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2001 Volume 17 Issue 6
2001, 17(06): 481-483
doi: 10.3866/PKU.WHXB20010601
Abstract:
TiO2,CoS and SnO2 respectively by itself is inactive for the reduction of SO2 or/and NO by CO;however,we discovered that both TiO2-CoS (1:1 mass ratio) and TiO2SnO2 (1:1 mass ratio) composite compounds are very active for such reactions,at 300－350 ℃,the conversion of SO2 to S,NO to N2 are over 90％,and the selectivity towards S or N2 are over 95％.These mean that there are synergism effects between TiO2 and CoS,TiO2 and SnO2.It was confirmed by XRD characteriza tion that TiO2 and CoO,TiO2 and SnO2 transform to rutile after calcinations at 500 ℃,however,individual TiO2(anatase) can only transform to rutile up to 900℃.Therefore ,it is suggested that the synergism effects must be related to these composites comcound which exist as rutile structure.The study of the reaction me chanism and model of active phase are underway.
TiO2,CoS and SnO2 respectively by itself is inactive for the reduction of SO2 or/and NO by CO;however,we discovered that both TiO2-CoS (1:1 mass ratio) and TiO2SnO2 (1:1 mass ratio) composite compounds are very active for such reactions,at 300－350 ℃,the conversion of SO2 to S,NO to N2 are over 90％,and the selectivity towards S or N2 are over 95％.These mean that there are synergism effects between TiO2 and CoS,TiO2 and SnO2.It was confirmed by XRD characteriza tion that TiO2 and CoO,TiO2 and SnO2 transform to rutile after calcinations at 500 ℃,however,individual TiO2(anatase) can only transform to rutile up to 900℃.Therefore ,it is suggested that the synergism effects must be related to these composites comcound which exist as rutile structure.The study of the reaction me chanism and model of active phase are underway.
2001, 17(06): 484-487
doi: 10.3866/PKU.WHXB20010602
Abstract:
A simple method of calculating the interaction force and energy per unit area between two dissimilar plates with high potentials at constant surface potentials has been presented in Ref.[3],in which strong interaction of plates with high potentials was discussed. Using linear superposition,approximate expressions have been derived for weak repulsive interaction energy and force between parallel plates with high surface potential.Combining the results of Ref.[3], the double layer repulsive interaction between parallel plates with high surface potential has been integrally generalized.Juncture of strong and weak interaction is at κh=4,and the relative error is largest at this point,～10％. od agreementof the present results with the exact numerical results calculated by the computer is found over a wider range of the plate separation.Using Derjaguin's method and the improved Derjaguin's method the expressions of the interaction free energy between two dissimilar spheres with high surface potentials have also been derived.However,the range of application of the equations of interaction energy for the spheres are narrower than that of the plates.
A simple method of calculating the interaction force and energy per unit area between two dissimilar plates with high potentials at constant surface potentials has been presented in Ref.[3],in which strong interaction of plates with high potentials was discussed. Using linear superposition,approximate expressions have been derived for weak repulsive interaction energy and force between parallel plates with high surface potential.Combining the results of Ref.[3], the double layer repulsive interaction between parallel plates with high surface potential has been integrally generalized.Juncture of strong and weak interaction is at κh=4,and the relative error is largest at this point,～10％. od agreementof the present results with the exact numerical results calculated by the computer is found over a wider range of the plate separation.Using Derjaguin's method and the improved Derjaguin's method the expressions of the interaction free energy between two dissimilar spheres with high surface potentials have also been derived.However,the range of application of the equations of interaction energy for the spheres are narrower than that of the plates.
2001, 17(06): 488-490
doi: 10.3866/PKU.WHXB20010603
Abstract:
The alkyl oxyethyelenated propane sulfonates were synthesized,their structures were verified by element analysis and 1H NMR.The surface tension,critical micelle concentration,Krafft point and molecular mean minimum area of the surfactants aqueous solutions were obtained,and some characteristics of the novel surfactant were acquired.
The alkyl oxyethyelenated propane sulfonates were synthesized,their structures were verified by element analysis and 1H NMR.The surface tension,critical micelle concentration,Krafft point and molecular mean minimum area of the surfactants aqueous solutions were obtained,and some characteristics of the novel surfactant were acquired.
