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1994 Volume 11 Issue 4
1994, 11(4): 1-7
Abstract:
Porous silicon (PS) is a kind of new material which has great potential applications in developing super large scale integrated circuits and all silicon optointergrated circuits,In this paper,different formation conditions of PS are reviewed,and the latest developments of the research on its physical and chemical properties and formation mechanism ar epresented.Applications in manufacturing PS Iight emitting devices and other fields are discussed.
Porous silicon (PS) is a kind of new material which has great potential applications in developing super large scale integrated circuits and all silicon optointergrated circuits,In this paper,different formation conditions of PS are reviewed,and the latest developments of the research on its physical and chemical properties and formation mechanism ar epresented.Applications in manufacturing PS Iight emitting devices and other fields are discussed.
1994, 11(4): 8-13
Abstract:
Recent progress in the researches of chemical reactions of C60 is reviewed with emphasis on the addition reactions,such as halogenation,reactions with nitrenes and carbenes,cycloaddition,and addition through free radicals.
Recent progress in the researches of chemical reactions of C60 is reviewed with emphasis on the addition reactions,such as halogenation,reactions with nitrenes and carbenes,cycloaddition,and addition through free radicals.
1994, 11(4): 14-20
Abstract:
ecent advances in research on polyimide LB films is reviewed,including the preparation methods,structures,and applications of polyimide LB films.
ecent advances in research on polyimide LB films is reviewed,including the preparation methods,structures,and applications of polyimide LB films.
1994, 11(4): 21-24
Abstract:
Eight title compounds were synthesized by condensation of substituted phenoxy acetyl chlorides and α-hydroxy alkyl phosphonates.Their structures were characterized by elemental analysis,IR,1H NMR,31P NMR measurements and their herbicidal activities and plant growth regularing activities were tested.Some of them (Ig,Ic,Id,Ih,and Ii) were found to exhibit a marked activity.
Eight title compounds were synthesized by condensation of substituted phenoxy acetyl chlorides and α-hydroxy alkyl phosphonates.Their structures were characterized by elemental analysis,IR,1H NMR,31P NMR measurements and their herbicidal activities and plant growth regularing activities were tested.Some of them (Ig,Ic,Id,Ih,and Ii) were found to exhibit a marked activity.
1994, 11(4): 25-30
Abstract:
The mechanism of the solid-solid phase transition in the perovskite-type layer of the title complex has been studied by infrared spectroscopy.The phase transition is related to the structural change of alkyl chains and it is mainly arises from the change of the packing structure and conformational order-disorder change in the alkyl chains.The phase transition is accompanied by an obvious decrease of the hydrogen bond strength.The "umelting" of the chains occurs owing to the TG defects near the terminal groups and GTG+GTG',as well as GG defects at higher temperature,It is found that the frequencies of an in-phase and an out-of-phase streching of C-C bonds are sensitive to the phase transition of the "chain melting".
The mechanism of the solid-solid phase transition in the perovskite-type layer of the title complex has been studied by infrared spectroscopy.The phase transition is related to the structural change of alkyl chains and it is mainly arises from the change of the packing structure and conformational order-disorder change in the alkyl chains.The phase transition is accompanied by an obvious decrease of the hydrogen bond strength.The "umelting" of the chains occurs owing to the TG defects near the terminal groups and GTG+GTG',as well as GG defects at higher temperature,It is found that the frequencies of an in-phase and an out-of-phase streching of C-C bonds are sensitive to the phase transition of the "chain melting".
1994, 11(4): 31-34
Abstract:
The polyschiff base Pd(Ⅱ) complexes were used as catalysts to hydrogenate aromatic nitrocompounds at room temperature and ordinary pressure.Nitrobenzene was hydrogenated quantitatively,the conversion for most other aromatic nitrocompounds was also up to 90% The catalyst is stable,For hydrogenation of nitrobenzene after reusing around 80 times,the fast rate of taken-up hydrogen remained 25mL/min.The catalyst reused for 10 times has been proved by XPS to be Pd(Ⅱ) complex.
The polyschiff base Pd(Ⅱ) complexes were used as catalysts to hydrogenate aromatic nitrocompounds at room temperature and ordinary pressure.Nitrobenzene was hydrogenated quantitatively,the conversion for most other aromatic nitrocompounds was also up to 90% The catalyst is stable,For hydrogenation of nitrobenzene after reusing around 80 times,the fast rate of taken-up hydrogen remained 25mL/min.The catalyst reused for 10 times has been proved by XPS to be Pd(Ⅱ) complex.
