乙苯氧化脱氢反应Fex/TiO2的催化性能研究

新型氧化钛负载铁催化剂Fex/TiO2在低温乙苯空气氧化脱氢制苯乙烯反应中具有良好的催化活性。350 ℃,使用Fe7/TiO2催化剂,当Fe的质量分数为7%时,可获得14.6%乙苯单程转化率和99.0%的苯乙烯选择性。通过X衍射、表面吸附、热分析及扫描电镜仪器分析表征,考察氧化钛负载铁催化剂在乙苯低温氧化脱氢反应中的催化作用。350 ℃乙苯可被活化,催化剂活性的高低取决于活性物种Fe(III)的分布状态和质量分数。     

Copolymerization of carbon dioxide and propylene oxide under inorganic oxide supported rare earth ternary catalyst

Recently, rare earth ternary coordination catalyst represented as Y(CCl₃OO)₃‐Glycerin‐ZnEt₂ has been used for producing poly(propylene carbonate) (PPC, an alternating copolymer of carbon dioxide and propylene oxide) in industry scale, but its catalytic activity needs further improvement. One reason for the relatively low catalytic activity lied in that only 11.7% of active center was efficient due to possible embedding of active center in the heterogeneous catalyst. In this report, supporting strategy was developed, where Y(CCl₃OO)₃‐Glycerin‐ZnEt₂ was supported on various inorganic oxides. Two supporting methods were carried out. One way was to mix Y(CCl₃OO)₃‐Glycerin with inorganic oxide first and then ZnEt₂ was dropped to form the supported catalyst, and the other was to make Y(CCl₃OO)₃‐Glycerin‐ZnEt₂ at first and then mixing with inorganic oxides. The former showed decreasing catalytic activity compared with corresponding unsupported rare earth ternary catalyst, while an improvement of 16–36% in catalytic activity was realized in the latter. PPC with an average number molecular weight (M_n) of over 100 kg/mol and carbonate unit (CU) content of higher than 96% was prepared by both supported catalysts. The catalytic activity of the supported catalyst depended significantly on the supports, which increased in the following order: α‐Al₂O₃ < MgO < ZnO ≈ SiO₂ <γ‐Al₂O₃. γ‐Al₂O₃ was the best support for rare earth ternary catalyst, which showed a remarkable 36% increase in catalytic activity, corresponding to the utilization of 17% of active center. Although MgO supported catalyst gave only an 8% increase in catalytic activity, the M_n and CU content of PPC were raised to about 143 kg/mol and 99%, whereas the PPC from common rare earth ternary catalyst was about 108 kg/mol and 97%, respectively. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis and characterization of oligomer from 1-decene catalyzed by supported Ziegler-Natta catalyst

Oligomer of 1-decene was synthesized with Ziegler-Natta catalyst which consisted of TiCl₄ and Et₂AlCl, using MgCl₂ as support. The effects of temperature, Al/Ti ratio, time, and concentration of the catalyst on polymerization behaviors were investigated. The results showed that the catalyst system was desirable for the oligomerization of 1-decene with good catalytic activity, 143.8 kg oligo/mol Ti h, under typical conditions. The oligomer obtained was characterized with GC-MASS, GC and ¹³C NMR methods. Those results indicated that the oligomer was of a mixture consisting of di-, tri-, tetra- and pentamer. The ¹³C NMR data also implied that chain propagation of the oligomer involved primarily head-to-tail 1,2-insertions, as well as head-to-head and tail-to-tail 2,1-insertions.     

用于吖内酯合成的二氧化钛纳米晶体材料PriyankaAnandgaonker,GaneshKulkarni,SureshGaikwad,AnjaliRajbhoj简

Titanium dioxide nanoparticles were prepared by a electrochemical reduction method using parameters such as current density, solvent polarity, distance between electrodes, and concentration of stabilizers to control the size of the nanoparticles. The nanoparticles were characterized by UV-Vis spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy, and their catalytic performance was tested for the synthesis of a series of 4-aryldiene-2-phenyl-5(4)-oxazolones from the cyclodehydration and condensation of the respective aldehyde, hippuric acid and acetic anhydride. Easy availability, reusability and eco-friendliness were some prominent features of the nanocrystalline titanium dioxide catalyst.     

