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2006 Volume 22 Issue 5
2006, 22(05): 517-522
doi: 10.3866/PKU.WHXB20060501
Abstract:
TiO2/ AC (activated carbon) composite photocatalysts were prepared by acid catalyzed hydrolysis method followed by calcinations in N2 atmosphere. Photocatalytic activity of TiO2/wAC (w: the mass fraction of AC, %) was investigated through the photocatalytic degradation of phenol, methyl orange, and Cr6+ in the present of TiO2/wAC. The separability of TiO2/AC was determined by gravity-sedimentation. XRD, DRS, FTIR, SEM, and N2 adsorption isotherm were used to characterize the crystal structure, spectra characteristics, and surface properties of the obtained catalysts. The results showed that TiO2/wAC catalysts with optimal AC content 5%(w) exhibited more higher activity than P-25 and TiO2, as well as od decantability, less activity lost after several runs and less sensitive to pH change.Result of DRS revealed no electronic change when AC was added. Better TiO2 distribution and less agglomeration can be achieved when optimal AC content adopted. Result of FTIR suggests that a conjugation effect was presented between the AC bulk and Ti—O bond. Suitable pollutant concentration environment and less agglomeration provided by AC was the main cause for the high activity of TiO2/5AC. The performance of the prepared TiO2/5AC catalyst revealed great practical potential in waste water treatment.
TiO2/ AC (activated carbon) composite photocatalysts were prepared by acid catalyzed hydrolysis method followed by calcinations in N2 atmosphere. Photocatalytic activity of TiO2/wAC (w: the mass fraction of AC, %) was investigated through the photocatalytic degradation of phenol, methyl orange, and Cr6+ in the present of TiO2/wAC. The separability of TiO2/AC was determined by gravity-sedimentation. XRD, DRS, FTIR, SEM, and N2 adsorption isotherm were used to characterize the crystal structure, spectra characteristics, and surface properties of the obtained catalysts. The results showed that TiO2/wAC catalysts with optimal AC content 5%(w) exhibited more higher activity than P-25 and TiO2, as well as od decantability, less activity lost after several runs and less sensitive to pH change.Result of DRS revealed no electronic change when AC was added. Better TiO2 distribution and less agglomeration can be achieved when optimal AC content adopted. Result of FTIR suggests that a conjugation effect was presented between the AC bulk and Ti—O bond. Suitable pollutant concentration environment and less agglomeration provided by AC was the main cause for the high activity of TiO2/5AC. The performance of the prepared TiO2/5AC catalyst revealed great practical potential in waste water treatment.
2006, 22(05): 523-527
doi: 10.1016/S1872-1508(06)60018-1
Abstract:
The phase structures and electrochemical properties of the V2.1TiNi0.4Zrx (x =0 ～0.06) hydrogen storage electrode alloys have been investigated. It is found that all the alloys consist of a main phase of V－based solid solution with a bcc structure and a secondary phase with a three－dimensional network structure. The secondary phase precipitates along the grain boundaries of the main phase. For the alloys with Zr content x＝0.02, the secondary phase is the TiNi－based phase. As x reaches 0.04, the secondary phase changes into the C14－type Laves phase. Moreover, the unit cells of both the main phase and the secondary phase expand with the increasing Zr content. Electrochemical measurements show that activation behavior and maximum discharge capacities of the Zr－added alloy are better than those of V2.1TiNi0.4 alloy. As the Zr content in the alloy increases, their high－rate dischargeability is improved significantly, but their cycle stability degrades gradually. For the alloy with the Zr content of x=0.04, the best overall electrochemical performances are obtained.
The phase structures and electrochemical properties of the V2.1TiNi0.4Zrx (x =0 ～0.06) hydrogen storage electrode alloys have been investigated. It is found that all the alloys consist of a main phase of V－based solid solution with a bcc structure and a secondary phase with a three－dimensional network structure. The secondary phase precipitates along the grain boundaries of the main phase. For the alloys with Zr content x＝0.02, the secondary phase is the TiNi－based phase. As x reaches 0.04, the secondary phase changes into the C14－type Laves phase. Moreover, the unit cells of both the main phase and the secondary phase expand with the increasing Zr content. Electrochemical measurements show that activation behavior and maximum discharge capacities of the Zr－added alloy are better than those of V2.1TiNi0.4 alloy. As the Zr content in the alloy increases, their high－rate dischargeability is improved significantly, but their cycle stability degrades gradually. For the alloy with the Zr content of x=0.04, the best overall electrochemical performances are obtained.
2006, 22(05): 528-531
doi: 10.3866/PKU.WHXB20060503
Abstract:
Three-dimensionally ordered macroporous(3DOM) SiC patterns were fabricated successfully on silicon substrate using polydimethylsiloxane (PDMS) elastometric stamp as mold, silica spheres as template, polycarbosilane (PCS) as preceramic polymer. The preparing process included the formation of patterned silica template, precursor infiltration into the template, curing of the precursor, demolding of PDMS mold, pyrolysis of the cured preceramic polymer pattern and etching of the silica template. The results show that the dimension of SiC pattern can be controlled by using PDMS molds with different dimensions and the pore diameter in the patterned porous ceramic can be tailored by using different sizes of silica sphere template. The pores pack together to be a three-dimensionally ordered structure and the small windows originated from the contacting points of the silica spheres endow the porous patterns with a three-dimensionally penetrated structure. The prepared macroporous ceramic patterns will be potentially applied in chemical harsh conditions due to the advanced properties of the SiC ceramic.