1994, 11(4): 35-39
Abstract:
Survey has been carried out to select a suitable hydroxyl oxime reagent to extract copper from a leaching solution of sulphating roasting calcine of gold containing sulphide ores.The behaviours of extraction and stripping of copper and impurities in leaching solution have been investigated both in bench scale and contra-current experiments in a mixer-setteler.A new extraction-electrowinning process has been suggested,which ensures an optimum copper recovery and purity,and paticularly,no harm for the cyanidation of gold and silver in the copper leaching residue.
Survey has been carried out to select a suitable hydroxyl oxime reagent to extract copper from a leaching solution of sulphating roasting calcine of gold containing sulphide ores.The behaviours of extraction and stripping of copper and impurities in leaching solution have been investigated both in bench scale and contra-current experiments in a mixer-setteler.A new extraction-electrowinning process has been suggested,which ensures an optimum copper recovery and purity,and paticularly,no harm for the cyanidation of gold and silver in the copper leaching residue.
1994, 11(4): 40-44
Abstract:
The radiation effects on the polyamide 1010 samples of various aggregation states and the crystal damage induced by irradiation have been investigated by WAXD and SAXS techniques,The results indicated that the cross-linking and scission of the irradiated polyamide 1010 samples occurred mainly in the amorphous region and interphase (or crystal surface) and the crystal damage induced by irradiation started from crystal surface,extending into the inner portion of the crystal with increasing radiation dose.The portion of irradiation damage for the (010) plane is greater than that for the (100) plane.The post-radiation effects induced by heat-treatment,a further crosslinking and scission affect the formation and perfection of the (010) plane and cause a decrease of crystallite size L100 and the cryst-sllinity of the samples.
The radiation effects on the polyamide 1010 samples of various aggregation states and the crystal damage induced by irradiation have been investigated by WAXD and SAXS techniques,The results indicated that the cross-linking and scission of the irradiated polyamide 1010 samples occurred mainly in the amorphous region and interphase (or crystal surface) and the crystal damage induced by irradiation started from crystal surface,extending into the inner portion of the crystal with increasing radiation dose.The portion of irradiation damage for the (010) plane is greater than that for the (100) plane.The post-radiation effects induced by heat-treatment,a further crosslinking and scission affect the formation and perfection of the (010) plane and cause a decrease of crystallite size L100 and the cryst-sllinity of the samples.
1994, 11(4): 45-49
Abstract:
Eight Charge transfer complexes of type TTF·M(dmit)2(M=Zn,Ni,Cu) were svnthesized.The raman spectra of the complexes showed that the lower the reduction potential (Ep) of the donor part of the complex,the larger the charge transfer degree (ρ) of the complex with the same acceptor。
Eight Charge transfer complexes of type TTF·M(dmit)2(M=Zn,Ni,Cu) were svnthesized.The raman spectra of the complexes showed that the lower the reduction potential (Ep) of the donor part of the complex,the larger the charge transfer degree (ρ) of the complex with the same acceptor。
1994, 11(4): 50-53
Abstract:
new series of solid solution NdSr1-xMxNiO4(M=Ca,0.0≤x≤1.0;M=Ba,0.0≤x≤0.6) were synthesized by solid state reaction method,and their structures,magnetic and electical properties and IR spectra have been studied.All the samples crystallized in tetragonal system,with exception of the NdCaNiO_4 which crystallized in orthorhombic system.IR spectra of NdSr1-xMxNiO4 showed that the lengths of two Ni-D bonds decrease with the increase of Ca contents.The electric conduction changed from metalic type to semi-conductive type,when x≥0.4(M=Ca,Ba),and the room temperature resistivities of NdSr1-xMxNiO4 increased with the increase of Ca contents.Magnetic susceptibility measurements revealed that Ni3+ ions in all the samples at 77~300K Were in low-spin state.
new series of solid solution NdSr1-xMxNiO4(M=Ca,0.0≤x≤1.0;M=Ba,0.0≤x≤0.6) were synthesized by solid state reaction method,and their structures,magnetic and electical properties and IR spectra have been studied.All the samples crystallized in tetragonal system,with exception of the NdCaNiO_4 which crystallized in orthorhombic system.IR spectra of NdSr1-xMxNiO4 showed that the lengths of two Ni-D bonds decrease with the increase of Ca contents.The electric conduction changed from metalic type to semi-conductive type,when x≥0.4(M=Ca,Ba),and the room temperature resistivities of NdSr1-xMxNiO4 increased with the increase of Ca contents.Magnetic susceptibility measurements revealed that Ni3+ ions in all the samples at 77~300K Were in low-spin state.
