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2000 Volume 17 Issue 3
2000, 17(3): 233-237
Abstract:
Organic/inorganic hybrid materials poly(styrene-co-maleic anhydride)/tetra-ethylsilicate as a support for titanium catalysts have been used in ethylene polymerization. The structures of the supported catalysts have been studied by IR and XPS. The morphology and structure of the organic/inorganic hybrid materials have been investigated by DSC, SEM and TEM. The results show that the organic/inorganic hybrid supported catalysts only have a moderate activity for ethylene polymerization: 1.72×106 g/(h·mol), giving polydispersity of polyethylene about 4.0 and bulk density of 0.3~0.39 g/cm3.
Organic/inorganic hybrid materials poly(styrene-co-maleic anhydride)/tetra-ethylsilicate as a support for titanium catalysts have been used in ethylene polymerization. The structures of the supported catalysts have been studied by IR and XPS. The morphology and structure of the organic/inorganic hybrid materials have been investigated by DSC, SEM and TEM. The results show that the organic/inorganic hybrid supported catalysts only have a moderate activity for ethylene polymerization: 1.72×106 g/(h·mol), giving polydispersity of polyethylene about 4.0 and bulk density of 0.3~0.39 g/cm3.
2000, 17(3): 238-242
Abstract:
Solid materials Li3PO4, FePO4 and 5% Li3PO4·FePO4 were prepared by a method of precipitation. The behavior of laser stimulated oxidative coupling of methanol to ethandiol on these materials have been studied by XRD, IR, TPD techniques and laser stimulated surface reaction(LSSR). The results showed that there are two kinds of methanol adsorption on the solid surfaces: molecular adsorption of C-H site of CH3OH on P=O bonds of catalysts and dissociation adsorption of CH2OH radicals on Lewis acid sites of metal. The adsorption types were depended on the interaction between Li3PO4 and FePO4. Selective excitation of the surface P=O bonds by 1077 cm-1 laser photon caused the activation of surface lattice oxygen,which on reacting with adsorbed CH3OH and dehydrogenating it to CH2OH led to oxidative coupling of CH2OH to ethandiol on Lewis acid sites. Increase of the reaction temperature had the effects of replenishing the energy density of laser photon and promoting the desorption of the products. It also caused thermal reactions with formation of by products, e.g. dimethyl ether, formaldehyde and ethylene.
Solid materials Li3PO4, FePO4 and 5% Li3PO4·FePO4 were prepared by a method of precipitation. The behavior of laser stimulated oxidative coupling of methanol to ethandiol on these materials have been studied by XRD, IR, TPD techniques and laser stimulated surface reaction(LSSR). The results showed that there are two kinds of methanol adsorption on the solid surfaces: molecular adsorption of C-H site of CH3OH on P=O bonds of catalysts and dissociation adsorption of CH2OH radicals on Lewis acid sites of metal. The adsorption types were depended on the interaction between Li3PO4 and FePO4. Selective excitation of the surface P=O bonds by 1077 cm-1 laser photon caused the activation of surface lattice oxygen,which on reacting with adsorbed CH3OH and dehydrogenating it to CH2OH led to oxidative coupling of CH2OH to ethandiol on Lewis acid sites. Increase of the reaction temperature had the effects of replenishing the energy density of laser photon and promoting the desorption of the products. It also caused thermal reactions with formation of by products, e.g. dimethyl ether, formaldehyde and ethylene.
2000, 17(3): 243-247
Abstract:
The solubility properties of ZnSO4-Val-H2O system in the whole concentration range were investigated by a phase equilibrium method. The results indicate that it is a simple system, there is not any new compound there. Compounds Zn(Val)SO4·H2O and Zn(Val)2·H2O have been prepared and characterized.
The solubility properties of ZnSO4-Val-H2O system in the whole concentration range were investigated by a phase equilibrium method. The results indicate that it is a simple system, there is not any new compound there. Compounds Zn(Val)SO4·H2O and Zn(Val)2·H2O have been prepared and characterized.
2000, 17(3): 248-251
Abstract:
Nanosized iron particles have been prepared by W/O microemulsion method. The XRD, SEM, TEM and IR results show that the ultrafine particles are coated surfactants and have following properties: average size about 120 nm, density about 3.00 g/cm3, specific saturation magnetization es=92.4 Am2/kg, residual magnetism r=3.89 Am2/kg, coercive force He=4218.8 A/m. The magneto-rheological fluid prepared from the ultrafine iron particles have good magneto-rheological property and subsidence stability.