Hierarchical TiO2 microspheres supported ultrasmall palladium Nanocrystals: A highly efficient catalyst for Suzuki reaction

A hierarchical titanium dioxide microspheres-supported palladium catalyst (Pd/TiO₂-350) was prepared and characterized using BET, XRD, XPS, SEM, EDX, and TEM analyses. An ICP-OES analysis of Pd/TiO₂-350 further confirmed the successful Pd immobilization on TiO₂ with a palladium loading of 0.1 mmol g^?1. Pd/TiO₂-350 efficiently catalyzed the Suzuki-Miyaura reaction of aryl iodides with arylboronic acids to give the corresponding biaryl derivatives in good to excellent yields. After the reaction, the catalyst was recovered by centrifugation and reused three times without significant loss of its catalytic activity. Moreover, the loading of palladium species further decreased to 0.001 mol%, and the total turnover number and turnover frequency of the catalyst reached as high as 99 000 and 0.57 s^?1, respectively.     

Efficient cenosphere supported catalyst for the esterification of n-octanol with acetic acid

An efficient heterogeneous acid catalyst was developed using cenospheres, a byproduct of coal-fired thermal power plants by the method of wet impregnation. Catalyst characterization was carried out using various analytical techniques, namely, Fourier transform infrared, X-ray diffraction, field emission gun scanning electron microscopy and Brunauer–Emmett–Teller surface area and surface acidity analysis. The characterization revealed the excellent catalytic activity of the catalyst for the esterification reaction of n-octanol and acetic acid. Various reaction parameters, namely, catalyst loading, a molar ratio of alcohol/acid and reaction temperature were evaluated and optimized by response surface methodology using the Box–Behnken model. The response surface methodology model equations corresponding to the conversion of acid and % yield of ester were developed. The model well predicted the optimal reaction conditions, which were validated experimentally with good agreement. The excellent catalytic performance was observed in the esterification reaction with high conversion of acid (95.34%) and high yield of n-octyl acetate (94.81%). Reusability study of the catalyst showed that the catalyst could be used efficiently up to three reaction cycles. This study explores the use of cenospheres to prepare a solid acid catalyst for the industrially important esterification reactions.     

Unique hydrogenation activity of supported tin catalyst: Selective hydrogenation catalyst for unsaturated aldehydes

Selective hydrogenation of unsaturated aldehydes, crotonaldehyde (CH₃CH=CHCH=O) and cinnamaldehyde (C₆H₅CH=CHCH=O), has been studied over SiO₂-supported monometallic Sn and bimetallic Rh---Sn catalysts in the liquid phase. Over a silica-supported monometallic Rh catalyst, Rh/SiO₂, no unsaturated alcohol (crotyl alcohol or cinnamyl alcohol) was formed, whereas considerable amounts of the corresponding saturated aldehyde and saturated alcohol were obtained. The selectivity to the unsaturated alcohol was improved over the Rh---Sn bimetallic catalyst. The selectivity to the corresponding unsaturated alcohol attained ca. 65% over the Rh---Sn bimetallic catalysts. On the other hand, The supported Sn catalyst showed markedly high selectivity to the unsaturated alcohols. The selectivity of the Sn/SiO₂, attained 95% to crotyl alcohol and 100% to cinnamyl alcohol, respectively. Although the conversion of each unsaturated aldehyde over Rh---Sn/SiO₂ catalysts was greater than that over Sn/SiO₂ catalysts, the selectivity of Sn/SiO₂ catalysts to the corresponding unsaturated alcohols was superior to that over Rh---Sn/SiO₂. The selectivity of Sn/SiO₂ was also compared with that of Rh---Sn/SiO₂ at a similar conversion of the unsaturated aldehydes. The selectivity of Sn/SiO₂ was significantly greater than that of the Rh---Sn bimetallic catalyst. These results indicate that the high selectivity over Sn/SiO₂ was ascribed not to low conversion but to intrinsic selectivity of the Sn catalyst.     