1994, 11(4): 54-57
Abstract:
The polyphenoloxidase has been isolated from banana peel by extraction with cold acetone.The catechol oxidation reaction catalyzed by polyphenoloxidase is selected as a model to study the oxidase catalyzed oxidation by using an oxygen electrode,The activation energy of the reaction was calculated to be 23.6kJ·mol-1,and the Michae's constant 1.58×10-2 mol/L.Nine compounds were found to have inhibition effects on the activity of the oxidase,The inhibition kinetics and the mechanism of the catechol oxidation have been investigated by using benzoic acid as inhibitor.The results showed that the copper ions which was found in the polyphenoloxidase may activate the substrates and the combination of the copper ions with inhibitor results in the inhibition effect on the catalytic oxidation.
The polyphenoloxidase has been isolated from banana peel by extraction with cold acetone.The catechol oxidation reaction catalyzed by polyphenoloxidase is selected as a model to study the oxidase catalyzed oxidation by using an oxygen electrode,The activation energy of the reaction was calculated to be 23.6kJ·mol-1,and the Michae's constant 1.58×10-2 mol/L.Nine compounds were found to have inhibition effects on the activity of the oxidase,The inhibition kinetics and the mechanism of the catechol oxidation have been investigated by using benzoic acid as inhibitor.The results showed that the copper ions which was found in the polyphenoloxidase may activate the substrates and the combination of the copper ions with inhibitor results in the inhibition effect on the catalytic oxidation.
1994, 11(4): 58-61
Abstract:
(hydroxymethyl) acrylamide were copolymerized by seed emulsion copolymerization.The stabilities,rheological properties,and the morphological structure of the latex particles were investigated.The effects of acrylic acid,technique of polymerization,and feed content of N-(hydroxymethyl) acrylamide on the properties of the latexes were also investigated.
(hydroxymethyl) acrylamide were copolymerized by seed emulsion copolymerization.The stabilities,rheological properties,and the morphological structure of the latex particles were investigated.The effects of acrylic acid,technique of polymerization,and feed content of N-(hydroxymethyl) acrylamide on the properties of the latexes were also investigated.
1994, 11(4): 62-65
Abstract:
The gelation behaviour of the polyaniline (PAn)/N-methyl-2-pyrrolidone (NMP) solution was studied by rheological method.A critical concentration near 0.05g/mL for the PAn/NMP solution at room temperature was observed.The gelation rate was found to be dependent on the solvent,molecular weight of PAn,and the temperature of the solution.The insoluble fraction in the PAn solution could accelerate the gelation.The pseudo-plastic and thixotropic behavior of the PAn/NMP gel obveously revealed the existence of physical cross-linking in the PAnlNMP solution under participation of the solvent.
The gelation behaviour of the polyaniline (PAn)/N-methyl-2-pyrrolidone (NMP) solution was studied by rheological method.A critical concentration near 0.05g/mL for the PAn/NMP solution at room temperature was observed.The gelation rate was found to be dependent on the solvent,molecular weight of PAn,and the temperature of the solution.The insoluble fraction in the PAn solution could accelerate the gelation.The pseudo-plastic and thixotropic behavior of the PAn/NMP gel obveously revealed the existence of physical cross-linking in the PAnlNMP solution under participation of the solvent.
1994, 11(4): 66-68
Abstract:
The title solid solution has been prepared by coprecitation,The (Fe1-xSbx)2O3 of up to x=0.2 has a structure of corundum as α-Fe2O3.The substitution of Sb5+ for Fe3+ site in α-Fe2O3 leads to the decrease of resistance one order of magnitude lower and remarkable improvement in sensitivity to reducing gases.
The title solid solution has been prepared by coprecitation,The (Fe1-xSbx)2O3 of up to x=0.2 has a structure of corundum as α-Fe2O3.The substitution of Sb5+ for Fe3+ site in α-Fe2O3 leads to the decrease of resistance one order of magnitude lower and remarkable improvement in sensitivity to reducing gases.