Nanosized iron particles have been prepared by W/O microemulsion method. The XRD, SEM, TEM and IR results show that the ultrafine particles are coated surfactants and have following properties: average size about 120 nm, density about 3.00 g/cm3, specific saturation magnetization es=92.4 Am2/kg, residual magnetism r=3.89 Am2/kg, coercive force He=4218.8 A/m. The magneto-rheological fluid prepared from the ultrafine iron particles have good magneto-rheological property and subsidence stability.
2000, 17(3): 252-255
Abstract:
A fume silica-bound poly-V-(p-diphenylphosphinophenyl)propylsiloxane palladium(Ⅱ) complex was synthesized from 4-bromo-4-allylbenzene via hydrosilylation with triethoxysilane in the presence of tetrakis(triphenylphosphine)platinum complex as catalyst, phosphatization with potassium diphenylphosphide, sequentially, followed by immobilization on fume silica and reaction with palladium chloride. The title complex exhibited good catalytic activity in Heck carbonylation of aryl halides with aniline or butyl alcohol and can be used repeatedly without serious loss of activity. A possible structure pattern of the polymeric palladium complex has been suggested.
A fume silica-bound poly-V-(p-diphenylphosphinophenyl)propylsiloxane palladium(Ⅱ) complex was synthesized from 4-bromo-4-allylbenzene via hydrosilylation with triethoxysilane in the presence of tetrakis(triphenylphosphine)platinum complex as catalyst, phosphatization with potassium diphenylphosphide, sequentially, followed by immobilization on fume silica and reaction with palladium chloride. The title complex exhibited good catalytic activity in Heck carbonylation of aryl halides with aniline or butyl alcohol and can be used repeatedly without serious loss of activity. A possible structure pattern of the polymeric palladium complex has been suggested.
2000, 17(3): 256-259
Abstract:
Squalane has been used as a simulated substrate to investigate the reaction mechanism of maleic anhydride in grafting onto ethylene-propylene copolymer in the presence of a peroxide initiator. Mass spectrometric analysis shows the products contain both poly(maleic anhydride) and squalane grafted maleic anhydride. This result indicates that instead of 150℃, the ceiling polymerization temperature of maleic anhydride as suggested by Gaylo rd, maleic anhydride can form short chain homopolymer even at 170℃, the reaction tempe rature used in this paper, in case of V(sq): W (MA): W (init)=100:2:0.2. 13C NMR study shows that maleic anhydride can be grafted onto both methine carbons and methylene carbons of squalane, but the amount of maleic anhydride grafted onto methine carbons is greater than that onto methylene carbons. Most maleic anhydride are grafted onto squalane in form of single unit due to the inter-and intramolecular hydrogen transfer.
Squalane has been used as a simulated substrate to investigate the reaction mechanism of maleic anhydride in grafting onto ethylene-propylene copolymer in the presence of a peroxide initiator. Mass spectrometric analysis shows the products contain both poly(maleic anhydride) and squalane grafted maleic anhydride. This result indicates that instead of 150℃, the ceiling polymerization temperature of maleic anhydride as suggested by Gaylo rd, maleic anhydride can form short chain homopolymer even at 170℃, the reaction tempe rature used in this paper, in case of V(sq): W (MA): W (init)=100:2:0.2. 13C NMR study shows that maleic anhydride can be grafted onto both methine carbons and methylene carbons of squalane, but the amount of maleic anhydride grafted onto methine carbons is greater than that onto methylene carbons. Most maleic anhydride are grafted onto squalane in form of single unit due to the inter-and intramolecular hydrogen transfer.
2000, 17(3): 260-263
Abstract:
Four cationic meso-tetrakis(4-N-pyridyl)porphyrin derivatives 5,10,15,20 tetra kis (4-N-benzylpyridyl)porphyrin(H2TBPyP), 5,10,15,20-tetrakis(4-N-propylpyridyl)porphyrin(H2TPPyP), 5,10,15,20 tetrakis(4-N-ethylpyridyl)porphyrin(H2TEPyP), 5,10,15,20-tetrakis(4-N-methylpyridyl)porphyrin(H2TMPyP), and their cobalt complexes have been synthesized. Some of the porphyrin compounds were characterized by elemental analysis, matrix-assisted laser desorption/ionization time of flight-mass spectrometry(MALDI-TOF-MS), UV-Vis, FTIR, 1H NMR and cyclic voltammetry.
Four cationic meso-tetrakis(4-N-pyridyl)porphyrin derivatives 5,10,15,20 tetra kis (4-N-benzylpyridyl)porphyrin(H2TBPyP), 5,10,15,20-tetrakis(4-N-propylpyridyl)porphyrin(H2TPPyP), 5,10,15,20 tetrakis(4-N-ethylpyridyl)porphyrin(H2TEPyP), 5,10,15,20-tetrakis(4-N-methylpyridyl)porphyrin(H2TMPyP), and their cobalt complexes have been synthesized. Some of the porphyrin compounds were characterized by elemental analysis, matrix-assisted laser desorption/ionization time of flight-mass spectrometry(MALDI-TOF-MS), UV-Vis, FTIR, 1H NMR and cyclic voltammetry.
