Synthesis, characterization of bimetallic Sn-Zn-MCM41 and its catalytic performance in the hydroxylation of phenol

A series of Sn-Zn modified-MCM41 has been synthesized by direct hydrothermal method and characterized using ICP, XRD, TG/DTA, FT-IR, HRTEM and N_2-adsorption techniques. Catalytic performances of the obtained materials were evaluated in the hydroxylation of phenol with H₂O₂. Results indicated that all the samples exhibited typical hexagonal arrangement of mesoporous structure with high surface area and the heteroatoms were probably incorporated into the framework of MCM41. Catalytic tests revealed that the bimetallic incorporated materials were effective catalysts in the hydroxylation of phenol. The conversion of phenol could be reach to 56.8% for the catalysts with Sn: Zn: Si = 2.69: 4.57: 100 (molar ratio) under the optimized reaction conditions. Moreover, the materials containing Sn and Zn exhibited higher catalytic activity than monometallic Sn and Zn modified MCM41.     

Synthesis of Fe-MCM-48 and its catalytic performance in phenol hydroxylation

Highly ordered Fe-MCM-48 was synthesized by a mixed templation method under low molar ratio (0.17:1) of mixed surfactants to silica and characterized by XRD, ²⁹Si-MAS NMR, ESR, and UV-Visible. Its catalytic activity and selectivity was studied for phenol hydroxylation using H₂O₂ (30%). The substituting element (Fe³⁺) is partially incorporated into the framework position forming a new type of active site which raises the phenol conversion to 43.6% and the diphenol (the mixture of catechol (CAT) and hydroquinone (HQ)) selectivity to 97.7%.     

镧、钒取代MCM-41分子筛的结构表征及其在苯酚羟基化反应中的催化性能

采用水热法合成了双金属镧(La)和钒(V)取代MCM-41分子筛催化剂,使用X射线衍射、N2吸附、傅里叶变换红外光谱、紫外-可见漫反射光谱以及热重等表征技术研究了催化剂的结构。结果表明,该材料具有高度有序的二维六方结构,金属La和V以高度分散的四配位状态存在于分子筛的骨架中。在苯酚过氧化氢羟基化反应中La-V-MCM-41分子筛表现出比TS-1催化剂更好的催化活性和选择性,金属La和V协同作用,在提高H2O2有效利用率的同时,增加了目标产物苯二酚中对苯二酚的含量。La-V-MCM-41催化剂可以通过焙烧活化的方法进行再生使用。     

Cu-HMS的合成和催化苯酚羟基化反应研究

分别以CuCl₂、CuAc₂和Cu(NH₃)⁺₄为铜源,正硅酸乙酯为硅源,十二胺为模板剂,在室温下合成了Cu-HMS系列介孔分子筛催化剂。XRD、FT-IR、孔容测定和元素分析结果表明,铜原子嵌入到介孔HMS骨架中将使HMS的晶胞发生扩张,孔容增大;使用Cu(NH₃)⁺₄合成的Cu-HMS-3样品其结晶有序度好、骨架铜含量高。在催化苯酚羟基化反应中,Cu-HMS-3催化剂显示出最佳的催化性能。在优化的反应条件下,可获得35%的苯酚转化率和90%以上的二酚选择性。     

Ti-MCM-41分子筛催化剂的合成、表征及催化性能

以正硅酸四甲酯为硅源,钛酸四异丙酯为钛源,在异丙醇和水的混合溶液中室温下合成了Ti-MCM-41介孔分子筛,采用TEM、N 2吸附-脱附、XRD、UV-Vis和Raman等研究了分子筛的结构特性。并以过氧化氢异丙苯为氧化剂,考察了硅烷化处理后的Ti-MCM-41分子筛催化剂在丙烯环氧化反应中的催化性能。结果表明,与骨架外六配位钛物种相比,骨架内四配位钛物种活化有机过氧化物的能力更强,速率更快;四配位钛物种是环氧丙烷生成的活性物种,而六配位钛物种的存在则会导致反应副产物的生成。合成时添加适量的异丁醇可有效促进钛物种进入分子筛骨架中,并增大比表面积和孔体积,进而改善Ti-MCM-41催化剂的丙烯环氧化催化性能。性能最佳的催化剂上过氧化氢异丙苯转化率可达94.7%,环氧丙烷选择性可达95.8%。     

