The oxidation kinetics and products distribution of methyl phenyl sulfide( Ph SMe),a commonly used simulant of mustard gas( HD),in aqueous H2O2 solution catalyzed by sodium molybdate were investigated. Methyl phenyl sulfoxide( Ph S( O) Me) and methyl phenyl sulfone( Ph S( O)2Me) are two oxidation products of Ph SMe in the catalyzed H2O2 solution. The apparent rate constant of the primary oxidation( Ph SMe→Ph S( O) Me)( kap1)and secondary oxidation( Ph S( O) Me→Ph S( O)2Me)( kap 2) in Na2 Mo O4-H2O2 solution are two orders of magnitude larger than kap1 and kap2in alkali-modified H2O2 solution without any catalyst respectively.95 Mo NMR tests of the Na2 Mo O4-H2O2 solution indicate that Mo Ox( OO)( 4- x)2-would be formed in the solution and Mo( O2)42-seems to be the major reactive intermediate at the mole ratio of H2O2/ Mo O42-= 10 used in the kinetic test. The yield of Ph S( O)2Me on reaction time in H2O2 solution catalyzed by Na2 Mo O4is not significantly inhibited by free radical s cavengers and antioxidants,and a direct oxygen transfer from O-O in Mo( O2)42-to the S atom is supposed to be responsible for the primary and secondary oxidation of sulfides.
The oxidative desulfurization of thiophene( Tp) and methylthiophene( m Tp) over defect TS-1( TS-d)catalyst was investigated using 7T /45 T two-layered ONIOM2 method. The following oxidation mechanism at TS-d was hypothesized: First,H2O2 adsorbed to TS-d,then underwent proton transfer to generate monobidentate titanium hydroperoxo complex. There are two ways to proton transfer,a single proton and double proton transfer. Studies have shown that the isomer of bidentate titanium hydroperoxo complex is more reactive and slightly more stable.Therefore,the reaction was continued with bidentate titanium hydroperoxo complex. Tp and m Tp were oxidized to sulfoxide,and further oxidized to sulfone. The calculated data are consistent with the experimental results.
Titanium dioxide is an excellent photocatalyst,which can be utilized to load pure metal on its surface with photocatalytic reduction deposition process. In this study,pure metallic platinum was loaded on the surface of TiO2particles with UV light irradiation to construct Pt / TiO2catalyst for ammonia oxidation process. The Pt loading of catalyst is decreased to about 0. 2 gPt/ gTiO 2,ant specific surface area is as large as 10 m2/ g. With such catalyst, the ammonia conversion in ammonia oxidation process can reach 100% at 600 ~ 700 ℃,which is lower than the application temperature in present nitric acid industry,800 ~ 900 ℃,and the sublimation temperature of PtO2,850 ℃. Furthermore,there is no platinum loss and reaction active reduction of catalysts for 400 hours' continuous running. Therefore,this Pt / TiO2catalyst has exhibits a valuable application prospect of precious metal in nitric acid industry.
MoVTe catalyst was prepared using co-precipitation method and its catalytic performance for one step o xidation of propylene to acrylic acid was then investigated. XRD,ICP,EDS,H2-TPR and NH3-TPD characterization techniques were applied to confirm the structures and surface properties of catalysts. Results showed that the appropriate amount of Nb doping could improve the selectivity of MoVTe catalyst for acrylic acid significantly, in which the selectivity and yield of acrylic acid were increased from 34. 1% and 24. 7% to 83. 5% and 48. 8% r espectively. This is because the Nb atom could enhance the stability of Te atom on the surface of the catalyst, which played an important role for producing acrylic acid. In addition,on the basis of Nb doping,B doping could increase the amount of active sites of Te4 += O·Te3 +─O·,which could subsequently increase the propylene conversion. Results showed the highest propylene conversion and yield of acrylic acid was 89. 8% and 64. 8%,r espectively.
