Ultrasound-assisted synthesis of nanosized hierarchical ZSM-5 and its catalytic performance as the support for heteropolyacid

Nanosized hierarchical micro-mesoporous ZSM-5 material has been successful synthesized using the double templating approach performed by a two-step crystallization process. The synthesis route involved static hydrothermal aging and ultrasonic-assisted aging. It was established that ZSM-5 synthesized under appropriate ultrasound stimulation possessed larger cumulative pore volume and smaller crystal size than that of samples synthesized without ultrasound stimulation. A serious of micro-mesoporous ZSM-5 supported HPW catalysts with various acid loadings were prepared by the impregnation method. The catalytic performances were investigated in the alkylation of o-xylene with styrene. Alkylation results showed that HPW/micro-mesoporous ZSM-5 exhibited better activities than that of HPW/microporous ZSM-5 catalyst. HPW-20/micro-mesoporous ZSM-5 catalyst had the best catalytic performances in terms of yield and stability, which can be attributed to its maximum medium strong acid amount and its smaller particle size which is favorable for fast diffusion of products.     

Catalytic oxidative desulfurization of gasoline using phosphotungstic acid supported on MWW zeolite

Catalysts for the desulfurization of gasoline samples were synthesized via the immobilization of well-dispersed phosphotungstic acid (HPW) on Mobil composition of matter-twenty-two (MWW) zeolite. Characterization results indicated that these catalysts possess a mesoporous structure with the retention of the Keggin structure of immobilized HPW. Relevant reaction parameters influencing sulfur removal were systematically investigated, including HPW loading, catalyst dosage, temperature, initial S-concentration, molar ratio of oxidant to sulfide (O/S), volume ratio of MeCN to model oil (Ext./oil), and sulfide species. The 40 wt-% HPW/MWW catalyst exhibited the highest catalytic activity with 99.6% dibenzothiophene sulfur removal from prepared samples. The 40 wt-% HPW/MWW catalyst was recycled four times and could be easily regenerated. Finally, as an exploratory study, straight-run-gasoline and fluid catalytic cracking gasoline were employed to accurately evaluate the desulfurization performance of 40 wt-% HPW/MWW. Our research provides new insights into the development and application of catalysts for desulfurization of gasoline.     

Oxidative desulfurization of diesel fuel by mesoporous phosphotungstic acid/SiO2: the effect of preparation methods on catalytic performance

Two kinds of mesoporous phosphotungstic acid/SiO₂ (HPW/SiO₂) have been synthesized by amino-functionalized (AF) method and evaporation-induced self-assembly (EISA) method, and their catalytic performance was investigated for deep oxidative desulfurization of benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) in diesel oil. Various analysis techniques such as XRD, TEM, N₂ adsorption/desorption isotherms, FT-IR and ³¹P MAS NMR spectra have been used to investigate the pore structure and chemical properties of the resultant catalysts. The structural and spectroscopic analysis indicates both catalysts have a highly ordered 2D hexagonal mesostructure. HPW/SiO₂-EISA can maintain the Keggin structure of HPW molecules and has a high BET surface area (403 m²/g). But in the AF method, the mesostructure of SBA-15 are partially blocked after the introduction of HPW molecules, and the Keggin structure of HPW molecules has been damaged. The catalytic performance results also show that HPW/SiO₂-EISA exhibits higher catalytic activity and stability compared to HPW/SiO₂-AF. As for HPW/SiO₂-EISA, the conversions of DBT, 4,6-DMDBT and BT are found to be 99.6, 97.6, 94.8 %, respectively. It shows a good maintenance of activity even after the 7th cycle of use. While corresponding conversions by using HPW/SiO₂-AF are found to be 90.2, 89.1 and 87.6 %, and the DBT conversion decreases to 75.7 % after the 5th cycle of use.     

