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1985 Volume 1 Issue 5
1985, 1(05): 397-403
doi: 10.3866/PKU.WHXB19850501
Abstract:
The chemical shifts and linewidths for aluminum chloride in ethyl ether have been studied by O'Reilly~[1], Haragushi~[2] and Kidd. But-different values have been reported. Up to now the divergence of shifts and linewidths is still present on this question.
In studying the Ziegler-Natta catalyst, the ~(27)Al NMR datum of AlCl_3 Et_2O complex are very important. So we must re-examine them.
It has been verified that the chemical shifts and Iinewidths of the complex in ether are 100.9 ppm and 125Hz respectively, and no...
The chemical shifts and linewidths for aluminum chloride in ethyl ether have been studied by O'Reilly~[1], Haragushi~[2] and Kidd. But-different values have been reported. Up to now the divergence of shifts and linewidths is still present on this question.
In studying the Ziegler-Natta catalyst, the ~(27)Al NMR datum of AlCl_3 Et_2O complex are very important. So we must re-examine them.
It has been verified that the chemical shifts and Iinewidths of the complex in ether are 100.9 ppm and 125Hz respectively, and no...
1985, 1(05): 404-411
doi: 10.3866/PKU.WHXB19850502
Abstract:
The ultraviolet spectra of N-(substituted phenyl)-ethylglycinates (RPhGEt, R=p-OCH_3, p-CH_3, m-CH_3, -H, m-OCH_3, m-Cl, p-Cl, m-NO_2, p-NO_2) have been determened in water, dioxane, dioxane-water, ethyl alcohol, ehtyl ester, heptane and benzene by means of a Baokmann DU-8B spectrophotometer. The experimental results showed that:
(1) The bathochromic shift of ultraviolet absorption spectra of RPhGEt in various solvents was observed to compare with the characterized absorption hands of benzene. The energy difference between ground state and first excited state of RPhGEt followed the order:
p-OCH_3<p-CH_3<m-CH_3<-H<m-OCH_3; p-NO_2<m-NO_2<p-Cl<m-Cl<m-OCH_3
(2) ...
The ultraviolet spectra of N-(substituted phenyl)-ethylglycinates (RPhGEt, R=p-OCH_3, p-CH_3, m-CH_3, -H, m-OCH_3, m-Cl, p-Cl, m-NO_2, p-NO_2) have been determened in water, dioxane, dioxane-water, ethyl alcohol, ehtyl ester, heptane and benzene by means of a Baokmann DU-8B spectrophotometer. The experimental results showed that:
(1) The bathochromic shift of ultraviolet absorption spectra of RPhGEt in various solvents was observed to compare with the characterized absorption hands of benzene. The energy difference between ground state and first excited state of RPhGEt followed the order:
p-OCH_3<p-CH_3<m-CH_3<-H<m-OCH_3; p-NO_2<m-NO_2<p-Cl<m-Cl<m-OCH_3
(2) ...
1985, 1(05): 412-419
doi: 10.3866/PKU.WHXB19850503
Abstract:
MoO_3/γ-Al_2O_3, MoO_3╱TiO_2, and MoO_3╱SiO_2 samples prepared by impregnation method were reduced at 480 ℃ by H_2 flow(1 atm, 50 ml min~(-1)) for an hour and characterized by XPS without exposure to the air.
The ratios of XPS intensities(I_(Mo3d)/I_(A12p), I_(Mo3d)/I_(Ti2p) and I_(Mo3d)/I(si2p) of reduced samples have been measured and compared with that of the oxidative pre cursors (Fig.1-3). For All samples which contain crystalline MoO_3, the ratios are dramatically increased after reduction. We consider that a lot of molybdena has migrated from internal to external surface of the carriers during reduction. The monolayer molybdena supported on γ-Al_2O_3, TiO_2 or SiO_2 carriers shows quite different behaviours. On TiO_2, it condensed slightly. On SiO_2, it migrated partly from internal to external surface of the carrier. On γ-Al_2O_3, it neither condensed and the surfaces of the carriers is: Mo(Al)>Mo(Ti)>Mo(Si). This is also the order of the stabilities of the monolayer of molybdena on these carriers.