2001, 17(06): 491-495
doi: 10.3866/PKU.WHXB20010604
Abstract:
Greenhouse effect has been received more and more attention in the field of environment protection recently. N2O is an important geenhouse effect gas, whose effect is 206 times stronger than that of CO2. Some researches show that beacuse of coupling relationship and competition effect between different trace gases, other trace gases can affect N2O′s life and ozone′s depletion speed in the atmosphere. In order to give an instructive theoretical reference to experimental researchers, AM1 molecular orbital methods using the restricted Hartree-Fock (RHF) calculation have been applied to investigate the mechanism of the reaction of H2O2 with N2O. The results show that this is a multistep reaction. Along the reaction path there are two transition states, one internal rotational barrier and two intermediates. The step from Re to IM1 is the ratecontrolling step, whose activation energy is 323.04 kJ•mol1. The whole reaction is exothermic, with the heat of formation equals to －147.67 kJ•mol－1.
Greenhouse effect has been received more and more attention in the field of environment protection recently. N2O is an important geenhouse effect gas, whose effect is 206 times stronger than that of CO2. Some researches show that beacuse of coupling relationship and competition effect between different trace gases, other trace gases can affect N2O′s life and ozone′s depletion speed in the atmosphere. In order to give an instructive theoretical reference to experimental researchers, AM1 molecular orbital methods using the restricted Hartree-Fock (RHF) calculation have been applied to investigate the mechanism of the reaction of H2O2 with N2O. The results show that this is a multistep reaction. Along the reaction path there are two transition states, one internal rotational barrier and two intermediates. The step from Re to IM1 is the ratecontrolling step, whose activation energy is 323.04 kJ•mol1. The whole reaction is exothermic, with the heat of formation equals to －147.67 kJ•mol－1.
2001, 17(06): 496-500
doi: 10.3866/PKU.WHXB20010605
Abstract:
Aiming at researching and developing new compounded suspensions to sever as electrorheological fluid (ERF), a metal core/polymer coating compounded suspension for ERF has been designed according to the principle of media polarization. Based on this evolution,a series of metal core/high polymer coating compounded particles such as Zn/polystyrenebutylacrylate compounded particles, Ni/polystyrenebutyl acrylate compounded particles, Ni/polystyrene compounded particles, Zn/polystyrene compounded particles have been prepared adopting the emulsion polymerization together with the microencapsulation techniques as well as the acidalkali matching theory which was initially suggested by Fowkes(schematically depicted in Fig.1). The micromorphologies of these compounded particles were measured using scan electron microscophy(the SEM photography of Fig.2 exhibits the coated condition of these particles) and the ERF performance of these compounded particles have alse been carried out. The performance test results indicate that the mechanical properties (refer to Fig.5～10 ) and the stability of ERF were improved, i.e. shear strength was no less than 2 kPa and segregation resistance was intensified signi ficantly compared with that of metal core, which shows that these materials are promising for acting as ERF though further modification should be necessary. Besides, from the performance test results it is apparently found that different compounded suspensions made up of different metal cores or polymer coatings possess various mechanical properties,and explanations for this phenomenon will discussed in detail elsewhere.
Aiming at researching and developing new compounded suspensions to sever as electrorheological fluid (ERF), a metal core/polymer coating compounded suspension for ERF has been designed according to the principle of media polarization. Based on this evolution,a series of metal core/high polymer coating compounded particles such as Zn/polystyrenebutylacrylate compounded particles, Ni/polystyrenebutyl acrylate compounded particles, Ni/polystyrene compounded particles, Zn/polystyrene compounded particles have been prepared adopting the emulsion polymerization together with the microencapsulation techniques as well as the acidalkali matching theory which was initially suggested by Fowkes(schematically depicted in Fig.1). The micromorphologies of these compounded particles were measured using scan electron microscophy(the SEM photography of Fig.2 exhibits the coated condition of these particles) and the ERF performance of these compounded particles have alse been carried out. The performance test results indicate that the mechanical properties (refer to Fig.5～10 ) and the stability of ERF were improved, i.e. shear strength was no less than 2 kPa and segregation resistance was intensified signi ficantly compared with that of metal core, which shows that these materials are promising for acting as ERF though further modification should be necessary. Besides, from the performance test results it is apparently found that different compounded suspensions made up of different metal cores or polymer coatings possess various mechanical properties,and explanations for this phenomenon will discussed in detail elsewhere.
