功能化离子液体修饰的SBA-15固定化Burkholderia cepacia脂肪酶

采用含不同碳链长度咪唑环的烷基功能化离子液体修饰介孔材料SBA-15,并通过X-射线衍射、元素分析、N2吸附-脱附、红外光谱和扫描电镜等方法研究了离子液体修饰对SBA-15结构的影响.以三乙酸甘油酯的水解为探针反应,考察了甲基、丁基、辛基等不同链长烷基取代咪唑类离子液体修饰的SBA-15固定化Burkholderia cepacia脂肪酶(BCL)的酶活、最适反应条件及稳定性等酶学性质.结果表明,离子液体修饰后材料保持了原有的介孔结构,其固定化酶对温度及低pH的敏感度降低,比活力及稳定性均显著提高.其中甲基功能化离子液体修饰的SBA-15固定化酶的比活力最高,是原粉SBA-15固定化酶的2.4倍;辛基功能化离子液体修饰的SBA-15固定化酶的热稳定性、储存稳定性、重复使用性及有机溶剂耐受性最佳.     

Synthesis of SBA-15 from low cost silica precursor obtained from sugarcane leaf ash and its application as a support matrix for lipase in biodiesel production

Ordered mesoporous silica material was synthesized from a low-cost precursor, sugarcane leaf ash, was used as a support matrix for lipase for the production of biodiesel. The mesoporous samples were characterized using Fourier transform infra red spectroscopy. The surface topography and morphology of the mesoporous materials were studied using scanning electron microscope. The pore diameter, pore volume, Brunauer Emmett and Teller surface area of the mesoporous material were determined by N₂ gas adsorption technique. Different pore size Santa Barbara Acid-15 (SBA-15) samples were synthesized and their lipase immobilization capacity and specific enzyme activity of immobilization lipase were determined and compared. Lipase from Candida Antarctica immobilized on SBA-15 (C) had shown maximum percentage immobilization and specific enzyme activity. The immobilized lipase mesoporous matrix was used for biodiesel production from crude non-edible Calophyllum inophyllum oil. The percentage yield of fatty acid methyl ester, 97.6 % was obtained under optimized conditions: 100 mg of lipase immobilized on SBA-15, 6:1 methanol to oil molar ratio, the reaction of 2 g C. inophyllum oil with methanol.     

Functionalized ionic liquid modified mesoporous silica SBA-15: a novel, designable and efficient carrier for porcine pancreas lipase

A series of functionalized ionic liquid modified mesoporous silicas SBA-15 (FIL-SBA) were synthesized by modulating the loading and cation/anion ratio of the functionalized ionic liquid (FIL). The prepared materials FIL-SBA were used as a novel carrier system to immobilize porcine pancreas lipase (PPL). Enzymatic activity and reusability of the immobilized enzyme were investigated using the triacetin hydrolysis reaction. The combined advantages of the nano-sized pore diameter, large surface area and high pore volume of SBA-15, and the tunable properties of the FIL for enzymes immobilized in FIL-SBA gave a maximum improvement of 570% in relative activity, with 63% retention of initial activity after five cycles of use. Carriers and immobilized enzymes were characterized using nitrogen adsorption, small-angle X-ray diffraction (SXRD), Fourier transform infrared (FT-IR), elemental analysis, nuclear magnetic resonance (NMR), scanning and transmission electron microscopy (SEM and TEM). It was shown that the introduction of FIL influenced the catalytic behavior of PPL significantly by changing the structure and surface properties of the carriers.     

金复合介孔SBA-15吸附血红蛋白在H2O2电催化反应中的应用

以P123嵌段共聚物表面活性剂为模板剂制备介孔氧化硅SBA-15,并用沉积-沉淀(DP)法在SBA-15介孔表面负载纳米Au颗粒制备得到金复合介孔SBA-15材料(Au-SBA-15).再以Au-SBA-15材料制备玻碳修饰电极,将血红蛋白固定于修饰电极上用循环伏安法考察其对不同浓度H₂O₂溶液的电催化反应.在固定了血红蛋白的Hb/Au-SBA-15/GC修饰电极上,H₂O₂在+0.95 V处出现了氧化峰,且随着H₂O₂浓度的增大峰电流不断增加,说明金复合介孔氧化硅材料具有良好的生物兼容性,有利于血红蛋白的固定,其修饰电极对H₂O₂溶液具有一定的电催化作用.     