Multi-wall carbon nanotube supported tungsten hexacarbonyl: an efficient and reusable catalyst for epoxidation of alkenes with hydrogen peroxide

Highly efficient epoxidation of alkenes with H₂O₂ catalyzed by tungsten hexacarbonyl supported on multi-wall carbon nanotubes (MWCNTs) modified with 1,2-diaminobenzene is reported. The prepared catalyst, [W(CO)₆@DAB-MWCNT], was characterized by elemental analysis, scanning electron microscopy, FT-IR, and diffuse reflectance UV-Vis spectroscopic methods. The prepared catalyst was applied as an efficient catalyst for green epoxidation of alkenes with hydrogen peroxide in CH₃CN. This heterogeneous metal carbonyl catalyst showed high stability and reusability in epoxidation without loss of its catalytic activity.     

Methanol synthesis from carbon dioxide and hydrogen over Mn-promoted copper/zinc/zirconia catalysts

Mn-promoted copper/zinc/zirconia - catalysts have been investigated. Our investigations confirmed literature informations concerning advantageous influence of zirconium on the catalyst activity. Doping of Mn to Cu/Zn/Zr catalyst additionally increases the rate of methanol production. This revised version was published online in June 2006 with corrections to the Cover Date.     

Methanol dehydrogenation in the liquid phase with Ru/active carbon catalyst

In contrast to the gas-phase reaction, the liquid-phase reaction of methanol with Ru/C catalyst scarcely gave methane. Product distribution strongly depended on reaction conditions even under atmospheric pressure.     

Titania supported copper catalysts for methanol synthesis from carbon dioxide

The effect of co-catalyst (ZnO or ZrO₂) has been tested for hydrogenation of CO₂ on CuO/TiO₂ and CuO/Al₂O₃. CuO−ZnO/TiO₂ catalyst showed the highest activity for methanol synthesis. Kinetic parameters were also determined.     

碳负载钯催化剂对Heck反应的催化性能

研究了钯碳催化剂对芳基卤和取代芳基卤与丙烯酸和苯乙烯的Heck芳基化反应的催化性能.结果表明:在反应温度为80℃、反应时间为8h、四丁基溴化铵(TBABr)作为溶剂和三丁胺作为碱的条件下,钯碳催化剂对不同取代芳基卤与丙烯酸和苯乙烯的Heck芳基化反应具有良好的催化性能,产物收率在80%以上.     

Potassium-decorated active carbon supported Co-Mo-based catalyst for water-gas shift reaction

The effect of potassium-decoration was studied on the activity of water-gas shift (WGS) reaction over the Co-Mo-based catalysts supported on active carbon (AC), which was prepared by incipient wetness co-impregnation method. The decoration of potassium on active carbon in advance enhances the activities of the CoMo-K/AC catalysts for WGS reaction. Highest activity (about 92% conversion) was obtained at 250 ? C for the catalyst with an optimum K 2 O/AC weight ratio in the range from 0.12 to 0.15. The catalysts were characterized by TPR and EPR, and the results show that activated carbon decorated with potassium makes Co-Mo species highly dispersed, and thus easily reduced and sulfurized. XRD results show that an appropriate content of potassium-decoration on active carbon supports may favors the formation of highly dispersed Co 9 S 8 -type structures which are situated on the edge or a site in contact with MoS 2 , K-Mo-O-S, Mo-S-K phase. Those active species are responsible for the high activity of CoMo-K/AC catalysts.     

Effective production of γ-valerolactone from biomass-derived methyl levulinate over CuOx-CaCO3 catalyst

The production of γ-valerolactone (GVL) from lignocellulosic biomass has become a focus of research owing to its potential applications in fuels and chemicals. In this study, (n)CuO_x-CaCO₃ (where n is the molar ratio of Cu to Ca) compounds were prepared for the first time and shown to function as efficient bifunctional catalysts for the conversion of biomass-derived methyl levulinate (ML) into GVL, using methanol as the in-situ hydrogen source. Among the catalysts with varied Cu/Ca molar ratios, (3/2)CuO_x-CaCO₃ provided the highest GVL yield of 95.6% from ML. The incorporation of CaCO₃ with CuO resulted in the formation of Cu⁺ species in a CuO_x-CaCO₃ catalyst, which greatly facilitated the hydrogenation of ML. Notably, CuO_x-CaCO₃ also displayed excellent catalytic performance in the methanolysis products of cellulose, even in the presence of humins. Therefore, a facile two-step strategy for the production of GVL from cellulose could be developed over this robust and inexpensive catalyst, through the integration of cellulose methanolysis catalyzed by sulfuric acid, methanol reforming, and ML hydrogenation in methanol medium.     