2001, 17(06): 501-506
doi: 10.3866/PKU.WHXB20010606
Abstract:
It is predicted that there are two geometrical configurations of the slipped parallel (C2h) and T shaped (C2v) carbon dioxide dimer using the density functional theory(DFT) with basis sets 631G or 6311G.The normal vibration analysis has showed 12 vibrational modes for C2h,which can be classified in three types ,i.e.ν11(bu),ν1(ag),ν9(bu)and ν4(ag) contributed mainly by intramolecular stretching vibrations,ν8(bg),ν12(bu),ν6(au) and ν5(ag) contributed mainly by intramolecular bending vibrations,and ν7(au),ν10(bu), ν2(ag) and ν3(ag) provided by intermolecular vibrations with frequencies 20～100 cm－1.The (CO2)2 is a typical weakly bound molecule based on its small dissociation energy 2 kJ•mol－1 and normal vibration modes.
It is predicted that there are two geometrical configurations of the slipped parallel (C2h) and T shaped (C2v) carbon dioxide dimer using the density functional theory(DFT) with basis sets 631G or 6311G.The normal vibration analysis has showed 12 vibrational modes for C2h,which can be classified in three types ,i.e.ν11(bu),ν1(ag),ν9(bu)and ν4(ag) contributed mainly by intramolecular stretching vibrations,ν8(bg),ν12(bu),ν6(au) and ν5(ag) contributed mainly by intramolecular bending vibrations,and ν7(au),ν10(bu), ν2(ag) and ν3(ag) provided by intermolecular vibrations with frequencies 20～100 cm－1.The (CO2)2 is a typical weakly bound molecule based on its small dissociation energy 2 kJ•mol－1 and normal vibration modes.
2001, 17(06): 507-510
doi: 10.3866/PKU.WHXB20010607
Abstract:
The affinity between magnetic particles (Fe3O4) and monomer or its polymer is a key factor affecting the function of microspheres in the preparation of encapsulated magnetic micro spheres(EMMS).Silane coupling [KH570,CH2C(CH3)C(O)OC3H6Si(OCH3)3] was used for the surface modification of fine magnetic particles with 0.2～0.3 μm in size and tetrahedron in crystal form.Ethanol/water solution was used as modification medium for silane coupling.Fourier transform infrared spectrometer and X-ray photoelectron spectra analysis show that the coupling bonds chemically on the particle surface,leading to the affinity improvement between magnetic particles and monomer or its polymer.The encapsulated magnetic microspheres synthesized by dispersion polymerization of styrene in the presence of modified Fe3O4 particles are significantly improved compared with that when unmodified Fe3O4 particles are used.
The affinity between magnetic particles (Fe3O4) and monomer or its polymer is a key factor affecting the function of microspheres in the preparation of encapsulated magnetic micro spheres(EMMS).Silane coupling [KH570,CH2C(CH3)C(O)OC3H6Si(OCH3)3] was used for the surface modification of fine magnetic particles with 0.2～0.3 μm in size and tetrahedron in crystal form.Ethanol/water solution was used as modification medium for silane coupling.Fourier transform infrared spectrometer and X-ray photoelectron spectra analysis show that the coupling bonds chemically on the particle surface,leading to the affinity improvement between magnetic particles and monomer or its polymer.The encapsulated magnetic microspheres synthesized by dispersion polymerization of styrene in the presence of modified Fe3O4 particles are significantly improved compared with that when unmodified Fe3O4 particles are used.
2001, 17(06): 511-515
doi: 10.3866/PKU.WHXB20010608
Abstract:
ABO2(A=Cu; B=Cr,Al,Fe) complex oxides have been prepared by amorphous citrate precursors method. Formation of singlephase dalofossite structure was confirmed by XRD examination. A conventional fixed-bed micro-reaction technique was used in measuring the catalytic activities of these complex oxides for CO NO reaction under both oxidizing and reducing conditions. CuAlO2 and CuCrO2 show od catalytic activity towards CONO reaction. CuCrO2 was quite stable and no changes in the bulk phase composition were detected even after long time CONO reaction under both oxidizing and reducing conditions. CuAlO2, which was stable enough under oxidizing conditions, was partly reduced to Cu0 after long time catalytic reaction under reducing conditions. Although no phase composition chan ges were detected in CuFeO2 bulk phase after long time catalytic test under oxidizing conditions, partial reduction on the surface can be expected. After catalytic test under reducing conditions, CuFeO2 totally converted to Cu0 and CuFe2O4.Compared with those catalysts of perovskite structure, ABO2 samples show much better catalytic activity for CONO reaction.