1994, 11(4): 69-73
Abstract:
From the structure date of the rare earth ethylsulphates RE(C2H5SO4)3·9H2O (RE=La→Lu,except Pm),their efficient valence electrons,efficient valence densities and average coordinatiOn numbers of bonds etc,have been calculated by using the chemical bond theory of complex crystals of dielectric description.The results showed that in the crystals tbere are 16 kinds of bond which may be classified approximately in six types,namely:RP-O,O-H,S-O,C-O,C-C,and C-H.On the basis of the bondparameters of these bonds the refractive indexes of the crystals vvere thus calculated,the results were in good agreement vvith the experimentals.
From the structure date of the rare earth ethylsulphates RE(C2H5SO4)3·9H2O (RE=La→Lu,except Pm),their efficient valence electrons,efficient valence densities and average coordinatiOn numbers of bonds etc,have been calculated by using the chemical bond theory of complex crystals of dielectric description.The results showed that in the crystals tbere are 16 kinds of bond which may be classified approximately in six types,namely:RP-O,O-H,S-O,C-O,C-C,and C-H.On the basis of the bondparameters of these bonds the refractive indexes of the crystals vvere thus calculated,the results were in good agreement vvith the experimentals.
1994, 11(4): 74-77
Abstract:
Plasma-induced graft copolymerization of methyl methacrylate to nascent polypropylene (PP) povvder has been investigated,The samples vvere characterized by FT-IR and verified to be grafted copolymer,The dependence of grafting yields on plasma treatment power,time,and copolymerization time,temperature was determined.The influences of thediluent and particle sizes of PP on the grafting yield were studied.Auto-acceleration effect during grafting and acceleration effect resulted from diluents were found.
Plasma-induced graft copolymerization of methyl methacrylate to nascent polypropylene (PP) povvder has been investigated,The samples vvere characterized by FT-IR and verified to be grafted copolymer,The dependence of grafting yields on plasma treatment power,time,and copolymerization time,temperature was determined.The influences of thediluent and particle sizes of PP on the grafting yield were studied.Auto-acceleration effect during grafting and acceleration effect resulted from diluents were found.
1994, 11(4): 78-80
Abstract:
Conductive polypyrrole (PPy) films were prepared on the surface of YBa2CuO7 superconductors through electrochemical synthesis or chemical method to prevent YBa2CuO7 from corroding in reactive environments.The resuIts showed that the electrochemical polymerization destroyed the superconductivity of YBa2CuO7,whereas the chemical coating of PPy/PVC on YBa2h3O7 did not affect the superconductivity.Furthermore,the chemical PPy/PVC coatings could greatly improve the superconductors stability in water and acid.
Conductive polypyrrole (PPy) films were prepared on the surface of YBa2CuO7 superconductors through electrochemical synthesis or chemical method to prevent YBa2CuO7 from corroding in reactive environments.The resuIts showed that the electrochemical polymerization destroyed the superconductivity of YBa2CuO7,whereas the chemical coating of PPy/PVC on YBa2h3O7 did not affect the superconductivity.Furthermore,the chemical PPy/PVC coatings could greatly improve the superconductors stability in water and acid.
1994, 11(4): 81-84
Abstract:
rradiation of the PTMSP homogeneous membranes by UV light (253.7nm) in air caused Oxidation of the membrane surface,elimination of-Si(CH3)3 and α-CH3 groups anddegradation,The UV irradiated PTMSP membranes exhibit a higher hydrophilicity and better gas permeation properties with gas selectivity being improved.The oxygen-nitrogen separation coefficient αo2/N2 increased from l.5 to 4.7,but the oxygen permeation coefficient Po2 decreased from 8600 to 340 barrer.
rradiation of the PTMSP homogeneous membranes by UV light (253.7nm) in air caused Oxidation of the membrane surface,elimination of-Si(CH3)3 and α-CH3 groups anddegradation,The UV irradiated PTMSP membranes exhibit a higher hydrophilicity and better gas permeation properties with gas selectivity being improved.The oxygen-nitrogen separation coefficient αo2/N2 increased from l.5 to 4.7,but the oxygen permeation coefficient Po2 decreased from 8600 to 340 barrer.
