介孔材料对乳液聚合稳定性的影响

研究了十二烷基硫酸钠(SDS)在不同介孔材料(MCM-41、MCM-48、SBA-15)存在下的临界胶束浓度(CMC),讨论了介孔材料对间歇乳液聚合的影响。研究表明:孔径最大的介孔材料SBA-15存在下SDS的CMC增加最多;在聚合体系中加入介孔材料对单体转化率没有影响,但增加了乳液聚合时的凝聚率,其中使用小孔径的MCM-41凝聚物较少,而颗粒较大的MCM-48凝聚物较多,同时所得乳液聚合物的分子量下降,分子量分布变宽。     

加氢脱硫催化剂载体的研究进展

综述了加氢脱硫催化剂载体的研究现状及其发展趋势,分别从单组分载体、复合氧化物载体、分子筛和改性载体4个方面论述了加氢脱硫催化剂载体各自的优缺点。单组分载体重点介绍了A12O3、TiO2、炭载体;复合氧化物载体主要对铝基、钛基二元复合氧化物以及三元复合氧化物载体进行了综述;并且对以MCM-41、SBA-15和KIT为代表的介孔分子筛做了介绍;还描述了近年来以改性MCM-41、SBA-15、活性炭为主要研究对象的改性的分子筛。最后指出改性载体尤其是改性分子筛将是未来研究的焦点。     

介孔二氧化硅氨基改性及其CO_2吸附性能的研究进展

综述了介孔二氧化硅氨基改性及其CO2吸附性能的研究进展,主要介绍了MCM-41、SBA-15氨基改性的研究情况。同时对浸渍法和嫁接法在介孔二氧化硅氨基改性过程中的优缺点进行了讨论。最后,提出了介孔二氧化硅氨基改性在CO2吸附方面的研究方向。     

酞菁铜/介孔分子筛复合催化剂催化氧化巯基乙醇的研究

采用浸渍法将α-八-(异戊氧基)酞菁铜分别负载在SBA-15和MCM-41介孔分子筛上,制备了CuPc/SBA-15和CuPc/MCM-412种复合催化剂。通过紫外-可见吸收光谱、红外光谱和N2吸附方法对催化剂的结构和组成进行了表征。测试了2种催化剂对巯基乙醇的催化氧化性能,并考察了温度对催化氧化活性的影响。实验结果表明,在pH=11时,CuPc/SBA-15催化氧化巯基乙醇的转化率高于CuPc/MCM-41;随着温度的升高,CuPc/SBA-15对巯基乙醇的转化率逐渐增大,并计算了CuPc/SBA-15催化反应在25℃时的活化能Ea为30.50kJ/mol。     

环丙胺改性正渗透膜的制备及耐氯性能研究

采用界面聚合的方法,将环丙胺接枝到复合膜表面制备出高耐氯性能的聚酰胺正渗透膜。采用扫描电子显微镜(SEM),原子力显微镜(AFM),傅里叶红外光谱(FTIR)对复合膜进行表征。并以去离子水为进料液,2.0 mol/L的氯化钠溶液为汲取液,对膜进行正渗透实验。研究发现,相比于原始膜,当环丙胺的添加量为1.0wt%和1.5wt%时,膜的表面开始变得更加光滑,其Ra由48.7 nm降至41.4 nm和34.8 nm。同时表现出了很好的分离性能和耐氯性能,改性后膜的盐截留率从99.0%分别增加到99.3%和99.7%;在pH为9的条件下,经过20 000 mg/(L·h)的氯化后,2种改性膜的盐截留率要比未改性膜高出15.1%和19.7%;即使在pH为4的酸性条件下,经过20 000 mg/(L·h)的氯化后,2种改性膜的盐截留率依然比未改性膜高出15.9%和24.4%。     

