混合胺改性SBA-15的二氧化碳吸附特性

为实现廉价高效的二氧化碳捕集，新型燃烧后CO₂捕集固体吸附材料的设计和开发具有重要的研究意义。为提高CO₂吸附量，胺功能化改性吸附剂的方法主要有湿浸渍和表面嫁接。基于此，提出了“混合胺”修饰的概念，把湿浸渍和表面嫁接两种改性技术结合起来。把3-氨丙基三甲氧基硅烷（APTS）嫁接到分子筛SBA-15孔道表面，再把聚乙烯亚胺（PEI）浸渍到载体孔道的间隙，制备出高密度胺功能化的CO₂吸附剂。主要考察了不同含量的PEI和APTS功能化SBA-15的结构性能、CO₂吸附量及胺吸附效率。CO₂吸附结果表明，混合胺功能化SBA-15吸附主要依赖于动力学扩散。其中，SBA-15-（APTS-0.5-PEI-50），SBA-15-（APTS-1.0-PEI-50）和SBA-15-（APTS-2.0-PEI-30）在75℃时具有很好的吸附潜力。混合胺功能化SBA-15的胺吸附效率介于单纯嫁接和单纯浸渍的胺功能化SBA-15之间。     

有序介孔分子筛SBA-15的改性研究进展

综述了有序介孔分子筛SBA-15材料由于其骨架缺陷少,导致催化活性较低,为了扩展其在催化、大分子吸附领域的应用,需要在SBA-15表面引入活性组分的现状。从改性机理和方法出发,并结合了近年来国内外研究现状,SBA-15在金属改性和酸改性领域的应用,对今后的研究方向做出了展望。     

有序介孔分子筛SBA-15的改性研究进展

综述了有序介孔分子筛SBA-15材料由于其骨架缺陷少,导致催化活性较低,为了扩展其在催化、大分子吸附领域的应用,需要在SBA-15表面引入活性组分的现状。从改性机理和方法出发,并结合了近年来国内外研究现状,SBA-15在金属改性和酸改性领域的应用,对今后的研究方向做出了展望。     

介孔SBA-15分子筛的改性研究进展

SBA-15作为介孔分子筛材料中的代表已经成为当今化工领域的研究热点之一。它具有高度有序六方孔道结构,并且具有大的比表面积、规则有序的孔道结构、良好的热稳定性、方便对其进行功能化改性、可反复再生利用等一系列优点,被广泛应用。本文介绍了在SBA-15上掺杂金属及其化合物、嫁接有机基团、负载固体酸三种改性手段,并对其改性后的样品做了性能评价,得出理想的改性条件及反应条件,在此基础上笔者展望了SBA-15的发展前景。     

组装法制备巯基改性磁性SBA-15

采用热分解法制备了单分散、平均粒径约15nm的锰铁氧体磁性纳米粒子。通过正硅酸乙酯与磁性纳米粒子表面油酸盐的配体交换将磁性纳米粒子锚定在SBA-15表面。并且将负载过程与巯基改性过程耦合制备了巯基改性的磁性SBA-15。考察了合成SBA-15过程中干燥方式对其结构和性质的影响,研究了负载磁性纳米粒子和巯基改性顺序对巯基改性磁性SBA-15的结构和性能的影响。结果表明,喷雾干燥法合成的SBA-15介孔孔壁较薄,但具有更大的比表面积、孔体积和平均孔径。以其为载体时磁性纳米粒子负载量更大,所得磁性SBA-15的饱和磁强度更高。当将巯基改性和负载磁性纳米粒子分为前后两步时,巯基改性SBA-15的表面疏水环境有利于吸附疏水磁性纳米粒子,所得磁性SBA-15负载磁性纳米粒子量更大,饱和磁强度更高。磁性纳米粒子粒径大于SBA-15孔径,其主要负载于SBA-15外表面,有利于得到介孔孔道通畅的磁性SBA-15。巯基改性的磁性SBA-15的孔体积介于0.56~0.6cm³/g,比表面积介于353~432m²/g,饱和磁强度最高达到0.91emu/g,可作为一种大容量的吸附材料用于吸附分离、药物缓释等领域。     