Various CuO-ZnO/Al2O3 catalysts have been synthesized by citric acid sol-gel auto-combustion method and their performances for methanol synthesis from CO2 hydrogenation have been investigated.The effects of citric acid /nitrate ratio on physicochemical,morphologies and catalytic properties were studied by BET,XRD,SEM,XPS and H2-TPR.Catalytic activities of the prepared catalysts for methanol synthesis were tested in fixed-bed flow reactor.The results indicated that when 100% of stoichiometric amount of citric acid was used,the CuO-ZnO/Al2O3 catalyst exhibited an optimum catalytic behavior.The catalyst showed relatively smaller particle size,higher surface area and more uniform Cu dispersion.
SiO2-Al2O3 with 30% Al2O3 content has been synthesized via sol-gel procedures.The evolution of their surface properties during the heat treatment process from 500~900 ℃ has been characterized by Thermal gravity-Differential thermal analysis(TG-DTA),N2 adsorption,X-ray diffraction(XRD),Fourier transform infrared(FTIR) spectroscopy,FTIR spectroscopy of adsorbed Pyridine(Py-IR),and temperature programmed desorption of NH3(NH3-TPD).The catalytic performances were examined for the polymerization of tetrahydrofuran(THF).The experimental results indicated that high specific surface area,numerous Si—O—Al bonds and abundant acid sites were obtained at 500 ℃.As the temperature of heat treatment increased to 700 ℃,the textural parameters of SiO2-Al2O3 did not exhibit obvious change,while the amount of Si—O—Al bonds,total acid sites and acid density decreased.The strong acid sites became absent at this temperature.At 900 ℃,the specific surface area and pore volume decreased sharply and the pore size increased significantly.The amount of Si—O—Al bonds,total acid sites and acid density further decreased.The evaluation results showed that the yield and molecular weight(Mn) of the polytetrahydrofuran(PTHF) increased as the temperature increased.At 900 ℃,SiO2-Al2O3 displayed the highest acidity(47%) and the largest Mn(1710).
By means of XRD,BET,IR,EM,NH3-TPD techniques,the effect of Zr(OH)4 crystallization on the crystal structure,acidity and the isomerization performance of Ni-WO3/ZrO2 was studied.The results showed that the crystallization of Zr(OH)4 reduced the fraction of tetragonal zirconia.Strong acid sites on the catalyst and the isomerization activity waked with the crystallization of Zr(OH)4.
Acetophenone was selected as the model substrate, and monophasic and biphasic ionic liquid/buffer reaction systems were built respectively through three typical ionic liquids. The systematic study to the reaction characteristics of immobilized photosynthetic bacteria has been inuestigated. Based on optimization of reaction conditions and systems, we found that the use of ionic liquids instead of conventional solvents give better results than aqueous phase and organic phase systems. Furthermore, ionic liquids and immobilized cells can be recycled. The results indicate that immobilized photosynthetic bacteria can catalyze acetophenone to product corresponding （S）-phenylethanol mainly under the optimised conditions, such as in hydrophilic ionic liquid [ EMIM ] [ EtSO4 ] with 15 % volume fraction as monophasic ionic liquid/buffer reaction system. The yield and the enantiomeric excess values （ee） of （S）-phenylethanol were 82.7% and up to 99%, respectively. Ionic liquids not only enhance the catalytic reaction rate, but also increase the stability of biocatalysts. The reaction medium can be recycled and improve environmental friendiness of the systems.
The temperature programmed carburization (TPC) of MoO_3/Al_2O_3 was performed using liquid hydrocarbons as carbon sources. The effect of these hydrocarbons on the phase transformation of MoO_3/Al_2O_3 during TPC and the catalysts of its intermediate phases to the reactions of these hydrocarbons were investigated using online mass pectrometer (MS). The results of X-ray diffraction (XRD) and TPC-MS showed that different hydrocarbons had different activities for the transformation of MoO_3/Al_2O_3 within different temperature ranges. With regard to TPC of MoO_3/Al_2O_3, n-hexane was demonstrated to be the most effective among these hydrocarbons examined in our experiments. Also, some catalysts of intermediate phases formed during TPC were observed. These results provide valuable reference for choosing the suitable carbon sources and controlling preparation parameters properly in order to obtain the molybdenum carbide-based catalyst for different purposes.