Computer fitting for Mo3d spectra shows that there are only Mo~V and ...
MoO_3/γ-Al_2O_3, MoO_3╱TiO_2, and MoO_3╱SiO_2 samples prepared by impregnation method were reduced at 480 ℃ by H_2 flow(1 atm, 50 ml min~(-1)) for an hour and characterized by XPS without exposure to the air.
The ratios of XPS intensities(I_(Mo3d)/I_(A12p), I_(Mo3d)/I_(Ti2p) and I_(Mo3d)/I(si2p) of reduced samples have been measured and compared with that of the oxidative pre cursors (Fig.1-3). For All samples which contain crystalline MoO_3, the ratios are dramatically increased after reduction. We consider that a lot of molybdena has migrated from internal to external surface of the carriers during reduction. The monolayer molybdena supported on γ-Al_2O_3, TiO_2 or SiO_2 carriers shows quite different behaviours. On TiO_2, it condensed slightly. On SiO_2, it migrated partly from internal to external surface of the carrier. On γ-Al_2O_3, it neither condensed and the surfaces of the carriers is: Mo(Al)>Mo(Ti)>Mo(Si). This is also the order of the stabilities of the monolayer of molybdena on these carriers.
Computer fitting for Mo3d spectra shows that there are only Mo~V and ...
1985, 1(05): 420-423
doi: 10.3866/PKU.WHXB19850504
Abstract:
The molecular orbital energy, charge distribution, and Mulliken's bond order in neodymium chloride complex with isopropanol have been calculated with an INDO method. The calculation showed that after coordination, the molecular orbi tal energies corresponding to Nd—Cl bond were increased, the Nd—Cl bond orders were decreased, and the net charges on Nd and Cl were decreased. The results indi cate that the charge transfer of Cl→Nd caused by orbital overlapping and the re pulsion of negative charge added on Nd against the valent charge of Nd—Cl lead to increasing the energy levels and weakening the Nd—Cl bonds, which effectively activates the Nd—Cl bonds. It can be expected that the alkylation reaction to form active species may be favorably carried out.
Besides, the complex activation for Nd—Cl is of certain choice.
The molecular orbital energy, charge distribution, and Mulliken's bond order in neodymium chloride complex with isopropanol have been calculated with an INDO method. The calculation showed that after coordination, the molecular orbi tal energies corresponding to Nd—Cl bond were increased, the Nd—Cl bond orders were decreased, and the net charges on Nd and Cl were decreased. The results indi cate that the charge transfer of Cl→Nd caused by orbital overlapping and the re pulsion of negative charge added on Nd against the valent charge of Nd—Cl lead to increasing the energy levels and weakening the Nd—Cl bonds, which effectively activates the Nd—Cl bonds. It can be expected that the alkylation reaction to form active species may be favorably carried out.
Besides, the complex activation for Nd—Cl is of certain choice.
1985, 1(05): 424-430
doi: 10.3866/PKU.WHXB19850505
Abstract:
The kinetics of propylene oxidation over Bi_2Mo_3O_(12)-Bi_2O_3 catalyst in a differ ential flow reactor has been investigated. The partial pressures of propylene and oxygen coverd the range of 0.05-0.95 atm and 0.07-0.80 arm, respectively. Kee ping their partial pressures less than 0.30 atm, the rate of acrolein formation took first order for propylene and 0.5 order for oxygen. The apparent activation energy was 30.1 kcal/mol.
On the other hand, the kinetics of acrolein formation did not follow any power rate equation when the partial pressure of propylene or oxygen became larger than 0.30 atm. A maximum rate of acrolein formation appeared.
...
The kinetics of propylene oxidation over Bi_2Mo_3O_(12)-Bi_2O_3 catalyst in a differ ential flow reactor has been investigated. The partial pressures of propylene and oxygen coverd the range of 0.05-0.95 atm and 0.07-0.80 arm, respectively. Kee ping their partial pressures less than 0.30 atm, the rate of acrolein formation took first order for propylene and 0.5 order for oxygen. The apparent activation energy was 30.1 kcal/mol.