无机物负载体的制备和表征及其催化苯酚羟基化的研究

研究了低硅铝比沸石分子筛及天然矿土硅铝酸盐负载无机盐或氧化物为催化剂,催化氧化苯酚制取邻、对位二元酚。用化学常量法分析了负载离子的含量,采用XRD、IR、DRS、Mossbauer谱等手段,对催化剂进行表征。研究了不同金属离子无机盐的各种载体催化剂的催化活性,证明了热稳定性差的沸石及矿土负载改性为六配位非骨架杂原子的无孔道致密相,对苯酚羟化反应有较好的催化活性,n沸石1作催化剂,溶剂用水,苯酚与H2O2摩尔比为3：1,pH值为1．5(Fe改性),4(Cu改性),温度为60℃(Fe改性)、80℃(Cu改性),时间为1h,催化剂的量为苯酚的1／10,催化剂有一定再生能力,重复3次使用效果较好。     

铁铝交联黏土催化剂的制备及其苯直接羟基化的催化性能

通过直接向稀释的黏土悬浮液中加入Fe-Al交联剂制备了不同物质的量比的铁铝交联黏土催化剂。研究了该催化剂在苯/H2O2直接羟基化制备苯酚反应中的催化性能。结果表明,铁铝交联黏土催化剂在苯直接羟基化反应中具有良好的催化活性,苯酚收率最高可达4.9%,选择性可高达73.5%。运用XRD、FT-IR、TG-DSC、SEM等手段对铁铝交联黏土催化剂进行了表征。     

Synthesis,characterization of Al-rich ZSM-12 zeolite and their catalytic performance in liquid-phase tert-butylation of phenol

Al-rich ZSM-12 zeolites were synthesized using N,N,N′,N′-tetraethylbicyclo[2.2.2]oct-7-ene-2,3:5,6-dipyrrolidinium diiodide as template under hydrothermal conditions. Their physico-chemical properties were characterized using XRD, ICP-AES, SEM, N₂ adsorption, ²⁷Al MAS NMR and NH₃-TPD. The results indicated that Al-rich ZSM-12 zeolites with low Si/Al ratios of 8–23 were successfully crystallized. Catalytic properties of the prepared zeolites were studied in the tert-butylation of phenol. Higher para selectivity was obtained on the Al-rich ZSM-12 zeolites compared with other types of zeolites.     

Fe-SBA-16介孔分子筛的制备及其催化苯酚羟基化反应性能

以正硅酸乙酯为硅源,F127为模板剂,采用水热合成法直接合成不同铁含量的Fe-SBA-16分子筛。通过X射线衍射、N₂物理吸附-脱附、红外光谱、紫外-可见漫反射光谱等分析手段对催化剂的结构进行表征。研究了Fe-SBA-16在以H₂O为溶剂,H₂O₂为氧化剂的苯酚羟基化反应中的催化活性并考察了不同的反应条件（Fe含量、反应温度、反应时间、催化剂用量、反应物配比）对催化性能的影响。结果表明,在一定铁含量的条件下合成出的Fe-SBA-16样品均保持了SBA-16介孔分子筛的立方笼状介孔结构和高的比表面积,且Fe被成功地引入到SBA-16骨架上。当Si/Fe=30时,Fe-SBA-16催化剂表现出良好的催化活性和选择性。反应温度为65℃,反应时间为2h,苯酚：双氧水为1：0.4时催化活性最好,苯酚的转化率为30.8%,邻苯二酚与对苯二酚的选择性分别为64.3%与30.5%。     

VOx/AlPO4催化剂合成及其催化苯羟基化反应性能

以异丙醇铝与磷酸为原料,离子液体1-丁基-3-甲基咪唑溴盐([Bmim]Br)与二正丙胺为共模板剂合成了Al PO₄,进而采用水热法将V₂O₅负载于Al PO₄载体制备了VO_x/Al PO₄催化剂。采用XRD、SEM、TEM、Mapping、FTIR、N₂吸附-脱附、XPS对催化剂进行了表征,考察了其在苯羟基化反应中的催化性能。结果表明,钒氧化物负载量为16%(以V₂O₅和Al PO₄的总质量为基准,下同)的催化剂具有最多且分布均匀的V⁴⁺活性中心、契合反应的酸性微环境,在催化剂用量为0.2 g,苯用量4 mL,质量分数30%的H₂O₂用量12.5 mL,乙腈用量15 mL,反应温度70℃,反应时间7 h的条件下,苯转化率为53.4%,苯酚选择性为98.4%。基于催化剂表征分析及性能评估,推测催化反应机理...     