氧化硅有序介孔材料MCM-41的微波水热合成及用于组装ZnO纳米粒子

与传统水热合成工艺相比,采用微波水热合成新工艺可以快速合成比表面积大、孔体积和孔径大、孔径分布范围更窄、孔洞呈六方排布的有序介孔材料MCM-41.微波水热合成工艺合成的MCM-41具有合成效率高、成功率高等特点,为此类介孔材料商业化提供了高效的技术手段.采用传统水热工艺合成MCM-41通常需要48～72 h,而采用微波水热合成技术仅需要30 min.采用X射线粉晶衍射(XRD),氮气吸附等技术手段对合成MCM-41材料的物相、比表面积、孔体积、孔径等进行了表征.采用微波水热合成MCM-41的工艺参数为:微波处理的温度120 ℃,时间30 min,微波辐射功率500 W,经过滤、洗涤、干燥、焙烧等处理后,得到的MCM-41具有六方排布的孔系,晶格常数a0=4.4nm,比表面积可达1113 m2/g,平均孔径为2.7 nm,与选用同样配方采用传统水热合成工艺合成的MCM-41的性能相当,却极大提高了合成效率.采用微波水热合成工艺,同样可以合成立方晶系的MCM-48和六方晶系的SBA-15等介孔氧化硅分子筛材料.此外,在微波合成的MCM-41中采用液相工艺成功组装了ZnO纳米粒子,并对组装在MCM-41中的纳米ZnO粒子进行了光催化降解苯酚的实验研究.     

Co掺杂对Ce/MCM-41和Ce/SBA-15催化剂催化氧化甲苯性能的影响

以分子筛为载体,采用等体积浸渍法制备Ce/SBA-15、Ce/MCM-41、Ce Co/SBA-15和Ce Co/MCM-41催化剂。用N2吸附-脱附、X射线衍射、扫描电子显微镜、H2程序升温还原、X射线光电子能谱和傅立叶变换红外光谱等对载体和催化剂进行表征,并考察催化剂催化氧化甲苯的活性。结果表明,与载体相比,随着Ce和Co的浸渍,催化剂的比表面积和孔容下降,但仍然保持了载体的有序介孔结构。引入的Ce和Co没有进入分子筛骨架,而是以立方相固溶体形式存在于分子筛表面和孔道中。催化剂催化氧化甲苯活性顺序依次为:Ce Co/SBA-15>Ce Co/MCM-41>Ce/MCM-41>Ce/SBA-15。共浸渍Ce和Co的催化剂活性明显优于只浸渍Ce的催化剂,活性与其还原性能直接相关,Ce Co/SBA-15催化剂具有最低的还原温度和最好的供氧能力,从而表现出最优的催化性能。     

石墨烯/SnO2改性碳纤维阳极降解水中普萘诺尔

采用水热法在碱性条件下制备了石墨烯(G)/SnO₂纳米复合材料,并应用静电纺丝技术以及通过预氧化、碳化等程序制备了基于聚丙烯腈(PAN)掺杂G/SnO₂的改性碳纤维膜(MCFs),并对其进行了SEM、TEM、XRD等表征;将MCFs负载于支撑材料上制成改性碳纤维阳极,同时搭建了电催化反应模块,探究不同条件对所制备阳极催化降解普萘诺尔(PRO)的影响。结果表明,阳极电势和改性碳纤维膜的质量是影响降解率的主要因素;当阳极负载膜的质量相同时,在负载MCFs的情况下催化体系对PRO的降解率远高于负载未掺杂G/SnO₂的碳纤维膜(CFs)的情况;阳极负载MCFs的质量约为80 mg时,体系的PRO的降解率达到了82.6%。     