On the other hand, the kinetics of acrolein formation did not follow any power rate equation when the partial pressure of propylene or oxygen became larger than 0.30 atm. A maximum rate of acrolein formation appeared.
...
1985, 1(05): 431-441
doi: 10.3866/PKU.WHXB19850506
Abstract:
"In-situ" infrared spectraphotometer cell designed and constructed by ourselves has been used to identify the surface species of CO and H_2 on copper-based cata lyst at elevated pressures and temperatures. Having conquered the difficulty due to the low transparency of Cu-ZnO-Al_2O_3 catalyst, the authors have obtained convin cible experimental results concerning surface intermediates on catalyst which can be used to speculate the reaction mechanism of methanol synthesis from syngas over Cu-ZnO-Al_2O_3 catalyst.
From the spectra of CO and H_2 on catalysts, it could be drawn that M—O—C—M and M—CO and M—H are surface species under reaction conditions. A competitive adsorption between CO and H_2 on the same sites has been verified, the adsorptive capacity of H_2 at equilibrium is greater than that of CO, indicating the ther-modynamic superiority of H_2 over CO. At higher temperatures, the dissociated adsorption of H_2 dominates the active centers. At low temperatures the active centers are entirely occupied by CO.
...
"In-situ" infrared spectraphotometer cell designed and constructed by ourselves has been used to identify the surface species of CO and H_2 on copper-based cata lyst at elevated pressures and temperatures. Having conquered the difficulty due to the low transparency of Cu-ZnO-Al_2O_3 catalyst, the authors have obtained convin cible experimental results concerning surface intermediates on catalyst which can be used to speculate the reaction mechanism of methanol synthesis from syngas over Cu-ZnO-Al_2O_3 catalyst.
From the spectra of CO and H_2 on catalysts, it could be drawn that M—O—C—M and M—CO and M—H are surface species under reaction conditions. A competitive adsorption between CO and H_2 on the same sites has been verified, the adsorptive capacity of H_2 at equilibrium is greater than that of CO, indicating the ther-modynamic superiority of H_2 over CO. At higher temperatures, the dissociated adsorption of H_2 dominates the active centers. At low temperatures the active centers are entirely occupied by CO.
...
1985, 1(05): 442-447
doi: 10.3866/PKU.WHXB19850507
Abstract:
The chemiluminescence reaction of tin with N_2O and O_2 have been investigated in a beam-gas apparatus under the pressure range of 10~(-4)—10~(-2) torr. The chemiluminescent spectra recorded for both reactions under single-collision conditions have been recognized as the emission of b~3Π(0) and b'3Π(1) state to the ground state of SnO produced in the reaction. For the reaction of Sn with N_2O, the emission from a~3∑-X~1∑ transition obviously becomes enhanced with in creasing of background gas pressure. The relative population of a~3∑ state on v=0 and v=1 as well as the emission intensity of a~3∑ and b~1Π(1) states to X~1∑ state of SnO have been measured also. The total cross section of collision is about 0.32 nm. In analyzing the experimental results, it is found that the production of electronically excited SnO molecule from the reaction of Sn with N_2O may proceed with the following mechanism:
Sn(~3P_2)+N_2O(X~1∑)→SnO[b~3Π(0), b′~3Π(1)]+N_2(X~1∑~+_g)
and
Sn+N_2O(X~1∑~+)→SnO(i)+N_2O(X~1∑~+_g)
in which i is a long-lived electronic state.
The chemiluminescence reaction of tin with N_2O and O_2 have been investigated in a beam-gas apparatus under the pressure range of 10~(-4)—10~(-2) torr. The chemiluminescent spectra recorded for both reactions under single-collision conditions have been recognized as the emission of b~3Π(0) and b'3Π(1) state to the ground state of SnO produced in the reaction. For the reaction of Sn with N_2O, the emission from a~3∑-X~1∑ transition obviously becomes enhanced with in creasing of background gas pressure. The relative population of a~3∑ state on v=0 and v=1 as well as the emission intensity of a~3∑ and b~1Π(1) states to X~1∑ state of SnO have been measured also. The total cross section of collision is about 0.32 nm. In analyzing the experimental results, it is found that the production of electronically excited SnO molecule from the reaction of Sn with N_2O may proceed with the following mechanism:
Sn(~3P_2)+N_2O(X~1∑)→SnO[b~3Π(0), b′~3Π(1)]+N_2(X~1∑~+_g)
and
Sn+N_2O(X~1∑~+)→SnO(i)+N_2O(X~1∑~+_g)
in which i is a long-lived electronic state.