六方介孔氧化硅负载磷钨酸的催化性能

采用浸渍法将磷钨酸(HPW)负载于六方介孔氧化硅(HMS)上,制备HPW改性HMS介孔材料HPW/HMS,对其进行了表征;以HPW/HMS为催化剂,催化2-萘甲醚(2-MN)与乙酸酐(AA)的酰化反应,考察了各因素对催化反应的影响. 结果表明,HPW高度分散在HMS上,HPW/HMS的酸量和酸强度随HPW负载量增加而增加. 在温度120℃、时间4 h、催化剂用量0.3 g及2-萘甲醚/乙酸酐摩尔比1:2条件下,2-萘甲醚转化率为75.3%(mol),目标产物2-甲氧基-1-萘乙酮的选择性达83.0%(mol). 催化剂可回收再利用,催化活性略有降低.     

3D graphene aerogel anchored tungstophosphoric acid catalysts: Characterization and catalytic performance for levulinic acid esterification with ethanol

3D graphene aerogel (GA) was synthesized from graphene oxide (GO) using a hydrothermal procedure combined with freeze-drying. Then, they were used to assemble the supported H₃PW₁₂O₄₀ (HPW) catalysts. The optimization of the reaction parameters for levulinic acid esterification with ethanol was performed and the catalytic performance of the HPW/GA catalysts was comparatively investigated. The results showed that these catalysts had abundant porous structure. In particular, they were found to be efficient in the synthesis of ethyl levulinate, which is promising in reducing the consumption of petroleum-derived fossil fuels.     

One-pot synthesis of cyclohexanone oxime from cyclohexanol on a single site multifunctional catalyst: H3PW12O40 incorporated on exfoliated montmorillonite

Exfoliated montmorillonite (ex-MMT) incorporated with H₃PW₁₂O₄₀ (HPW) was prepared by introducing HPW to cetyltrimethylammonium bromide modified MMT. HPW-ex-MMT was characterized by XRD, FT-IR, TGA, N₂ adsorption-desorption, UV–vis DRS, ³¹P MAS NMR, contact angle and SEM. CTAB played a decisive role in the introduction and dispersion of HPW on ex-MMT. HPW-ex-MMT exhibited good catalytic performance in one-pot synthesis of oxime from alcohol with aqueous ammonia and hydrogen peroxide. The high catalytic performance is attributed to highly dispersed HPW over ex-MMT and highly hydrophobic surface of 20% HPW-ex-MMT. The catalyst could be recovered and reused several times without significant deactivation of catalytic performance.     

Syntheses of PAM microgel surfacely covered with alkyl quaternary ammonium surfactant/Keggin‐type polyoxometalate complexes

The composite microspheres of poly(lacrylamide) microgels (PAM) surfacely covered with [2‐(methacryloyloxy)ethyl]dodecyldimethylammonium (MEDDAB)‐tungstophosphate (HPW) complexes (MEDDAB‐HPW) were synthesized by using ion‐exchange reaction between MEDDAB located within the porous PAM microgels and HPW in aqueous solution. The morphology and component of the composite microspheres were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis, respectively. The results indicated that PAM/MEDDAB‐HPW composite microsphere with different hierarchical surface structures could be obtained by controlling the weight ratio of MEDDAB to HPW in the microgels and cross‐linking degree of PAM microgels. Although the surface morphologies of the composite microspheres prepared in different conditions were different, a general feature was that the composite microspheres have the core‐shell structure and the wrinkly surface covered with the particles of MEDDAB‐HPW complexes. The formation of the wrinkly surface is attributed to the difference in shrinkage between inside and outside of PAM microgel frameworks due to deposition of MEDDAB‐HPW on the surface, and the formation of MEDDAB‐HPW small particles originates from the reaction between MEDDAB aggregation and HPW. For this composite microsphere, PAM hydrogel core is suitable to store water‐soluble substances, and the shell composed of the surfactant/Keggin‐type polyoxometalate complexes is not only amphiphilic but also catalytic. Additionally, PAM/MEDDAB‐HPW composite microspheres with big size and MEDDAB‐HPW particles with small size make the composite microspheres not only easy for separation but also beneficial for catalysis. This material provides an example to construct microreactors with new structure used in diphase catalytic reaction. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Hierarchical ordered meso/macroporous H<Subscript>3</Subscript>PW<Subscript>12</Subscript>O<Subscript>40</Subscript>/SiO<Subscript>2</Subscript> catalysts with superior oxidative desulfurization activity