Three-dimensionally ordered macroporous(3DOM) SiC patterns were fabricated successfully on silicon substrate using polydimethylsiloxane (PDMS) elastometric stamp as mold, silica spheres as template, polycarbosilane (PCS) as preceramic polymer. The preparing process included the formation of patterned silica template, precursor infiltration into the template, curing of the precursor, demolding of PDMS mold, pyrolysis of the cured preceramic polymer pattern and etching of the silica template. The results show that the dimension of SiC pattern can be controlled by using PDMS molds with different dimensions and the pore diameter in the patterned porous ceramic can be tailored by using different sizes of silica sphere template. The pores pack together to be a three-dimensionally ordered structure and the small windows originated from the contacting points of the silica spheres endow the porous patterns with a three-dimensionally penetrated structure. The prepared macroporous ceramic patterns will be potentially applied in chemical harsh conditions due to the advanced properties of the SiC ceramic.
2006, 22(05): 532-537
doi: 10.3866/PKU.WHXB20060504
Abstract:
Mesoporous TiO2-CeO2(m-TiO2-CeO2) was synthesized using n-cetylpyridinium chloride(C16PyCl) as a structure-directing agent under room temperature and neutral condition. The as-synthesized mesoporous samples were characterized by FT-IR, XRD, and N2 adsorption methods. The incorporation of Ce4 + ions into the channel wall dramatically improves the mesoporous structure. After ruthenium loaded by the impregnating method, the Ru particles strongly interact with the mesoporous mixed supports. Although a fairly large part of the particles are considered to be confined in the blind pores, the catalytic activity of ruthenium supported on m-TiO2-CeO2 for methanol decomposition to carbon monoxide and hydrogen is significantly higher than that of ruthenium supported on m-TiO2. A synergistic effect between Ru and CeO2 was observed for promoting the catalytic properties of Ru.
Mesoporous TiO2-CeO2(m-TiO2-CeO2) was synthesized using n-cetylpyridinium chloride(C16PyCl) as a structure-directing agent under room temperature and neutral condition. The as-synthesized mesoporous samples were characterized by FT-IR, XRD, and N2 adsorption methods. The incorporation of Ce4 + ions into the channel wall dramatically improves the mesoporous structure. After ruthenium loaded by the impregnating method, the Ru particles strongly interact with the mesoporous mixed supports. Although a fairly large part of the particles are considered to be confined in the blind pores, the catalytic activity of ruthenium supported on m-TiO2-CeO2 for methanol decomposition to carbon monoxide and hydrogen is significantly higher than that of ruthenium supported on m-TiO2. A synergistic effect between Ru and CeO2 was observed for promoting the catalytic properties of Ru.
2006, 22(05): 538-541
doi: 10.1016/S1872-1508(06)60019-3
Abstract:
Based on the relativistic effective cores potential (RECP/SDD) for Pd atom and AUG-cc-pVTZ basisfunction for N atom, the structures of PdN and PdN2 have been optimized using B3LYP method. The results show thatthe ground state of PdN is 4[SIGMA]- and the ground state of PdN2 is C[infinity]V symmetry and 1[SIGMA]+ state. The Murrell-Sorbie potential energy function of PdN molecule has been fitted through the least square fitting, and the potential energy function of PdN2 is given by many-body expansion theory. The potential energy curves describe the structure character of PdN and PdN2 ground state molecules rightly, which details the inner transfer process of Pd. There is a saddle of C2V structure(RNN=0.11700 nm, RPdN=0.22088 nm). The energy barrier of inner transfer is 0.5197 eV, which is close to the calculated value of 0.4560 eV.
Based on the relativistic effective cores potential (RECP/SDD) for Pd atom and AUG-cc-pVTZ basisfunction for N atom, the structures of PdN and PdN2 have been optimized using B3LYP method. The results show thatthe ground state of PdN is 4[SIGMA]- and the ground state of PdN2 is C[infinity]V symmetry and 1[SIGMA]+ state. The Murrell-Sorbie potential energy function of PdN molecule has been fitted through the least square fitting, and the potential energy function of PdN2 is given by many-body expansion theory. The potential energy curves describe the structure character of PdN and PdN2 ground state molecules rightly, which details the inner transfer process of Pd. There is a saddle of C2V structure(RNN=0.11700 nm, RPdN=0.22088 nm). The energy barrier of inner transfer is 0.5197 eV, which is close to the calculated value of 0.4560 eV.
2006, 22(05): 542-547
doi: 10.3866/PKU.WHXB20060506
Abstract:
Density functional theory has been employed to investigate the π-complexation adsorption of aromatic sulfur compounds such as thiophene (TP), benzothiophene (BT), dibenzothiophene (DBT), and 4, 6-dimethyldibenzothiophene (4, 6-DMDBT) by ion exchanging faujasite type zeolites with Cu+ and Ag+ cations. The calculations were based on the cluster models of 16T (H22Si15AlO22), and performed with BLYP function and DNP basis set. The effective core potential basis set was used for transition metal atoms. The calculated interaction energies indicated that the adsorption ability of the ion exchangingYzeolites for thiophenic compounds followed the order: Cu(I)-Y >Ag(I)-Y. Their adsorption ability for thiophenic compounds is higher than that for benzene. The calculated adsorption energy of the thiophenic compounds increased as 4, 6-DMDBT
Density functional theory has been employed to investigate the π-complexation adsorption of aromatic sulfur compounds such as thiophene (TP), benzothiophene (BT), dibenzothiophene (DBT), and 4, 6-dimethyldibenzothiophene (4, 6-DMDBT) by ion exchanging faujasite type zeolites with Cu+ and Ag+ cations. The calculations were based on the cluster models of 16T (H22Si15AlO22), and performed with BLYP function and DNP basis set. The effective core potential basis set was used for transition metal atoms. The calculated interaction energies indicated that the adsorption ability of the ion exchangingYzeolites for thiophenic compounds followed the order: Cu(I)-Y >Ag(I)-Y. Their adsorption ability for thiophenic compounds is higher than that for benzene. The calculated adsorption energy of the thiophenic compounds increased as 4, 6-DMDBT
2006, 22(05): 548-551
doi: 10.1016/S1872-1508(06)60020-X
Abstract:
An organic cation [C18mim]+ formed from [C18mim]Br, one type of ionic liquids, can into the interlayer of sodium montmorillonite (MMT) through the ion-exchanging reaction. The adsorption state, the adsorption amount,and the aggregative structure of [C18mim]+ in the interlayer ofMMThave been investigated by thermogravimetric analysis (TGA), wide-angle X-ray diffraction (XRD), and Fourier transforminfrared spectroscopy (FTIR). The results indicated that there is a maximum chemical adsorption of [C18mim]+ in the interlayer of MMT, but the total amount of adsorbed [C18mim]+ in the interlayer of MMT increases with the physical adsorption of [C18mim]+. With the increasing amount of adsorbed [C18mim]+ in the interlayer of MMT, the aggregative structures of [C18mim]+ become more ordered, leading to an obvious increase of the interlayer distance of MMT.