Dendritic poly(amidoamine)(PAMAM)-salicylidene salen palladium complex of the first generation (PAMAMSAPd) was synthesized and characterized by elemental analysis,FT-IR,UV-vis,Fluorescence spectra and NMR. It was evaluated as catalyst precursor in the Heck cross-coupling of iodobenzene (or its derivatives) and conjugate alkenes. For the cross-coupling reaction of iodobenzene with acrylic acid,the optimal condition was established as follows: 10mmol PhI,nPhI: nAA: nEt3N=1∶1.5∶2.5,3.0×10-3g PAMAMSAPd,4mL DMF and 100℃ reaction temperature in the inert ambience. Under the above reaction condition,the yield of cinnamate can reach 96.5% at 90min reaction time. This dendimer complex was a phosphine-free,highly efficient and stable dendrimer catalyst for Heck reaction. In addition,this dendrimer catalyst could be used at least for four times without significant loss of yield.
The performance of the Cu/Zn/(Fe, Mn, Cr)/AlO catalysts were investigated at 220 ℃ for methanol steam reforming . The mole ratio of steam to methanol was 1.3, and the liquid space velocity was 1.5 h-1. The adding of Cr can enhance conversion of methanol and reduce CO production rate .CO content decreased 54% while the methanol conversion increased 20% under 220 ℃ with Cu30Zn15Cr45Al10 catalyst.
A series of Fe_2O_3/SiO_2 catalysts were prepared by impregnation method. The catalyst samples were characterized by means of XRD, BET, TG-DTG and SEM. The effects of the loading amount of Fe and the temperature of calcination on the catalytic activity for oxidation of 2-ethylhexanol to 2-ethylhexanoic acid using Fe_2O_3/SiO_2 catalyst were investigated, and the optimum conditions for catalyst preparation were determined. The results showed, when the loading amount of Fe was 4% and the temperature of calcination was 500℃, the catalyst had better catalytic performance because of the distributed uniformly and same grain size of active component Fe_2O_3 formed, and larger specific surface area, the selectivity and yield of 2-ethylhexanoic acid could reach 55.14% and 22.41%, respectively.
Impregnation-precipitation method was applied to support the nano-meter supported nano-ZrO2/Al2O3 composite supports.Praseodymium oxide and neodymium oxide with different content were doped into the ZrO2/Al2O3 composite supports to improve the surface properties of the ZrO2.The SO42-/REXOY-ZrO2/Al2O3 catalysts were obtained by supporting SO42-onto the composite supports doped by rare earth oxides.Crystalline structures、 surface area、 pore diameter distribution and acid properties of the catalysts were characterized by XRD,BET,in-suit FTIR,and TPD.The α-pinene isomerization reaction was chosen to investigate the catalytic properties of the catalysts.The results indicated that with the siutable rare earth doping,the grain size of the ZrO2 was decreased and the surface area of the catalysts was increased.The existence of the rare earth oxide increased the coordination adsorption of SO42-which had the directive influence on the acid site number and acid strength to increase the activity of the catalysts.
The Palladium-catalyzed amidocarbonylation of benzaldehyde, acetamide and CO using different co-catalysts in various solvents such as N-methylpyrrolidone (NMP), acetonitrile, polyethyleneglycol(PEG) and 1-hexyl-3-methylimidazolium hexafluorophosphate was investigated. The used co-catalysts included hexadecyl trimethyl ammonium bromide, tetrabutyl ammonium bromide, and lithium bromide. In contrast with high boiling point solvent NMP, the separation and purification of the product were greatly simplified and the reaction interface became more friendly using acetonitrile, PEG and 1-hexyl-3-methylimidazolium hexafluorophosphate as solvents. For the first time PEG was employed as solvent in the reaction.