A series of phosphotungstic acid (HPW)/SiO₂ materials with hierarchical meso/macroporous structure were synthesized by evaporation-induced self-assembly method (EISA), using nonionic surfactant (P123) and polystyrene (PS) spheres as templates. SEM images displayed uniform macropores with an average pore size of 210 nm. TEM, small-angle XRD and N₂ adsorption–desorption isotherms confirmed the existence of the ordered mesoporous structures, embedded in the wall of macropores. The wild-angle XRD and FT-IR spectra proved Keggin-type HPW dispersed homogeneously in the silica framework. With the amount of added PS spheres, the density of the macropores increased, the hierarchically ordered porous HPW/SiO₂ possessed two-dimensional (2D) hexagonal (p6mm) mesostructures and uniform periodic macropores. The ODS catalytic activity of these samples were tested, the result showed that the meso/macroporous HPW/SiO₂ catalyst with proper PS beads usage displayed much higher catalytic activity than other catalysts. In addition, the reusability of the meso/macroporous HPW/SiO₂ catalyst was investigated, the activity of catalyst has not obviously decreased even after eight times.     

Synthesis of highly dispersed phosphotungstic acid encapsulated in MIL-100(Fe) catalyst and its performance in heterogeneous oxidative desulfurization

Highly efficient HPW(x)/MIL-100(Fe) catalysts with different phosphotungstic acid (HPW) loading (x, wt%) were successfully synthesized by a one-step hydrothermal method and characterized by XRD, SEM, FTIR, and BET. The influences of HPW loading, catalyst dosage, temperature, and O/S molar ratio on oxidative desulfurization (ODS) were investigated. The results indicated that the HPW(x)/MIL-100(Fe) retained the structure of its parent MIL-100(Fe). The MIL-100(Fe) presented a high surface area, which is beneficial to dispersion of HPW. The HPW(x)/MIL-100(Fe) with HPW loading of 40% exhibited excellent ODS activity. At a temperature of 50?°C, a catalyst dosage of 0.06?g, and an O/S molar ratio of 4, 100% desulfurization was achieved within 90?min for benzothiophene, dibenzothiophene, and 4,6-dimethyl-dibenzothiophene. The high catalytic activity of HPW(x)/MIL-100(Fe) can be attributed to highly dispersed HPW active sites with a high specific surface area.     

The Effect of Proton Hydration in Wells-Dawson and Keggin Type Heteropolyacids on their Catalytic Activity in Gas Phase ETBE Synthesis

The influence of proton hydration in Wells-Dawson H₆P₂W₁₈O₆₂ (HP2W) and Keggin H₃PW₁₂O₄₀ (HPW) type heteropolyacids on their catalytic activity in ethyl-tert-butyl ether (ETBE) synthesis in gas phase was investigated. In the case of samples with the content of crystallisation water per one proton below 0.8 ([H₂O]/[H⁺] < 0.8), the catalytic activity related to the mass unit of the HP2W was higher than that of the HPW in accordance with the order of proton concentration in mass unit. On the other hand, the activity related to one mole of protons indicated higher activity in the HPW than in the HP2W in accordance with the order of acid strength. In the series of samples with [H₂O]/[H⁺] > 0.8 the activity was much higher for the HP2W than the HPW and maximum of both catalytic activity and ethanol sorption capacity was observed for the HP2W. The possible role of the secondary structure of the hydrates was discussed.     

介孔分子筛Ti-HMS的合成及其催化性能

采用直接合成、嫁接、浸渍不同方法合成了介孔分子筛Ti-HMS样品.用X射线粉末衍射(XRD)、傅里叶变换红外光谱(FT IR)、低温N<,2>吸附-脱附、固体紫外-可见漫反射(UV-DRS)等手段对样品进行了表征,并在温和条件下考察了样品对过氧化氢液相氧化环己烯的催化性能.结果表明,Ti-HMS都很好的保持了母体HMS...     