ABO2(A=Cu; B=Cr,Al,Fe) complex oxides have been prepared by amorphous citrate precursors method. Formation of singlephase dalofossite structure was confirmed by XRD examination. A conventional fixed-bed micro-reaction technique was used in measuring the catalytic activities of these complex oxides for CO NO reaction under both oxidizing and reducing conditions. CuAlO2 and CuCrO2 show od catalytic activity towards CONO reaction. CuCrO2 was quite stable and no changes in the bulk phase composition were detected even after long time CONO reaction under both oxidizing and reducing conditions. CuAlO2, which was stable enough under oxidizing conditions, was partly reduced to Cu0 after long time catalytic reaction under reducing conditions. Although no phase composition chan ges were detected in CuFeO2 bulk phase after long time catalytic test under oxidizing conditions, partial reduction on the surface can be expected. After catalytic test under reducing conditions, CuFeO2 totally converted to Cu0 and CuFe2O4.Compared with those catalysts of perovskite structure, ABO2 samples show much better catalytic activity for CONO reaction.
2001, 17(06): 516-520
doi: 10.3866/PKU.WHXB20010609
Abstract:
CCl2 free radicals were produced by dc discharge of CCl4(in Ar).Ground electronic state CCl2 radical was electronically excited to A 1B1 (0,4,0) state with Nd:YAG laser pumped dye laser at 541.52 nm.Experimental quenching data of CCl2 (A 1B1 and a 3B1) by alkanes were obtained by observing time resolved fluorescence from the excited CCl2 radicals transition,which showed a superposition of two exponential decay components.The stateresolved rate constants kA and ka were first time acquired by analyzing and treating these data by using threelevelmodel,which was put forward by us.kA and ka increase on the whole with increasing the number of C－H bonds in alkanes.
CCl2 free radicals were produced by dc discharge of CCl4(in Ar).Ground electronic state CCl2 radical was electronically excited to A 1B1 (0,4,0) state with Nd:YAG laser pumped dye laser at 541.52 nm.Experimental quenching data of CCl2 (A 1B1 and a 3B1) by alkanes were obtained by observing time resolved fluorescence from the excited CCl2 radicals transition,which showed a superposition of two exponential decay components.The stateresolved rate constants kA and ka were first time acquired by analyzing and treating these data by using threelevelmodel,which was put forward by us.kA and ka increase on the whole with increasing the number of C－H bonds in alkanes.
2001, 17(06): 521-525
doi: 10.3866/PKU.WHXB20010610
Abstract:
The trajectory calculations of the reaction Sr＋HF on the extended LondonEyring PolanyiSato (LEPS) potential energy surface have been carried out to study the dependence of product rotational alignment on the collision energies. The calculated results for the reaction of Sr＋HF were compared with the predictions from the constrained product orbital angular momentum model. The final rotational angular momentum was found to be perpendicularly polarized with respect to the reagents′ relative velocity vector. The higher the collision energies are the more anisotropic is the distribution of the product rotational angular momentum vector.
The trajectory calculations of the reaction Sr＋HF on the extended LondonEyring PolanyiSato (LEPS) potential energy surface have been carried out to study the dependence of product rotational alignment on the collision energies. The calculated results for the reaction of Sr＋HF were compared with the predictions from the constrained product orbital angular momentum model. The final rotational angular momentum was found to be perpendicularly polarized with respect to the reagents′ relative velocity vector. The higher the collision energies are the more anisotropic is the distribution of the product rotational angular momentum vector.
2001, 17(06): 526-530
doi: 10.3866/PKU.WHXB20010611
Abstract:
We have analyzed the galvanostatic discharge process of insertion electrodes controlled by lithium ion diffusion in solid materials. It is demonstrated by mathematic calculation that the discharge capacity of insertion electrode depends on the value of Q(defined as the ratio of discharge hour rate and diffusion time constant). The galvanostatic discharge curve of spinel LiMn2O4 cathode and graphite anode have been simulated. The effect of particle size on the discharge capacity of spinel LiMn2O4 cathode and graphite anode is evaluated.