1985, 1(05): 448-454
doi: 10.3866/PKU.WHXB19850508
Abstract:
Using TEA CO_2 laser 9.6R (14) line as excitation source, Fourier transforma tion IR spectrometer as measuring instrument, NO and O_2 as scavenger of CF_3 ra dical, we have studied the dynamics of multiphotoa dissociation of CF_3I.
It was found that O_2 and NO can both be used to trap the CF_3 radical resul ted from IR multiphoton dissociation of CF_3I. From the investigation of the de pendence of the IR MPD yield of CF_3I and the buffer gas pressure and from the measurement of multiphoton absorption of CF_3I, small molecule character was found for CF_3I when it was excited by IR laser. It was observed that buffer gases can reduce the early bottleneck effect. An energy grained master equation was used to simulate the dependence of MPD yield of CF_3I and laser fluence under collisionless and early bottleneck effect neglectable condition. The calculated value is in agreement with the experimental data.
Using TEA CO_2 laser 9.6R (14) line as excitation source, Fourier transforma tion IR spectrometer as measuring instrument, NO and O_2 as scavenger of CF_3 ra dical, we have studied the dynamics of multiphotoa dissociation of CF_3I.
It was found that O_2 and NO can both be used to trap the CF_3 radical resul ted from IR multiphoton dissociation of CF_3I. From the investigation of the de pendence of the IR MPD yield of CF_3I and the buffer gas pressure and from the measurement of multiphoton absorption of CF_3I, small molecule character was found for CF_3I when it was excited by IR laser. It was observed that buffer gases can reduce the early bottleneck effect. An energy grained master equation was used to simulate the dependence of MPD yield of CF_3I and laser fluence under collisionless and early bottleneck effect neglectable condition. The calculated value is in agreement with the experimental data.
1985, 1(05): 455-459
doi: 10.3866/PKU.WHXB19850509
Abstract:
The concept of semiconductor solid junction was first introduced into the tra ditional electrochemistry. The cathodic process of A electrode was discussed. Some of the phenomena were explained quite satisfactoryly with a new mechanism based on the semiconductor high-low junction, these phenomena can not be explai ned by ordinary theories.
The concept of semiconductor solid junction was first introduced into the tra ditional electrochemistry. The cathodic process of A electrode was discussed. Some of the phenomena were explained quite satisfactoryly with a new mechanism based on the semiconductor high-low junction, these phenomena can not be explai ned by ordinary theories.
1985, 1(05): 460-463
doi: 10.3866/PKU.WHXB19850510
Abstract:
The kinetics of nucleophilic substitution reactions between trans-(Ph_2PMe)_2 Ni(C_6Cl_5)Cl and pyridine and various substituted pyridines in ethanol has been studied. In the presence of NH_4Cl (0.004M), the pseudo-first-order rate cons tant can be expressed by
k_(obs)=(k_1′[am]/(k_2/k_3)[Cl~-]+([am])+k_(am)′[am])
The rate constants and their corresponding activation parameters have been measu red and a reaction mechanism is proposed. The results show that the rate of sub stitution reactions is primarily verned by steric effect rather rather than the basicity of the entering group.
The kinetics of nucleophilic substitution reactions between trans-(Ph_2PMe)_2 Ni(C_6Cl_5)Cl and pyridine and various substituted pyridines in ethanol has been studied. In the presence of NH_4Cl (0.004M), the pseudo-first-order rate cons tant can be expressed by
k_(obs)=(k_1′[am]/(k_2/k_3)[Cl~-]+([am])+k_(am)′[am])
The rate constants and their corresponding activation parameters have been measu red and a reaction mechanism is proposed. The results show that the rate of sub stitution reactions is primarily verned by steric effect rather rather than the basicity of the entering group.