分子筛−氧化锌复合填料的制备及其结构对光学性能的影响

探究了分子筛(MS)的结构和氧化锌(ZnO)的负载方式对分子筛?氧化锌(MS-ZnO)复合填料光学性能的影响,以研制高紫外?可见光?近红外(UV-VIS-NIR)反射型热控填料.先采用正硅酸乙酯(TEOS)为原料制备出SBA-15和MCM-48两种不同结构的分子筛.然后采用后嫁接法或直接生长法将ZnO分别负载于它们之中,形成具有多界面反射结构的ZnO/SBA-15和ZnO/MCM-48和具有包覆结构的Zn-SBA-15和Zn-MCM-48.所得SBA-15和MCM-48分子筛整体的紫外反射率超过0.95.采用不同结构分子筛制备的Zn/SBA-15粉体和Zn/MCM-48粉体经过高温煅烧后的太阳吸收比都为0.05.ZnO负载方式受分子筛结构的影响较大,三维孔道结构的分子筛MCM-48较简单的二维孔道结构SBA-15更易与ZnO复合形成包覆结构,且经历高温化学相变生成Zn2SiO4后,Zn-MCM-48比ZnO/MCM-48拥有更好的光反射能力,太阳吸收比只有0.03.用不同结构的分子筛改性都可以得到光学性能比ZnO更好的MS-ZnO复合填料.采用实验周期短的直接生长法制备的MS-ZnO复合填料虽然受限于分子筛的结构,但拥有更高的UV-VIS-NIR反射能力.     

溶胀嵌入脂肪酸分子制备高脱硼反渗透膜

采用“溶胀-嵌入-收缩”方法改性聚酰胺反渗透膜，制备了一种高脱硼反渗透膜。通过甲醇溶胀增加了高分子链之间的距离，为疏水性癸酸分子的嵌入提供了场所，然后在压力和浓差极化共同作用下，改性分子选择性嵌入聚酰胺膜的孔内；当甲醇分子离开后，聚酰胺膜收缩将癸酸分子固定在高分子网络中。实验借助溶胀和分子嵌入以及溶胀后的收缩调节聚酰胺膜的孔径大小；利用脂肪酸的疏水性降低聚酰胺膜的极性，从而实现增加空间位阻和减少氢键结合位点数量的目的。实验结果显示，改性膜的脱硼率和截盐率均明显升高，截盐率从90.36%增加到96.46%，脱硼率从未改性膜的47.85%增加到77.32%，渗透液的硼含量达到WTO的使用标准。虽然水和硼的渗透性均下降，但是水和硼的渗透选择性增加，证明该方法有利于提高水硼选择性。     

Room temperature blue-green photoluminescence of MCM-41, MCM-48 and SBA-15 mesoporous silicas in different conditions

The photoluminescence (PL) properties of siliceous MCM (MCM-41 and MCM-48) and SBA-15, no Na-containing MCM-41, and modified SBA-15 by silylation were comparatively investigated in dry and damp conditions, displaying the highest PL intensity of MCM-48. The PL intensity of MCM-41 is lower than that of SBA-15 in dry conditions, but reverse in damp conditions. In comparison with that of Na-containing MCM-41, the PL intensity of MCM-41 without Na⁺ is stronger. The PL intensity of modified SBA-15 by silylation is decreased in dry conditions, and however, against moisture and degradation in damp conditions. Twofold coordinated silicon centers in the tested samples are responsible for the blue-green bands at 440 nm. The shoulder peaks around 460–490 nm occurred in damp conditions are assigned to peroxy free radicals.     

Novel utilization of mesoporous molecular sieves as supports of cobalt catalysts in Fischer–Tropsch synthesis