We have analyzed the galvanostatic discharge process of insertion electrodes controlled by lithium ion diffusion in solid materials. It is demonstrated by mathematic calculation that the discharge capacity of insertion electrode depends on the value of Q(defined as the ratio of discharge hour rate and diffusion time constant). The galvanostatic discharge curve of spinel LiMn2O4 cathode and graphite anode have been simulated. The effect of particle size on the discharge capacity of spinel LiMn2O4 cathode and graphite anode is evaluated.
2001, 17(06): 531-536
doi: 10.3866/PKU.WHXB20010612
Abstract:
Both vapor diffusion approach and batch mode are often used approaches for protein crystallization. The light scattering method is a powerful tool particularly for prenucleation study. However, all light scattering studies were limited to the crystallization process of the batch mode. To apply dynamic light scattering technique to the protein crystallization study for the vapor diffusion approach, as well as the batch mode, a special sample cell (see Fig.1) was desired in the present work. It has two separate parts, a scattering cell and a thin tube filled with salt solution. The results showed that our special cell was reliable for light scattering study(see table 1). In our experiments, vapor diffusion approach was mainly used. Sodium acetate buffer solution, 0.04 mol•L－1, pH=4.5, was mixed with sodium chloride,whose final concentration was 0.345 mol•L－1. Chicken egg white lysozyme was dissolved in the above solution with a concentration of 50 mg•mL－1 and 25 mg•mL－1. Two lysozyme dissolution ways were used. One was lysozyme dissolved in only sodium acetate buffer solution and another is in buffer solution with sodium chloride. Their results were different(see Fig.2 and Fig.5), that showed NaCl played an important role in the interaction of lysozyme molecules. Due to the feature of vapor diffusion approach, it was verified that the force between lysozyme moleculars in the solution is weak during the whole crystallization process, which is desirable for crystal growth, namely, lysozyme molecules kept in monomolecule or aggregation of bimolecules in solution when lysozyme crystal grew. Besides, our results show that there is a significant difference between this approach and the batch mode(decreasing temperature) even if other parameters are the same. This significant difference is the direct result of different ways of supersaturation. Vapor diffusion approach, compared to batch mode is a more temperate, precisely controlled way to realize supersaturation.
Both vapor diffusion approach and batch mode are often used approaches for protein crystallization. The light scattering method is a powerful tool particularly for prenucleation study. However, all light scattering studies were limited to the crystallization process of the batch mode. To apply dynamic light scattering technique to the protein crystallization study for the vapor diffusion approach, as well as the batch mode, a special sample cell (see Fig.1) was desired in the present work. It has two separate parts, a scattering cell and a thin tube filled with salt solution. The results showed that our special cell was reliable for light scattering study(see table 1). In our experiments, vapor diffusion approach was mainly used. Sodium acetate buffer solution, 0.04 mol•L－1, pH=4.5, was mixed with sodium chloride,whose final concentration was 0.345 mol•L－1. Chicken egg white lysozyme was dissolved in the above solution with a concentration of 50 mg•mL－1 and 25 mg•mL－1. Two lysozyme dissolution ways were used. One was lysozyme dissolved in only sodium acetate buffer solution and another is in buffer solution with sodium chloride. Their results were different(see Fig.2 and Fig.5), that showed NaCl played an important role in the interaction of lysozyme molecules. Due to the feature of vapor diffusion approach, it was verified that the force between lysozyme moleculars in the solution is weak during the whole crystallization process, which is desirable for crystal growth, namely, lysozyme molecules kept in monomolecule or aggregation of bimolecules in solution when lysozyme crystal grew. Besides, our results show that there is a significant difference between this approach and the batch mode(decreasing temperature) even if other parameters are the same. This significant difference is the direct result of different ways of supersaturation. Vapor diffusion approach, compared to batch mode is a more temperate, precisely controlled way to realize supersaturation.
2001, 17(06): 537-541
doi: 10.3866/PKU.WHXB20010613
Abstract:
Silver nanoparticles can be synthesized in liquid crystal systems formed by nonionic surfactant AEO7 and AgNO3 aqueous solution. The surfactant AEO-7 acts as both reductive and protective agent in the synthetic process. In the system of surfactant with ethoxyl groups, it is believed that ethoxyl groups can form hydroperoxides, and these hydroperoxides endow the surfactant the ability of reduction. The effects of reaction time, concentration,temperature and the characters of the liquid crystal system have all been studied. Silver nanoparticles stop growing with the prolonging of reaction time to certain period. This indicates that the particle′s enlarging is due to self-growing process, but not aggregating of particles. And the average diameters of silver particles obtained are all smaller than 10 nm.