2000, 17(3): 264-267
Abstract:
Some solid bases Zr(HPO4)2-x [O3PCH2CH2N(CH3)2]x·H2O-NaOH were prepared by treating zirconium dimethylaminoethyl phosphonate-phosphate supporter with 5% NaOH solution and characterized by elemental analysis, IR, TG DTG, DTA and BET surface area measurements. The base strengths of the solid bases were of 9.3~15.0, which corresponded to that of solid sodium carbonate. Their base numbers were measured by benzoic acid titration method to be in dependence with x value. The influences of the x value, temperature keeping time in the preparation of the supporter were studied. The solid bases showed high catalytic activity in typical Knoevenagel condensation reaction in high product yields and little side reactions. The solid base catalysts can be reused for 6 to 7 times and easily regenerated.
Some solid bases Zr(HPO4)2-x [O3PCH2CH2N(CH3)2]x·H2O-NaOH were prepared by treating zirconium dimethylaminoethyl phosphonate-phosphate supporter with 5% NaOH solution and characterized by elemental analysis, IR, TG DTG, DTA and BET surface area measurements. The base strengths of the solid bases were of 9.3~15.0, which corresponded to that of solid sodium carbonate. Their base numbers were measured by benzoic acid titration method to be in dependence with x value. The influences of the x value, temperature keeping time in the preparation of the supporter were studied. The solid bases showed high catalytic activity in typical Knoevenagel condensation reaction in high product yields and little side reactions. The solid base catalysts can be reused for 6 to 7 times and easily regenerated.
2000, 17(3): 268-271
Abstract:
The synthesis and thermal degradability of poly(DL-lactide) were investigated. Key factors affecting the polymer molecular weight were found to be monomer purity, initator concentration and the vacuum and drying levels during sealing of the polymerization reaction ampoule. DSC and TGA were used to study the glass transition temperature and the thermal decomposition. It was found that poly(DL-lactide) is a thermal unstable polymer. Polymer precipitation can reduce the residual of monomer, initiator and oligomer and significantly lower the rate and extent of thermal degradation.
The synthesis and thermal degradability of poly(DL-lactide) were investigated. Key factors affecting the polymer molecular weight were found to be monomer purity, initator concentration and the vacuum and drying levels during sealing of the polymerization reaction ampoule. DSC and TGA were used to study the glass transition temperature and the thermal decomposition. It was found that poly(DL-lactide) is a thermal unstable polymer. Polymer precipitation can reduce the residual of monomer, initiator and oligomer and significantly lower the rate and extent of thermal degradation.
2000, 17(3): 272-275
Abstract:
In the course of cis-copolymerization of butadiene(BD) with isoprene(IP) by using Nd(naph)3-Al(C2H5)3-(t-C4H9)Cl as catalyst in toluene, tert-butylchloride or allyl chloride was added to give a soluble, gel-free cyclized copolymer. Some parameters affecting the cyclization were investigated. The preliminary results of IR, 1H NMR analyses confirmed the cyclization of both BD and IP units and that the IP units were cyclized in a greater extent than BD units.
In the course of cis-copolymerization of butadiene(BD) with isoprene(IP) by using Nd(naph)3-Al(C2H5)3-(t-C4H9)Cl as catalyst in toluene, tert-butylchloride or allyl chloride was added to give a soluble, gel-free cyclized copolymer. Some parameters affecting the cyclization were investigated. The preliminary results of IR, 1H NMR analyses confirmed the cyclization of both BD and IP units and that the IP units were cyclized in a greater extent than BD units.
2000, 17(3): 276-279
Abstract:
The ZrO2-Al2O3 supports were prepared by the decomposition-precipitation method. The sulfur-tolerant water-gas shift Co-Mo-K catalysts were prepared by impregnation. The effects of ZrO2-Al2O3 support on the activity and thermal stability of Co-Mo-K catalyst have been studied through activity evaluation. Using BET, XRD, TG and XPS techniques the structures of the supports and catalysts, the reduction property, sulfur and water adsorbabilities of the catalysts have been investigated. The results show that the ZrO2-Al2O3 supported Co-Mo-K catalysts exhibit a high activity, especially at low temperatures. The conversion of CO could reach up to 72.8% at 250℃ over the Z8 catalyst, being 25% higher than that over V-Al2O3 supported catalyst. The thermal stability, water and sulfur adsorbab ility and reduction property of the catalyst are all found improved on the ZrO2-Al2O3 support.