纳米TiO_2、NiO和CuO的制备、表征及催化苯酚羟基化反应研究

分别采用均匀沉淀法和固相法合成纳米级的TiO2,NiO和CuO颗粒,用XRD,TEM等对其结构和形貌进行了表征,用纳米TiO2,NiO和CuO为催化剂,对苯酚羟基化反应的活性进行研究。结果表明,纳米TiO2,NiO和CuO颗粒催化苯酚羟基化反应具有较好的催化活性,苯酚的转化率分别达到25.3%,28.3%和27.5%。     

Synthesis, characterization, and catalytic phenol hydroxylation of a novel complex oxide HxV2Zr2O9.H2O

A novel type of complex oxide H_xV₂Zr₂O_9.H _2O with V⁴⁺ and V⁵⁺ mixed valence has been hydrothermally synthesized in a V₂O₅-ZrO₂-H₂O system at 240°C for 5 days in presence of NaF. The catalytic data over these complex oxides show that these complex oxides are catalytically very active in phenol hydroxylation by 30% aqueous hydrogen peroxide, and their catalytic activity is dependent on crystal size of the catalysts. The phenol conversion over the catalyst with crystal size of 7 μm is twice that over the catalyst with crystal size of 35 μm. The V⁵⁺ species are suggested to be the catalytic active sites. Some other factors which influence the catalytic activity were also investigated. This revised version was published online in July 2006 with corrections to the Cover Date.     

Influence of preparation parameters on characteristics of zirconia-pillared clay using ultrasonic technique and its catalytic performance in phenol hydroxylation reaction

Ultrasonication method was employed for preparation of zirconia-pillared montmorillonite (Zr-PILC) by using polyhydroxy zirconium cation. The influences of various preparation parameters such as pH, concentration of pillaring agent, aging period on physico-chemical properties of Zr-PILCs are reported. The characterization was done by using different characterizing tools such as powder X-ray diffraction (XRD), thermal analysis (TG/DTA), Fourier transform infrared spectroscopy (FTIR), X-ray photo-electron spectroscopy (XPS), X-ray fluorescence spectroscopy (XRF) and surface area measurements. Effective pillaring was obtained in the pH range 2.0–2.8 at reduced preparation time by using ultrasonication. Ultrasonication, especially at higher pH and concentration of pillaring agent with no aging after ultrasonic agitation of the clay slurry was found to increase zirconium content and specific BET surface area leaving no scope for remarkable increase in d001 spacing. The presence of -OH groups attached to Zr has been revealed by pyridine-adsorbed FITR, TG/DTA and XPS techniques. The acidic character, ease of accessibility and good dispersion of active sites in Zr-PILC were found to be controlling factors for the challenging activity in hydroxylation reaction of phenol. Probably, this first report on the use of Zr-PILC in hydroxylation of phenol and its preparation by employing ultrasonication technique may attract great attention in the catalysis area of academic and industrial importance.     

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.     

Fabrication and catalytic performance of meso-ZSM-5 zeolite encapsulated ferric oxide nanoparticles for phenol hydroxylation

An encapsulation-structured Fe₂O₃@meso-ZSM-5 (Fe@MZ5) was fabricated by confining Fe₂O₃ nanoparticles (ca. 4 nm) within the ordered mesopores of hierarchical ZSM-5 zeolite (meso-ZSM-5), with ferric oleate and amphiphilic organosilane as the iron source and meso-porogen, respectively. For comparison, catalysts with Fe₂O₃ (ca. 12 nm) encapsulated in intra-crystal holes of meso-ZSM-5 and with MCM-41 or ZSM-5 phase as the shell were also prepared via sequential desilication and recrystallization at different pH values and temperatures. Catalytic phenol hydroxylation performance of the as-prepared catalysts using H₂O₂ as oxidant was compared. Among the encapsulation-structured catalysts, Fe@MZ5 showed the highest phenol conversion and hydroquinone selectivity, which were enhanced by two times compared to the Fe-oxide impregnated ZSM-5 (Fe/Z5). Moreover, the Fe-leaching amount of Fe@MZ5 was only 3% of that for Fe/Z5. The influence of reaction parameters, reusability, and ·OH scavenging ability of the catalysts were also investigated. Based on the above results, the structure-performance relationship of these new catalysts was preliminarily described.     