Silver nanoparticles can be synthesized in liquid crystal systems formed by nonionic surfactant AEO7 and AgNO3 aqueous solution. The surfactant AEO-7 acts as both reductive and protective agent in the synthetic process. In the system of surfactant with ethoxyl groups, it is believed that ethoxyl groups can form hydroperoxides, and these hydroperoxides endow the surfactant the ability of reduction. The effects of reaction time, concentration,temperature and the characters of the liquid crystal system have all been studied. Silver nanoparticles stop growing with the prolonging of reaction time to certain period. This indicates that the particle′s enlarging is due to self-growing process, but not aggregating of particles. And the average diameters of silver particles obtained are all smaller than 10 nm.
2001, 17(06): 542-546
doi: 10.3866/PKU.WHXB20010614
Abstract:
The mechanism of the electrochemical oxidation of adrenaline was studied using fastscan cyclic voltammetry as a major means.In 1 mol•dm－3 H2SO4,the electrooxidation of adrenaline showed the elementary characteristics of diffusion and were companied by the weak adsorption of electroactive species.In the case of fastscan test,the electrooxidation of adrenaline was considered to obey EC(electron transferchemical reaction) mechanism..When the concentration of adrenaline was below 1.00×10－3 mol•dm－3,the characteristics of adsorption was easily detected.And the characteristics of adsorption became more evident as the concentration of adrenaline was decreased or the potential scan rate was increased.The transfer coefficient α and the rate constant of the electrochemical reaction ks were calculated as 0.264 and 31.81 s－1 respectively.
The mechanism of the electrochemical oxidation of adrenaline was studied using fastscan cyclic voltammetry as a major means.In 1 mol•dm－3 H2SO4,the electrooxidation of adrenaline showed the elementary characteristics of diffusion and were companied by the weak adsorption of electroactive species.In the case of fastscan test,the electrooxidation of adrenaline was considered to obey EC(electron transferchemical reaction) mechanism..When the concentration of adrenaline was below 1.00×10－3 mol•dm－3,the characteristics of adsorption was easily detected.And the characteristics of adsorption became more evident as the concentration of adrenaline was decreased or the potential scan rate was increased.The transfer coefficient α and the rate constant of the electrochemical reaction ks were calculated as 0.264 and 31.81 s－1 respectively.
2001, 17(06): 547-551
doi: 10.3866/PKU.WHXB20010615
Abstract:
A new method to design FCC catalyst for producing lighter olefin and diesel was developed and the USYbased catalyst was synthesized by means of this method. The USY zeolites ultrastablized in the hydrothermal treatment were further modified with tartaric acid in unbuffed system. The crystal structure, surface area and pore distribution,thermal stability and microactivity for catalytic cracking of modified samples were respectively characterized by XRD, N2adsorption,DTA and MAT techniques. The result shows that the Si/Al ratios,crystallinities and thermal stabilities of modified USY samples are effectively improved;simultaneously, the crystal cell size and particle size are obviously decreased. The pore system (micropore and secondary mesopore) is positively developed and the pore distribution is obviously optimized. The optimization of pore and acid sites results in the preferable production of lighter olefins and diesels in FCC process. This means that FCC reaction on modified USY zeolite leads to deep cracking in micropores and partial cracking in mesopores. Optimization of this mo dified USY zeolite might result in a novel FCC catalyst.
A new method to design FCC catalyst for producing lighter olefin and diesel was developed and the USYbased catalyst was synthesized by means of this method. The USY zeolites ultrastablized in the hydrothermal treatment were further modified with tartaric acid in unbuffed system. The crystal structure, surface area and pore distribution,thermal stability and microactivity for catalytic cracking of modified samples were respectively characterized by XRD, N2adsorption,DTA and MAT techniques. The result shows that the Si/Al ratios,crystallinities and thermal stabilities of modified USY samples are effectively improved;simultaneously, the crystal cell size and particle size are obviously decreased. The pore system (micropore and secondary mesopore) is positively developed and the pore distribution is obviously optimized. The optimization of pore and acid sites results in the preferable production of lighter olefins and diesels in FCC process. This means that FCC reaction on modified USY zeolite leads to deep cracking in micropores and partial cracking in mesopores. Optimization of this mo dified USY zeolite might result in a novel FCC catalyst.
2001, 17(06): 552-554
doi: 10.3866/PKU.WHXB20010616
Abstract:
V2O5SiO2(VSiO) supported CuNiK2O catalysts for the synthesis of dimethyl carbonate were prepared using isovolumic impregnation. Based on TPR,TPD, IR and microreactor techniques, the effect of K2O on the adsorption and reaction of CO2 and CH3OH on the catalyst were characterized. The results show that addition of K2O exerts obvious influence on the charge distribution of the active sites on CuNi/VSiO catalyst,increases the intensities of CO2 horizontal adsorption state, while that of the dissociation state of methanol descends. When the ratio of K is above 15 ％, K2CO3 is formed on the catalyst. Moreover,the main reaction products of CO2 and CH3OH on CuNiK2O/VSiO catalyst are still DMC, H2O, CO and CH2O,and with the addition of K2O, the conversion of reactants rise, but the selectivity of by-products decreases.
V2O5SiO2(VSiO) supported CuNiK2O catalysts for the synthesis of dimethyl carbonate were prepared using isovolumic impregnation. Based on TPR,TPD, IR and microreactor techniques, the effect of K2O on the adsorption and reaction of CO2 and CH3OH on the catalyst were characterized. The results show that addition of K2O exerts obvious influence on the charge distribution of the active sites on CuNi/VSiO catalyst,increases the intensities of CO2 horizontal adsorption state, while that of the dissociation state of methanol descends. When the ratio of K is above 15 ％, K2CO3 is formed on the catalyst. Moreover,the main reaction products of CO2 and CH3OH on CuNiK2O/VSiO catalyst are still DMC, H2O, CO and CH2O,and with the addition of K2O, the conversion of reactants rise, but the selectivity of by-products decreases.
2001, 17(06): 555-559
doi: 10.3866/PKU.WHXB20010617
Abstract:
Six novel pyrrometheneBF2 complexes,of which five compounds have not been reported,were synthesized and characterized.Their relationships between st ructure and photophysical behavior were studied with the aid of fluorescence and triplet state absorption spectra.The results indicate that,compared to 8alkyl pyrrometheneBF2 complexes,the compounds containing 8aryl exhibit high fluore scence quantum yield and rather low triplet state absorption.
Six novel pyrrometheneBF2 complexes,of which five compounds have not been reported,were synthesized and characterized.Their relationships between st ructure and photophysical behavior were studied with the aid of fluorescence and triplet state absorption spectra.The results indicate that,compared to 8alkyl pyrrometheneBF2 complexes,the compounds containing 8aryl exhibit high fluore scence quantum yield and rather low triplet state absorption.
2001, 17(06): 560-564
doi: 10.3866/PKU.WHXB20010618
Abstract:
The solubization of the W/O microemulsion of NA(naphthenic acid)/kerosene/NH3•H2O system has been investigated.The effect of salt,cosurfactant (-alcohol) on solubization of the microemulsion has been studied by the theory of cohesive energies(theory of Rratio).The results show that theory of R-ratio mayexplain the effect of concentration of salt,such as LiCl,NaCl,KCl,NaNO3,Na2SO4,NH4Cl,on maximum solubization (Φm) of the microemulsion,but can not explain the differences of the effect of these salt on Φm(to see Fig.1).We have found that,the rateQ(Q=z/r) of salt was correlated with the effect of salt on Φm(to seeTab.1).Theory of Rratio can only explain the effect of fraction mass of part alconols,such as noctyl and nheptyl and nhexyl alcohol on Φm,but can not explain the effect of isobutyl alcohol,n butyl alcohol,npentanol and isoamyl alconol on Φm (to see Fig.2).So theory of Rratio has it's limitations in explaination of the phenomenons of solubization of W/O microemulsion.
The solubization of the W/O microemulsion of NA(naphthenic acid)/kerosene/NH3•H2O system has been investigated.The effect of salt,cosurfactant (-alcohol) on solubization of the microemulsion has been studied by the theory of cohesive energies(theory of Rratio).The results show that theory of R-ratio mayexplain the effect of concentration of salt,such as LiCl,NaCl,KCl,NaNO3,Na2SO4,NH4Cl,on maximum solubization (Φm) of the microemulsion,but can not explain the differences of the effect of these salt on Φm(to see Fig.1).We have found that,the rateQ(Q=z/r) of salt was correlated with the effect of salt on Φm(to seeTab.1).Theory of Rratio can only explain the effect of fraction mass of part alconols,such as noctyl and nheptyl and nhexyl alcohol on Φm,but can not explain the effect of isobutyl alcohol,n butyl alcohol,npentanol and isoamyl alconol on Φm (to see Fig.2).So theory of Rratio has it's limitations in explaination of the phenomenons of solubization of W/O microemulsion.