An organic cation [C18mim]+ formed from [C18mim]Br, one type of ionic liquids, can into the interlayer of sodium montmorillonite (MMT) through the ion-exchanging reaction. The adsorption state, the adsorption amount,and the aggregative structure of [C18mim]+ in the interlayer ofMMThave been investigated by thermogravimetric analysis (TGA), wide-angle X-ray diffraction (XRD), and Fourier transforminfrared spectroscopy (FTIR). The results indicated that there is a maximum chemical adsorption of [C18mim]+ in the interlayer of MMT, but the total amount of adsorbed [C18mim]+ in the interlayer of MMT increases with the physical adsorption of [C18mim]+. With the increasing amount of adsorbed [C18mim]+ in the interlayer of MMT, the aggregative structures of [C18mim]+ become more ordered, leading to an obvious increase of the interlayer distance of MMT.
2006, 22(05): 552-556
doi: 10.3866/PKU.WHXB20060508
Abstract:
Oleic acid-modified CuS nanoparticles, which can be placed in a long stretch of time without any occurrence of nanoparticle aggregation, were successfully synthesized in-situ in base oil at room temperature. TEM study showed that the average size of the surface-modified nanoparticles prepared by this method was about 30 nm. IR study indicated that the surface of inorganic CuS nanoparticles reacted with carboxyl group of oleic acid via chemical adsorption, which resulted in a layer of organic modification on the surface of CuS nanoparticles and greatly improved their oil-soluble ability. Friction and wear study demonstrated that this kind of lubricant additives could greatly improve the property of antiwear and friction reduction of the base oil. As the increase of additive concentration, both the friction coefficient and wear scar diameter began to dramatically decrease. When the additive concentration was 0.1%(w), both of them reached the lowest points. However, with the further increase of additive concentration both of them began to increase. SEM study proved that the reason was that the oleic acid-modified CuS nanoparticles could help to formfirmlubricating membrane between the surfaces of the friction pairs.
Oleic acid-modified CuS nanoparticles, which can be placed in a long stretch of time without any occurrence of nanoparticle aggregation, were successfully synthesized in-situ in base oil at room temperature. TEM study showed that the average size of the surface-modified nanoparticles prepared by this method was about 30 nm. IR study indicated that the surface of inorganic CuS nanoparticles reacted with carboxyl group of oleic acid via chemical adsorption, which resulted in a layer of organic modification on the surface of CuS nanoparticles and greatly improved their oil-soluble ability. Friction and wear study demonstrated that this kind of lubricant additives could greatly improve the property of antiwear and friction reduction of the base oil. As the increase of additive concentration, both the friction coefficient and wear scar diameter began to dramatically decrease. When the additive concentration was 0.1%(w), both of them reached the lowest points. However, with the further increase of additive concentration both of them began to increase. SEM study proved that the reason was that the oleic acid-modified CuS nanoparticles could help to formfirmlubricating membrane between the surfaces of the friction pairs.
2006, 22(05): 557-561
doi: 10.3866/PKU.WHXB20060509
Abstract:
Stereodynamics for the S(1D)+D2 reaction have been studied at a collision energy of 22.18 kJ·mol-1 on an ab initio potential energy surface by using time-independent quantum reactive scattering theory. The calculated differential cross sections show forward/backward peaking with weakly asymmetry, which is in agreement with the quasiclassical and experimental results. The state-resolved polarization-dependent differential cross sections and polarization parameters show that the product polarization tends toward a less anisotropic distribution, which indicates existence of a long-lived complex during the reaction because of the existence of deep well on the potential energy surface.
Stereodynamics for the S(1D)+D2 reaction have been studied at a collision energy of 22.18 kJ·mol-1 on an ab initio potential energy surface by using time-independent quantum reactive scattering theory. The calculated differential cross sections show forward/backward peaking with weakly asymmetry, which is in agreement with the quasiclassical and experimental results. The state-resolved polarization-dependent differential cross sections and polarization parameters show that the product polarization tends toward a less anisotropic distribution, which indicates existence of a long-lived complex during the reaction because of the existence of deep well on the potential energy surface.
2006, 22(05): 561-568
doi: 10.3866/PKU.WHXB20060510
Abstract:
ABEEM/MM model has been applied to compute various properties characterizing the larger water clusters (H2O)n (n=11~16), such as optimized geometries, the hydrogen bond number, cluster binding energies, stabilities,ABEEMcharge distributions, dipole moments, structural parameters, the average hydrogen bond number and strength, the incremental cluster binding energies. The results indicate that the transition from cubes to cages occurs for (H2O)n at n=12, and that the abundance of pentamers increases with increasing cagelike character.
ABEEM/MM model has been applied to compute various properties characterizing the larger water clusters (H2O)n (n=11~16), such as optimized geometries, the hydrogen bond number, cluster binding energies, stabilities,ABEEMcharge distributions, dipole moments, structural parameters, the average hydrogen bond number and strength, the incremental cluster binding energies. The results indicate that the transition from cubes to cages occurs for (H2O)n at n=12, and that the abundance of pentamers increases with increasing cagelike character.