The ZrO2-Al2O3 supports were prepared by the decomposition-precipitation method. The sulfur-tolerant water-gas shift Co-Mo-K catalysts were prepared by impregnation. The effects of ZrO2-Al2O3 support on the activity and thermal stability of Co-Mo-K catalyst have been studied through activity evaluation. Using BET, XRD, TG and XPS techniques the structures of the supports and catalysts, the reduction property, sulfur and water adsorbabilities of the catalysts have been investigated. The results show that the ZrO2-Al2O3 supported Co-Mo-K catalysts exhibit a high activity, especially at low temperatures. The conversion of CO could reach up to 72.8% at 250℃ over the Z8 catalyst, being 25% higher than that over V-Al2O3 supported catalyst. The thermal stability, water and sulfur adsorbab ility and reduction property of the catalyst are all found improved on the ZrO2-Al2O3 support.
2000, 17(3): 280-283
Abstract:
Eleven rare earth complexes with bis-schiff base ligand(L) derived from N,N' bis[(1-phenyl-3-methyl-5-hydroxy pyrazolinyl-4)2-thenoylmethylidyne]ethylenediimine have been synthesized. The general formula of the complexes was characterized to be [REL(NO3)2]NO3, (RE=La,Pr,Nd,Sm,Eu,Tb,Dy,Ho,Er,Yb,Y) by IR, UV-Vis, 1H NMR, 13C NMR and fluorescence spectroscopy measurements. The antibacterial tests indicated they have high antibacterial activities against S.aureus, B.subtillis, E.coli, E.carotovora and C.flaccumfaciens.
Eleven rare earth complexes with bis-schiff base ligand(L) derived from N,N' bis[(1-phenyl-3-methyl-5-hydroxy pyrazolinyl-4)2-thenoylmethylidyne]ethylenediimine have been synthesized. The general formula of the complexes was characterized to be [REL(NO3)2]NO3, (RE=La,Pr,Nd,Sm,Eu,Tb,Dy,Ho,Er,Yb,Y) by IR, UV-Vis, 1H NMR, 13C NMR and fluorescence spectroscopy measurements. The antibacterial tests indicated they have high antibacterial activities against S.aureus, B.subtillis, E.coli, E.carotovora and C.flaccumfaciens.
2000, 17(3): 284-287
Abstract:
The influences of vapor on the oxidative dehydrogenation of ethane(ODHE) to ethylene over promoted Mn-Na2WO4/SiO2 catalyst have been investigated. The results indi cate that the presence of vapor is favorable for catalyst to increase the ethylene selectivity. Ethylene in yield up to 52% is obtained under conditions of: V (C2H6): V (O2): V (H2O, g)= 1:0.65:3.8, GHSV=1600 h-1, 740℃ with 10 mL catalyst. Excess vapor caused the catalyst selectivity to be decreased. The results are discussed in terms of destruction of W-O-Si species and phase transformation based on the XRD and XPS measurements.
The influences of vapor on the oxidative dehydrogenation of ethane(ODHE) to ethylene over promoted Mn-Na2WO4/SiO2 catalyst have been investigated. The results indi cate that the presence of vapor is favorable for catalyst to increase the ethylene selectivity. Ethylene in yield up to 52% is obtained under conditions of: V (C2H6): V (O2): V (H2O, g)= 1:0.65:3.8, GHSV=1600 h-1, 740℃ with 10 mL catalyst. Excess vapor caused the catalyst selectivity to be decreased. The results are discussed in terms of destruction of W-O-Si species and phase transformation based on the XRD and XPS measurements.
2000, 17(3): 288-291
Abstract:
The Perkin method for coumarin synthesis from salicylaldehyde and acetic anhydride has been improved by using calcium acetate as catalyst and polyethylene glycol as activator. The influences of the catalyst, activator, acetic anhydride and thermostatic reaction temperature and time on the yield of coumarin were studied. The yield of coumarin could be reached up to 86.6% with lower consumption of acetic anhydride in case the total molar ratio of acetic anhydride to salicylaldehyde=1.9:1 and the reaction was kept 0.5 h at 212~216℃ when the reaction was close to the end.
The Perkin method for coumarin synthesis from salicylaldehyde and acetic anhydride has been improved by using calcium acetate as catalyst and polyethylene glycol as activator. The influences of the catalyst, activator, acetic anhydride and thermostatic reaction temperature and time on the yield of coumarin were studied. The yield of coumarin could be reached up to 86.6% with lower consumption of acetic anhydride in case the total molar ratio of acetic anhydride to salicylaldehyde=1.9:1 and the reaction was kept 0.5 h at 212~216℃ when the reaction was close to the end.