纯硅介孔分子筛SBA-15表面的手性移植

聚环氧乙烯醚-聚环氧丙烯醚-聚环氧乙烯醚(EO20PO70EO20)三嵌段高分子为模板剂制备了SBA-15分子筛. 用3-氨丙基-三乙氧基硅烷对SBA-15进行改性, 改性后SBA-15表面上的氨基再与(+)-O,O'-二苯甲酰基-L-酒石酸酐(DBTA)进行酰化反应, 以酰胺键将该手性羧酸连接在SBA-15表面上. XRD和氮气吸附结果表明, 材料经过处理后仍然保持良好的孔性质; 13C和29Si魔角旋转核磁共振(MAS NMR)谱图表明, SBA-15与氨丙基化合物的作用是共价成键, 表面修饰度达25%; 从傅里叶变换红外(FTIR) 光谱可见, 有部分修饰氨基与DBTA成功地进行了酰化反应, 以一个羧基裸露的形式将该二元羧酸化合物连接在表面上; 从孔径分布图可知, 胺丙基修饰之后孔减小了1.5 nm, 与DBTA修饰后孔尺寸又减少0.5 nm, 说明胺丙基化合物是头对头垂直连接在Si表面上, 而酒石酸分子是采取平行方式侧卧在氨基表面.     

Burkholderia Cepacia脂肪酶在氨基功能化离子液体修饰的SBA-15上的共价固定

合成了氨基以及氨基功能化离子液体修饰的介孔材料SBA-15(NH₂-SBA和NH₂-IL-SBA), 并以戊二醛为活化剂对NH₂-IL-SBA进行活化处理(CA-NH₂-IL-SBA), 通过元素分析、 N₂吸附-脱附、 X射线衍射、 红外光谱等方法研究了修饰及活化对SBA-15结构的影响. 将所得新型固定化载体用于Burkholderia cepacia脂肪酶(BCL)的吸附固定、 共价交联固定及聚集包被固定. 以三乙酸甘油酯的水解为模型反应, 考察了固定化BCL的酶活、 最适反应条件、 稳定性等酶学性质. 结果表明, 离子液体修饰后的载体保持了原有的孔道结构, 与氨基修饰以及原粉SBA-15吸附固定的BCL(BCL-NH₂-SBA和BCL-SBA-15)相比, 其固定化酶的比活力和稳定性都得到了明显提高, 对温度及低pH的敏感性降低. 其中聚集包被固定的BCL在获得了相对较高酶负载量的同时显示了最好的稳定性, 其热稳定性和重复使用性分别为BCL-SBA-15的4倍和2倍.     

Submicron particles of SBA-15 modified with MgO as carriers for controlled drug delivery

Submicron particles with modified surface were synthesized by a simple one-pot synthesis approach and used as drug carrier for controlled release. Due to the alkalinity of MgO species on the surface, the amount of a model drug, ibuprofen, adsorbed on the modified surface was increased as compared to pure silica SBA-15 although the surface area was decreased by the surface modification. FTIR investigation indicated that the adsorption state of ibuprofen on MgO modified SBA-15 was different from that on pure silica SBA-15 and pure crystal ibuprofen. The result obtained from in vitro release test exhibited that the surface modification greatly decreased the ibuprofen release rate. In first 6 h in vitro release test, only 63% of the adsorbed ibuprofen was released from the MgO/SBA-15 (Si/Mg=20). In contrast, the release of ibuprofen was complete in 1 h from the pure silica SBA-15 under the same release conditions. The surface modified with MgO created affinity with acidic ibuprofen molecules and retarded the release rate from the mesoporous matrix. In addition, the release rate of ibuprofen could be modulated by varying the content of MgO, and was found to decrease with increasing amount of MgO on surface of SBA-15 submicron particles.     