Synthesis,characterization of hierarchical TS-1 and its catalytic performance for cyclohexanone ammoximation

A hierarchical titanium silicate (TS-1) that possesses large open voids has been prepared by using a dissolution/re-crystallization process. Carbon black was introduced as a hard template during the synthesis process to generate defects both inside and on the surface of crystals, then TPAOH post-treatment was applied, as a result, a novel TS-1 zeolite crystal with large open voids was successfully synthesized. The synthesized hierarchical TS-1 was characterized by XRD, FTIR, SEM, TEM and N₂ physisorption. Compared with the traditional TS-1 and hollow TS-1, the activity of hierarchical TS-1 in cyclohexanone ammoximation was improved and attributed to the macropores that linked the voids inside the zeolite directly to the outer surface.     

三核铜配合物的合成、表征及其催化性能

采用溶剂热法合成了以三核碘化亚铜（CuI）四面体结构为活性中心的硅氢加成反应催化剂,探讨了物料比对产物收率的影响。结果说明了当配体与碘化亚铜的摩尔比为1：6时,产物收率最高。通过元素分析、傅里叶红外光谱分析、X射线光电子能谱分析、X射线单晶体衍射分析、紫外可见光光谱分析、热失重分析对配合物的化学组成、空间结构及性能进行表征,并进一步通过甲基苯基乙烯基树脂和甲基苯基含氢硅油的硅氢加成反应进行催化固化效果验证。结果说明了在催化剂填加量为0.04%、固化温度为150℃的优化条件下反应24h,共混体系固化效果最佳。该配合物对硅氢加成反应具有很好的催化性能,并且原料成本低、制备方法简单、晶体颗粒方便储存,有望解决硅氢加成反应中贵金属催化剂的高成本问题。     

低成本TS-1分子筛的制备及其苯酚羟基化性能研究

以四丙基氢氧化铵为模板剂,采用较低碱浓度水解成胶和较高模板剂浓度晶化的新工艺合成了低成本的TS-1分子筛,并优化了合成条件。样品的XRD和FT-IR表征证明,Ti原子成功进入分子筛的骨架中。结果表明,在水解成胶碱浓度为8%左右、晶化模板剂浓度20%时合成的TS-1分子筛,其催化苯酚羟基化反应中,苯酚的转化率达到20.56%。该合成在保证TS-1分子筛高催化活性的基础上,模板剂四丙基氢氧化铵（TPAOH）的用量明显降低,从而大大降低合成成本。     

微波法制备HMS包络合铁配合物催化剂催化苯酚羟基化反应

以表面含氨基的HMS为载体,利用微波法在载体孔内合成8-羟基喹啉铁（FeⅡ-Oxine）、邻苯二酚铁（FeⅡ-Cat）和邻菲洛啉铁（FeⅡ-Phen）负载型催化剂（FeⅡ-L/HMS,L=Oxine,Cat或Phen）,再在载体孔口接枝聚酰胺-酯型二代树状分子(A),制得FeⅡ-L/HMS-A包络合型催化剂。XRD、FT-IR、Fe含量分析和苯酚羟基化反应结果表明,铁配合物能够被有效包络合到HMS孔内,显示出较好的苯酚羟基化活性,具有良好的重复使用性能,是一种介孔分子筛固载金属配合物简便、有效和环境友好的方法。     

Synthesis, characterization and catalytic application for wet oxidation of phenol of iron-containing clays

High-surface-area pillared clays (PILC) were prepared from naturally occurring montmorillonites by exchanging interlayer ions to polyoxocations containing (i) aluminum (Al₁₃-PILC), (ii) iron adsorpted onto Al₁₃-PILC, and (iii) iron and aluminum located within the same complex (Fe_0.8Al_12.2-PILC). The obtained Fe_0.8Al_12.2-PILCs were characterized by DR–UV–vis and IR spectroscopy, XRD, ESR, scanning electron microscopy and low temperature N₂ adsorption measurements. Important factors affecting catalyst activity and phenol removal efficiencies have been studied, i.e. the effect of pH, temperature, catalyst concentration and stability of the catalyst.