2000, 17(3): 292-295
Abstract:
The propylene polymerization in the presence of monocyclopentadienyltitanium compound and methylaluminoxane(MAO) carried out in an autoclave. The effect of different solvents on the propylene polymerization was compared. With the raise of n(Al)/n(Ti) ratio, the activity of the catalyst increased firstly and then decreased, but the molecular weight of PP was independent of it. The catalytic activity increased linearly with monomer pressure, while the molecular weight of the polymer decreased slightly with an increase in monomer pressure. The products were characterized by 13C NMR, DSC and tensile strength measurement. The high molecular weight atactic polypropylene had a good elasticity.
The propylene polymerization in the presence of monocyclopentadienyltitanium compound and methylaluminoxane(MAO) carried out in an autoclave. The effect of different solvents on the propylene polymerization was compared. With the raise of n(Al)/n(Ti) ratio, the activity of the catalyst increased firstly and then decreased, but the molecular weight of PP was independent of it. The catalytic activity increased linearly with monomer pressure, while the molecular weight of the polymer decreased slightly with an increase in monomer pressure. The products were characterized by 13C NMR, DSC and tensile strength measurement. The high molecular weight atactic polypropylene had a good elasticity.
2000, 17(3): 296-299
Abstract:
Trace nickel in waste solution from process of diamond cleaning by acid is determined by second order differential simple oscillographic voltammetry. The results show that in 0.20 mol/L NH4Ac-0.005 mol/L KNO3-0.02% diacetyldioxime solution the peak height of the oscillogram depends linearly on the concentration of Ni2+ ranged from 3×10-7 to 3.5×10-6mol/L. The regressive equation is Y=0.3583+1.365×105c(Ni2+) (mol/L). r=0.9970. The detection limit is 6×10-8mol/L. The method is simple, rapid and sensitive.
Trace nickel in waste solution from process of diamond cleaning by acid is determined by second order differential simple oscillographic voltammetry. The results show that in 0.20 mol/L NH4Ac-0.005 mol/L KNO3-0.02% diacetyldioxime solution the peak height of the oscillogram depends linearly on the concentration of Ni2+ ranged from 3×10-7 to 3.5×10-6mol/L. The regressive equation is Y=0.3583+1.365×105c(Ni2+) (mol/L). r=0.9970. The detection limit is 6×10-8mol/L. The method is simple, rapid and sensitive.
2000, 17(3): 300-303
Abstract:
The synthesis of potassium hexafluoronickelate(Ⅳ) on the condition of high temperature and high pressure and its decomposition at high temperature have been studied. The result showed that fluorine gas can be quickly absorbed by a mixture of potassium fluoride and nickel fluoride at temperature above 225℃ and pressure of about 2.0 MPa. The FT-IR spectra and Raman spectra verified the formation of potassium hexafluoronickelate(Ⅳ). When the temperature is raised to 250℃, potassium hexafluoronickelate(Ⅳ) will be decomposed to produce fluorine gas with a pressure reaching to 620 kPa at 350℃. The purity of fluorine is higher than 99%. It is suggested that potassium hexafluoronickelate(Ⅳ) can be used as a fluorine source.
The synthesis of potassium hexafluoronickelate(Ⅳ) on the condition of high temperature and high pressure and its decomposition at high temperature have been studied. The result showed that fluorine gas can be quickly absorbed by a mixture of potassium fluoride and nickel fluoride at temperature above 225℃ and pressure of about 2.0 MPa. The FT-IR spectra and Raman spectra verified the formation of potassium hexafluoronickelate(Ⅳ). When the temperature is raised to 250℃, potassium hexafluoronickelate(Ⅳ) will be decomposed to produce fluorine gas with a pressure reaching to 620 kPa at 350℃. The purity of fluorine is higher than 99%. It is suggested that potassium hexafluoronickelate(Ⅳ) can be used as a fluorine source.
2000, 17(3): 304-306
Abstract:
The Li4SiO4 has been prepared by the sol-gel method and characterized by IR, DTA, TG, XRD, SEM and AC impedance measurements. The results showed that in comparison with the solid-state method Li4SiO4 could be obtained by sol-gel method at lower temperature and the products exhibited smaller particle size and higher ionic conductivity.
The Li4SiO4 has been prepared by the sol-gel method and characterized by IR, DTA, TG, XRD, SEM and AC impedance measurements. The results showed that in comparison with the solid-state method Li4SiO4 could be obtained by sol-gel method at lower temperature and the products exhibited smaller particle size and higher ionic conductivity.
