores were prepared and tested as a support. Materials with varying pore diameters in the range 5–10 nm were synthesized using a non-ionic block copolymer by controlling the synthesis temperature. Thiol-group was introduced to the porous materials via siloxypropane tethering either by post synthesis grafting or by direct synthesis. These materials were characterized using XRD, SEM, TEM, N₂ adsorption, and elemental analysis. Trypsin-supported on the solids prepared was active and stable for hydrolysis of N-α-benzoyl-DL-arginine-4-nitroanilide (BAPNA). Without applying thiol-functionalization, cubic Ia3d mesoporous silica with ca. 5.4 nm average pore diameter was found to be superior to SBA-15 for trypsin immobilization and showed a better catalytic performance. However, enzyme immobilized on the 5% thiol-functionalized SBA-15 prepared by directly synthesis was found to be the most promising and was also found recyclable.     

Adsorption of l-histidine over mesoporous carbon molecular sieves

Mesoporous carbon, CMK-3, was prepared by large pore hexagonal mesoporous silica SBA-15. The structural order and textural properties of all the materials were studied by XRD, HRTEM, and nitrogen adsorption. Adsorption of l-histidine (His) over various porous adsorbents such as CMK-3, SBA-15, and activated carbon was studied from solutions with different pH. His adsorption was observed to be pH dependent with maximum adsorption near the isoelectric point of the amino acid. CMK-3 showed a larger amount of His adsorption as compared to SBA-15 and the conventional adsorbent, namely activated carbon. CMK-3 registers the total adsorption capacity of ca. 1350 μmol g⁻¹ which is ca. 12 times higher than the adsorption capacity of SBA-15. This large difference could be mainly due to the stronger hydrophobic interaction between the non-polar side chains of amino acids and the hydrophobic surface of the mesoporous carbon as compared to mesoporous silica. The influence of ionic strengths on the adsorption of His was also studied and the results are discussed. Nitrogen adsorption of CMK-3 after His adsorption confirmed that His molecules are tightly packed inside the mesopores.     

SiW12／SBA-15介孔分子筛催化合成月桂酸乙酯

用传统的水热合成法制备纯硅介孔分子筛SBA-15,将SiW12负载在SBA—15上。采用x射线衍射（XRD）、红外光谱（IR）对不同负载量的催化剂进行了表征。表征结果表明,催化剂SiW12／SBA-15仍具有纯硅SBA-15的介孔结构,SiW12的Keggin结构保持完整。该催化剂用于月桂酸与乙醇的酯化反应,重点考察了硅钨酸的负载量、反应温度、酸醇比、催化剂用量等因素对酯化反应性能的影响。得到最佳反应条件为：硅钨酸的负载量为25％,反应温度90℃,酸醇比1：2．5,催化剂用量为月桂酸质量的1％,反应时间4h。催化剂再生实验结果认为,SiW12／SBA-15介孔分子筛具有良好的再生性能和稳定性。     

Synthesis of mesoporous materials SBA-15 and CMK-3 from fly ash and their application for CO2 adsorption

A supernatant solution of silicate species extracted from coal fly ash in a power plant by alkali fusion was used in acidic condition to prepare a mesoporous silica SBA-15. The SBA-15 was used as a template for the synthesis of a mesoporous carbon CMK-3 using sucrose as a carbon source. Characterization of the produced mesoporous materials by XRD, N₂ adsorption-desorption, SEM, and TEM confirmed the formation of well-ordered hexagonal mesostructures. Textural properties were found close to those prepared by pure chemicals. SBA-15 after polyethyleneimine impregnation and CMK-3 were tested for carbon dioxide adsorption, successfully demonstrating the possibility of recycling the industrial waste product in a power plant into a useful adsorbent.     