2006, 22(05): 569-573
doi: 10.3866/PKU.WHXB20060511
Abstract:
TiO2 thin films were prepared on modified PET(poly(ethylene terephthalate)) substrates by an improved l-gel method. The as-prepared samples were characterized with X-ray diffraction (XRD), atomic force microscopy(AFM), and UV-Vis spectra. The results show that the interfacial compatibility between organic substrate and inorganic film has been improved after PET substrate was modified with silane coupling agent, and TiO2 films with transparency,uniformity, od adhesion, and high photocatalytic activity can be formed on PET surface. Moreover, the TiO2 thin films with different ratios of anatase/brookite were prepared successfully by controlling the preparation conditions, and the hydrophilicity of the TiO2 thin filmwas improved with proper content of brookite.
TiO2 thin films were prepared on modified PET(poly(ethylene terephthalate)) substrates by an improved l-gel method. The as-prepared samples were characterized with X-ray diffraction (XRD), atomic force microscopy(AFM), and UV-Vis spectra. The results show that the interfacial compatibility between organic substrate and inorganic film has been improved after PET substrate was modified with silane coupling agent, and TiO2 films with transparency,uniformity, od adhesion, and high photocatalytic activity can be formed on PET surface. Moreover, the TiO2 thin films with different ratios of anatase/brookite were prepared successfully by controlling the preparation conditions, and the hydrophilicity of the TiO2 thin filmwas improved with proper content of brookite.
2006, 22(05): 574-578
doi: 10.3866/PKU.WHXB20060512
Abstract:
La0.8Sr0.2Ga0.8Mg0.2O3(LSGM8282) and La0.8Sr0.2Ga0.8Mg0.15Co0.05O3 (LSGMC5) are two kinds of excellent electrolytes for intermediate temperature solid oxide fuel cells (ITSOFCs ). LSGM8282 and LSGMC5 were prepared using solid state reaction in this study. Total electrical conductivities and electronic conductivities of LSGM8282 and LSGMC5 were comparatively studied using four-probe AC impedance spectrometry and Hebb-Wagner polarization.The results showed that the total electrical conductivity of LSGM8282 had no dependency on oxygen partial pressures. However, the total electrical conductivity of LSGMC5 increased with the decrease in oxygen partial pressures under high oxygen partial pressures. Within the temperature range of 973-1173 K, the orders of dependency of the electron conduction and hole conduction of LSGM8282 on the oxygen partial pressure was -1/4 and 1/4, respectively. Within the temperature range of 1073-1173 K, the orders of dependency of the electron conduction and hole conduction of LSGMC5 on the oxygen portial pressure was -1/4 and about 1/8, respectively. The oxygen ion conductivity of LSGM8282 had no dependency on oxygen partial pressures, while that of LSGMC5 increased with the decrease in oxygen partial pressures under high oxygen partial pressures.
La0.8Sr0.2Ga0.8Mg0.2O3(LSGM8282) and La0.8Sr0.2Ga0.8Mg0.15Co0.05O3 (LSGMC5) are two kinds of excellent electrolytes for intermediate temperature solid oxide fuel cells (ITSOFCs ). LSGM8282 and LSGMC5 were prepared using solid state reaction in this study. Total electrical conductivities and electronic conductivities of LSGM8282 and LSGMC5 were comparatively studied using four-probe AC impedance spectrometry and Hebb-Wagner polarization.The results showed that the total electrical conductivity of LSGM8282 had no dependency on oxygen partial pressures. However, the total electrical conductivity of LSGMC5 increased with the decrease in oxygen partial pressures under high oxygen partial pressures. Within the temperature range of 973-1173 K, the orders of dependency of the electron conduction and hole conduction of LSGM8282 on the oxygen partial pressure was -1/4 and 1/4, respectively. Within the temperature range of 1073-1173 K, the orders of dependency of the electron conduction and hole conduction of LSGMC5 on the oxygen portial pressure was -1/4 and about 1/8, respectively. The oxygen ion conductivity of LSGM8282 had no dependency on oxygen partial pressures, while that of LSGMC5 increased with the decrease in oxygen partial pressures under high oxygen partial pressures.
2006, 22(05): 579-583
doi: 10.3866/PKU.WHXB20060513
Abstract:
Several temperature-and pH-sensitive poly(methacrylic acid-g-N, N-diethylacrylamide) (P(MAA-g-DEAM))graft copolymerswith different compositionswere synthesized by free-radical copolymerization utilizing macromonomer technique. The phase behaviors of P(MAA-g-DEAM) in dilute aqueous solutions were investigated by UV-Vis transmittance measurements and fluorescence probe technique. Studies demonstrated that the P (MAA-g-DEAM)copolymers had temperature-and pH-sensitivities, the two sensitivities were independent each other. These graft copolymers with different compositions had the approximately identical lower critical solution temperature (LCST), their critical phase transition pH values were dependent on the composition of graft copolymers and increased with increasing mass fraction of PDEAM. The PMAA main chain of P(MAA-g-DEAM) in dilute aqueous solution is an expanded coil conformation when the solution pH is higher than 5.5, and the PMAA main chain of P(MAA-g-DEAM) in dilute aqueous solution is a hyper-coiled conformation when the solution pH is less than 5.5. The unique properties of the graft copolymers may find some uses in the design and synthesis of novel nanocomposite materials.