Zn/SBA-15介孔吸附剂的制备及脱附低浓度H_2S性能

以介孔材料SBA-15为载体、过渡金属（Zn、Fe、Mn、Cu、Co和Ni）氧化物为活性组分,用等体积浸渍法制备了过渡金属氧化物负载型介孔脱硫剂,通过XRD和比表面积测定对其进行表征。结果显示,Zn负载的SBA-15对H2S吸附效果最好;Zn离子负载量为23%时,Zn/SBA-15对H2S穿透吸附量最大,为29.7 mg/g吸附剂;考察流速、反应温度以及杂质气体存在对Zn/SBA-15吸附脱除低浓度H2S的影响,并研究了Zn/SBA-15吸附脱除H2S的再生性能,结果表明在空气氛围下,Zn/SBA-15吸附剂在573 K可再生,循环使用4次穿透硫容不发生变化。     

配体功能化负载型磷钼酸催化剂的制备及其氧化脱硫性能研究

以有机配体功能化的SBA-15为载体,将Co取代的磷钼酸（Co-POM）负载于功能化SBA-15载体上制备负载型催化剂。利用XRD、FT-IR、BET、TEM、TG等对催化剂结构进行表征。结果表明,—octyl、—NH₂基团成功嫁接到载体SBA-15上;催化剂的整体结构没有发生明显改变,催化剂活性组分均匀地分散在介孔SBA-15的表面和孔道中。以二苯并噻吩（DBT）为底物进行氧化脱硫反应,考察催化剂结构对催化活性的影响。结果表明,—octyl和—NH₂基团双功能化的催化剂（CO-POM-octyl-NH₂-SBA-15）脱硫效果最好,在反应温度为60℃、负载量为30%、反应时间为8 h、剂油体积比为1∶1的最佳反应条件下,催化剂对DBT脱除率达到94.95%。循环使用5次后,催化性能没有明显降低,具有良好的循环稳定性。     

氨基改性SBA-15介孔分子筛的制备及其铬离子吸附性能

以3-氨丙基三甲氧基硅烷(APTMS)为氨基改性试剂,采用后嫁接法制备氨基功能化的SBA-15介孔分子筛。利用扫描电子显微镜、透射电子显微镜、X-射线衍射仪、氮气吸附-脱附等温线和傅里叶红外光谱等表征手段对氨基改性SBA-15介孔分子筛的形貌、结构进行了分析。考察了吸附时间、吸附温度和溶液pH等因素对铬离子(Ⅵ)吸附率的影响。结果表明:与纯SBA-15介孔分子筛相比,氨基改性后的SBA-15分子筛对铬离子(Ⅵ)具有更好的吸附性能。     

介孔SBA-15有机化修饰对PMMA杂化材料力学性能的影响

采用硅烷偶联剂对SBA-15进行了有机化修饰(即:SBA-15-G),利用在位分散聚合法制备了SBA-15/PMMA和SBA-15-G/PMMA杂化材料,研究了SBA-15和SBA-15-G在PMMA基体中的介观有序性和分散性以及对杂化材料的力学性能的影响规律。结果表明有机化修饰使SBA-15孔容、孔径和比表面积减小,表面亲油性提高;SBA-15和SBA-15-G在基体中仍保持长程有序结构;有机化修饰改善了SBA-15在基体中的分散性和与基体的界面结合,显著增强了杂化材料的力学性能。当SBA-15-G为4%时,杂化材料的拉伸强度和模量分别提高了45%和40.4%,当SBA-15-G为2%时冲击强度达到最大,比基体提高了36.6%。,     