粒径对磺酸官能化介孔材料性能的影响

以聚乙氧基-聚丙氧基-聚乙氧基三嵌段共聚物(P123)为模板剂、正硅酸乙酯(TEOS)为硅源,保持P123和TEOS的浓度比,改变P123和TEOS在合成体系中的浓度,水热法合成了系列具有不同粒径的介孔分子筛SBA-15.采用后合成法,将3-巯基丙摹三甲氧基硅烷(MPTMS)嫁接到具有不同粒径的介孔分子筛SBA-15表面上,经氧化后得到含有强酸性的磺酸基因的固体酸样品SBA-15-SO_3H.采用SEM、XRD、FT-IR、TG-DTA、N_2吸附以及酯化反应考察了粒径对所制备的SBA-15-SO_3H的物化性能和催化性能的影响.结果表明,SBA-15的粒径大小对MPTMS在其上的嫁接量没有很人影响,但对后续氧化过程有较大的影响,SBA-15粒径的减小有利于巯基被氧化为磺酸基,导致磺酸的负载量随着粒径的减少而增大.SBA-15-SO_3H在乙酸和乙醇的酯化反应中表现出不同的催化性能,催化性能的差异是粒径大小、酸量及磺酸基和巯基相互作用的综合结果.     

介孔分子筛SBA-15的研究进展

自从介孔分子筛SBA - 15首次合成出来 ,成为众多研究领域的一个研究热点。文章综述了介孔分子筛SBA -15的合成及机理 ,影响孔径尺寸的因素及研究应用进展 ,介孔分子筛SBA - 15在催化、吸附和分离及纳米材料等领域具有广泛的应用前景。     

An overview of ordered mesoporous material SBA-15: synthesis,functionalization and application in oxidation reactions

Ordered mesoporous materials are attracting wide concern because of their applications in the field of catalysis, adsorption, separations, drug delivery systems and gas sensors owing of their extremely high surface area combined with well-defined pore structures with narrow pore size distributions. Various mesoporous materials such as MCM-41, MCM-48, SBA-15 and SBA-16 have been reported in past two decades. Synthesis of mesoporous materials involves the concept of aggregation of surfactants as structure directing agents under acidic or basic conditions. The dimensions of these mesopores can be obtained by type of surfactant, auxiliary chemicals and synthesis conditions. At present, SBA-15 has attracted more attention among different mesoporous silica structures due to their desirable properties such as thick pore wall and hexagonal mesopores (4–12 nm), high surface area, ease of synthesis and functionalization and high thermal and mechanical stability. In last few years, great effort has been made on the development of various methods for the synthesis of mesoporous materials as support for oxidation reactions. The aim of this review article is to focus mainly on mesoporous SBA-15 together with its application as support for various oxidation reactions.     

Hydrothermal stability and catalytic activity of mesoporous aluminum-containing SBA-15

Mesoporous silica structure SBA-15 and Al-containing SBA-15 (AlSBA) were synthesized and tested their activity in catalytic cracking of waste fatty acid mixture (palm oil based) in a fixed-bed micro-reactor. The catalytic activity of AlSBA was improved and more selective towards gasoline fraction present in the organic liquid product (OLP) as compared to mesoporous siliceous material SBA-15. Even though the hydrothermal stability of AlSBA was poorer but the sample with Si/Al ratio of 20 was found to be comparable with SBA-15. The hydrothermal stability of AlSBA was higher than AlMCM-41 with similar cracking activity and thus AlSBA is a more potential cracking catalyst.     

介孔材料SBA-15的改性及其应用研究进展

文章综述了介孔材料SBA-15的改性方法,包括有机功能化改性、杂原子改性和负载活性组分。在此基础上评述了改性SBA-15的应用研究进展,重点介绍了其在催化和吸附领域的应用进展。通过改性引入杂原子或有机官能团或负载活性组分,根据催化反应或吸附分离等性能要求可以有目的地进行功能化调控,可大大拓展其应用范围。     

介孔SBA-15的孔径尺寸对小牛血清蛋白和溶菌酶蛋白吸附的影响(英文)

