Synthesis,characterization of triphenyltin grafted on SBA-15 mesoporous silica and its catalytic performance for the synthesis of 4-methylacetophenone

The production of Ph3Sn–O–SBA-15 (Ph3SnSBA) was achieved by heating triphenyltin chloride and SBA-15 in N-methylpyrrolidone at 190 °C for 5 h using triethylamine as a catalyst. The composition, structure, and sur-face physical and chemical properties of Ph3SnSBA were characterized using inductively coupled plasma-atomic emission spectroscopy (ICP-AES), 13C, 119Sn and 29Si solid-state nuclear magnetic resonance (NMR) spectroscopy in situ pyridine infrared spectroscopy (Py-IR), N2 adsorption–desorption isotherms, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results of ICP-AES and organic elemental analysis showed that the grafting yield of Sn was 17%(by mass) for Ph3SnSBA. The elemental analysis and solid-state NMR results for Ph3SnSBA were consistent with grafting of triphenyltin on SBA-15. The N2 adsorption–desorption, XRD and TEM analyses showed that Ph3SnSBA retained an ordered hexagonal mesoporous structure, resulting in decreases in the surface area, pore size and mesopore volume, and an increase in acidity as compared with SBA-15. The Hammett acidity function (H0) value and the number of acid sites for Ph3SnSBA, obtained by the Hammett methods, were 2.77–3.30 and 2.07 mmol·g?1, respectively. The Friedel–Crafts acylation of toluene and acetic anhydride over Ph3SnSBA was investigated. The yield of methylacetophenone (MAP) and the selectivity for 4-methylacetophenone (PMAP) were 79.56%and 97.12%, respectively, when the conditions were n (toluene):n (anhydride)=2.0:1.0 with 6%(by mass) catalyst, and heating under reflux for 5 h. The PMAP selectivity stil reached 93.11%when Ph3SnSBA was used for the fifth time under the same reaction conditions.     

Structure and catalytic properties of Pd encapsulated in mesoporous silica SBA-15 fabricated by two-solvent strategy

The two-solvent method was employed to prepare Pd encapsulated in mesoporous silica (Pd/SBA-15). A 3.01 wt% Pd loading was achieved without the loss of pore ordering. Highly dispersed and uniform palladium nanoparticles could be detected using transmission electron microscopy confirming also the absence of large particles outside the mesopore silica. The catalytic activities of the Pd/SBA-15 nanocomposites were investigated in Heck coupling reactions with activated and non-activated aryl substrates. The Pd/SBA-15 nanocomposite exhibits excellent catalytic activities and reuse ability in air for the Heck carbon–carbon coupling reactions.     

Formation of catalytic active sites in copper and manganese modified SBA-15 mesoporous silica

A series of copper and manganese oxides modified SBA-15 mesoporous silicas with different composition was prepared by incipient wetness impregnation with the corresponding nitrate precursors and compared with the analogous materials supported on conventional SiO₂. Nitrogen physisorption, XDR, FTIR, UV–Vis and temperature programmed reduction with hydrogen were used for samples characterization. Their catalytic activity was tested in ethyl acetate oxidation and methanol decomposition. The ordered porous structure of the support facilitates the interaction between different metal oxide nanoparticles and increases their dispersion due to the formation of mixed oxide phase. The ethyl acetate oxidation on SBA-15 binary materials is suppressed due to the lower accessibility of the metal oxide particles, located deeply into the micro-meso pores of the support. The reaction medium which forms during the methanol decomposition provides the reduction/decomposition transformations with the mixed oxide phase. The final phase composition of finely dispersed Cu/CuO and MnO_x particles stabilizes in a highly dispersed state into the porous matrix of SBA-15 support and increases the catalytic activity in methanol decomposition due to the appearance of synergistic effect between them.     

Influence of polyhydric solvents on the catalytic &; adsorption properties of self-oriented mesoporous SBA-15 silica

Mesoporous materials (2–50 nm) have generated much interest due to its multi-faceted applications as catalysts, adsorbents and drug delivery systems. This study is the first of its kind to systematically investigate the effect of polyhydric solvents on the morphology, catalytic and adsorption properties of self-oriented mesoporous silica. Three different mesoporous SBA-15 silica materials were synthesized using Water (SW), Glycerol (SG) and Ethylene Glycol (SEG) as solvent. They were characterized using FE-SEM, HR-TEM, small angle XRD, FT-IR, BET and solid state NMR. Morphological studies such as pore characteristics, surface area and the functionalization were carried out by comparing their catalytic and adsorption properties. Each mesoporous sample was used to catalyze biodegradable aliphatic polyester synthesis namely poly (butylene succinate), poly (butylene pimelate) and poly (butylene sebacate) and compared with a conventional homogeneous catalyst SnCl₂·2H₂O. The results offered higher purity and yield of polyesters and they took the order as SW > SG > SEG. The adsorption efficiency of each mesoporous sample was compared using the fluorescent dye Rhodamine-B and it took a reverse order (SEG > SG > SW) to that of the catalytic efficiency. This difference may be attributed to the difference in free active sites, ordered morphology of pores and surface area. The synthesized polyesters were characterized using FT-IR, ¹H NMR, XRD, GPC, DSC and the adsorption studies, using UV–Visible spectrophotometer.     