2000, 17(3): 307-309
Abstract:
The ion-exchangers of H2TiO3 type for Li+ were prepared from TiO2 and Li2CO3(or LiOH), followed by calcinating at 400~800℃. The ion-exchangers showed an unusual high selectivity for Li+ in mixtures of alkali metal and alkaline earth metal ions. The exchange capacity for Li+ was 25.34 mg/g. The selectivity order was Li+>>Mg2+ > Ca2+ > Na+,K+. Being applied in brine of a local natural gas well, an exchange rate and elution rate for Li+ up to 97% and 98%, respectively, were achieved.
The ion-exchangers of H2TiO3 type for Li+ were prepared from TiO2 and Li2CO3(or LiOH), followed by calcinating at 400~800℃. The ion-exchangers showed an unusual high selectivity for Li+ in mixtures of alkali metal and alkaline earth metal ions. The exchange capacity for Li+ was 25.34 mg/g. The selectivity order was Li+>>Mg2+ > Ca2+ > Na+,K+. Being applied in brine of a local natural gas well, an exchange rate and elution rate for Li+ up to 97% and 98%, respectively, were achieved.
2000, 17(3): 310-312
Abstract:
The particles of Ml(NiCuAlZn)5 hydrogen storage alloy (Ml denotes La-rich rare earth mixture) were encapsulated with copper in sulfuric acid solution of CuSO4. The discharge characteristics of the alloy were improved, especially at high discharge rates. The XRD analysis indicated that the crystal structure of Ml(NiCuAlZn)5 remained unchanged in encapsulation. The SEM images showed that copper encapsulation effectively improved the corrosion resistance of the alloy.
The particles of Ml(NiCuAlZn)5 hydrogen storage alloy (Ml denotes La-rich rare earth mixture) were encapsulated with copper in sulfuric acid solution of CuSO4. The discharge characteristics of the alloy were improved, especially at high discharge rates. The XRD analysis indicated that the crystal structure of Ml(NiCuAlZn)5 remained unchanged in encapsulation. The SEM images showed that copper encapsulation effectively improved the corrosion resistance of the alloy.
2000, 17(3): 313-315
Abstract:
The selective oxidation of propane over vanadium-phosphorus oxide(VPO) catalyst has been investigated by using chromatography in a pulse reactor. The results showed that it is the lattice oxygen that oxidizes propane to form acrylic acid and acetic acid. This mechanism was also supported by TPD and XPS data. It is concluded that the oxidation of propane takes place on the surface of the catalyst according to Mars-van Krevelen mechani sm, so that it could be implemented in a circulating fluidized bed(CFB) riser reactor. The re oxidation of VPO catslyst is found to be the rate-controlling step in the oxidation reaction.
The selective oxidation of propane over vanadium-phosphorus oxide(VPO) catalyst has been investigated by using chromatography in a pulse reactor. The results showed that it is the lattice oxygen that oxidizes propane to form acrylic acid and acetic acid. This mechanism was also supported by TPD and XPS data. It is concluded that the oxidation of propane takes place on the surface of the catalyst according to Mars-van Krevelen mechani sm, so that it could be implemented in a circulating fluidized bed(CFB) riser reactor. The re oxidation of VPO catslyst is found to be the rate-controlling step in the oxidation reaction.
2000, 17(3): 316-318
Abstract:
The nanosized PbO was selected for pH-sensitive material and a screen printed technique was used to fabricate the solid pH electrode. Such an electrode showed a linear response in the pH range of 2~13 with response sensitivity of -64.3 mV/pH. It exhibited even more satisfied pH-response performance in corrosion medium containing HF.
The nanosized PbO was selected for pH-sensitive material and a screen printed technique was used to fabricate the solid pH electrode. Such an electrode showed a linear response in the pH range of 2~13 with response sensitivity of -64.3 mV/pH. It exhibited even more satisfied pH-response performance in corrosion medium containing HF.
2000, 17(3): 319-321
Abstract:
The catalytic decomposition of dichlorodifluoromethane(CFC-12) in the presence of water vapour has been carried out on WO3/Al2O3 prepared by impregnating Al(OH)3 with aqueous ammonium metatungstate followed by drying and calcining at 700℃ in air. On WO3/Al2O3 CFC-12 was decomposed completely at 305℃, while on simple Al2O3 it needed 370℃; WO3 had only a poor activity. NH3-TPD results showed that this enhancement in activity can be explained in terms of the great acidity of WO3/Al2O3. No by-product was detected during decomposition of CFC-12 on WO3/Al2O3, but on unmodified Al2O3 CFC-13 was found to be amounted to 4%. The CFC-12 conversion over WO3/Al2O3 at 295℃ decreased from 97% to 90% in first 8 h and then took a steady value.