In this paper,the effects of pore-size of SBA-15 on the adsorption kinetics and equilibrium of large protein molecules Bovine serum albumin(BSA)and lysozyme(LYS)have been investigated.The mesoporous molecular sieve SBA-15 with six different pore sizes were synthesized with P123 triblock copolymer as the template agent,and 1,3,5-trimethylbenzene(TMB)and isopropyl alcohol as the pore-expanding agent.The samples were characterized by N2 adsorption/desorption,Scanning Electron Microscopy(SEM),Transmission Electron Microscopy(TEM)and X-Ray Diffraction(XRD).It is found that BSA and LYS were adsorbed rapidly on SBA-15 materials with large pores.The BSA adsorption capacity of sieve with the pore diameter of 21.4 nm reached 500 mg·g-1 within 25 minutes.However,if the pore diameter was smaller than 14 nm,the BSA adsorption capacity of the sieve was only about 220 mg·g-1.The adsorption equilibrium data fits in the Langmuir model,where the coefficient of effective use of specific area of mesoporous molecular sieve was found to be 0.03,0.18,0.37 and 0.48,corresponding to the pore diameter of 10.1 nm,13.2 nm,15.4 nm and 21.4 nm,respectively.The equilibrium loading amount of LYS on SBA-15 materials with pore size of 15.4 nm could be up to 1000 mg·g-1.The coefficient of effective use of surface area of mesoporous molecular sieve with diameter of 3.9 nm,7.4 nm,10.1 nm,13.2 nm and 15.4 nm was 0.10,0.47,0.56,0.71 and 0.79,respectively.It is also noted that greater pore size of mesoporous molecular sieve would lead to a higher coefficient of effective use of surface area.     

Applications of Amine-functionalized Mesoporous Silica in Fine Chemical Synthesis

SBA-15 silica containing homogeneously distributed amine-functional groups and of fiber or platelet morphology was prepared through a modified co-condensation method using P123 copolymer as template under acidic condition. Synthetic factors which led to well-ordered mesoporous materials with high loadings of various amine groups were discussed. The resultant mesoporous materials were efficient base catalysts in Knoevenagel and Claisen–Schmidt addition reactions. The activities over SBA-15 materials with different amino-functional groups are compared. Moreover, the advantage of ordered large mesopores of SBA-15 in catalyzing liquid phase reactions was demonstrated, and the reaction rate could be further increased when SBA-15 was with platelet morphology and short mesochannels.     

介孔分子筛固载Keggin结构钼钨磷杂多酸的制备及表征

用萃取法合成了两种 Keggin结构的钼钨磷杂多酸 ,用水热法制取了 AIMCM- 41介孔分子筛 ,经离子交换制成 HAIMCM- 41 ;浸渍法制取固载型 HPA/ HAIMCM- 41催化剂。用 IR、XRD对其结构和性能进行了表征。结果表明合成的 HPA具有典型的 Keggin结构而 HAIMCM- 41具有典型的介孔性质 ,固载后 HPA的 Keggin结构基本保持     

SBA-15 mesoporous silica modified with metal oxides by MDD method in the role of DeNOx catalysts

SBA-15 mesoporous silica was modified with metal (Al, Ti, Cu, Fe) oxides by the molecular designed dispersion (MDD) method using acetylacetonate complexes of metals as precursors of the catalytically active components. The modified mesoporous silicas were characterized with respect to texture (BET), composition (EPMA), coordination and aggregation of transition metal species (UV–vis-DRS), reducibility of the deposited transition metals (TPRed) and surface acidity (FT-IR). Deposition of aluminium and titanium species on the SBA-15 surface significantly increased its acidity, mainly by generation of strong Lewis acid sites. Copper and iron deposited on the surface of pure SBA-15 were present nearly exclusively in the form of mononuclear cations. Deposition of Fe or Cu on the SBA-15 supports modified with alumina or titania resulted in a formation of significant amounts of oligomeric metal oxide clusters. The SBA-15 based samples have been found to be active and selective catalysts of the DeNO_x process. The modification of the silica surface with titanium or aluminium prior to the deposition of iron or copper significantly improved the activity of the SBA-15 based catalysts.     

Flash induction calcination: A powerful tool for total template removal and fine tuning of the hydrophobic/hydrophilic balance in SBA-15 type silica mesoporous materials

A new rapid calcination method has been used to completely remove the organic template from SBA-15 ordered mesoporous silica, and to preserve a high number of silanol in these materials. This calcination method provided by an induction furnace was found to considerably reduce the calcination time and therefore the energy consumption associated. Moreover, adjustment of both calcination temperature and duration allowed tuning the hydrophobic/hydrophilic balance of the mesoporous SBA-15 silica materials. For comparison, short and long time conventional muffle furnace calcination was performed. The induction calcination was also successfully applied to different type of mesoporous silica materials such as SBA-16 and MCM-41.