1994, 11(4): 85-87
Abstract:
Some vegetable oils were epoxidized at 60℃ for 6 hours under pressure of 0.15MPa and at the feed ratio(by weight) of oil:H2O2(50%):HCOOH(85%):H2SO4 (98%)=100:50:9:2 The epoxide numbers of the epoxidized soy bean oil,sunflower oil,as well as corn oil were 6.2%~6.6% and 6.O%~6.4%,respectively. The iodine numbers of the epoxidized oils were less than 3mg/g.
Some vegetable oils were epoxidized at 60℃ for 6 hours under pressure of 0.15MPa and at the feed ratio(by weight) of oil:H2O2(50%):HCOOH(85%):H2SO4 (98%)=100:50:9:2 The epoxide numbers of the epoxidized soy bean oil,sunflower oil,as well as corn oil were 6.2%~6.6% and 6.O%~6.4%,respectively. The iodine numbers of the epoxidized oils were less than 3mg/g.
1994, 11(4): 88-90
Abstract:
The electrochemical oxidation process of sulfur dioxide on the poly CoPP electrode was studied by cyclic voltammetry,steadystate method,chronoamperometry and chronopotentiometry.The actions of sulfur dioxide have been compared with that on the nobel metalel ectrods.The mechanism of the oxidation of sulfur dioxide has been discussed.
The electrochemical oxidation process of sulfur dioxide on the poly CoPP electrode was studied by cyclic voltammetry,steadystate method,chronoamperometry and chronopotentiometry.The actions of sulfur dioxide have been compared with that on the nobel metalel ectrods.The mechanism of the oxidation of sulfur dioxide has been discussed.
1994, 11(4): 91-93
Abstract:
The structures and physical properties of aromatic polyamides prepared by the polycondensation of terephthaloyl or isophthaloyl dichlorides with 2,4,6-trimethyl-1,3-phenylenediamine have been studied by IR,DSC,TG techniques,The solubilities of the polyamides were improved by the introduction of methyl groups into benzene rings.
The structures and physical properties of aromatic polyamides prepared by the polycondensation of terephthaloyl or isophthaloyl dichlorides with 2,4,6-trimethyl-1,3-phenylenediamine have been studied by IR,DSC,TG techniques,The solubilities of the polyamides were improved by the introduction of methyl groups into benzene rings.
1994, 11(4): 94-96
Abstract:
The molecular morphology of CuTPP has been investigated through depositing on HOPG using Langmuir-Blodgett technique.High resolution STM images showed that the CuTPP molecules presented plane cyclic shape of diameter l.0nm,without strand and helix structure.The result is very close to the ideal structure of a CuTPP molecule.The conditions of STM imaging of CuTPP molecules have been discussed.
The molecular morphology of CuTPP has been investigated through depositing on HOPG using Langmuir-Blodgett technique.High resolution STM images showed that the CuTPP molecules presented plane cyclic shape of diameter l.0nm,without strand and helix structure.The result is very close to the ideal structure of a CuTPP molecule.The conditions of STM imaging of CuTPP molecules have been discussed.
1994, 11(4): 97-100
Abstract:
A polymeric borohydride anion reducing reagent (BER) was preparedfromhome-made 7ll# strong basic anion-exchange resin and potassium borohydride,The BER has a capacity of 3.2mmol BH4⊖/g.The procedure of ester reduction by using this polymeric reductant was simple and gave a higher yield of alcohols.The polymeric reductant can be regenerated and used repeatedly.
A polymeric borohydride anion reducing reagent (BER) was preparedfromhome-made 7ll# strong basic anion-exchange resin and potassium borohydride,The BER has a capacity of 3.2mmol BH4⊖/g.The procedure of ester reduction by using this polymeric reductant was simple and gave a higher yield of alcohols.The polymeric reductant can be regenerated and used repeatedly.
1994, 11(4): 101-103
Abstract:
A novel method for the synthesis of N-pivot crown ethers is described.It is based on the reaction of 2,3-benzo-10-aza-l,4,7,13-tetraoxacyclopentadeca-2-ene with carbon disulfide in the presence of sodium hydroxide,which gave a sodium salt of substituted dithio-carbamic acid in gdod yield.The latler underwent a nucleophilic substitution with some alkyl halides,giving mono-,di-and tri-crown ethers,
A novel method for the synthesis of N-pivot crown ethers is described.It is based on the reaction of 2,3-benzo-10-aza-l,4,7,13-tetraoxacyclopentadeca-2-ene with carbon disulfide in the presence of sodium hydroxide,which gave a sodium salt of substituted dithio-carbamic acid in gdod yield.The latler underwent a nucleophilic substitution with some alkyl halides,giving mono-,di-and tri-crown ethers,
1994, 11(4): 104-106
Abstract:
The thermal behavior of some thermotropic liquid crystalline polyester-imides have been examined by DSC and TGA techniques.It is found that the content of aliphatic diamines with different chain lengths (C5,C6 and C10) showed a definite influences on the temperatures of glass transition and phase transition of the TLC polymers.