1985, 1(05): 464-470
doi: 10.3866/PKU.WHXB19850511
Abstract:
The dissolved Al~(3+) amounts of various alumina (Ketjen CK 300, Degussa Alu minium Oxid C, Tonerdo γ-Al_2O_3 and Changling Al_3O_3) in different concentrations of acid (HCl, H_2PtCl_6) and the saturated adsorption amounts of H_2PtCl_6 on the above alumina were determined by EDTA complexometric method and by spectro photometry using SnCl_2. It was found that various alumina showed different Al~(3+) amounts in above acids, the more the dissolved Al~(3+) amounts of alumina are the higher the saturated adsorption amounts of H_2PtCl_6 on alumina used, followed the sequence: Degussa=Tonerdo<Changling<CK-300. The adsorption isotherms of H_2PtCl_6 on the alumina mentioned above all followed Langmuir adsorption isotherm.
The catalysts tested Temperature Programmed Reduction (TPR) and Desorption (TPD) were prepared by wet impregnation of the aforementioned alumina with H_2PtCl_6, followd by precalcination in a fix-bed reactor under air flow for 1 hr at 500 ℃. The TPR and TPD measurements of the catalysts were performed “in situ”. According to the TPR profiles, the appearance of high temperature reduction peak (at ~650 ℃) depends on the nature of alumina used. It seemed namely that there was a close correlation between the dissolved Al~(3+) amounts and the high temperature reduction peak (HTPR). The CK 300 supported Pt catalyst, possessed the highest dissolved Al~(3+) amounts, showed a distinct HTRP, but no HTRP appeared for the lowest one e.g. Pt/Degussa, except Pt/Tonerdo (Tonerdo Al_2O_3 itself showed a HTRP at 685 ℃). The HTRP may be ascribed to the existence of irreducible Pt (soluble platinum) which was created by the adsorption of Pt within the lattice defect of alumina, formed during impregnation with H_2PtCl_6, and by subsequent deposit of Al~(3+) during evaporation.
...
The dissolved Al~(3+) amounts of various alumina (Ketjen CK 300, Degussa Alu minium Oxid C, Tonerdo γ-Al_2O_3 and Changling Al_3O_3) in different concentrations of acid (HCl, H_2PtCl_6) and the saturated adsorption amounts of H_2PtCl_6 on the above alumina were determined by EDTA complexometric method and by spectro photometry using SnCl_2. It was found that various alumina showed different Al~(3+) amounts in above acids, the more the dissolved Al~(3+) amounts of alumina are the higher the saturated adsorption amounts of H_2PtCl_6 on alumina used, followed the sequence: Degussa=Tonerdo<Changling<CK-300. The adsorption isotherms of H_2PtCl_6 on the alumina mentioned above all followed Langmuir adsorption isotherm.
The catalysts tested Temperature Programmed Reduction (TPR) and Desorption (TPD) were prepared by wet impregnation of the aforementioned alumina with H_2PtCl_6, followd by precalcination in a fix-bed reactor under air flow for 1 hr at 500 ℃. The TPR and TPD measurements of the catalysts were performed “in situ”. According to the TPR profiles, the appearance of high temperature reduction peak (at ~650 ℃) depends on the nature of alumina used. It seemed namely that there was a close correlation between the dissolved Al~(3+) amounts and the high temperature reduction peak (HTPR). The CK 300 supported Pt catalyst, possessed the highest dissolved Al~(3+) amounts, showed a distinct HTRP, but no HTRP appeared for the lowest one e.g. Pt/Degussa, except Pt/Tonerdo (Tonerdo Al_2O_3 itself showed a HTRP at 685 ℃). The HTRP may be ascribed to the existence of irreducible Pt (soluble platinum) which was created by the adsorption of Pt within the lattice defect of alumina, formed during impregnation with H_2PtCl_6, and by subsequent deposit of Al~(3+) during evaporation.
...