The catalytic decomposition of dichlorodifluoromethane(CFC-12) in the presence of water vapour has been carried out on WO3/Al2O3 prepared by impregnating Al(OH)3 with aqueous ammonium metatungstate followed by drying and calcining at 700℃ in air. On WO3/Al2O3 CFC-12 was decomposed completely at 305℃, while on simple Al2O3 it needed 370℃; WO3 had only a poor activity. NH3-TPD results showed that this enhancement in activity can be explained in terms of the great acidity of WO3/Al2O3. No by-product was detected during decomposition of CFC-12 on WO3/Al2O3, but on unmodified Al2O3 CFC-13 was found to be amounted to 4%. The CFC-12 conversion over WO3/Al2O3 at 295℃ decreased from 97% to 90% in first 8 h and then took a steady value.
2000, 17(3): 322-324
Abstract:
Cobalt titanate and gallium titanate zeolites were synthesized hydrothermally using tetraethylammonium hydroxide and/or tetrapropylammonium bromide as template. The study of the effects of pH value, amount and feed order of template and reaction time on the products indicated that the most important factor was the pH value of the reaction medium, which must be in between 2 to 6 to give zeolite crystals. The products have been characterized by XRD, SEM, DTA, IR, UV-Vis and N2 adsorption techniques to be microporous zeolites, where Ti atoms are in complexation forms of TiO4 and TiO6. The Co titanate and Ga titanate zeolites had specific area of 263 and 204 m2/g, respectively.
Cobalt titanate and gallium titanate zeolites were synthesized hydrothermally using tetraethylammonium hydroxide and/or tetrapropylammonium bromide as template. The study of the effects of pH value, amount and feed order of template and reaction time on the products indicated that the most important factor was the pH value of the reaction medium, which must be in between 2 to 6 to give zeolite crystals. The products have been characterized by XRD, SEM, DTA, IR, UV-Vis and N2 adsorption techniques to be microporous zeolites, where Ti atoms are in complexation forms of TiO4 and TiO6. The Co titanate and Ga titanate zeolites had specific area of 263 and 204 m2/g, respectively.
2000, 17(3): 325-327
Abstract:
Title polymeric complex(EPU-Eu(Ⅲ)) was obtained from triisobutoxy euro-pium Eu(C3H7O)3 with electropolyurushiol in isobutyl alcohol. The structure and property of the complex were characterized by FT-IR, XPS, DMTA, AES, TG-DTA and fluorescence spectrophotometry. The complex with Eu(Ⅲ) content reached up to 9.6% was insoluble in most organic solvents. Its electric resistance was 1.25×105 MΩ(that of EPU was 7.90×104 MΩ). Its Tg and thermal resistance was considerably greater than that of EPU.
Title polymeric complex(EPU-Eu(Ⅲ)) was obtained from triisobutoxy euro-pium Eu(C3H7O)3 with electropolyurushiol in isobutyl alcohol. The structure and property of the complex were characterized by FT-IR, XPS, DMTA, AES, TG-DTA and fluorescence spectrophotometry. The complex with Eu(Ⅲ) content reached up to 9.6% was insoluble in most organic solvents. Its electric resistance was 1.25×105 MΩ(that of EPU was 7.90×104 MΩ). Its Tg and thermal resistance was considerably greater than that of EPU.
2000, 17(3): 328-330
Abstract:
Nine N, N'-diacyl adipic dihydrazides were synthesized. The compounds all exhibited remarkable inhibiting effects on the aging of polypropylene (PP) contacted with copper and their metal deactivation activity was increased with increase in their molecular weight. They didn't reduce the mechanical property of PP. The most effective were N, N'-dihexanoyl adipic dihydrazide and N, N'-dioctanoyl adipic dihydra zide. At 150℃ their aging periods for PP film were ov er 510 hours.
Nine N, N'-diacyl adipic dihydrazides were synthesized. The compounds all exhibited remarkable inhibiting effects on the aging of polypropylene (PP) contacted with copper and their metal deactivation activity was increased with increase in their molecular weight. They didn't reduce the mechanical property of PP. The most effective were N, N'-dihexanoyl adipic dihydrazide and N, N'-dioctanoyl adipic dihydra zide. At 150℃ their aging periods for PP film were ov er 510 hours.
2000, 17(3): 331-333
Abstract:
The corrosion resistance behavior of silane agents(SA) for iron based substrate have been studied. A series of detection methods were used simutaneously for effective analysis and monitoring the hydrolysis process of SA films. It consists of the on-line FTIR spectroscopy, conductivity measurement, XPS(for structure and component analysis), elliptical spectroscopy(for film thickness analysis) and electrochemical method(for corrosion examination). The results showed that the rational thickness of the SA films was about 82 nm and there were chemical bondings between the iron substrate and SA film, which produces a large amount of silanols in hydrolysis.