FT-IR spectroscopy online was used to investigate DECP(Diethyl chlorophosphite)degraded by photocatalytic oxidation on nano-TiO2(P25).GC-MS spectrograph was used to analyze the products.It is possible to predict the mechanism of gas-solid phase photocatalytic degradation of DECP.The reaction may be take place by follow pathway:electron-hole couple was produced in illuminated TiO2 by UV irradiated,and the couple evoke reactions with DECP,H2O,-OH to produce various radicals.DECP can be degraded to inorganic compounds by the chain-reaction of radicals.The products include CO2,H2O,CO,HCl,et al.The chain-reaction will be terminated when radicals vanish,and the intermediates were produced,such as methane,alcohol,ethanal,DEHP(Diethyl hydroxyphosphonate),DEP(Diethyl phosphate),TEP(Triethyl phosphate),et al.
α-AlF3·3H20 were prepared in low temperature using Al and HF.β-AlF3 was prepared by heating α-AlF3·3H20. The fluorination catalyst were characterized by XRD. Activity of fluorination catalyst were evaluated by fluoro-chloro exchange reaction. The AlF3 catalyst shows better fluorination activity.
Temperature rising behavior of a series of metal oxides was studied under microwave irradiation. It was found that the metal oxides of VB、 VIII、 IB and IIB , especially Co_ 3 O_ 4 、 NiO、 V_ 2 O_ 5 exhibited good temperature rising behavior. Some non-noble metal oxide catalysts were prepared and their temperature rising behavior and the catalytic activity for oil fume purification were examined. The V_ 2 O_ 5 catalysts exhibited the stable temperature rising behavior and the highest catalytic activity. The addition of 1% La_ 2 O_ 3 to the supported V_ 2 O_ 5 catalysts enhanced the catalytic activity for oil fume purification.
In this paper, catalyst performance and carbon deposition of different catalysts for reforming of methane and propane with CO-2 and O-2 in a fluidized bed reactor were investigated. TG, Laser Raman and TEM were used to characterize the carbon species and carbon amount. The results showed that a lot of whisker carbon was observed on pure and Pd(Pt)-modified nickel-based catalysts, it was attributed to the strong cracking property for methane and propane. Little deposited carbon was observed on pure Ni/SiO-2 and catalysts modified by alkaline or rare earth metals, and no deposited carbon was observed on nickel based catalyst modified by CaO. The resistance of carbon deposition was enhanced by promotion of the basicity of CaO-modified catalyst.
A Zr-ZSM-11 molecular sieve was synthesized by hydrothermal method with tetrabutylammonium bromide as the template. The effects of Si/Zr ratio, crystallization temperature, alkali content, crystallization time, template content on crystallization of Zr-ZSM-11 molecular sieve were investigated, and the synthesized zeolites were characterized by XRD, SEM and EDX. It is shown that the formation of Zr-ZSM-11 is affected by many factors. Generally, the optimum synthetic conditions are as follows: temperature, in the range of 120 to 140 ℃; alkali content, ca 4.7; the ratio of Si to Zr, above 20; and the crystallization time above 40 h. The SEM images show that the synthesized zeolite is a well crystallized claviform crystal, and the existence of Zr atom in the frame of zeolite was confirmed by EDX analysis.
The polymer-supported metallocene catalyst was prepared by first copolymerization of metallocene with unsaturated double bond substituent, styrene and divinyl benzene, and then reacted with ethyl lithium, finally complexed by tetrabutyl titanate. Polymerizations of styrene were attempted in the presence of the supported metallocene catalytic system. Polymerization reactions were investigated at different polymerization conditions such as polymerization temperature,kinds of grignard reagents, Mg/Ti mole ratio and so on. The results demonstrated that catalytic activity of metallocene is increased by supported and catalytic activity of the supported catalyst is depended on the structure of copolymer-supported metallocene, polymerization conditions.
