The four-dimensional time-dependent quantum dynamics calculations for reactions of group IV hydride with H are carried out by employing the semirigid vibrating rotor target model and the time-dependent wave packet met...The four-dimensional time-dependent quantum dynamics calculations for reactions of group IV hydride with H are carried out by employing the semirigid vibrating rotor target model and the time-dependent wave packet method. The reaction possibility, cross section and rate constants for reactions (H+SiH_4 and H+GeH_4) in different initial vibrational and rotational states are obtained. The common feature for such kind of reaction process is summarized. The theoretical result is consistent with available measurement, which indicates the credibility of this theory and the potential energy surface.展开更多
The kinetics of the catalytic reforming reaction of methane with carbondioxide to produce synthesis gas on a Ni/α-Al_2O_3 and a HSD-2 type commercial catalyst has beenstudied. The results indicate that the reaction o...The kinetics of the catalytic reforming reaction of methane with carbondioxide to produce synthesis gas on a Ni/α-Al_2O_3 and a HSD-2 type commercial catalyst has beenstudied. The results indicate that the reaction orders are one and zero for methane and carbondioxide, respectively, when the carbon dioxide partial pressure was about 12.5-30.0 kPa and thetemperature was at 1123-1173 K. However, when the carbon dioxide partial pressure was changed to30.0-45.0 kPa under the same temperature range of 1123-1173 K, the reaction orders of methane andcarbon dioxide are one. Furthermore, average rate constants at different temperatures weredetermined.展开更多
Time-dependent quantum wave packet calculations were carried out for the F ＋ HBr reaction on the latest London-Erying-Polanyi-Sato potential energy surface constructed by Persky et al. The calculated reaction probabi...Time-dependent quantum wave packet calculations were carried out for the F ＋ HBr reaction on the latest London-Erying-Polanyi-Sato potential energy surface constructed by Persky et al. The calculated reaction probabilities dramatically increase near the zero collision energy and then slightly decrease with increasing collision energy, which corresponds well to the behavior of a barrierless reaction. The effects of reagent HBr excitation were examined, it is shown that both the vibrational and the rotational excitations of reagent HBr have a negative effect on the reactivity of F ＋ HBr. The integral cross-section for the ground state of the reagent HBr decreases at a low collision energy and then becomes plat with increasing collision energy, which is reasonable for the feasibility of such an exothermal reaction. The rate constant that was obtained is slightly higher than that obtained in the quasi-classical trajectory calculation.展开更多
Iodization of dietary salt is recommended to prevent and control iodine deficiency disorders. The kinetic study of dietary iodized salt proves to be of interest not only for the determination of the conditions of prod...Iodization of dietary salt is recommended to prevent and control iodine deficiency disorders. The kinetic study of dietary iodized salt proves to be of interest not only for the determination of the conditions of production of iodine, but also for a good knowledge of the kinetic and thermodynamic parameters of the reaction. In this work, two salt brands were studied and one of them was used for the kinetic study. The kinetic study showed that the reaction proceeded slowly at a medium rate. Since the reaction admits a global order equal to 1, potassium iodide has no influence on this reaction rate. The concentration of iodate ions introduced in the dietary salt is a kinetic parameter that affects the reaction rate. Calculated rate constant was inversely proportional to time. The study has therefore determined experimentally kinetic parameters of the reaction between iodate and iodide ions.展开更多
The reactivity of radical-molecular addition reaction was studied in terms of density-functional theory (DFT) and Hartree-Fock theory (HFT). It was found that the DFT method can give more accurate estimated result tha...The reactivity of radical-molecular addition reaction was studied in terms of density-functional theory (DFT) and Hartree-Fock theory (HFT). It was found that the DFT method can give more accurate estimated result than the HFT method. The reason might be that the energy of the highest occupied molecular orbital (HOMO) in DFT is not the ionization energy, but rather represents the change in the total energy with respect to the change in occupation number of electrons in the HOMO, consistent with the concept of the transition state. The energy of HOMO in HFT is the ionization energy, which may represent more properly the property of the products and reactants themselves.展开更多
