Metathesis of 1-butene and 2-butene to propene over Re2O7 supported on macro-mesoporous γ-alumina prepared via a dual template method

Macro-mesoporous γ-alumina support(MMA) was prepared by a sol-gel route in aqueous medium using pseudo-boehmite as aluminum source and polystyrene microspheres and Pluronic P123 as hard and soft dual templates,respectively.MMA had a BET specific surface area of about 259 m2 g-1,total pore volume of about 1.61 cm3 g-1,macropore diameter of about 102 nm,and mesopore diameter of about 14 nm.Re2O7/MMA and conventional Re2O7/Al2O3 were prepared by a incipient-wetness impregnation method,and their catalytic performances in the metathesis of 1-butene and 2-butene were tested in a fixed-bed tubular reactor.The result showed that Re2O7/MMA possessed higher activity and far longer working life-span than conventional Re2O7/Al2O3.     

Preparation of mesoporous alumina with large pore size and their supported rhenium oxide catalysts in metathesis of 1-butene and 2-butene to propene

Mesoporous γ-aluminas with large pore size(up to 19 nm,denoted as MA19) are prepared from dispersed pseudo-boehmite using pluronic P123 as template.It is found that these mesoporous alumina supported rhenium oxide catalysts were more active and have far longer working life-span in gas-phase metathesis of 1-butene and 2-butene to propene than rhenium oxide on conventional alumina with small pore size(5 nm).At 60°C and atmospheric pressure with WHSV = 1 h-1,the similar stable conversions of butene(ca.55%) for all the 13 wt% Re 2 O 7 /alumina catalysts were obtained near the chemical equilibrium,and the stable working life-spans of Re 2 O 7 /MA19 were far longer than that of Re 2 O 7 /Al 2 O 3,being about 70 h and 20 h,respectively.     

乙烷氧化脱氢用Ni/Al2O3催化剂中活性镍物种前驱体（英文）

Ni/Al2O3 catalysts for oxidative dehydrogenation(ODH) of ethane were prepared by impregnation of Al2O3 with nickel acetate or nickel nitrate,and by mechanical mixing of NiO and Al2O3.The Ni-based catalysts were characterized by N2 adsorption-desorption,X-ray diffraction,diffuse reflectance UV-visible diffuse reflectance spectroscopy,and temperature-programmed reduction of hydrogen.The results showed that formation of crystalline NiO particles with a size of < 8 nm and/or non-stoichiometric NiO species in the Ni/Al2O3 catalysts led to more active species in ODH of ethane under the investigated reaction conditions.In contrast,tetrahedral Ni species present in the catalysts led to higher selectivity for ethene.Formation of large crystalline NiO particles(22-32 nm) over Ni/Al2O3 catalysts decreased the selectivity for ethene.     

Methanation of syngas over coral reef-like Ni/Al_2O_3 catalysts

Coral reef-like Ni/Al2O3 catalysts were prepared by co-precipitation of nickel acetate and aluminium nitrate with sodium carbonate aqueous solution in the medium of ethylene glycolye.Methanation of syngas was carried out over coral reef-like Ni/Al2O3 catalysts in a continuous flow type fixed-bed reactor.The structure and properties of the fresh and used catalysts were studied by SEM,N2 adsorption-desorption,XRD,H2-TPR,O2-TPO,TG and ICP-AES techniques.The results showed that the coral reef-like Ni/Al2O3 catalysts exhibited better activity than the conventional Ni/Al2O3-H2O catalysts.The activities of coral reef-like catalysts were in the order of Ni/Al2O3-673>Ni/Al2O3-573>Ni/Al2O3- 473>Ni/Al2O3-773.Ni/Al2O3-673-EG catalyst showed not only good activity and improved stability but also superior resistance to carbon deposition,sintering,and Ni loss.Under the reaction conditions of CO/H2(molar ratio)=1:3,593 K,atmospheric pressure and a GHSV of 2500 h-1,CH4 selectivity was 84.7%,and the CO conversion reached 98.2%.     

Preparation and properties of magnetic alumina microspheres with a γ-Fe_2O_3/SiO_2 core and Al_2O_3 shell

Magnetic alumina composite microspheres with γ-Fe 2 O 3 core/Al 2 O 3 shell structure were prepared by the oil column method. A dense silica layer was deposited on the surface of γ-Fe 2 O 3 particles (denoted as γ-Fe 2 O 3 /SiO 2 ) with a desired thickness to protect the iron oxide core against acidic or high temperature conditions. γ-Fe 2 O 3 /SiO 2 /Al 2 O 3 particles with about 85 wt% Al 2 O 3 were obtained and showed to be suitable for practical applications as a magnetic catalyst or catalyst support due to their magnetic properties and pore structure. The products were characterized with scanning electron microscope (SEM) and transmission electron microscope (TEM), nitrogen adsorption-desorption, and vibrating sample magnetometer (VSM). The specific surface area and pore volume of the γ-Fe 2 O 3 /SiO 2 /Al 2 O 3 composite microspheres calcined at 500 ? C were 200 m 2 /g and 0.77 cm 3 /g, respectively.     

Preparation and properties of thermoexpandable polymeric microspheres

In this paper,thermoexpandable polymeric microspheres were prepared by suspension polymerization with acrylonitrile(AN) and methyl methacrylate(MMA) as monomers and i-butane as a blowing agent.The micromorphology and thermal stability were researched by polarized microscopy and TGA.The diameter of the expandable microspheres increased from about 20 mm(unexpanded) to 40–80 mm(expanded) upon heating.The maximum expansion volume was higher than 22 times of the original volume and the density of the expanded microspheres was about 16.7 kg/m3.The blowing agent content in microspheres was about 20 wt% and To.e.,Tm.e.and To.s.were 80 8C,120–130 8C and 140–145 8C,respectively.     

Preparation and characterization of ultrafine Fe-Cu-based catalysts for CO hydrogenation

The ultrafine particles of a new style Fe-Cu-based catalysts for CO hydrogenation were prepared by impregnating the organic sol of Fe（OH）3 and Cu（OH）2 onto the activated Al2O3, in which the organic sol of Fe（OH）3 and Cu（OH）2 were prepared in the microemulsion of dodecylbenzenesulfonic acid sodium（S）/n-butanol（A）/toluene（O）/water with V（A）/V（O） = 0.25 and W（A）/W（S） = 1.50. This catalyst was characterized by particle size analysis, XRD and TG. The results of particle size analysis showed that Fe（OH）3 particles with a mean size of 17.1 nm and Cu（OH）2 particles with an average size of 6.65 um were obtained. TG analysis and XRD patterns suggested that 673 K is the optimal calcination temperature. CO hydrogenation produced C＋OH with a high selectivity above 58 wt% by using the ultrafine particles as catalyst, and the total alcohol yield of 0.250 g·ml^-1 ·h^-1 was obtained when the contents of Al2O3 and K were 88.61 wt% and 1.60 wt%, respectively.     

Production of propylene from an unconventional metathesis of ethylene and 2-pentene over Re2O7/SiO2-Al2O3 catalysts

An unconventional metathesis of ethylene and 2-pentene over Re2O7/SiO2-Al2O3 catalysts has been studied as an alternative route for the production of propylene. Complete conversion of 2-pentene and propylene yield as high as 88 wt% were obtained under mild reaction conditions at 35°C and atmospheric pressure. Unlike the conventional metathesis of ethylene and 2-butenes in which isomerization is a competing side reaction, the isomerization of 1-butene product from the unconventional metathesis of ethylene and 2-pentene to 2-butenes can further react with excess ethylene in the feed, resulting in additional increase in propylene yield. The secondary metathesis reaction was found to be favored under ethylene/2-pentene (E/2P) molar ratio 3 and gas hourly space velocity (GHSV) 1000 h-1 at the reaction temperature of 35°C. No catalyst deactivation was observed during the 455 min time-on-stream under the selected reaction conditions.     

Role of support nature （γ-Al2O3 and SiO2-Al2O3） on the performances of rhenium oxide catalysts in the metathesis of ethylene and 2-pentene

The metathesis of ethylene and 2-pentene was studied as an alternative route for propylene production over Re2O7/γ-Al2O3 and Re2O7/SiO2-Al2O3 catalysts. Both NH3 temperature-programmed desorption (NH3-TPD) and H2 temperature-programmed reduction (H2-TPR) results showed that Re2O7/SiO2-Al2O3 exhibited stronger acidity and weaker metal-support interaction than Re2O7/γ-Al2O3. At 35 60℃, isomerization free metathesis was observed only over Re2O7/γ-Al2O3, suggesting that the formation of metal-carbene metathesis active sites required only weak acidity. Our results suggest that on the Re2O7/SiO2-Al2O3, hydrido-rhenium species ([Re]-H) were formed in addition to the metathesis active sites, resulting in the isomerization of the initial 1-butene product into 2-butenes. A subsequent secondary metathesis reaction between these 2-butenes and the excess ethylene could explain the enhanced yields of propylene observed. The results demonstrate the potential for high yield of propylene from alternative feedstocks.     

Ni/Al2O3 catalysts for CO methanation: Effect of Al2O3 supports calcined at different temperatures

The correlation between phase structures and surface acidity of Al2O3 supports calcined at different temperatures and the catalytic performance of Ni/Al2O3 catalysts in the production of synthetic natural gas(SNG) via CO methanation was systematically investigated. A series of 10 wt% NiO/Al2O3 catalysts were prepared by the conventional impregnation method, and the phase structures and surface acidity of Al2O3 supports were adjusted by calcining the commercial γ-Al2O3 at different temperatures(600–1200 C). CO methanation reaction was carried out in the temperature range of 300–600 C at different weight hourly space velocities(WHSV = 30000 and 120000 mL·g-1h-1) and pressures(0.1 and 3.0 MPa). It was found that high calcination temperature not only led to the growth in Ni particle size, but also weakened the interaction between Ni nanoparticles and Al2O3 supports due to the rapid decrease of the specific surface area and acidity of Al2O3 supports. Interestingly, Ni catalysts supported on Al2O3 calcined at 1200 C(Ni/Al2O3-1200) exhibited the best catalytic activity for CO methanation under different reaction conditions. Lifetime reaction tests also indicated that Ni/Al2O3-1200 was the most active and stable catalyst compared with the other three catalysts, whose supports were calcined at lower temperatures(600, 800 and 1000 C). These findings would therefore be helpful to develop Ni/Al2O3 methanation catalyst for SNG production.     

CH_4 reforming with CO_2 for syngas production over La_2O_3 promoted Ni catalysts supported on mesoporous nanostructured γ-Al_2O_3

Nanostructured γ-Al2O3 with high surface area and mesoporous structure was synthesized by sol-gel method and employed as catalyst support for nickel catalysts in methane reforming with carbon dioxide. The prepared samples were characterized by XRD, N2adsorption-desorption,TPR, TPO, TPH, NH3-TPD and SEM techniques. The BET analysis showed a high surface area of 204 m2 g-1and a narrow pore-size distribution centered at a diameter of 5.5 nm for catalyst support. The BET results revealed that addition of lanthanum oxide to aluminum oxide decreased the specific surface area. In addition, TPR results showed that addition of lanthanum oxide increased the reducibility of nickel catalyst. The catalytic evaluation results showed an increase in methane conversion with increasing lanthanum oxide to 3 mol% and further increase in lanthanum content decreased the catalytic activity. TPO analysis revealed that the coke deposition decreased with increasing lanthanum oxide to 3 mol%. SEM and TPH analyses confirmed the formation of whisker type carbon over the spent catalysts. Addition of steam and O2 to dry reforming feed increased the methane conversion and led to carbon free operation in combined processes.     

A Novel Synthesis of Alkaline Earth Silicate Phosphor Sr3MgSi2O8： Eu^2＋, Dy^3＋

A novel method for synthesizing long afterglow silicate phosphor Sr3MgSi2O8：Eu^2＋,Dy^3＋using TEOS and inorganic powders as reactants was reported. Acetic acid as a catalyzer controlled the hydrolysis of TEOS by adjusting pH value of the system. The morphologies of precursor were characterized by transmission electron microscope （TEM）. The structure and optical properties of the phosphor powders were systematically investigated by means of X-ray diffraction and spectrofluorometry. TEM images have reflected the core-shell structure and quasi-spherical morphology of the precursor particles. It was found that the single-phase Sr3MgSi2O8 crystalline structures were obtained at 1050 and 1250 ℃ for the samples prepared with the nano-coating method and the solid state reaction, respectively. The emission intensities of the phosphors prepared by the present method were higher than those by the conventional process. Also, the afterglow characteristic was better than that prepared by solid-state reaction in the comparable condition.     

Bowl-shaped poly(3,4-ethylenedioxythiophene)/γ-Fe2O3 composites with elecromagnetic function

In this paper, electromagnetic poly(3,4-ethylenedioxythiophene)/γ-Fe2O3 (PEDOT/γ-Fe2O3 ) micro-bowls, 1 2 μm in diameter, were prepared by a simple environment-friendly process. In this method, the aqueous solution of cetyltrimethylammonium bromide (CTAB) instead of any organic solvent was used. FeCl3 acted as a source of Fe Ⅲ for the formation of γ-Fe2O3 and as an oxidant for the polymerization of 3,4-ethylenedioxythiophene (EDOT). The bowl-shaped morphology of PEDOT/γ-Fe2O3 composites was strongly influenced by the concentration of CTAB, FeCl2 , ammonia solution and the reaction temperature. The saturation magnetization of PEDOT/γ-Fe2O3 micro-bowls increased with the increase of FeCl2 concentration and reached 6.20 Am2 /kg at the FeCl2 concentration of 0.30 mol/L. The conductivity of the PEDOT/γ-Fe2O3 composites was in the range of 101 S/cm. The electrical and magnetic sources of PEDOT/γ-Fe2O3 micro-bowls were confirmed by SEM-EDX, TEM, XRD and XPS spectra. And the possible formation mechanism of PEDOT//γ-Fe2O3 was proposed.     

溶胶-凝胶法制备金属铂高分散的二氧化钛薄膜

Uniform and crack free TiO 2 thin films with highly dispersed platinum were prepared from i PrOH TTIP DEA H 2O system containing H 2PtCl 6·6H 2O as metal source by sol gel method. The microstructure and morphology of the films were characterized by TEM and XRD respectively. It was found that the Pt particles dispersed in the films and had a homogeneous distribution in the shape of sphere with an average size of about 5 nm. This study also showed that the doping with few percent of Pt resulted in the formation of pure rutile phase at a temperature as low as 550 ℃, whereas the same pure phase was formed at the temperature higher than 650 ℃ in TiO 2 or Au/TiO 2 thin films.     

In situ carbon nanotube synthesis by the reduction of NiO/γ-Al_2O_3 catalyst in methane

The synthesis of carbon nanotubes (CNTs) via chemical vapour deposition of methane on NiO/γ-Al2O3 catalyst has been investigated.The reduction behavior of NiO/γ-Al2O3 by methane was studied using thermogravimetric (TG) and X-ray diffraction (XRD) techniques.It was found that the NiO supported on γ-Al2O3,was reduced to Ni0 in methane atmosphere in the temperature range of 710-770℃.The catalytic activity of NiO/γ-Al2O3 for CNTs synthesis by in situ chemical vapour deposition of methane during the reduction was also investigated.Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to observe the CNTs produced at various reduction temperatures.The results indicated that the reduction temperature exhibits obvious influence on the morphology and the yield of CNTs.CNTs with the diameter of about 20 nm were obtained at reduction temperature of 750℃,and higher reduction temperature (such as 800 and 850℃) led to an increase in CNTs diameter and a decrease in CNTs yield.     

Isobutane dehydrogenation over chromia alumina catalysts prepared from MIL-101: Insight into chromium species on activity and selectivity

Various mesoporous chromia alumina catalysts were prepared by five different methods based on a metal-organic framework MIL-101 and their catalytic performances over isobutane dehydrogenation were investigated. The highly dispersed chromium species were produced on catalyst KCr Al-I1 with largest specific surface area of 198 m2 g-1prepared with aluminium isopropoxide(Al(i-OC3H7)3) by ultrasonic impregnation method. However, the catalyst KCr Al-I2 synthesized by stirring impregnation possessed crystalline α-Cr2O3 phase, which was poorly dispersed. Two types of Cr-rich and Al-rich Crx Al2-xO3 solid solutions, designated as Cr Al-I and Cr Al-II phase, were formed over the catalysts KCr Al-I3(prepared by Al(i-OC3H7)3with nitric acid regulation), KCr Al-C4(prepared by aluminium chloride hexahydrate) and KCr Al-N5(prepared by aluminium nitrate nonahydrate). Catalytic evaluation results revealed that KCr Al-I1 exhibited the high isobutane conversion due to its highly dispersed chromium species. However, KCr Al-I3, KCr Al-C4 and KCr Al-N5 showed the higher isobutene selectivity(95.2%-96.4%) on account of the formation of chromia alumina solid solutions in the catalysts. Moreover, the solid solution over the chromia alumina catalysts could greatly suppress the coke formation.     

改性磁性壳聚糖微球对Cu2+、Cd2+和Ni2+的吸附性能

Fe3O4/ chitosan magnetic microspheres of 50 to 80 滋m were prepared using the inverse phase emulsion dispersion and chemical crosslinking technology, and then modified with ethylenediamine for use in the adsorption of heavy metal ions. The adsorption properties of the modified Fe3O4/chitosan toward Cu2+, Cd2+ and Ni2+ were investigated. It was found that the adsorption capacities of Cu2+ and Ni2+ increased with pH, and a maximum adsorption for Cd2+ occurred at pH=3. The saturated adsorption capacities calculated by Langmuir isotherms were 54.3 mg·g-1 for Cu2+, 20.4 mg·g-1 for Cd2+, and 12.4 mg·g-1 for Ni2+, respectively. The adsorption kinetics were well described by pseudo-second-order equation models. The experimental results showed that the Fe3O4/chitosan modified with ethylenediamine presented higher adsorption selectivity for Cu2+ than for Cd2+ and Ni2+ in all studied pH ranges.     

Effects of preparation conditions of Au/FeOx/Al203 catalysts prepared by a modified two-step method on the stability for CO oxidation

Composite oxide FeO x /Al 2 O 3 -supported gold catalysts were prepared by a modified two-step method. The effects of preparation conditions on the initial catalytic activity and long-time stability were studied for CO oxidation. XRD, XPS and in situ FTIR were employed to investigate the state of FeO x and the species on the catalyst surface. The results showed that Au/FeO x /Al 2 O 3 catalysts prepared by this method exhibited high activity and high stability in a wide pH value range. Calcination pretreatment was proved to be beneficial to improving the activity and stability. The beneficial effects of FeO x acting as a structural promoter could be ascribed to the ability to supply active oxygen species. As the precursor of FeO x , Fe(NO 3 ) 3 is superior to FeCl 3 for obtaining higher stability.     

PREPARATION AND CHARACTERIZATION OF DOXORUBICIN-LOADED MAGNETIC ANTICANCER NANOPARTICLES

Doxorubicin（ADM）-loaded magnetic anticancer nanoparticles, using Fe3O4 as core, doxorubicin as model drug and polyvinylpyrrolidone （PVP） as matrix, were prepared by inverse emulsion polymerization. The experimental results showed that the average diameter of Fe3O4 particles was 19.8nm. The X-ray diffraction itzdicated that the prepared Fe3O4 particle was pure cubic Fe3O4, The results obtained by SEM showed the magnetic nanoparticles under optimal operating condition had a smooth spherical surface, LLS showed an average size of 78. 7nm. And IR results demonstrated that they consisted of ADM, PVP and Fe3O4.     

Magnetically recyclable Pd/γ-AlOOH@Fe_3O_4 catalysts and their catalytic performance for the Heck coupling reaction

Novel magnetically recyclable Pd/γ-AlOOH@Fe3O4 catalysts were prepared using γ-AlOOH@Fe3O4 as a magnetic supporter and nano-Pd particles as the active catalytic component.The structure of the catalysts was characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),N2 adsorption-desorption,and a vibration sample magnetometer(VSM).The catalytic activity and recyclability for the Heck coupling reaction were investigated.Results showed that the magnetic γ-AlOOH@Fe3O4 possessed a core-shell structure,as well as that the nano-Pd particles were 6–8 nm and had been well dispersed in the γ-AlOOH shell.In the Heck coupling reactions,the magnetic Pd/γ-AlOOH@Fe3O4 catalysts exhibited good catalytic activity and recyclability.For the(0.021 mol%)Pd/γ-AlOOH@Fe3O4 catalyst,the bromobenzene conversion and product yield reached about 100%and 96.3%,respectively,under a 120°C reaction temperature and 12 h reaction time.After being recycled 8 times,the conversion of bromobenzene and the recovery of the catalyst were about 90%and 93%,respectively.The nano-Pd particles were kept well dispersed in the used Pd/γ-AlOOH@Fe3O4 catalyst.