One-pot hydrothermal preparation of SBA-15 supported Keggin-type 12-tungstophosphoric heteropolyacid mesoporous material and its bifunctional catalytic performance

In this work, a series of 12-tungstophosphoric acid (HPW) catalysts supported on mesoporous molecular sieves SBA-15 were prepared by a one-pot hydrothermal method and their physical and chemical properties were characterized by various techniques such as fourier transform infrared spectroscopy, powder X-ray diffraction, nitrogen adsorption–desorption and transmission electron microscopy. It has been found that all the catalysts retained the mesopore structure of SBA-15 and the primary Keggin-type structure of heteropoly acid. The surface areas and pore volumes of HPW-SBA-15 decreased with the increase of HPW heteropoly acid loadings. HPW units were mostly encapsulated inside the mesopores of SBA-15. The prepared catalysts showed excellent multifunctional catalytic properties. Their bifunctional catalytic performances were examined by photo-catalytic degradation of rhodamine-B dye and microwave-catalytic synthesis of isoamyl acetate. The sample with 20 wt% loading of 12-tungstophosphoric acid was found to be more active than the other catalysts under the photo and microwave-catalytic reaction conditions. Accordingly, reasons for the catalytic activity difference were simply explicated by the effect of HPW concentration on the physicochemical characteristic of HPW-SBA-15 catalysts such as surface areas, porosity, and mesostructure.     

Preparation,characterization and catalytic performance of HPW-TUD-1 catalyst on oxidative desulfurization

By incorporating H₃PW₁₂O₄₀ (HPW) heteropolyacid into mesoporous TUD-1 materials, a series of HPW-TUD-1 catalysts were synthesized. Nitrogen adsorption–desorption isotherm, XRD and FTIR characterizations showed that these catalyst exhibited mesoporous structure, and HPW presented in the catalysts with Keggin structure. The catalytic performances of the HPW-TUD-1 catalysts were tested through the oxidative desulfurization (ODS) process of dibenzothiophene (DBT) model oil. The results showed that the obtained 20HPW-TUD-1 catalyst displayed excellent catalytic activity and recover ability for ODS. The desulfurization rate of DBT reached up to 98.1%, and almost no catalytic activity loss was observed after three recycles of the catalyst.     

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。     

SAPO分子筛上氯甲烷催化转化制氯乙烯单体

采用水热合成法制备了SAPO分子筛,考察磷与铝物质的量比对SAPO分子筛催化转化氯甲烷制氯乙烯单体反应催化性能的影响.结果表明,SAPO-34在氯甲烷催化转化制备氯乙烯单体反应中,表现出较好的催化性能及稳定性.     

H3PW12O40 immobilized on silylated palygorskite and catalytic activity in esterification reactions

The surface of acid-activated palygorskite (Pa) was modified by grafting 3-aminopropyltriethoxysilane (APTES) (the silylated Pa denoted Pa_APTES) for immobilization of phosphotungstic acid (H₃PW₁₂O₄₀, HPW). The samples were characterized by Fourier transform infrared spectroscopy (FTIR), N₂ adsorption–desorption, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS). The catalytic activity was tested for the esterification of n-butanol with acetic acid. Both HPW/Pa_APTES and HPW/Pa showed high and specific catalytic activity on the first use. Repeated use, decreased the catalytic activity of HPW/Pa_APTES slowly, that of HPW/Pa strongly. Due to its unique properties, low cost and ready availability, HPW/Pa_APTES provides a satisfactory option for catalyzing esterification reactions.     