Several temperature-and pH-sensitive poly(methacrylic acid-g-N, N-diethylacrylamide) (P(MAA-g-DEAM))graft copolymerswith different compositionswere synthesized by free-radical copolymerization utilizing macromonomer technique. The phase behaviors of P(MAA-g-DEAM) in dilute aqueous solutions were investigated by UV-Vis transmittance measurements and fluorescence probe technique. Studies demonstrated that the P (MAA-g-DEAM)copolymers had temperature-and pH-sensitivities, the two sensitivities were independent each other. These graft copolymers with different compositions had the approximately identical lower critical solution temperature (LCST), their critical phase transition pH values were dependent on the composition of graft copolymers and increased with increasing mass fraction of PDEAM. The PMAA main chain of P(MAA-g-DEAM) in dilute aqueous solution is an expanded coil conformation when the solution pH is higher than 5.5, and the PMAA main chain of P(MAA-g-DEAM) in dilute aqueous solution is a hyper-coiled conformation when the solution pH is less than 5.5. The unique properties of the graft copolymers may find some uses in the design and synthesis of novel nanocomposite materials.
2006, 22(05): 584-589
doi: 10.3866/PKU.WHXB20060514
Abstract:
TiO2/[alpha]-Al2O3 was prepared with TiCl4 as starting material, and the catalytic activities of CuO/TiO2/[alpha]-Al2O3 were examined using a GC micro-reactor NO+CO reaction system. The catalysts, especially 12%CuO/TiO2/[alpha]-Al2O3,showed high activities in NO+CO reaction. The NO conversion temperatures(T100%) were 300C[deg]and 275C[deg]for the catalysts pretreated by air and H2, respectively. The structural and reduction properties of CuO/TiO2/[alpha]-Al2O3 catalysts were analyzed using the H2-TPR, XRD, and FT-IR methods. It was found that proper amount of TiO2 increased the CuO dispersion on TiO2/[deg]-Al2O3. The 12%CuO/TiO2/[alpha]-Al2O3 catalyst had four reduction peaks ([alpha], [beta],[gamma] , and [delta]). The [alpha] and [deg]peaks were attributed to the reductions of highly dispersed CuO and crystalline CuO on the exposed TiO2 of TiO2 / [alpha]-Al2O3, respectively. On the other hand, the [beta] and [gamma]peaks were attributed to the reductions of highly dispersed CuOand crystalline CuOon TiO2/[alpha]-Al2O3, respectively. H2-pretreated 12%CuO/15%TiO2/[alpha]-Al2O3 had a strong adsorption of NO and CO, N2O and NO2 were formed. When NO and CO were adsorbed by 12%CuO/15%TiO2/[alpha]-Al2O3 the peak temperatures of N2O absorption were 200[deg]and 150C[deg] for the catalysts pretreated by air and H2, respectively.
TiO2/[alpha]-Al2O3 was prepared with TiCl4 as starting material, and the catalytic activities of CuO/TiO2/[alpha]-Al2O3 were examined using a GC micro-reactor NO+CO reaction system. The catalysts, especially 12%CuO/TiO2/[alpha]-Al2O3,showed high activities in NO+CO reaction. The NO conversion temperatures(T100%) were 300C[deg]and 275C[deg]for the catalysts pretreated by air and H2, respectively. The structural and reduction properties of CuO/TiO2/[alpha]-Al2O3 catalysts were analyzed using the H2-TPR, XRD, and FT-IR methods. It was found that proper amount of TiO2 increased the CuO dispersion on TiO2/[deg]-Al2O3. The 12%CuO/TiO2/[alpha]-Al2O3 catalyst had four reduction peaks ([alpha], [beta],[gamma] , and [delta]). The [alpha] and [deg]peaks were attributed to the reductions of highly dispersed CuO and crystalline CuO on the exposed TiO2 of TiO2 / [alpha]-Al2O3, respectively. On the other hand, the [beta] and [gamma]peaks were attributed to the reductions of highly dispersed CuOand crystalline CuOon TiO2/[alpha]-Al2O3, respectively. H2-pretreated 12%CuO/15%TiO2/[alpha]-Al2O3 had a strong adsorption of NO and CO, N2O and NO2 were formed. When NO and CO were adsorbed by 12%CuO/15%TiO2/[alpha]-Al2O3 the peak temperatures of N2O absorption were 200[deg]and 150C[deg] for the catalysts pretreated by air and H2, respectively.
2006, 22(05): 590-595
doi: 10.3866/PKU.WHXB20060515
Abstract:
Co-YSZ/HAp nano-composite coating and nano-HAp single coating were deposited on Ti substrate using the combination of electrocodeposition and electrophoretic deposition, and electrophoretic depositions, respectively.Surface and cross section morphologies of the coatings were observed by scanning electron microscope. Element distribution and crystal phase of the coatings were analyzed by energy dispersive spectrum and X-ray diffraction. The adhesive strength of the coating and Ti substrate was determined by shear strength testing. The results indicate that the adhesive strength of Co-YSZ/HAp nano-composite coating and Ti substrate is higher than that of nano-HAp single coating and Ti substrate. It shows that Co-YSZ as an interlayer reduces the mismatch of the thermal expansion coefficients between HAp and titaniumand Co-YSZ/HAp nano-composite coating has better mechanical properties.
Co-YSZ/HAp nano-composite coating and nano-HAp single coating were deposited on Ti substrate using the combination of electrocodeposition and electrophoretic deposition, and electrophoretic depositions, respectively.Surface and cross section morphologies of the coatings were observed by scanning electron microscope. Element distribution and crystal phase of the coatings were analyzed by energy dispersive spectrum and X-ray diffraction. The adhesive strength of the coating and Ti substrate was determined by shear strength testing. The results indicate that the adhesive strength of Co-YSZ/HAp nano-composite coating and Ti substrate is higher than that of nano-HAp single coating and Ti substrate. It shows that Co-YSZ as an interlayer reduces the mismatch of the thermal expansion coefficients between HAp and titaniumand Co-YSZ/HAp nano-composite coating has better mechanical properties.