1985, 1(05): 471-475
doi: 10.3866/PKU.WHXB19850512
Abstract:
Using precision static oxygen bomb combustion calorimeter, the standard energies of combustion of tetraphenylpophyrin, tetra (ρ-methylphenyl)-porphyrin, tetra(ρ-methoxyphenyl) porphyrin, and tetra(o-aminophenyl)-porphyrin at 298.15 K were determined to be -36.1279±0.0103, -36.9368±0.0120, -32.8427±0.0104, and -33.5453±0.0240 kJg~(-1), respectively. The corresponding standard enthalpies of formation at 298.15 K were calculated to be 621.3±8.5, 478.6±10.3, -171.1±9.7, and 474.2±17.2 kJ mol~(-1). The uncertainties of the results were given twice the final overall standard deviation of mean.
Using precision static oxygen bomb combustion calorimeter, the standard energies of combustion of tetraphenylpophyrin, tetra (ρ-methylphenyl)-porphyrin, tetra(ρ-methoxyphenyl) porphyrin, and tetra(o-aminophenyl)-porphyrin at 298.15 K were determined to be -36.1279±0.0103, -36.9368±0.0120, -32.8427±0.0104, and -33.5453±0.0240 kJg~(-1), respectively. The corresponding standard enthalpies of formation at 298.15 K were calculated to be 621.3±8.5, 478.6±10.3, -171.1±9.7, and 474.2±17.2 kJ mol~(-1). The uncertainties of the results were given twice the final overall standard deviation of mean.
1985, 1(05): 476-481
doi: 10.3866/PKU.WHXB19850513
Abstract:
This paper reports our studies on HCl+NaCl+PrOH+H_2O system by mesns of emf measurements of the cell without liquid junction as type (A)
Pt, H_2 (latm) |HCI (m_A), NaCl (m_B), PrOH(x), H_2O(1-x)| AgCl-Ag (A)
at constant total ionic strengths I=0.1, 0.5, 1.0, 2.0 and 3.0 mol kg~(-1), at 298.15 K, where m_A and m_B are the molalities of HCl and NaCl, respectively, x is the molar fraction of PrOH in mixed solvents, x=0.05.
The results show that HCI approximately follows Harned's Rule from I=0.1 to 3.0 mole kg~(-1)...
This paper reports our studies on HCl+NaCl+PrOH+H_2O system by mesns of emf measurements of the cell without liquid junction as type (A)
Pt, H_2 (latm) |HCI (m_A), NaCl (m_B), PrOH(x), H_2O(1-x)| AgCl-Ag (A)
at constant total ionic strengths I=0.1, 0.5, 1.0, 2.0 and 3.0 mol kg~(-1), at 298.15 K, where m_A and m_B are the molalities of HCl and NaCl, respectively, x is the molar fraction of PrOH in mixed solvents, x=0.05.
The results show that HCI approximately follows Harned's Rule from I=0.1 to 3.0 mole kg~(-1)...
1985, 1(05): 482-486
doi: 10.3866/PKU.WHXB19850514
Abstract:
The effect of α-propylene glycol, glycol, and glycerin on the phase behavior of water-hexane-dodecylsulfonate-hexanol(as cosurfactant) system was investigated. These additivcs all increase the region of O/W type microemulsion, and the amount of solubilized hexane at the optimum ratio of hexanol/dodecylsulfonate, among them, α-propylene glycol is the best. Disscusion was given in four aspects:
1. Do these additives play any part on the interfacial adsorption?
2. Do they change the HLB value of the surfactant or the cosurfactant?
3. What effect do they have on liquid crystaline phase?
4. Do they change the solubility of the surfactant in the equeous solution?
The effect of α-propylene glycol, glycol, and glycerin on the phase behavior of water-hexane-dodecylsulfonate-hexanol(as cosurfactant) system was investigated. These additivcs all increase the region of O/W type microemulsion, and the amount of solubilized hexane at the optimum ratio of hexanol/dodecylsulfonate, among them, α-propylene glycol is the best. Disscusion was given in four aspects:
1. Do these additives play any part on the interfacial adsorption?
2. Do they change the HLB value of the surfactant or the cosurfactant?
3. What effect do they have on liquid crystaline phase?
4. Do they change the solubility of the surfactant in the equeous solution?
1985, 1(05): 487-492
doi: 10.3866/PKU.WHXB19850515
Abstract:
