SBA-15复合材料的制备及其催化合成环己酮乙二醇缩酮

将金属离子嫁接在SBA-15的孔道中作为催化剂,考察其催化合成环己酮乙二醇缩酮的性能。使用FT-IR、SEM和XRD对催化剂的结构进行表征,结果表明合成的催化剂为目标催化剂。固定环己酮用量为0.2 mol,当乙二醇与环己酮的摩尔比为1.7:1,催化剂的用量为反应底物质量的1.2%,带水剂环己烷的用量为14 mL,反应时间为100 min时,Co/SBA-15催化合成效果最好,环己酮乙二醇缩酮的收率为89.8%。     

Copper and chromium modified SBA-15: C-radiolabeling catalytic study

Novel ¹¹C-radiolabeling catalytic approach is applied for the characterization of copper and chromium modified SBA-15 materials. The method is based on the selective adsorption of ¹¹C-methanol on different catalytic sites with the detection of the products of the conversion. The high CO₂ and methylformate selectivity is related to the activity of CuO and Cr₂O₃ species, while copper chromate nanoparticles facilitate the formation of dimethoxymethane.     

Effect of different lanthanum source and preparation method on the lanthanum-doped mesoporous SBA-15 synthesis

Lanthanum-substituted mesoporous SBA-15 molecular sieve has been prepared by direct synthesis and post-synthesis procedures using lanthanum nitrate or lanthanum chloride as lanthanum source. Characterizations by atomic absorption, X-ray diffraction, nitrogen adsorption, UV–Vis spectra analysis, FT–IR spectroscopy and scanning electron microscopy have been carried out to evaluate the efficiency of the incorporation of lanthanum by these procedures. Results showed that Lanthanum was well incorporated into the hexagonal framework of SBA-15 molecular sieves by these two procedures. These LaSBA-15 mesoporous molecular sieves retain the hexagonal order and physical properties of siliceous SBA-15 material. Compared to lanthanum chloride, the lanthanum nitrate is a suitable lanthanum source, which can match the hydrolysis rate of silicon precursor and composite materials possess larger specific surface area, uniform mesopore size distribution.     

不同铝源对SBA-15分子筛改性影响

为比较不同铝源对SBA-15分子筛改性的影响,以正硅酸乙酯为硅源,分别用异丙醇铝、氯化铝和硝酸铝对SBA-15分子筛进行改性, 运用XRD、N2等温吸附-脱附、SEM、 TEM和气相色谱对样品进行表征。将3种不同铝源改性SBA-15分子筛与USY分子筛复合制备加氢裂化催化剂,在固定床微型反应装置进行加氢裂化性能评价,结果表明,异丙醇铝在酸性条件下水解生成的Al(OH)^-₄更容易进入SiO₂骨架中,生成的产物异丙醇不影响铝离子的掺杂,由于异丙醇铝与正硅酸乙酯的水解速率一致,改性后所得材料孔分布更均一,规整性更高。将异丙醇铝对SBA-15分子筛改性后,与USY制备的复合分子筛催化剂用于正十二烷加氢裂化反应,选择性和转化率优于氯化铝和硝酸铝改性的分子筛。     

无溶剂法镧改性SBA-15的制备、表征及催化性能

以介孔分子筛SBA-15为载体,采用固相研磨法掺杂La元素,以SO₄^2-或S₂O₈^2-为助催化剂同时掺杂在介孔分子筛中增强SBA-15表面活性中心,制备了La-SO₄^2-/SBA-15和La-S₂O₈^2-/SBA-15负载型固体酸催化剂。用X射线衍射、透射电镜、低温N2吸附－脱附、红外光谱、热重分析和NH₃-TPD等分析方法对改性材料的结构性能及表面酸性能进行了表征。表征结果显示,制得的La-SO₄^2-/SBA-15和La-S₂O₈^2-/SBA-15保持高度有序的二维六方介孔结构。用Hammett指示剂法测得La-SO₄^2-/SBA-15和La-S₂O₈^2-/SBA-15表面酸强度（H₀）分别为2.77~3.30和0.78~0.99,表明制备的改性材料为固体酸。以改性的SBA-15为催化剂,催化合成乙酸正丁酯,在酸醇物质的量比为1∶1.2、催化剂用量0.375 g（为冰醋酸质量的5%）和反应时间140 min的条件下,采用La-S₂O₈^2-/SBA-15和La-SO₄^2-/SBA-15为催化剂,其酯化率分别为97.31%和89.28%。     

负载型Pd/SBA—15催化剂催化性能研究

将负载型催化剂Pd/SBA—15用于催化邻氯硝基苯加氢。考察了反应温度、催化剂用量对Pd/SBA—15催化性能的影响,并考察了催化剂的使用寿命。实验结果表明,Pd/SBA—15催化剂表现出很好的催化性能,有望应用于工业生产。     

V/SBA-15的制备及催化氧化性能研究

以柠檬酸处理过的偏钒酸铵为钒源,采用后合成法制备出了V/SBA-15负载型催化剂,研究其在氧化苯乙烯制苯甲醛反应中的催化性能.结果表明,在钒负载量低于15％时,V/SBA-15仍保持SBA-15的高度有序的二维六方孔道结构,且具有较大的比表面积和孔体积,负载的活性组分金属钒氧化物均匀分布在介孔分子筛表面;在优化条件下催化氧化苯乙烯制苯甲醛,苯乙烯转化率达65.62％,苯甲醛的选择性81.21％,且V/SBA-15具有较好的催化剂稳定性.     

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.     

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.     

V/SBA-15的水热合成法制备及其催化氧化性能研究

为了制备负载型介孔分子筛V/SBA-15并研究其在乙苯制苯乙酮反应中的催化性能,以P123(三嵌段共聚物)为模板剂,正硅酸乙酯为硅源,柠檬酸氧钒配合物为前驱体,在酸性条件下采用水热法一步合成了V/SBA-15有序介孔材料,利用XRD,BET,FT-IR等手段对所合成的V/SBA-15材料进行了结构表征,并在乙苯制苯乙酮反应中以苯乙酮选择性和收率来验证催化剂的催化性能。实验结果表明:此合成材料具有类似于SBA-15的高度有序的六方介孔结构,活性组分钒均匀分散在介孔氧化硅基体中;在催化氧化乙苯制苯乙酮反应的优化条件下,苯乙酮选择性和收率分别为80.87%,35.26%。     

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.     

水热分散法制备PW_(12)/SBA-15催化剂及其催化性能的研究

利用水热分散法在分子筛SBA-15上负载Keggin型结构的磷钨酸,得到负载型催化剂,采用XRD、FTIR、N2吸附-脱附等技术对其进行分析。将其用于柠檬酸三丁酯的催化合成,考察其催化性能。结果表明,磷钨酸负载量为20. 3%,催化剂用量为1. 7%,醇酸摩尔比为4∶1,反应温度为150℃,反应时间为5 h,酯化率达到95. 46%。催化剂重复使用8次,催化效果稳定。     

Characterization and catalytic properties of mesoporous CuO/SBA-16 prepared by different impregnation methods

CuO/SBA-16 catalysts were prepared by two different routes - the conventional impregnation method and the modified impregnation method with pH adjustment. These catalysts were characterized by X-ray diffraction (XRD), atomic absorption spectrometry (AAS), N₂ physisorption and hydrogen temperature programmed reduction (H₂-TPR) measurements which reveal that the cubic cagelike (Im3m) pore structure of the parent SBA-16 molecule sieves was well maintained throughout the synthesis. After introduction of Cu, a different CuO dispersion exists on these catalysts. The CuO/SBA-16 prepared by modified impregnation method has a single highly dispersed CuO which is considered as a highly efficient species for hydroxylation of phenol with H₂O₂. CuO/SBA-16 prepared by the conventional impregnation method shows the presence of bulk CuO species which is undesirable for this reaction.     

Characterization and catalytic properties of mesoporous CuO/SBA-16 prepared by different impregnation methods

CuO/SBA-16 catalysts were prepared by two different routes – the conventional impregnation method and the modified impregnation method with pH adjustment. These catalysts were characterized by X-ray diffraction (XRD), atomic absorption spectrometry (AAS), N₂ physisorption and hydrogen temperature programmed reduction (H₂-TPR) measurements which reveal that the cubic cage-like (Im3m) pore structure of the parent SBA-16 molecule sieves was well maintained throughout the synthesis. After introduction of Cu, a different CuO dispersion exists on these catalysts. The CuO/SBA-16 prepared by modified impregnation method has a single highly dispersed CuO which is considered as a highly efficient species for hydroxylation of phenol with H₂O₂. CuO/SBA-16 prepared by the conventional impregnation method shows the presence of bulk CuO species which is undesirable for this reaction.     