调控表面活性剂浓度制备单分散SBA-15介孔材料

采用溶胶-凝胶水热法,调控反应参数和反应工艺制备SBA-15介孔材料。通过扫描电镜、透射电镜、X射线衍射以及氮气吸附-脱附分析表征表明,在一定范围,随着表面活性剂浓度增加,介孔材料SBA-15形貌出现由球形、陀螺形到米粒状的变化,介观有序度提高。在反应物料P123与Si物质的量比为0.012时,介孔材料的物性常数如晶面间距、比表面积、孔体积和最可几孔径较小。采用静态陈化-水热法研究不同表面活性剂浓度对介孔材料形貌演变的影响,为有效调控SBA-15介孔材料形貌提供必要依据。     

Investigation of the photodegradation properties of iron oxide doped mesoporous SBA-15 silica

Mesoporous silica (SBA-15) and iron oxide incorporated silica (Fe₂O₃-SBA-15) were synthesized by co-operative self-assembly technique. Samples were characterized using nitrogen adsorption–desorption isotherm, electron microscopic and spectroscopic techniques. The results confirm the uniform distribution of pores, presence of metal oxides in the pores as well as in the surface of the mesoporous wall and oxidation state of iron in the Fe₂O₃-SBA-15. The photocatalytic degradation of methylene blue (MB), sulphorhodamine B (SR-B) and methyl orange (MO) by Fe₂O₃-SBA-15 was investigated. It was observed that Fe₂O₃-SBA-15 degraded 98 % of MB, 96 % of SR-B and 99 % of MO within 3 h after exposure to sunlight. SBA-15 does not exhibit any photocatalytic effect. These results demonstrate the potential of Fe₂O₃-SBA-15 for environmental pollution control.     

Synthesis, characterization and catalytic application of mesoporous molecular sieves SBA-15 functionalized with phosphoric acid

The phosphoric acid groups has been successfully grafted on the surface of mesoporous molecular sieve SBA-15 to form a solid acid catalyst P-SBA-15 by post-synthesis method. The samples were characterized by means of XRD, FT-IR, SEM, TEM, ³¹P MAS NMR, NH₃-TPD, N₂ adsorption/desorption and the esterification reaction. The XRD and N₂ adsorption/desorption results indicate that P-SBA-15 catalyst keeps the 2D hexagonal mesoporous structure and opens channels with the lower surface area of 554.35?m²/g compared with that of SBA-15. The SEM and TEM results show that the figuration of P-SBA-15 behaves ??rod-like?? and phosphoric acid groups is scattered differently on the surface of P-SBA-15. The FT-IR and ³¹P MAS NMR results display that phosphorus species graft onto the surface of SBA-15, which provide the Br?nsted acid sites on the surface of P-SBA-15. The acidity of the generated Br?nsted acid sites on P-SBA-15 significantly is verified by NH₃-TPD. The esterification reaction results shows that catalytic activity of P-SBA-15 is enhanced significantly compared with that of SBA-15, and its stability is good.     

Immobilization of Co(III) using tethered cyclam ligand on SBA-15 mesoporous silica for aerial oxidation of ethylbenzene

Cyclam type macrocyclic ligand was tethered onto mesoporous silica surface through N-functionalization of the cyclam. The mesoporous silica was synthesized directly with in-built chloropropyl functional group by applying microwave synthesis approach and the cyclam ligand was tethered via the surface substitution reaction of the chloro group. The tethered cyclam ligand was proven to facilely accommodate Co(III) cation into its cavity. This Co(III)cyclam-functionalized mesoporous silica showed good catalytic activity in the aerial oxidation of ethylbenzene to give acetophenone as the major product, which exceeded 60%. The presence of pyridine ligand which bounded to the axial sites of the tethered Co(III)cyclam complex enhanced the activity of the catalyst with sustaining the selectivity.     

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.     

Physicochemical properties of poly(ethylene oxide)-based composite polymer electrolytes with a silane-modified mesoporous silica SBA-15

Mesoporous silica SBA-15 was surface-modified by γ-glycidoxypropyltrimethoxy silane (GPTMS), and novel poly(ethylene oxide) (PEO)-based composite polymer electrolytes (CPE) using the silane-modified SBA-15 (SBA-15-GPTMS) as filler were prepared and characterized. The results of the low-angle X-ray diffraction (XRD) patterns and Fourier-transform infrared (FT-IR) spectroscopy indicated that GPTMS has been successfully attached to the surface of SBA-15 with a high degree of mesoscopic hexagonal pore structure. The incorporation of SBA-15-GPTMS in the PEO-LiClO₄ matrix effectively reduced the PEO crystallinity and obviously improved the conductivity and electrochemical stability of the CPEs. The CPE with 10 wt.% SBA-15-GPTMS provided the highest conductivity among all the tested CPEs, about 2-3 orders of magnitude higher than that of the PEO-LiClO₄ matrix below the melting temperature of PEO. The reasons that the CPEs using SBA-15-GPTMS as filler showed higher conductivity than that with SBA-15 were discussed.     

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%。     

Preparation, characterization, and catalytic properties of the Mo2C/SBA-15 catalysts

A series of Mo₂C/SBA-15 catalysts with different Mo contents were prepared by temperature-programmed carburization (TPC). The materials obtained and their oxide precursors (MoO₃/SBA-15) were characterized by Nitrogen adsorption-desorption isotherms, X-ray diffraction (XRD), and Fourier transform-infrared (FT-IR) spectroscopy. The activities of the catalysts for deep hydrodesulfurization (HDS) of thiophene were evaluated. The results of N₂ adsorption-desorption isotherms indicated that the surface area and pore diameter of the oxide precursors increase after carburization. The XRD patterns show that Mo₂C particles are highly dispersed in the SBA-15 ordered mesoporous. The test results show that Mo₂C/SBA-15 catalysts have an excellent performance for the deep HDS under the lower temperature region.     

介孔分子筛SBA-15的乙基化修饰和表征

以乙基三乙氧基硅烷（ethanetriethoxy silane,其分子式为C2H5-Si（OC2H5）3）为偶联制,将乙基官能团接枝于SBA-15介孔分子筛孔道中,制备了无机-有机复合介孔材料C2H5-SBA-15,川小角X射线衍射,N2气吸附-脱附,元素分析,红外光谱和滴定法对复合材料进行了表征。结果表明,乙基有机基团不仅成功被接枝到了SBA-15孔道中,而月．保持了SBA-15的有序孔道结构。由于非极性官能团乙基的引入,使得合成的复合介孔材料具有很强的疏水性     

Direct synthesis of Cerium(III)-incorporated SBA-15 mesoporous molecular sieves by two-step synthesis method

Cerium(III)-incorporated SBA-15 (Ce-SBA-15) mesoporous molecular sieves were successfully synthesized by a two-step direct synthesis method in acid media, and characterized by XRD, UV–vis, ESR, TEM, N₂ adsorption and FT-IR. The Ce-SBA-15 samples prepared show highly ordered mesostructures with larger pore diameter, pore volume and uniform mesopore size distribution. The valence of cerium species incorporated into the frameworks of SBA-15 can be controlled by adjusting the pH value of the synthesis solution accurately. When the pH value of the solution is 6.0, Ce(III)-SBA-15 can be synthesized. If the pH value is higher than 6.0, the cerium species exist in the SBA-15 sample in form of Ce(IV). Moreover, it can be found that the two-step synthesis method is a feasible, effective and simple method to expand the pore size and the pore volume of SBA-15.     

Vanadium-containing ordered mesoporous silicas: Synthesis, characterization and catalytic activity in the hydroxylation of biphenyl

A series of vanadium-containing ordered mesoporous MCM-41 materials (V-OMS) have been synthesized by direct hydrothermal (V-MCM-41) and grafting (V/MCM-41) methods using hexadecyl trimethyl ammonium bromide (HDTMABr) as the structure-directing agent. The physico-chemical properties of the vanadium-containing materials were characterized in detail by ICP-OES, XRD, FT-IR, N₂ adsorption–desorption, DRUV-VIS, TPR, XPS and SEM techniques. The redox performances of the vanadium-modified mesoporous materials were tested in the hydroxylation of biphenyl using aqueous H₂O₂ (30 wt.%) as oxidant. For a better exploitation of the catalytic activity, the reaction parameters are optimized in terms of temperature, solvent, oxidant, etc. A comparison between the catalytic activity values of the vanadium-containing mesoporous materials prepared by the two routes shows that vanadium-substituted (V-MCM-41) materials had increased activity and improved selectivity for mono hydroxyl products in the hydroxylation reaction of biphenyl compared to the V/MCM-41 catalysts. The heterogenity of the catalysts was verified by a series of leaching studies. Both the catalysts enhance the leaching of active vanadia species during the reaction; among them, V/MCM-41 shows the least heterogenity.     

M/SBA-15(M=Cu、Fe、Cr)介孔分子筛的制备、表征及其催化NO+CO反应研究

以介孔分子筛SBA-15为载体,采用浸渍法制备M/SBA-15(M=Cu、Fe、Cr) 介孔分子筛催化剂。采用XRD、BET、FT-IR、H₂-TPR和XPS等对样品进行分析表征,在固定床微型反应器中评价M/SBA-15(M=Cu、Fe、Cr)分子筛催化剂催化NO+CO的反应性能。结果表明,负载金属的SBA-15分子筛仍保持高度有序的二维六方介孔结构,比表面积和孔径略有减少,负载的活性金属组分在SBA-15分子筛表面具有较高的分散度。Cu/SBA-15、Cr/SBA-15和Fe/SBA-15催化剂对NO+CO反应体系均有一定活性,但由于活性金属自身的特性及其在载体表面负载量的差异,3种催化剂上呈现的NO还原活性不同,顺序为：Cr/SBA-15＞Cu/SBA-15＞Fe/SBA-15。     

Direct synthesis and superior catalytic performance of V-containing SBA-15 mesoporous materials for oxidative dehydrogenation of propane

V-containing SBA-15 mesoporous materials have been directly synthesized in an acidic and peroxidic medium. Compared to V/SBA-15 and V/SiO₂ samples prepared by impregnation method, the materials thus synthesized show larger surface areas, higher dispersion and reducibility of VO _x species, and superior catalytic performance for oxidative dehydrogenation of propane.     

Grafting of lignin onto nanostructured silica SBA-15: preparation and characterization

The slow decline in oil reserves with mounting oil prices is pushing industry to find more sustainable sources for industrial manufacturing. Lignin is the second most abundant natural renewable biopolymer that is underutilized and has many functional groups (–OH, phenolics) that make the biopolymer a convenient substrate for materials manufacturing by the industry. The present study thus describes grafting of lignin onto nanostructured silica SBA-15 (Santa Barbara amorphous 15) by first silylating lignin with triethoxychlorosilane followed by treatment of silylated lignin with SBA-15. The resulting nanocomposite denoted as LIG–SBA-15-G was then characterized by powder X-ray diffraction, infra-red (FTIR), ³¹P nuclear magnetic resonance (³¹P NMR), N₂ adsorption (BET), scanning and transmission electron micrographs (SEM and TEM) and thermogravimetric analysis (TGA). X-ray data showed that LIG–SBA-15-G exhibited hexagonal structure closely similar to that observed for the SBA-15 host. FTIR of LIG–SBA-15-G showed characteristic absorption bands from lignin and attenuated Si–OH band due to its conversion to Si–O–Si ether bonds. Whereas, ³¹P NMR revealed that the majority of hydroxyl groups in lignin were replaced by Si–O–LIG ether bonds in LIG–SBA-15-G. SEM images of LIG–SBA-15-G displayed little changes in the macroscopic structure as compared to SBA-15. TEM images showed some disordered area in LIG–SBA-15-G and the grafted lignin appeared as black film on the silica surface. Using BET analysis the surface area of LIG–SBA-15-G was found to be 560 m² g^?1. Finally, TGA showed that LIG–SBA-15-G was more thermally stable than lignin and contained 13 % w/w lignin. Understanding the physicochemical and structural properties of the resulting lignin-nanosilica hybrid material should help engineer a robust and sustainable biomaterial suitable for various application, e.g. removal of contaminants from contaminated water.     

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。     

Experimental investigation of thermo-physical properties of platelet mesoporous SBA-15 silica particles dispersed in ethylene glycol and water mixture

This paper presents an experimental investigation of thermophysical properties of platelet mesoporous SBA-15 particles dispersed in 60:40 (v/v) ethylene glycol:water mixture. The effect of weight fraction of particles and temperature is studied on density, viscosity and thermal conductivity of nanofluids. The maximum measured thermal conductivity enhancement reaches up to 22% for the nanofluids containing 5 wt% of SBA-15 at 60 °C. The SBA-15 nanofluids show Newtonian behavior in the tested temperature range. Also, the relative density increases between 0.4% and 2.2% when the weight percent of the nanoparticles varies between 1 and 5 at 60 °C. Structural and morphological characterization of synthesized SBA-15 have been carried out using Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and N₂ adsorption–desorption isotherms methods.