Reaction kinetics of LiOH·H2O and CO2 within a closed system were studied under the adsorption of water vapor by composite silica gel of lanthanum chloride. At the reaction temperature of 273～323 K and initial C...Reaction kinetics of LiOH·H2O and CO2 within a closed system were studied under the adsorption of water vapor by composite silica gel of lanthanum chloride. At the reaction temperature of 273～323 K and initial CO2 pressures of 40～100 kPa, reaction kinetics obeyed the Erofeev model. The reaction rate decreased slightly while the initial CO2 pressure reduced. When the reaction occurred at 273～299 K, the reaction rate was so low that it was almost independent of the reaction temperature. However, as the temperature rose up to 300～323 K, LiOH·H2O dehydrated its crystal water, and both the dehydrated and reaction-generated water were evaporated from solid reactant. For the dehydration rate increased, the reaction rate also increased as the reaction temperature rose. While the temperature was higher than 323 K, the reaction apparent activation energy of LiOH·H2O and CO2, was higher than 52.5 kJ·mol-1 and close to 61.4 kJ·mol-1 of the LiOH·H2O dehydrated enthalpy variable at 298 K, in which anhydrous LiOH was the major reactant and showed the reaction characteristics of LiOH crystals.展开更多
A static method was employed to study the reaction kinetics of anhydrous lithium hydroxide (LiOH) and CO2. The reaction generated water was absorbed with the composite silica gel of lanthanum chloride to make the expe...A static method was employed to study the reaction kinetics of anhydrous lithium hydroxide (LiOH) and CO2. The reaction generated water was absorbed with the composite silica gel of lanthanum chloride to make the experiment repeatable. At the reaction temperature of 15～60 ℃ and initial CO2 pressures of 25～100 kPa, the reaction rate of anhydrous LiOH and CO2 decreased slightly with the reduction of initial CO2 pressure and the rise of reaction temperature, indicating that the reaction activation energy of LiOH and CO2 was negative and close to zero. During the middle period (1～5 min) of the isothermal reaction, the ratio of reaction efficiency was approximately the power of 0.4 to that of initial CO2 pressures. As anhydrous LiOH reacted to CO2, the solid product Li2CO3 covered on the surface of LiOH was not compact, so it did not hinder the subsequent reaction of absorbing the CO2 gas. The reaction kinetics of anhydrous LiOH and CO2 obeyed the Erofeev′s model.展开更多
High pressure synthesis of solid material tends to increase the density, coordination number, symmetry of material and shorten bond length. The solid synthesized at a high pressure and decompressed to ambient pressure...High pressure synthesis of solid material tends to increase the density, coordination number, symmetry of material and shorten bond length. The solid synthesized at a high pressure and decompressed to ambient pressure often exhibits a meta- stable ＂stretched＂ state, within the high pressure stability field. The crystal grown at a high pressure is of great importance with the development of high pressure technology. Crystal growth is an important factor in the material synthesis. And many me- thods including gas, solid and solution methods have been used to obtain various single crystalstl]. Especially, flux method is an important method for crystal growth, where the components of the desired substance dissolved in a solvent（flux） grow in the process of deposit.展开更多
Lanthanum hydroxide nanorods with a diameter of 10-20 nm and length up to 100-200 nm were synthesized through a direct reaction of La(NO3)3 and KOH under hydrothermal microemulsion conditions.X-ray diffraction（XRD） ...Lanthanum hydroxide nanorods with a diameter of 10-20 nm and length up to 100-200 nm were synthesized through a direct reaction of La(NO3)3 and KOH under hydrothermal microemulsion conditions.X-ray diffraction（XRD） and scanning electron microscope（SEM） were employed for the characterization of the structure,compositions and morphology of the obtained products.The results showed that the molar ratio of water to the surfactant CTAB,concentration of La(NO3)3,reactant temperature and reactant time all could affect the morphology and size of the lanthanum hydroxide nanorods.展开更多
基金Project supported bythe Beijing Education Committee Scientific Plan Fund (KM200711417006)
文摘Reaction kinetics of LiOH·H2O and CO2 within a closed system were studied under the adsorption of water vapor by composite silica gel of lanthanum chloride. At the reaction temperature of 273～323 K and initial CO2 pressures of 40～100 kPa, reaction kinetics obeyed the Erofeev model. The reaction rate decreased slightly while the initial CO2 pressure reduced. When the reaction occurred at 273～299 K, the reaction rate was so low that it was almost independent of the reaction temperature. However, as the temperature rose up to 300～323 K, LiOH·H2O dehydrated its crystal water, and both the dehydrated and reaction-generated water were evaporated from solid reactant. For the dehydration rate increased, the reaction rate also increased as the reaction temperature rose. While the temperature was higher than 323 K, the reaction apparent activation energy of LiOH·H2O and CO2, was higher than 52.5 kJ·mol-1 and close to 61.4 kJ·mol-1 of the LiOH·H2O dehydrated enthalpy variable at 298 K, in which anhydrous LiOH was the major reactant and showed the reaction characteristics of LiOH crystals.
基金Project supported bythe Beijing Education Committee Scientific Plan Fund (KM200711417006)
文摘A static method was employed to study the reaction kinetics of anhydrous lithium hydroxide (LiOH) and CO2. The reaction generated water was absorbed with the composite silica gel of lanthanum chloride to make the experiment repeatable. At the reaction temperature of 15～60 ℃ and initial CO2 pressures of 25～100 kPa, the reaction rate of anhydrous LiOH and CO2 decreased slightly with the reduction of initial CO2 pressure and the rise of reaction temperature, indicating that the reaction activation energy of LiOH and CO2 was negative and close to zero. During the middle period (1～5 min) of the isothermal reaction, the ratio of reaction efficiency was approximately the power of 0.4 to that of initial CO2 pressures. As anhydrous LiOH reacted to CO2, the solid product Li2CO3 covered on the surface of LiOH was not compact, so it did not hinder the subsequent reaction of absorbing the CO2 gas. The reaction kinetics of anhydrous LiOH and CO2 obeyed the Erofeev′s model.
基金Supported by the National Natural Science Foundation of China（No.21271082） and the Development of Science and Tech- nology Plan of Jilin Province, China（No.20110341）.
文摘High pressure synthesis of solid material tends to increase the density, coordination number, symmetry of material and shorten bond length. The solid synthesized at a high pressure and decompressed to ambient pressure often exhibits a meta- stable ＂stretched＂ state, within the high pressure stability field. The crystal grown at a high pressure is of great importance with the development of high pressure technology. Crystal growth is an important factor in the material synthesis. And many me- thods including gas, solid and solution methods have been used to obtain various single crystalstl]. Especially, flux method is an important method for crystal growth, where the components of the desired substance dissolved in a solvent（flux） grow in the process of deposit.
文摘Lanthanum hydroxide nanorods with a diameter of 10-20 nm and length up to 100-200 nm were synthesized through a direct reaction of La(NO3)3 and KOH under hydrothermal microemulsion conditions.X-ray diffraction（XRD） and scanning electron microscope（SEM） were employed for the characterization of the structure,compositions and morphology of the obtained products.The results showed that the molar ratio of water to the surfactant CTAB,concentration of La(NO3)3,reactant temperature and reactant time all could affect the morphology and size of the lanthanum hydroxide nanorods.