The thermal behavior of some thermotropic liquid crystalline polyester-imides have been examined by DSC and TGA techniques.It is found that the content of aliphatic diamines with different chain lengths (C5,C6 and C10) showed a definite influences on the temperatures of glass transition and phase transition of the TLC polymers.
1994, 11(4): 107-110
Abstract:
Blends of polystyrenel (Mw/Mn=1.15,Mw=8.59×102) and polystyrene-2(Mw/Mn=1.06,Mw=1.29×104) in weight ratio of 0,20,40,50,60,80 and 100% were prepared from benzene solution.The cast films of the blend were dried under vacuum at 35℃,40℃,55℃,65℃,75℃,105℃,and 130℃ for 2 days,respectively.The dependence of the glass transition temperatures on the composition of the blends have been studied by DSC technique.It is found that the experiment results were not fitted with those obtained from theFox,Gordon-Taylor,and Couchman equations.It appears that the parameter k (or △Cp2/△Cp1) in the mentioned equations,which only refers to the difference in heat capacity of the polymer before and after transition,is not reasonable.
Blends of polystyrenel (Mw/Mn=1.15,Mw=8.59×102) and polystyrene-2(Mw/Mn=1.06,Mw=1.29×104) in weight ratio of 0,20,40,50,60,80 and 100% were prepared from benzene solution.The cast films of the blend were dried under vacuum at 35℃,40℃,55℃,65℃,75℃,105℃,and 130℃ for 2 days,respectively.The dependence of the glass transition temperatures on the composition of the blends have been studied by DSC technique.It is found that the experiment results were not fitted with those obtained from theFox,Gordon-Taylor,and Couchman equations.It appears that the parameter k (or △Cp2/△Cp1) in the mentioned equations,which only refers to the difference in heat capacity of the polymer before and after transition,is not reasonable.
1994, 11(4): 111-113
Abstract:
The molecular orientation of crystalline and liqtiid crystalline states of poly (MMA-co-BMA) and ChN mixtures have been sttidied by X-ray diffraction.It was shown that the molecular orientation of smactic A liquid crystal can be frozen in the system at room temperature and the storage information was realized.
The molecular orientation of crystalline and liqtiid crystalline states of poly (MMA-co-BMA) and ChN mixtures have been sttidied by X-ray diffraction.It was shown that the molecular orientation of smactic A liquid crystal can be frozen in the system at room temperature and the storage information was realized.
1994, 11(4): 114-116
Abstract:
Two polymorphs of oxyvanadium phthalocyanine (VOPc),crystalline and amorohous were obtained and identified by X-ray powder diffraction,Both photoreceptors constructed by polymorphs incorporated with hydrazone compounds as CTL exhibited photoconductive properties in the infrared region.
Two polymorphs of oxyvanadium phthalocyanine (VOPc),crystalline and amorohous were obtained and identified by X-ray powder diffraction,Both photoreceptors constructed by polymorphs incorporated with hydrazone compounds as CTL exhibited photoconductive properties in the infrared region.
1994, 11(4): 117-119
Abstract:
Catalysts based on Al2O3 and Cr2O3 with rare earth elements as promoter were prepared by impregnation method.The role of promoters in catalytic dehydrogenation of isobutane has been evaluated and investigated by XPS,ESR,TPD,and TG-DTA.The results showed that addition of rare earth elements could improve the catalytic ability and stability of the catalyts in dehydrogenation of isobutane.
Catalysts based on Al2O3 and Cr2O3 with rare earth elements as promoter were prepared by impregnation method.The role of promoters in catalytic dehydrogenation of isobutane has been evaluated and investigated by XPS,ESR,TPD,and TG-DTA.The results showed that addition of rare earth elements could improve the catalytic ability and stability of the catalyts in dehydrogenation of isobutane.