Ionic liquid-containing polyethylene supported palladium: a green,highly efficient and stable catalyst for Suzuki reaction

The Suzuki coupling was carried out using a new, efficient and reusable polymer-supported Pd/IL catalyst (PEt@IL/Pd) under aqueous conditions. This catalyst was prepared through coacervation approach followed by treatment with Pd(OAc)₂. The FT-IR, SEM, TGA, TEM, XPS, ICP and EDX techniques were employed to characterize the PEt@IL/Pd. This catalyst exhibited high activity in the Suzuki coupling reaction under green conditions. Moreover, the catalyst could be recycled and reapplied for six times with no appreciable loss in its activity. The leaching test also showed high stability of catalytic Pd species under applied conditions.     

TiO2负载的高分散Cd团簇催化剂高效催化CO2加氢制甲醇

近年来,利用可再生能源分解水制氢进而开展二氧化碳资源化利用的研究引起了学术界和工业界的极大兴趣.科学层面上它暗合了自然光合作用的理念;应用层面上它把二氧化碳变废为宝,既可以得到人类必需的含碳化学品,又可以实现碳中和.甲醇被认为是二氧化碳资源化的最佳选择,可在动力、交通、化工等领域替代煤炭等传统化石能源,也是良好的载氢分...     

Effective hydrodeoxygenation bio-oil via natural zeolite supported transition metal oxide catalyst

Bio-oil from biomass pyrolysis is promising to be used as a sustainable biofuel and high-value-added chemical. However, the presence of high acid, water, and oxygenate causes corrosive properties, low higher heating value (HHV), and instability of the bio-oil component. Therefore, refining the bio-oil is essential to improve its quality. In this study, we introduced natural zeolite (HZ) impregnated with transition metal oxide (TMO) to refine the bio-oil using the hydrodeoxygenation method (HDO) at various catalyst ratios and temperatures. We find that ZnO/HZ 5% wt. shows the best catalytic performance, with the conversion of organic phase reaching ～ 50%. The refined bio-oil from Fe₂O₃, ZnO, and CuO has high-quality physicochemical properties with carbon, oxygen, water level, and HHV values are 37–52%, 40–53%, 8–27%, and 17–21 MJ/kg, respectively. This result represents a high catalytic performance for the hydrodeoxygenation process of bio-oil using natural zeolite-based transition metal oxide for better and low-cost biofuel production.     

TiO2 supported cobalt-manganese nano catalysts for light olefins production from syngas

Cobalt-manganese nano catalysts were prepared by sol-gel method. This research investigated the effects of different cobalt-manganese (Co/Mn = 1/1) loading, pH and calcination conditions on the catalytic performance of Co-Mn/TiO₂ catalysts for Fischer-Tropsch synthesis (FTS) in a fixed bed reactor. It was found that the catalyst containing 30wt%(Co-Mn)/TiO₂ was an optimal catalyst for the conversion of synthesis gas to light olefins especially propylene. The activity and selectivity of optimal catalyst were studied under different operational conditions. The results showed that the best operational conditions were H₂/CO= 1/1 molar feed ratio at 250 °C and GHSV= 1300 h^?1 under atmospheric pressure. Characterization of catalysts was carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N₂ adsorption-desorption measurements.     

Polymer supported chromium porphyrin as catalyst for polycarbonate formation in supercritical carbon dioxide

A new polymer-supported chromium porphyrin has been prepared and fully characterised; its catalytic activity and recyclability were investigated for the ring-opening copolymerisation of 1,2-cyclohexene oxide (CHO) and carbon dioxide (CO2).