The corrosion resistance behavior of silane agents(SA) for iron based substrate have been studied. A series of detection methods were used simutaneously for effective analysis and monitoring the hydrolysis process of SA films. It consists of the on-line FTIR spectroscopy, conductivity measurement, XPS(for structure and component analysis), elliptical spectroscopy(for film thickness analysis) and electrochemical method(for corrosion examination). The results showed that the rational thickness of the SA films was about 82 nm and there were chemical bondings between the iron substrate and SA film, which produces a large amount of silanols in hydrolysis.
2000, 17(3): 334-336
Abstract:
Two polym eric chelates of 8-dihydroxyquinoline synthesized from biquinoline monomer with zinc acetate and copper acetate, respectively, are reported. The effects of reactant amount, reaction time on the yield of products have been studied. The IR and photoluminescence(PL) emission spectra of monomer and chelates have been recorded. The uniform films of polymerica zobenzolbiquino line metal chelates were self-assembled on hydroxy-functional surfaces by alternately dipping in DMF solution of metal acetate and monomer.
Two polym eric chelates of 8-dihydroxyquinoline synthesized from biquinoline monomer with zinc acetate and copper acetate, respectively, are reported. The effects of reactant amount, reaction time on the yield of products have been studied. The IR and photoluminescence(PL) emission spectra of monomer and chelates have been recorded. The uniform films of polymerica zobenzolbiquino line metal chelates were self-assembled on hydroxy-functional surfaces by alternately dipping in DMF solution of metal acetate and monomer.
2000, 17(3): 337-339
Abstract:
A series of trifluorovinyl aryl ethers were synthesized by dehalogenation of 2-bromo-1,1,2, 2-tetrafluoroethyl aryl ethers which were prepared from the reaction of the corresponding phenoxides with 1,2-dibromo-1,1,2,2-tetrafluoroethane in tetraglyme.
A series of trifluorovinyl aryl ethers were synthesized by dehalogenation of 2-bromo-1,1,2, 2-tetrafluoroethyl aryl ethers which were prepared from the reaction of the corresponding phenoxides with 1,2-dibromo-1,1,2,2-tetrafluoroethane in tetraglyme.
2000, 17(3): 340-342
Abstract:
The single crystal of GdP5O14:Sm3+,Pr3+ (GdPP:Sm,Pr) was grown by the hydrothermal method. The crystal belongs to the monoclinic space group P21/C by X-ray powder diffraction results. The dependence of Pr3+ ion concentration in GdPP:Sm,Pr crystals on the emission intensity of 4G5/2→6H7/2 transitions of Sm3+ ion and the energy transfer between Sm3+ and Pr3+ ions have been investigated and discussed.
The single crystal of GdP5O14:Sm3+,Pr3+ (GdPP:Sm,Pr) was grown by the hydrothermal method. The crystal belongs to the monoclinic space group P21/C by X-ray powder diffraction results. The dependence of Pr3+ ion concentration in GdPP:Sm,Pr crystals on the emission intensity of 4G5/2→6H7/2 transitions of Sm3+ ion and the energy transfer between Sm3+ and Pr3+ ions have been investigated and discussed.
2000, 17(3): 343-345
Abstract:
LaFeO3 nanocrystals were synthesized by both citric acid and microemulsion methods. Their structures, sizes and morphologies were investigated by XRD and TEM. All the LaFeO3 obtained showed catalytic activity in decolorization of some organic dyes under irradiation of mercury lamp.
LaFeO3 nanocrystals were synthesized by both citric acid and microemulsion methods. Their structures, sizes and morphologies were investigated by XRD and TEM. All the LaFeO3 obtained showed catalytic activity in decolorization of some organic dyes under irradiation of mercury lamp.
2000, 17(3): 346-348
Abstract:
The 7-(phenylacetamido)deacetoxycephalosporin acid was prepared by ring expansion of penicillin G sulfoxide via its trimethylsiliated intermediate(protective silylation with N,N'-dimethylsilylurea) using HBr-4-methylpyridine as catalyst. The effects of catal-yst amount, reaction temperature and time were examined. Under optimum reaction condi tions product in 94% yield was obtained. The product has been characterized by IR and MS.
The 7-(phenylacetamido)deacetoxycephalosporin acid was prepared by ring expansion of penicillin G sulfoxide via its trimethylsiliated intermediate(protective silylation with N,N'-dimethylsilylurea) using HBr-4-methylpyridine as catalyst. The effects of catal-yst amount, reaction temperature and time were examined. Under optimum reaction condi tions product in 94% yield was obtained. The product has been characterized by IR and MS.