2006, 22(05): 596-601
doi: 10.3866/PKU.WHXB20060516
Abstract:
A laboratory study was carried out to investigate the secondary organic aerosol (SOA) products from photooxidation of the aromatic hydrocarbon ethylbenzene. The experiments were conducted by irradiating ethylbenzene/CH3ONO/NOx mixtures in a home-made smog chamber. Size distribution of the secondary organic aerosol particles was detected with an aerodynamic particle sizer spectrometer. The aerosol time-of-flight mass spectrometer (ATOFMS) was used to measure the chemical composition of individual secondary organic aerosol particle in real time. According to a large number of single aerosol mass spectra, the chemical composition of SOA was obtained statistically. The possible reaction mechanisms leading to these products were also discussed.
A laboratory study was carried out to investigate the secondary organic aerosol (SOA) products from photooxidation of the aromatic hydrocarbon ethylbenzene. The experiments were conducted by irradiating ethylbenzene/CH3ONO/NOx mixtures in a home-made smog chamber. Size distribution of the secondary organic aerosol particles was detected with an aerodynamic particle sizer spectrometer. The aerosol time-of-flight mass spectrometer (ATOFMS) was used to measure the chemical composition of individual secondary organic aerosol particle in real time. According to a large number of single aerosol mass spectra, the chemical composition of SOA was obtained statistically. The possible reaction mechanisms leading to these products were also discussed.
2006, 22(05): 602-607
doi: 10.3866/PKU.WHXB20060517
Abstract:
Collisional quantum interference (CQI) on rotational energy transfer was observed by Sha et al.(J. Chem.Phys., 1995, 102：2772) in static cell, and the integral interference angle which determines the magnitudes of the transition cross sections was measured. To obtain more precise information, the experiment in the molecular beam should be taken, as the integral interference angle is the average effect of the differential interference angle. Thedifferential interference angle of Λ-Related Quantum Interference of 1Π-state diatom was presented to measure the degree of coherence, by using the first order Born approximation of time-dependent perturbation theory. The anisotropic Lennard-Jones interaction potential is employed to simulate their interference angles. The relationships of the differential interference angle versus the factors of the experiment in the molecular beam, including experimental temperature, partners, the distance of the interaction and rotational quantum number, are obtained. And the various factors that influen ce the interference angles are discussed. This theoretical model is important to understand orperformin the experiment of the molecular beam.
Collisional quantum interference (CQI) on rotational energy transfer was observed by Sha et al.(J. Chem.Phys., 1995, 102：2772) in static cell, and the integral interference angle which determines the magnitudes of the transition cross sections was measured. To obtain more precise information, the experiment in the molecular beam should be taken, as the integral interference angle is the average effect of the differential interference angle. Thedifferential interference angle of Λ-Related Quantum Interference of 1Π-state diatom was presented to measure the degree of coherence, by using the first order Born approximation of time-dependent perturbation theory. The anisotropic Lennard-Jones interaction potential is employed to simulate their interference angles. The relationships of the differential interference angle versus the factors of the experiment in the molecular beam, including experimental temperature, partners, the distance of the interaction and rotational quantum number, are obtained. And the various factors that influen ce the interference angles are discussed. This theoretical model is important to understand orperformin the experiment of the molecular beam.
2006, 22(05): 608-615
doi: 10.1016/S1872-1508(06)60021-1
Abstract:
The absolute asymmetric synthesis of the title complexes Λ-(+)D-cis-[CoBr(NH3)(en)2]Br2(1) and Δ-(-)D-cis-[CoBr(NH3)(en)2]Br2(2)(en=1,2-ethylenediamine) as well as the improved optical resolution of cis-[CoBr(NH3)(en)2]Br2·2H2O(3) are described in detail. The products were characterized by means of elemental analysis, TG-DTA, optical rotation, UV-Vis, and CD spectra. The distribution of enantiomeric excess(ee) of cis-[CoBr(NH3)(en)2]Br2 in the absolute asymmetric synthesis was obtained by the measurements of their CD spectra. It was found that the complete resolution of rac-cis-[CoBr(NH3)(en)2]Br2·2H2Owas achieved by use of NH4(d-BCS) (ammonium d-α-bromocamphor-π-sulfonate) or NH4(l-BCS) while NH4(dl-BCS) could only be partially resolved by chiral cis-[CoBr(NH3)(en)2]Br2 at the same condition. It is deduced that there are notable differences in the chiral discrimination of the reciprocal resolution between cis-[CoBr(NH3)(en)2]Br2 and NH4BCS.Moreover, a new“catalysis-crystal induction”mechanismin the preparation of the chiral Co(III) complex is put forward.
The absolute asymmetric synthesis of the title complexes Λ-(+)D-cis-[CoBr(NH3)(en)2]Br2(1) and Δ-(-)D-cis-[CoBr(NH3)(en)2]Br2(2)(en=1,2-ethylenediamine) as well as the improved optical resolution of cis-[CoBr(NH3)(en)2]Br2·2H2O(3) are described in detail. The products were characterized by means of elemental analysis, TG-DTA, optical rotation, UV-Vis, and CD spectra. The distribution of enantiomeric excess(ee) of cis-[CoBr(NH3)(en)2]Br2 in the absolute asymmetric synthesis was obtained by the measurements of their CD spectra. It was found that the complete resolution of rac-cis-[CoBr(NH3)(en)2]Br2·2H2Owas achieved by use of NH4(d-BCS) (ammonium d-α-bromocamphor-π-sulfonate) or NH4(l-BCS) while NH4(dl-BCS) could only be partially resolved by chiral cis-[CoBr(NH3)(en)2]Br2 at the same condition. It is deduced that there are notable differences in the chiral discrimination of the reciprocal resolution between cis-[CoBr(NH3)(en)2]Br2 and NH4BCS.Moreover, a new“catalysis-crystal induction”mechanismin the preparation of the chiral Co(III) complex is put forward.
2006, 22(05): 616-621
doi: 10.1016/S1872-1508(06)60022-3
Abstract:
The equilibriumsolubility of the quaternary systemErCl3-CdCl2-HCl-H2O was determined at 298K and the corresponding equilibrium diagram was constructed. The quaternary system is complicated with four equilibrium solid phases CdCl2·H2O, 9CdCl2·2ErCl3·29H2O , CdCl2·7ErCl3·42H2O, and ErCl3·6H2O. The two newcompounds, 9CdCl2· 2ErCl3·29H2O and CdCl2·7ErCl3·42H2O, have not yet been reported in literatures, and have been characterized by XRD, TG-DTG, and fluorescence spectra. Results showed that the two compounds have fluorescence and upconversion fluorescence, and their intensities increase with the ErCl3 ratio increasing in CdCl2. 9CdCl2·2ErCl3· 29H2O loses its crystal water by three steps in the temperature range from 55 to 215℃, while CdCl2·7ErCl3·42H2O loses its crystal water by one step in the temperature range from65 to 188C℃.
The equilibriumsolubility of the quaternary systemErCl3-CdCl2-HCl-H2O was determined at 298K and the corresponding equilibrium diagram was constructed. The quaternary system is complicated with four equilibrium solid phases CdCl2·H2O, 9CdCl2·2ErCl3·29H2O , CdCl2·7ErCl3·42H2O, and ErCl3·6H2O. The two newcompounds, 9CdCl2· 2ErCl3·29H2O and CdCl2·7ErCl3·42H2O, have not yet been reported in literatures, and have been characterized by XRD, TG-DTG, and fluorescence spectra. Results showed that the two compounds have fluorescence and upconversion fluorescence, and their intensities increase with the ErCl3 ratio increasing in CdCl2. 9CdCl2·2ErCl3· 29H2O loses its crystal water by three steps in the temperature range from 55 to 215℃, while CdCl2·7ErCl3·42H2O loses its crystal water by one step in the temperature range from65 to 188C℃.
2006, 22(05): 622-626
doi: 10.1016/S1872-1508(06)60023-5
Abstract:
Based on the conclusion that different complexes have distinctive chemo-physical characters at interfaces,a specific scoring function was designed to select the effective structures in protein-protein docking procedure for the Other-type protein complexes, which are hard to predict. This scoring function was composed of the atomic contact energy (EACE), van der Waals, and electrostatic interaction energies. The weight of each term was obtained by the multiple linear regression approach. The test result on 17 Other-type complexes from CAPRI benchmark1 demonstrated that the combinatorial scoring function could delineate the interaction feature of the Other-type complexes and reflect the energy change during the complex formation, and it has certain capacity of discriminating effective structures fromnumbers of the docked modes. Compared to the residue pair potential (RP), the combinatorial score could gain a higher success rate. Ranking the predicted models of two targets in CARPI round 8, the combinatorial score also exhibits greater potential to distinguish the effective association modes.
Based on the conclusion that different complexes have distinctive chemo-physical characters at interfaces,a specific scoring function was designed to select the effective structures in protein-protein docking procedure for the Other-type protein complexes, which are hard to predict. This scoring function was composed of the atomic contact energy (EACE), van der Waals, and electrostatic interaction energies. The weight of each term was obtained by the multiple linear regression approach. The test result on 17 Other-type complexes from CAPRI benchmark1 demonstrated that the combinatorial scoring function could delineate the interaction feature of the Other-type complexes and reflect the energy change during the complex formation, and it has certain capacity of discriminating effective structures fromnumbers of the docked modes. Compared to the residue pair potential (RP), the combinatorial score could gain a higher success rate. Ranking the predicted models of two targets in CARPI round 8, the combinatorial score also exhibits greater potential to distinguish the effective association modes.
2006, 22(05): 627-630
doi: 10.3866/PKU.WHXB20060521
Abstract:
Y2O3 nanoparticle /carbon nanotube composite has been prepared by chemical liquid deposition. Y2O3 nanoparticle /carbon nanotube composite obtained has been characterized by SEM and XPS. The results show that Y2O3 nanoparticles are supported well on the surface of carbon nanotube. The thermal decomposition of ammonium perchlorate (AP) in the presence of Y2O3 nanoparticle /carbon nanotube composite has been investigated by DTA. The results indicate that Y2O3 nanoparticle /carbon nanotube composite has a strong catalytic effect on the thermal decomposition of AP. In comparison with that of pure Y2O3 nanoparticles, the catalytic performance of Y2O3 nanoparticle /carbon nanotube composite is superior to that of pure Y2O3 nanoparticles. When the quantity of Y2O3 nanoparticle /carbon nanotube composite is 4%(w), the catalytic effect is the best, and the peak temperature of high temperature decomposition of AP by 131.14 C[deg].
Y2O3 nanoparticle /carbon nanotube composite has been prepared by chemical liquid deposition. Y2O3 nanoparticle /carbon nanotube composite obtained has been characterized by SEM and XPS. The results show that Y2O3 nanoparticles are supported well on the surface of carbon nanotube. The thermal decomposition of ammonium perchlorate (AP) in the presence of Y2O3 nanoparticle /carbon nanotube composite has been investigated by DTA. The results indicate that Y2O3 nanoparticle /carbon nanotube composite has a strong catalytic effect on the thermal decomposition of AP. In comparison with that of pure Y2O3 nanoparticles, the catalytic performance of Y2O3 nanoparticle /carbon nanotube composite is superior to that of pure Y2O3 nanoparticles. When the quantity of Y2O3 nanoparticle /carbon nanotube composite is 4%(w), the catalytic effect is the best, and the peak temperature of high temperature decomposition of AP by 131.14 C[deg].
2006, 22(05): 631-634
doi: 10.3866/PKU.WHXB20060522
Abstract:
The chemical composition, percolation performace, and microscopic configuration of“intramolecular cross鄄linked”gel systems were investigated by changing the contents of Na+, Ca2+, Mg2+ ions and polymer concentration in water solvent. The results show that the viscosity of“intramolecular cross-linked”polymer solution changes not too much with time, but the resistance factor and residual resistance factor are obviously larger than those of the ordinary polymer solution with the same viscosity, and the residual resistance factor is larger than the resistance factor. The contents of Na+, Ca2+ and Mg2+ ions and polymer concentrations will affect the molecular configuration of the cross-linked polymer, in which the effect of Ca2+ and Mg2+ is the largest.
The chemical composition, percolation performace, and microscopic configuration of“intramolecular cross鄄linked”gel systems were investigated by changing the contents of Na+, Ca2+, Mg2+ ions and polymer concentration in water solvent. The results show that the viscosity of“intramolecular cross-linked”polymer solution changes not too much with time, but the resistance factor and residual resistance factor are obviously larger than those of the ordinary polymer solution with the same viscosity, and the residual resistance factor is larger than the resistance factor. The contents of Na+, Ca2+ and Mg2+ ions and polymer concentrations will affect the molecular configuration of the cross-linked polymer, in which the effect of Ca2+ and Mg2+ is the largest.
2006, 22(05): 635-637
doi: 10.3866/PKU.WHXB20060523
Abstract:
In a three-electrode system, dimethylformamide (DMF) and tetrabutyl ammoniumperchlorate (TBAP) used as solvent and supporting electrolyte, Pt micro-disk as working electrode, Pt plate as auxiliary electrode, saturated calomel electrode as reference electrode, the electrochemical behavior of nitrobenzene were studied by mean of cyclic voltammetry. The effects of scan rate and reactant concentration on electrochemical characteristics of nitrobenzene were investigated systematically. It was shown that the ArNO2/ArNO[rad]-2 redox reaction of nitrobenzene on Pt micro-disk electrode was a reversible process with one transfer electron. The control step in this electrochemical process was attributed to the diffusion of nitrobenzene or its electrochemical reductive product.
In a three-electrode system, dimethylformamide (DMF) and tetrabutyl ammoniumperchlorate (TBAP) used as solvent and supporting electrolyte, Pt micro-disk as working electrode, Pt plate as auxiliary electrode, saturated calomel electrode as reference electrode, the electrochemical behavior of nitrobenzene were studied by mean of cyclic voltammetry. The effects of scan rate and reactant concentration on electrochemical characteristics of nitrobenzene were investigated systematically. It was shown that the ArNO2/ArNO[rad]-2 redox reaction of nitrobenzene on Pt micro-disk electrode was a reversible process with one transfer electron. The control step in this electrochemical process was attributed to the diffusion of nitrobenzene or its electrochemical reductive product.
2006, 22(05): 638-643
doi: 10.3866/PKU.WHXB20060524
Abstract:
In order to investigate the effect of cryoprotective agent(CPA) on the eutectic crystallization of salt solution,differential scanning calorimetry (DSC) is used to study the eutectic phenomena of NaCl aqueous solutions with different concentrations of glycerol, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, and dimethyl sulfoxide.It is found that the eutectic crystallization is a super-cooling and random process. Cryoprotective agent can restrain the eutectic crystallization of NaCl aqueous solutions. The higher the concentration of cryoprotective agents, the less the enthalpy of eutectic crystallization and the bigger the capability of restraining the eutectic crystallization. The restraining effects of cryoprotective agents on eutectic crystallization are different. The best is glycerol and then is ethylene glycol, 1,2-propylene glycol, and 1,3-propylene glycol, respectively. The restraining capability of alcohols is largely determined by the ratio of molecular weight to number of hydroxyl group, and affected by the number of methyl group as well. The capability of dimethyl sulfoxide to restrain the eutectic phenomena of NaCl aqueous solutions is similar to that of ethylene glycol. It is also found that the glass transition and devitrification phenomena take place during the heating process.
In order to investigate the effect of cryoprotective agent(CPA) on the eutectic crystallization of salt solution,differential scanning calorimetry (DSC) is used to study the eutectic phenomena of NaCl aqueous solutions with different concentrations of glycerol, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, and dimethyl sulfoxide.It is found that the eutectic crystallization is a super-cooling and random process. Cryoprotective agent can restrain the eutectic crystallization of NaCl aqueous solutions. The higher the concentration of cryoprotective agents, the less the enthalpy of eutectic crystallization and the bigger the capability of restraining the eutectic crystallization. The restraining effects of cryoprotective agents on eutectic crystallization are different. The best is glycerol and then is ethylene glycol, 1,2-propylene glycol, and 1,3-propylene glycol, respectively. The restraining capability of alcohols is largely determined by the ratio of molecular weight to number of hydroxyl group, and affected by the number of methyl group as well. The capability of dimethyl sulfoxide to restrain the eutectic phenomena of NaCl aqueous solutions is similar to that of ethylene glycol. It is also found that the glass transition and devitrification phenomena take place during the heating process.
2006, 22(05): 644-648
doi: 10.3866/PKU.WHXB20060525
Abstract:
Modified polystyrene microspheres with silver shells were prepared by a novel electroless plating approach using complexation mechanismof triethanolamine(TEA) and silver ion to reduce oxidation-reduction potential difference and slow down the deposition speed of silver on modified polystyrene spheres. These samples were characterized by TEM, UV, XRD, and the synthesis conditions were also investigated. Experimental results show that uniformsilver shells can be deposited on the modified polystyrene spheres by this method.
Modified polystyrene microspheres with silver shells were prepared by a novel electroless plating approach using complexation mechanismof triethanolamine(TEA) and silver ion to reduce oxidation-reduction potential difference and slow down the deposition speed of silver on modified polystyrene spheres. These samples were characterized by TEM, UV, XRD, and the synthesis conditions were also investigated. Experimental results show that uniformsilver shells can be deposited on the modified polystyrene spheres by this method.