Mesoporous molecular sieves (MCM-41 and SBA-15) with different pore diameters have been studied as supports of high loading of Co catalysts, and the performances in FT synthesis have been examined with a fixed bed stainless steel reactor at 2.0 MPa for the purpose of efficient production of C₁₀–C₂₀ fraction as the main component of diesel fuel. The method of exchanging template ions in uncalcined MCM-41 with Co²⁺ ions is effective for holding 10–20% Co within the mesopores while keeping the structure regularity of MCM-41 to some extent, compared with the conventional impregnation method using calcined MCM-41. At 523 K, CO conversion and selectivity to C₁₀–C₂₀ hydrocarbons are both higher at larger loading of 20% Co for the exchanged catalysts with pore diameters of 2.7–2.9 nm. When four kinds of 20% Co/SBA-15 with the diameters of 3.5–13 nm, prepared by the impregnation method using an ethanol solution of Co acetate, are used in FT synthesis at 523 K, the catalyst with the diameter of 8.3 nm shows the largest CO conversion, which is higher than those over MCM-41 supported Co catalysts. At a lower temperature of 503 K, however, the acetate-derived Co is almost inactive. In contrast, the use of Co nitrate alone or an equimolar mixture of the acetate and nitrate as Co precursor drastically enhances the reaction rate and consequently provides high space–time yield (260–270 g C/kg_cat h) of C₁₀–C₂₀ hydrocarbons. The X-ray diffraction and temperature-programmed reduction measurements show that the dependency of the catalytic performance of 20% Co/SBA-15 on its precursor originates probably from the differences in not only the reducibility of the calcined catalyst but also the dispersion of metallic Co. Catalyst characterization after FT synthesis strongly suggests the high stability of the most effective Co/SBA-15 in the dispersion and reducibility of the oxide species and in the mesoporous structure.     

Extraction of Ultra Trace Amounts of Palladium on 9-Acridinylamine Functionalized SBA-15 and MCM-41 Nanoporous Silica Sorbents

The application of the modified MCM-41 and SBA-15 nanporous silicas in extraction of trace amounts of palladium is investigated and developed. Surface of nanoporous silicas, MCM-41 and SBA-15, were modified with 9-acridinylamine ligand and then utilized as solid-phase sorbents for the extraction of palladium. Different experimental conditions such as pH, flow rates of the sample, and eluent solution were studied. The type and the smallest amount of eluent for elution were optimized and the breakthrough volume and the influence of various cationic interferences on the adsorption was investigated. The recovery values in this method are greater than 95% and 98.5%. The obtained limits of detections (LOD) are lower than 0.17 ng mL^?1 and 0.15 ng mL^?1 for SBA-15 and MCM-41, respectively. The pre-concentration factors were calculated to be more than 193 and 187.5 for SBA-15 and MCM-41, respectively. The relative standard deviations (RSD) of the method are lower than 4% and 1.5%, and the adsorption capacities were also obtained to be more than 170 mg g^?1 and 195 mg g^?1 for SBA-15 and MCM-41, respectively. The proposed procedure was applied on real samples and the amount of palladium was successfully derived.     

改性介孔分子筛对布洛芬的吸附与控制释放

采用合成后改性将氨基嫁接进介孔MCM41和SBA-15孔道内,对功能化的2种分子筛进行药物吸附与控制释放的研究。利用红外光谱仪(IR)、智能重量分析仪(IGA)等表征手段对吸附剂的物理结构和化学组成进行表征。对药物布洛芬(IBU)的吸附量进行比较,结果表明,氨基改性的MCM41(MCM41-NH2)对布洛芬的吸附性能大...     

氧化石墨烯改性聚酰胺膜研究进展

聚酰胺膜广泛应用于海水淡化、苦咸水脱盐及废水处理等领域,复杂、多类型的应用场景对膜性能提出了更高要求。氧化石墨烯（GO）以优异的机械、化学稳定性及亲水性等优点引起了学者的广泛关注。利用GO改性聚酰胺膜,可以改善膜的水通量、抗污染及耐氯性等性能。综述了聚酰胺膜在酸性和含氯溶液中的降解过程,介绍了GO结构特征,重点关注了利用GO在聚酰胺膜支撑层中、支撑层与功能层间、功能层中及功能层表面进行改性以提高膜性能的研究进展,对GO改性聚酰胺膜中金属离子及水传质过程进行了简要介绍。最后,提出未来可以从完善GO改性聚酰胺膜抗污机理、提高GO在膜基质中的稳定性、提高GO在溶液中的分散性及增强GO改性聚酰胺膜耐酸性等方面作进一步研究。     