胺功能化介孔二氧化硅捕集CO2的研究进展

胺功能化介孔二氧化硅因其高选择性、高吸附容量、快速的吸附动力学、良好的再生性能和循环稳定性受到广泛关注,在二氧化碳捕集技术中具有优良的应用前景。本文比较了胺改性的M41S、SBA-n、KIT-n、介孔二氧化硅泡沫、介孔二氧化硅纳米球和六方介孔二氧化硅的吸附性能,总结了MCM-41和SBA-15的结构特点。介绍了胺化合物的负载方式——湿法浸渍、化学接枝和原位聚合的胺负载原理。分析了硅源、载体内部性质、气体选择性和不同添加剂对胺功能化介孔二氧化硅材料吸附二氧化碳能力的影响。最后,点明了吸附剂未来的发展目标,对胺功能化介孔二氧化硅材料的研究方向进行了展望。指出未来可关注介孔二氧化硅微观结构和温度对胺与二氧化碳相互作用的影响,增强胺功能化介孔二氧化硅的稳定性,推进其在实际环境下的应用。     

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.     

Sodium nitrate modified SBA-15 and fumed silica for efficient production of acrylic acid and 2,3-pentanedione from lactic acid

The catalytic conversion of lactic acid to acrylic acid and 2,3-pentanedione over sodium nitrate-supported mesoporous SBA-15 and fumed silica was studied. The yields of acrylic acid, 2,3-pentanedione, and acetaldehyde are 44.8%, 25.1%, and 13.3%, respectively, over the 23%NaNO₃/SBA-15 catalyst. The performance of the catalysts is strongly affected by NaNO₃ loading, catalyst texture and porosity, and product diffusion efficiency. A proper control of NaNO₃ loading can result in modification catalyst structure for improvement of 2,3-pentanedione selectivity. Under certain reaction conditions, the surface NaNO₃ species can readily transform to sodium lactate that functions as active component to catalyze the target reactions.     

活性纳米金颗料在介孔分子筛SBA-15上的分散

Chemical modification （CM） and deposition-precipitation （DP） methods were used for the dispersion of active Au nanoparticles on mesoporous silica materials in this work. XRD, TEM, N2 adsorption isotherms and UV-Vis absorption spectra were used to characterize in detail Au-SBA-15 materials prepared by the two methods. The analysis results showed that high loading （1.7%, by mass） and uniform Au nanoparticles （approximately 3 nm） were dispersed in the channels of mesoporous SBA-15 by the CM method. While for the DP method, most of Au nanoparticles with the size of 10—15nm were aggregated outside of the channels of SBA-15 and the actual loading of Au was only 0.38% （by mass）.     

Use of mesoporous SBA-15 for nanostructuring titania for photocatalytic applications

SBA15–TiO₂ samples prepared by introducing titanium with a grafting method and having TiO₂ loadings below 15 wt.% have been characterized by XRF, XRD, IR, porosimetry, SEM, HRTEM, and UV–Visible diffuse reflectance. Differently from the samples reported in the literature characterized by a high TiO₂ loading, no evidences have been found for the presence of titania particles inside or outside the mesopores of SBA-15. Three different titanium species were instead evidenced to be present. The first two derive from the reaction of titanium with silanol groups in the corona area of inner SBA-15 walls leading to the formation of either TiO₄ tetrahedral sites (by reaction by hydroxyl nests of surface defect sites) and/or pseudo-octahedral surface sites anchored by two (or more) Si or Ti ions through bridging oxygens. The third species derives from the reaction of titanium in the regions with high sylanol density, e.g. in the micropores located in the corona of SBA-15 channels, leading to the formation of TiO₂-like nanoareas (probably Si-doped) with dimensions of around 1–2 nm maximum. The potential interest of these materials as photocatalysts, for the presence of a TiO₂-like nanoareas highly accessible by reactants, is discussed.     