SBA-15固载磷钨酸催化剂的制备及催化合成叔丁基苯酚

以不同硅烷偶联剂改性的介孔分子筛SBA-15为载体、PW_(12)为催化剂,通过对SBA-15表面共价及非共价修饰制备磷钨酸@介孔分子筛/硅烷偶联剂复合催化剂PW_(12)@SBA-15/YSiX_3(YSiX_3=Apts、Atapts、Papts);并利用FT-IR、XRD、TEM、N_2吸附-脱附对其组成、结构及形貌进行表征。以改性SBA-15分子筛固载磷钨酸催化剂催化合成叔丁基苯酚为研究对象,考察不同硅烷偶联剂、反应温度、苯酚与叔丁醇物质的量比对催化合成叔丁基苯酚的影响,并获得合成叔丁基苯酚的最佳工艺条件,即反应温度145℃、n(苯酚)∶n(叔丁醇)=1∶2.5、重时空速2.2 h~(-1),该最佳反应条件下,PW_(12)@SBA-15/Apts催化剂催化合成叔丁基苯酚的催化活性最高,苯酚转化率为98.3%,2,4-二叔丁基苯酚选择性为57.3%.     

K_2O/SBA-15的制备及其催化性能研究

以介孔分子筛SBA-15为载体,负载KNO3后焙烧制得K2O/SBA-15固体碱催化剂,以合成丙烯酸正丁酯的酯交换反应为探针反应,在间歇式反应釜中对K2O/SBA-15催化剂进行催化活性评价。结果表明,当K2O负载量为2%,K2O/SBA-15催化剂对此酯交换反应的催化活性最高。     

磷钨酸/SBA-15催化氧化-萃取柴油脱硫

以自制的SBA-15为载体,磷钨酸为活性组分,用过量浸渍法制备了HPW/SBA-15催化剂,并采用SEM、BET和TG-DTA对催化剂进行表征分析。H₂O₂为氧化剂,十六烷基三甲基溴化铵（CTAB）为相转移剂,以二苯并噻吩（DBT）的模型化合物（DBT为溶质、正辛烷为溶剂）进行氧化脱除为探针反应,考察了磷钨酸负载量和HPW/SBA-15的焙烧温度对催化剂活性的影响,同时考察了氧化-萃取工艺条件对真实柴油脱硫效果的影响。实验结果表明,磷钨酸最佳负载量为30%,HPW/SBA-15在250℃焙烧处理时活性最高;在n(H₂O₂)：n(S)=6、HPW/SBA-15用量为2.5%（基于柴油质量）、CTAB用量为0.4%（基于柴油质量）、萃取级数为4、温度60℃反应1.5h的条件下,柴油硫含量从1317mg/L降到39mg/L,脱硫率达到97.0%、收率不低于85.0%。气相色谱结果显示,该催化氧化脱硫体系容易脱除柴油中加氢难以脱除的二苯并噻吩及其衍生物。     

Synthesis,characterization, and catalytic performance of highly dispersed vanadium grafted SBA-15 catalyst

Vanadium oxide grafted on mesoporous silica SBA-15 has been synthesized using a controlled grafting process. Its structure has been thoroughly investigated using different characterization techniques, including N₂-physisorption, X-ray diffraction, transmission electron microscopy (TEM), Raman spectroscopy, H₂ temperature-programmed reduction, X-ray absorption near-edge structure (XANES), and extended X-ray absorption fine structure (EXAFS). The spectroscopic results revealed that under dehydrated conditions, the grafted vanadium domains are highly dispersed on the SBA-15 surface, composed predominately of isolated VO₄ units with distorted tetrahedral coordination. The suggested (SiO)₃VO sites on the silica surface include one short bond (～1.54 Å) and three long bonds (1.74 Å). Methanol oxidation was used as a chemical probe reaction to examine the catalytic properties of these catalysts. At low vanadium loading, the vanadium species grafted on the surface show structural properties similar to those of vanadium-incorporated MCM-41 catalyst. However, the present mesoporous V-SBA-15 catalysts in the oxidation of methanol to formaldehyde show remarkable catalytic performance compared with that of VO_x/SBA-15 catalysts synthesized through a conventional wet impregnation method, which has been attributed to the homogeneous dispersion and uniformity of the catalytic vanadium species achieved on the SBA-15 support with large pore diameter and surface area. The acidic properties of V-SBA-15 was investigated by pyridine temperature-programmed desorption, which indicated the existence of both Lewis and Brönsted acid sites of the surface.     

SBA -15负载铁基氧化物催化剂上丙烷选择氧化催化性能的研究

用等体积浸渍法制备了SBA - 15负载铁基和钾修饰的Fe基氧化物催化剂,使用紫外-拉曼光谱对催化剂结构进行表征,并评价催化剂对丙烷的选择氧化活性与选择性.结果表明,介孔结构SBA - 15对丙烷选择氧化活性优于常规的SiO2;对于负载K- Fe/SBA - 15系列催化剂,低Fe负载量时,隔离的四配位Fe氧化物是丙烷...