Microcanonical rate constants k(E) and canonical rate constants k(T) for unimolecular reactions have been obtained through the calculations of cumulative reaction probabilities N(E) with the unsymmetrical Eckart poten...Microcanonical rate constants k(E) and canonical rate constants k(T) for unimolecular reactions have been obtained through the calculations of cumulative reaction probabilities N(E) with the unsymmetrical Eckart potential tunneling correction. By way of example, the reactions HCN→CNH (I) and FNC→NCF (II) have been employed. For reaction (I), the calculated rate constants are in agreement with the experimental data; for reaction (II), the results are in accordance with the rate constants kCVT/MEPSAG(T) calculated by the common program POLYRATE.展开更多
The reaction mechanism of SiCl4 with H2 has been studied theoretically using Gaussian 98 program at B3LYP/6-311G^＊ level. Three different reaction paths （a, b, c） in the gas phase were obtained. The geometries, vib...The reaction mechanism of SiCl4 with H2 has been studied theoretically using Gaussian 98 program at B3LYP/6-311G^＊ level. Three different reaction paths （a, b, c） in the gas phase were obtained. The geometries, vibrational frequencies and energies of every stagnation point in the reaction channel were calculated and the mechanisms have been confirmed. The results show that path a has an activation energy of 79.12 kcal/mol, which was considered as the main reaction path. Comparably, paths b and c have the energy barriers of 125.07 and 136.25 kcal/mol, respectively. The reaction rate constant was calculated by TST method over a wide temperature range of 900～1600 K, which further confirmed that path a was the main reaction channel展开更多
The reaction behavior of forming the hetero-nuclear β-type chelates of rare earth ions (RE 3+) with p-sulphoaminobromophosphonazo(BPA-pSN) in ClCH_2COOH-CH_3COONa buffer solutions were studied by a spectrophotometri...The reaction behavior of forming the hetero-nuclear β-type chelates of rare earth ions (RE 3+) with p-sulphoaminobromophosphonazo(BPA-pSN) in ClCH_2COOH-CH_3COONa buffer solutions were studied by a spectrophotometric method. The interaction of RE 3+ with BPA-pSN, which can forms hetero-nuclear β-type chelates having composition ratio of RE_1 (light rare earth):BPA-pSN:RE_2(heavy rare earth ion)=1∶3∶1, is a first-order reaction. Meanwhile, BPA-pSN can only forms homo-nuclear β-type chelates with heavy rare earth ions, having a composition ratio of RE∶BPA-pSN=1∶2 and being a second-order reaction. The rate constants of forming homo-and hetero-nuclear β-type chelates were obtained and the mechanism of forming hetero-nuclear β-type chelates was proposed.展开更多
Utilizing Gaussian94 program package, all species involved in decomposition reactions of o-pyridyl radical were optimized fully at B3LYP/6-311＋＋G^＊＊ level. Intrinsic reaction coordinate calculations were employed ...Utilizing Gaussian94 program package, all species involved in decomposition reactions of o-pyridyl radical were optimized fully at B3LYP/6-311＋＋G^＊＊ level. Intrinsic reaction coordinate calculations were employed to confirm the connections of the transition states and products, and transition states were ascertained by the number of imaginary frequency （0 or 1）. The reaction mechanism was elucidated by the vibrational mode analysis and electronic population analysis, and the reaction rate constants were calculated with transition state theory.展开更多
基金This work was supported in part by the National Natural Science Foundation of China (Grant Nos. 10174046, 10474060 and 10504017).
文摘The four-dimensional time-dependent quantum dynamics calculations for reactions of group IV hydride with H are carried out by employing the semirigid vibrating rotor target model and the time-dependent wave packet method. The reaction possibility, cross section and rate constants for reactions (H+SiH_4 and H+GeH_4) in different initial vibrational and rotational states are obtained. The common feature for such kind of reaction process is summarized. The theoretical result is consistent with available measurement, which indicates the credibility of this theory and the potential energy surface.
文摘The kinetics of the catalytic reforming reaction of methane with carbondioxide to produce synthesis gas on a Ni/α-Al_2O_3 and a HSD-2 type commercial catalyst has beenstudied. The results indicate that the reaction orders are one and zero for methane and carbondioxide, respectively, when the carbon dioxide partial pressure was about 12.5-30.0 kPa and thetemperature was at 1123-1173 K. However, when the carbon dioxide partial pressure was changed to30.0-45.0 kPa under the same temperature range of 1123-1173 K, the reaction orders of methane andcarbon dioxide are one. Furthermore, average rate constants at different temperatures weredetermined.