疏水性Cosalen/SBA-15的制备及在甲苯选择性氧化中的应用

以介孔分子筛SBA-15为载体, 先采用γ-氨丙基三乙氧基硅烷(APTES)进行氨基硅烷化修饰, 然后经甲基三乙氧基硅烷(MTES)疏水修饰后固载双水杨醛缩乙二胺合钴配合物(Cosalen). 采用傅里叶变换红外光谱、 紫外-可见漫反射光谱、 X射线光电子能谱、 元素分析、 等离子体发射光谱、 X射线衍射和氮气物理吸附等手段对制备的固载型催化剂Cosalen/SBA-15进行了物相结构和修饰程度的表征, 并考察了样品对甲苯、 苯甲醛和苯甲醇的吸附性能及在甲苯液相氧化反应中的催化性能. 结果表明, 固载型催化剂Cosalen/SBA-15的介孔结构和孔道有序性保持良好, Cosalen通过与氨基配位固载在修饰后的载体SBA-15上, 且高度分散, 氨基硅烷化和甲基修饰明显增强了其表面疏水性能, 对苯甲醛和苯甲醇的吸附量降低. 疏水性Cosalen/SBA-15协同N-羟基邻苯二甲酰亚胺(NHPI)催化甲苯液相分子氧氧化反应, 无溶剂体系在130 ℃下反应2 h, 甲苯转化率达到16.0%, 产物中苯甲醛和苯甲醇的总选择性为32.0%, 在一定程度上抑制了极性产物深度氧化为苯甲酸. 高温不利于苯甲醛和苯甲醇选择性的提高, 降低温度至110 ℃, 甲苯转化率达到12.9%时, 苯甲醛和苯甲醇的总选择性提高到43.9%.     

金复合介孔SBA-15吸附血红蛋白在H2O2电催化反应中的应用

以P123嵌段共聚物表面活性剂为模板剂制备介孔氧化硅SBA-15,并用沉积-沉淀(DP)法在SBA-15介孔表面负载纳米Au颗粒制备得到金复合介孔SBA-15材料(Au-SBA-15).再以Au-SBA-15材料制备玻碳修饰电极,将血红蛋白固定于修饰电极上用循环伏安法考察其对不同浓度H2O2溶液的电催化反应.在固定了血红蛋白的Hb/Au-SBA-15/GC修饰电极上,H2O2在+0.95 V处出现了氧化峰,且随着H2O2浓度的增大峰电流不断增加,说明金复合介孔氧化硅材料具有良好的生物兼容性,有利于血红蛋白的固定,其修饰电极对H2O2溶液具有一定的电催化作用.     

Reductive alkylation of lipase

Candida rugosa lipase was modified via reductive alkylation to increase its hydrophobicity to work better in organic solvents. The free amino group of lysines was alkylated using propionaldehyde with different degrees of modification obtained (49 and 86%). Far-ultraviolet circular dichroism (CD) spectroscopy of the lipase in aqueous solvent showed that such chemical modifications at the enzyme surface caused a loss in secondary and tertiary structure that is attributed to the enzyme unfolding. Using molecular modeling, we propose that in an aqueous environment the loss in protein structure of the modified lipase is owing to disruption of stabilizing salt bridges, particularly of surface lysines. Indeed, molecular modeling and simulation of a salt bridge formed by Lys-75 to Asp-79, in a nonpolar environment, suggests the adoption of a more flexible alkylated lysine that may explain higher lipase activity in organic solvents on alkylation.     

SBA-15固定化脂肪酶催化拆分萘普生甲酯水解反应

利用吸附法将柱状假丝酵母菌脂肪酶(Candida rugosa lipase,CRL)固定于SBA-15介孔分子筛上,在搅拌槽反应体系中催化拆分外消旋萘普生甲酯的水解反应,获得了光学纯对映体(S)-萘普生,考察了SBA-15性能和酶固定量对初始反应速率、产量、转化率、对映体过剩(eep)和对映体选择性(E)的影响.结果...     

Mesoporous SBA-15 materials modified with PW or W active species as catalysts for the epoxidation of olefins with H<Subscript>2</Subscript>O<Subscript>2</Subscript>

Five catalysts containing PW or W active species that anchored onto aminosilylated mesoporous silica SBA-15 by a post-grafting route were prepared and the resulting PW or W/APTES/SBA-15 hybrid materials were characterized by XRD, N₂ adsorption/desorption, surface area analysis, TEM, FT-IR, and ICP (inductively coupled plasma atomic emission spectroscopy). The names of these catalysts have been abbreviated as SBA-15m-a, SBA-15m-b, SBA-15m-c, SBA-15m-d, and SBA-15m-e according to the different active species. The PW or W active species were highly dispersed in the channels of the modified mesoporous materials. The interaction between PW or W species and amino groups grafted on the channel surface of SBA-15 led to the immobilization of PW or W species. Their catalytic activity in the epoxidation of cyclooctene with H₂O₂ as oxidant was investigated. Among them, SBA-15m-a showed the best performance, with 98.9% conversion and 98.4% selectivity. The catalyst could be reused for six times with a little decrease in activity.     