SBA-15 supports modified by Ti and Zr grafting for NiMo hydrodesulfurization catalysts

A series of Ti- and Zr-containing mesoporous SBA-15 supports and their respective NiMo catalysts were prepared to study the effect of the Ti and Zr loading into the support on the characteristics of Ni and Mo surface species and their catalytic activity in the 4,6-dimethyldibenzothiophene hydrodesulfurization (HDS). Ti and Zr-containing SBA-15 solids with different metal loading (up to 19 wt.% of TiO₂ or 22 wt.% of ZrO₂) were prepared by chemical grafting. The solids prepared were characterized by N₂ physisorption, X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy (DRS), temperature-programmed reduction (TPR), chemical analysis and HRTEM. The results show that Ti- and Zr-SBA-15 supports with highly dispersed Ti and Zr species can be obtained without substantial loss of SBA-15 characteristics. Zr grafted species showed somewhat better dispersion on the SBA-15 surface than the corresponding Ti counterparts. It was found that TiO₂ and, especially, ZrO₂ incorporation in the SBA-15 support leads to stronger interaction of Mo and Ni species with the support providing better dispersion to the oxidic and sulfided metal species (XRD, TPR, HRTEM). NiMo catalysts supported on Ti- and Zr-containing SBA-15 showed high activity in 4,6-dimethyldibenzothiophene HDS. It can be concluded therefore that SBA-15 materials grafted with Ti or Zr species show promising features as supports for Mo-based hydrotreating catalysts.     

介孔分子筛SBA-15的改性研究进展

从金属改性、酸改性和氧化物改性三方面综述了介孔分子筛SBA-15的改性研究进展,重点介绍了SBA-15表面功能化后引入金属改性的方法。评述了金属纳米粒子的制备对改性的SBA-15催化剂催化性能的影响。     

SBA-15负载杂多化合物在苹果酯合成中的催化性能

用浸渍法制备了一系列中孔二氧化硅分子筛SBA-15负载的磷钨酸(PW)及其铯盐和钾盐催化剂,考察了其在乙酰乙酸乙酯与乙二醇缩合制苹果酯反应中的催化性能, 并以N2吸附,Hammett指示剂和FT-IR等手段表征了催化剂的物化性质, 在水处理试验中考察了催化剂的稳定性,溶脱到水中的杂多化合物浓度用紫外可见分光光度仪测定.结果表明,在合成苹果酯的反应中,当PW的负载量低于30%,杂多酸盐负载量低于20%时,固体催化剂无活性;催化剂在反复使用过程中活性下降的量与活性组分在极性体系中的溶脱量成对应关系,说明催化剂活性下降的主要原因是杂多酸(盐)活性组分的流失造成的,而负载磷钨酸铯盐良好的催化稳定性来源于磷钨酸铯盐的难溶脱性.     

SBA-15 mesoporous silica modified with rhodium by MDD method and its catalytic role for N<Subscript>2</Subscript>O decomposition reaction

SBA-15 mesoporous silicas modified with rhodium were studied as catalysts for the N₂O decomposition reaction. Rhodium was deposited on SBA-15 by the Molecular Designed Dispersion (MDD) method using Rh(acac)₃ as a precursor of active phase. The same method was used for the deposition of Cu, Fe, Al and Ti. The SBA-15 support modified with metals were characterized with respect to metal loading (EPMA), structure (XRD), texture (BET), morphology (SEM), Rh dispersion (oxygen chemisorption), surface acidity (pyridine adsorption) and chemical nature of introduced copper and iron species (UV–vis-DRS). The rhodium-containing SBA-15 samples were found to be active catalysts for the N₂O decomposition reaction. Deposition of Al on the Rh-loaded catalyst increased its activity. An opposite effect was observed for the samples modified with Cu and Fe.     

过氧化氢溶液中痕量离子吸附分离用氨基功能化SBA-15的制备及性能

通过后接枝法制备了氨基功能化SBA-15介孔氧化硅(S-N),用于吸附过氧化氢溶液中的金属和阴离子及有机杂质制高纯过氧化氢.研究了接枝量对吸附剂结构和性能的影响并发现S-N中的氮含量随接枝剂用量增加而增加,最高为1.83％.S-N保留了高度有序的六方孔道结构,但比表面积和孔体积均随接枝量增加而下降.在过氧化氢溶液中,各...