2001, 17(06): 565-569
doi: 10.3866/PKU.WHXB20010619
Abstract:
The standard transfer Gibbs energies (ΔtrG°)of KBPh4 from reference solvent of water to water/ethanol, water/propanol, water/2 propanol,water/ethylene glycol, water/glycerol mixtures in different proportional ratio have been studied. The interactions of KBPh4 with the above mixed solvents were analyzed. The standard transfer Gibbs energy of cavity(ΔtrG°cav) and the standard transfer Gibbs energy of interaction(ΔtrG° int) from water to water/2propanol mixtu res at 298.15 K were calculated by the Scaled Particle Theory (SPT).
The standard transfer Gibbs energies (ΔtrG°)of KBPh4 from reference solvent of water to water/ethanol, water/propanol, water/2 propanol,water/ethylene glycol, water/glycerol mixtures in different proportional ratio have been studied. The interactions of KBPh4 with the above mixed solvents were analyzed. The standard transfer Gibbs energy of cavity(ΔtrG°cav) and the standard transfer Gibbs energy of interaction(ΔtrG° int) from water to water/2propanol mixtu res at 298.15 K were calculated by the Scaled Particle Theory (SPT).
2001, 17(06): 570-572
doi: 10.3866/PKU.WHXB20010620
Abstract:
Resonant twophoton ionization spectra of S1←S0 transition in complex oxylene…NH3(ND3) in supersonic molecular beam are observed using resonant two photon ionization,together with time of flight mass spectrometry. The spectra exhibit rich information on the complex intermolecular vdW vibrational modes.We have tentatively assigned all the observed spectral features.By analyzing the spectra,the stretching vibrational frequencies and two bending vibrational frequencies of the the complex are obtained.The structure of the complex has been obtained by abinitio computation method.
Resonant twophoton ionization spectra of S1←S0 transition in complex oxylene…NH3(ND3) in supersonic molecular beam are observed using resonant two photon ionization,together with time of flight mass spectrometry. The spectra exhibit rich information on the complex intermolecular vdW vibrational modes.We have tentatively assigned all the observed spectral features.By analyzing the spectra,the stretching vibrational frequencies and two bending vibrational frequencies of the the complex are obtained.The structure of the complex has been obtained by abinitio computation method.
2001, 17(06): 573-576
doi: 10.3866/PKU.WHXB20010621
Abstract:
The solubility properties of the zinc chlorideamino acids(Leu/Try/ Val/Thr) water systems at 25 ℃ in the whole concentration range have been investigated by equilibrium method, the corresponding phase diagrams and refractive index curves were constructed. The results indicate the formation of the congruently soluble compound of Zn(Leu)Cl2（A） in Leu system and the incongruently soluble compounds of Zn(Try)Cl2•1/2H2O(B)、 Zn(Val)Cl2 •H2O(C)、 Zn(Val)2Cl2(D)、 Zn(Thr)Cl2•H2O(E) and Zn(Thr)2Cl2(F) in Try/Val/Thr systems, which have not been reported in literature. According to the phase equilibrium result, six solid complexes have been prepared in water, and their compositions have been determined by chemical analysis which are consistent with the results of phase diagrams.
The solubility properties of the zinc chlorideamino acids(Leu/Try/ Val/Thr) water systems at 25 ℃ in the whole concentration range have been investigated by equilibrium method, the corresponding phase diagrams and refractive index curves were constructed. The results indicate the formation of the congruently soluble compound of Zn(Leu)Cl2（A） in Leu system and the incongruently soluble compounds of Zn(Try)Cl2•1/2H2O(B)、 Zn(Val)Cl2 •H2O(C)、 Zn(Val)2Cl2(D)、 Zn(Thr)Cl2•H2O(E) and Zn(Thr)2Cl2(F) in Try/Val/Thr systems, which have not been reported in literature. According to the phase equilibrium result, six solid complexes have been prepared in water, and their compositions have been determined by chemical analysis which are consistent with the results of phase diagrams.