基金Supported by the Open Project Program of Key Laboratory of Advanced Materials &Rheological Properties, Ministry of Educa-tion, China(No KF0504)
文摘Time-dependent quantum wave packet calculations were carried out for the F ＋ HBr reaction on the latest London-Erying-Polanyi-Sato potential energy surface constructed by Persky et al. The calculated reaction probabilities dramatically increase near the zero collision energy and then slightly decrease with increasing collision energy, which corresponds well to the behavior of a barrierless reaction. The effects of reagent HBr excitation were examined, it is shown that both the vibrational and the rotational excitations of reagent HBr have a negative effect on the reactivity of F ＋ HBr. The integral cross-section for the ground state of the reagent HBr decreases at a low collision energy and then becomes plat with increasing collision energy, which is reasonable for the feasibility of such an exothermal reaction. The rate constant that was obtained is slightly higher than that obtained in the quasi-classical trajectory calculation.
文摘Iodization of dietary salt is recommended to prevent and control iodine deficiency disorders. The kinetic study of dietary iodized salt proves to be of interest not only for the determination of the conditions of production of iodine, but also for a good knowledge of the kinetic and thermodynamic parameters of the reaction. In this work, two salt brands were studied and one of them was used for the kinetic study. The kinetic study showed that the reaction proceeded slowly at a medium rate. Since the reaction admits a global order equal to 1, potassium iodide has no influence on this reaction rate. The concentration of iodate ions introduced in the dietary salt is a kinetic parameter that affects the reaction rate. Calculated rate constant was inversely proportional to time. The study has therefore determined experimentally kinetic parameters of the reaction between iodate and iodide ions.
基金the Foundation of State Key Laboratory of Coal Conversion.
文摘The reactivity of radical-molecular addition reaction was studied in terms of density-functional theory (DFT) and Hartree-Fock theory (HFT). It was found that the DFT method can give more accurate estimated result than the HFT method. The reason might be that the energy of the highest occupied molecular orbital (HOMO) in DFT is not the ionization energy, but rather represents the change in the total energy with respect to the change in occupation number of electrons in the HOMO, consistent with the concept of the transition state. The energy of HOMO in HFT is the ionization energy, which may represent more properly the property of the products and reactants themselves.
基金Project supported by the National Natural Science Foundation of China
文摘Microcanonical rate constants k(E) and canonical rate constants k(T) for unimolecular reactions have been obtained through the calculations of cumulative reaction probabilities N(E) with the unsymmetrical Eckart potential tunneling correction. By way of example, the reactions HCN→CNH (I) and FNC→NCF (II) have been employed. For reaction (I), the calculated rate constants are in agreement with the experimental data; for reaction (II), the results are in accordance with the rate constants kCVT/MEPSAG(T) calculated by the common program POLYRATE.
基金This work was supported by the Foundation of Education Committee of Liaoning Province (No.990321076)
文摘The reaction mechanism of SiCl4 with H2 has been studied theoretically using Gaussian 98 program at B3LYP/6-311G^＊ level. Three different reaction paths （a, b, c） in the gas phase were obtained. The geometries, vibrational frequencies and energies of every stagnation point in the reaction channel were calculated and the mechanisms have been confirmed. The results show that path a has an activation energy of 79.12 kcal/mol, which was considered as the main reaction path. Comparably, paths b and c have the energy barriers of 125.07 and 136.25 kcal/mol, respectively. The reaction rate constant was calculated by TST method over a wide temperature range of 900～1600 K, which further confirmed that path a was the main reaction channel
文摘The reaction behavior of forming the hetero-nuclear β-type chelates of rare earth ions (RE 3+) with p-sulphoaminobromophosphonazo(BPA-pSN) in ClCH_2COOH-CH_3COONa buffer solutions were studied by a spectrophotometric method. The interaction of RE 3+ with BPA-pSN, which can forms hetero-nuclear β-type chelates having composition ratio of RE_1 (light rare earth):BPA-pSN:RE_2(heavy rare earth ion)=1∶3∶1, is a first-order reaction. Meanwhile, BPA-pSN can only forms homo-nuclear β-type chelates with heavy rare earth ions, having a composition ratio of RE∶BPA-pSN=1∶2 and being a second-order reaction. The rate constants of forming homo-and hetero-nuclear β-type chelates were obtained and the mechanism of forming hetero-nuclear β-type chelates was proposed.
文摘Utilizing Gaussian94 program package, all species involved in decomposition reactions of o-pyridyl radical were optimized fully at B3LYP/6-311＋＋G^＊＊ level. Intrinsic reaction coordinate calculations were employed to confirm the connections of the transition states and products, and transition states were ascertained by the number of imaginary frequency （0 or 1）. The reaction mechanism was elucidated by the vibrational mode analysis and electronic population analysis, and the reaction rate constants were calculated with transition state theory.