Selective removal of sulfur compounds in city-gas by adsorbents

Silver nitrate impregnated on beta zeolite (BEA), mesoporous silica MCM-41 and SBA-15 (AgNO₃/BEA, AgNO₃/MCM-41, AgNO₃/SBA-15) were prepared to remove sulfur compounds selectively in city-gas, which contains tetrahydrothiophene and tert-butylmercaptane. Sulfur adsorption capacity was determined when the sulfur concentration of effluent gas in breakthrough test reached 0.1 ppm, which is acceptable sulfur concentration for hydrogen production in a reformer for fuel cells. As the AgNO₃ concentration in AgNO₃/BEA, AgNO₃/MCM-41, and AgNO₃/SBA-15 increased, their sulfur adsorption capacities also increased. Although microporous zeolite BEA has smaller pore volume and lower surface area than those of mesoporous silica MCM-41 and SBA-15, the sulfur adsorption capacity of AgNO₃/BEA was higher than those of AgNO₃/MCM-41 and AgNO₃/SBA-15. Adsorbed sulfur molecules per impregnated silver nitrate and the shape change of breakthrough curves depending on the adsorption temperature showed that not only chemisorption but also physisorption was involved in sulfur compounds adsorption on AgNO₃ impregnated adsorbent. This work was presented at the 6 ^th Korea-China Workshop on Clean Energy Technology held at Busan, Korea, July 4–7, 2006.     

An efficient microwave-assisted Suzuki reaction using Pd/MCM-41 and Pd/SBA-15 as catalysts in solvent-free condition

Palladium catalysts, Pd/MCM-41 and Pd/SBA-15 were prepared by impregnation of an aqueous solution of [Pd(NH₃)₄]Cl₂ on MCM-41 and SBA-15. Palladium contents of Pd/MCM-41 and Pd/SBA-15 are 8.4% and 8.7%, respectively. It has been shown that these catalysts are very suitable to microwave-assisted Suzuki reactions under solvent-free condition. It is also found that the base additives for this reaction are K₂CO₃, Cs₂CO₃ or CsF. Thus, phenylboronic acid and phenyl iodide with Pd/MCM-41 produce biphenyl by microwave irradiation for 10 min in 97.4% yield. Phenyl bromide, instead of phenyl iodide, also proceeds the reaction with phenylboronic acid using Pd/MCM-41 or Pd/SBA-15 yielding biphenyl by microwave irradiation for 10 min in excellent yield. Whereas the reaction of phenyl chloride with phenylboronic acid gives poor yield in same condition. Various aryl iodides and aryl bromides are tested. In this paper our recent results of microwave-assisted Suzuki reaction using Pd/MCM-41 and Pd/SBA-15 under solvent-free condition are described.     

介孔氧化硅固载Yb(OTf)3的制备及催化葡萄糖生产乳酸

采用溶剂法和焙烧法制备了SBA-15和MCM-41两类介孔氧化硅,并以此为载体制备固载型三氟甲基磺酸镱(Yb(OTf)₃)催化剂。通过小角X射线衍射(SAXD)、氮气吸附/脱附、²⁹Si固体核磁共振光谱(NMR)、透射电子显微镜(TEM)及热重分析(TG)等方法对载体及催化剂进行表征,研究其在葡萄糖制备乳酸反应中的催化性能。结果表明：溶剂法制备的氧化硅表面羟基含量比焙烧法高,负载的磺酸基团和三氟甲基磺酸镱都更多,催化活性更高;SBA-15的平均孔径比MCM-41的大3 nm左右,这使得SBA-15具有更好的传质性能以及Yb(OTf)₂-SBA-15具有更好的催化性能。以Yb(OTf)₂-SBA-15-S为催化剂,在2 MPa N₂压力、190 ℃下反应60 min,乳酸的收率达到42.35%。