Synthesis of carboxyl-modified rod-like SBA-15 by rapid co-condensation

Carboxyl-modified SBA-15 rod-like mesoporous materials have been synthesized by a facile rapid co-condensation of tetraethylorthosilicate (TEOS) and 2-cyanoethyltriethoxysilane (CTES), followed by hydrolysis of cyanide groups in sulfuric acid. The concentration of carboxylic groups was varied by changing the silica source ratio of CTES/TEOS from 0.05 to 0.3. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that the uniform ordered mesoporous structure and rod-like morphology of SBA-15 have been preserved even at the high concentration of carboxylic groups employed. Characterization by Fourier transformed infrared spectroscopy (FTIR), solid-state NMR investigation indicated that carboxylic groups have been successfully grafted onto the surface of SBA-15 through siloxane bonds [(O(3))SiCH(2)CH(2)COOH. The negative charges of the modified SBA-15 materials were enhanced by the presence of the carboxylic groups on the surface. The capacity of lysozyme adsorption of the modified SBA-15 materials were found to be significantly improved as compared with pure silica SBA-15. The maximum amount of lysozyme adsorption on carboxyl-modified was increased with the pH of solution increased from 5.5 to 9.0.     

Physical and chemical adsorption of Mucor javanicus lipase on SBA-15 mesoporous silica. Synthesis, structural characterization, and activity performance

In this work a sample of SBA-15 mesoporous silica was synthesized and characterized by TEM, XRD, and N2 adsorption. The sample had a high value of specific surface area (1007 m2 g(-1)) and total pore volume (2.1 cm3 g(-1)). The pore diameter was 67 angstroms, so it was large enough to accommodate protein molecules inside the channels. Immobilization by physical adsorption of a commercial lipase preparation from Mucor javanicus was performed at different pH values (pH 5-8). pH 6 gave the highest lipase loading and hydrolytic activity of the corresponding biocatalyst. Chemical modification of the SBA-15 via glutardialdehyde allowed also the enzyme immobilization through chemical adsorption. This preparation was active toward tributyrin hydrolysis. On the contrary, very low activity toward triolein hydrolysis was observed. The reduction of the size of the channels due the immobilization process has been suggested as a possible explanation.     

SBA－15的二氧化钛改性及其光催化降解对氯苯酚

在“后合成”法在介孔二氧化硅SBA－15的孔壁表面键接了二氧化钛,并对其 结构进行了表征。改性后的SBA－15保持了规则的介孔结构,并在孔壁表面形成了 类似于锐钛型二氧化钛的Ti-O-Ti网络结构。光催化降解对氯苯酚的结果表明,经 过两次二氧化钛键接的样品表现出较高的光催化效率。但是由于对酚、醌等中间产 物的强烈吸附以及孔道中反应物质的扩散速度慢,使得其光催化活性略低于纯的锐 钛型二氧化钛。     

疏水双功能介孔固体酸的合成及其在乙酸乙酯酯化反应中的应用

通过水热合成法一步合成了具有不同疏水基团－CH₃ 、－(CH₃)₂ 和－(CH₃)₃的双功能介孔固体酸SBA-15-SO₃H－(CH₃)_x催化剂。通过X射线粉末衍射(XRD)、N₂吸脱附、元素分析等方法对催化剂进行了表征,并在乙酸乙酯酯化反应中进行催化性能评价。结果表明,随着疏水前驱体中甲基数的增加,样品的疏水性增强。SBA-15-SO₃H-(CH₃)_x催化剂的催化活性随着疏水性的增强而提高,而具有较强疏水性的材料SBA-15-SO₃H-(CH₃)₃在反应中具有较高的催化性能。以SBA-15-SO₃H-(CH₃)₃为催化剂,酯化反应的最优条件为：温度为120℃,乙酸与乙醇摩尔比为4∶1,催化剂质量分数为1 %,反应时间为1h。在此条件下,乙醇的转化率和乙酸乙酯的选择性分别为93%和100%。     