Nb-SBA-15催化合成2,4-二叔丁基苯酚

以介孔分子筛SBA-15为载体,采用浸渍法合成了Nb-SBA-15催化剂。通过XRD、BET和TG/DTA测试手段对样品进行了分析。以甲基叔丁基醚和苯酚为原料,研究了Nb-SBA-15在合成2,4-二叔丁基苯酚的反应中的催化活性,考察了反应条件对反应结果的影响。试验结果表明,Nb-SBA-15具有较好的催化活性和稳定性。适宜的烷基化反应条件为:Nb的负载量为15%(质量分数,以Nb2O5计),反应温度为160℃,甲基叔丁基醚(MTBE)与苯酚的摩尔比为2.0,反应时间为4.0h,催化剂用量为原料质量的4.55%。     

One-pot generation of mesoporous carbon supported nanocrystalline H3PW12O40 heteropoly acid with high performance in microwave esterification of acetic acid and isoamyl alcohol

Ordered mesoporous carbon-supported H₃PW₁₂O₄₀ heteropoly acid materials (HPW/OMCs) have been rationally synthesized for the first time. The method is based on the evaporation-induced triconstituent co-assembly effect using the sol–gel process, wherein soluble resol polymer is used as an organic precursor, and triblock copolymer F127 is used as a template. The ordered mesoporous carbon-supported H₃PW₁₂O₄₀ heteropoly acid materials were analyzed and characterized by X-ray diffraction, N₂ adsorption and desorption (BET), and transmission electron microscope. The mesoporous carbon-supported H₃PW₁₂O₄₀ materials possess an ordered mesostructure, narrow pore size distributions (around 2.8–3.6 nm), high pore volumes (up to 0.49 cm³ g^?1), high specific BET surface areas (up to 590 m² g^?1), tailorable HPW content (up to 30 wt%), and well dispersion of HPW particles. Moreover, the resultant mesoporous ordered mesoporous carbon-supported H₃PW₁₂O₄₀ materials exhibit high catalytic activity in microwave esterification of acetic acid and isoamyl alcohol. The obtained 20 % HPW/OMC catalyst exhibits high catalytic performance with 96.7 % of isoamyl acetate yield at temperature of 120 °C, alcohol/acid molar ratio of 2, catalyst amount of 0.2 g, microwave irradiation power of 800 W, and reaction time of 18 min. It was believed that the concentration of H₃PW₁₂O₄₀ have a crucial effect on the HPW/OMCs’ porosity, mesostructure and catalytic performance.     

Synthesis,characterization and desulfurization performance of MCM-41 functionalized with Cu by direct synthesis and organosilanes by grafting

Cu-incorporated MCM-41 was prepared by the direct synthesis method. The Cu-incorporated MCM-41 was then organically functionalized by grafting of organosilanes followed by the complexation of copper ions. The results of powder X-ray diffraction, Fourier transform infrared, and temperature-programmed reduction suggest the incorporation of Cu into the framework of MCM-41 during the direct synthesis process. The mesostructure of prepared samples is preserved after functionalization. The sulfur capacities for tert-butyl mercaptan, dimethyl sulfide, and dimethyl disulfide decrease in the same order (40)Cu–M > (40)Cu–M–N–Cu. The (40)Cu–M synthesized through the direct synthesis method also shows better desulfurization performance than M–Cu prepared by the incipient wetness impregnation method. This is attributed to the incorporated Cu species in the framework and well-dispersed CuO species of (40)Cu–M.     

HPW/Al2O3催化剂的制备、表征及催化四氢呋喃聚合的研究

采用溶胶-凝胶法结合超临界流体干燥技术制备了Al2O3气凝胶载体,以浸渍法制得Al2O3气凝胶负载磷钨酸固体酸催化剂(HPW/Al2O3)。利用N2吸附-脱附、X射线粉末衍射(XRD)、NH3程序升温脱附(NH3-TPD)、傅立叶变换红外光谱(FTIR)、吡啶吸附红外光谱(Py-IR)等手段对HPW/Al2O3催化剂的织构、结构、表面性质等进行了表征,并考察了该催化剂在四氢呋喃聚合反应中的催化性能。结果表明,HPW/Al2O3催化剂负载量在50%~70%能较好地保留HPW的Keggin结构,具有强的Br nsted酸性特征,催化剂的酸量与酸强度随HPW负载量的提高呈递增趋势,而聚合物的收率及相对分子质量(以下简称分子量)与催化剂的酸量间存在线性关系,酸量越大,收率越高,分子量越低。