Synthesis, characterization and catalytic behavior of functionalized mesoporous SBA-15 with various organo-silanes

Mesoporous silica SBA-15 has been synthesized and functionalized by one-step synthesis method to widen their various application possibilities. In this study, phenyltrimethoxysilane (PTMS), 3-mercaptopropyltrimethoxysilane (MPTMS) and trimethoxypropylsilane (TMPS) were used as silane precursors for the functionalization, and after treated with HCl solution, their catalytic activities were evaluated in the lactic acid-methanol esterification. The presence of anchoring of functional groups on SBA-15 was proved by XRD, FT-IR, BET surface area and pore size distributions. Good catalytic activity was observed especially for SBA-15-SO(3)H-MPTMS, and the catalytic activity order was determined as follows: SBA-15-SO(3)H-MPTMS>SBA-15-TMPS>SBA-15-PTMS, which is directly associated with the surface area, pore size and pore volume. As compared with homogeneous catalyst, SBA-15-SO(3)H-MPTMS heterogeneous catalyst shows remarkable performance, such as separation, recovery and reusability.     

New attempt at directly generating superbasicity on mesoporous silica SBA-15

Direct generation of superbasicity on mesoporous silica SBA-15 was realized by tailoring the host-guest interaction, and calcium species were selected as the guest in modifying SBA-15. The results show that calcium species could be homogeneously distributed on the surface of SBA-15. Because of the host-guest interaction, the decomposition of the supported calcium nitrate was apparently easier than the bulk one. Surprisingly, the calcium nitrates modified SBA-15 (CaNS) samples exhibited superbasicity with good preservation of the mesostructure after activation, differing from the potassium nitrate loaded SBA-15 samples that displayed weak basicity with collapsed mesostructure. The present superbasic CaNS materials also possess good water resistance and high surface areas, up to 429 m(2) g(-1), which is promising for their potential applications in adsorption and catalysis. Further investigation concerning the roles played by the guest in basicity formation on SBA-15 was conducted. The samples modified by Group 2 metal nitrates showed strong basicity with base strength (H-) of 22.5-27.0 and good preservation of mesostructure. In contrast, loading Group 1 metal nitrates on SBA-15 produced samples with weak basicity ( H-=9.3-15.0) and collapsed mesostructure after activation. Such differences can be related to the interaction between the resulting metal oxide and the silica support, as well as the mobility of the cations in the metal oxide.     

表面含磺酸基的介孔分子筛催化剂SBA-15-SO3H的制备及其催化性能

采用直接和后合成两种方法制备出含磺酸基的介孔分子筛SBA-15-SO₃H,用XRD和红外光谱分析制备过程中催化剂结构和组成的变化.结果表明,两种方法制备出的含磺酸基的催化剂都保持了SBA-15分子筛的完整晶体结构,并含有质子酸中心-SO₃H;固体核磁共振表征结果证明,两种方法都使MPTMS存在于分子筛的表面;用N₂吸附-脱附测定了它们的比表面积、孔径和孔容;TGA分析认为,MPTMS在分子筛表面的热稳定性大于300℃,酸碱滴定结果说明,直接法获得的催化剂的酸中心多于后合成法.酯化反应结果表明,直接法合成的催化剂比后合成法具有更高的稳定性,且简便、快捷、高效.     

APTS改性SBA-15负载Ni-B非晶态合金催化加氢脱硫性能的研究

采用共价接枝法制备APTS改性介孔分子筛SBA-15,将氨基官能团接枝到SBA-15表面.并采用化学还原法制备了Ni-B/SBA-15-APTS非晶态合金催化剂,以噻吩加氢脱硫为探针反应,研究了其催化加氢脱硫性能.结果表明,240℃时,APTS改性SBA-15所负载的Ni-B催化剂噻吩转化率达到50.8%,较未改性SBA-15所负载的催化剂噻吩转化率有显著地提高.由于氨基与Ni2+的配合作用,有助于Ni在催化剂中的分散,因而更容易被还原.ICP结果表明,在相同的制备条件下,相比未改性的SBA-15,APTS改性SBA-15使其催化剂中Ni的负载量增加,并且非晶态合金组成中Ni的含量也增大,B的含量降低,有利于提高催化剂的活性.