The La-ZSM-5 zeolite with different contents of La was synthesized by the hydrothermal method. The physico-chemical properties of the materials were studied. The results of FT-IR analyses indicated that La might be in...The La-ZSM-5 zeolite with different contents of La was synthesized by the hydrothermal method. The physico-chemical properties of the materials were studied. The results of FT-IR analyses indicated that La might be incorporated into the framework of ZSM-5 zeolite. The NH3-TPD analyses showed that the amount of weak acid sites of the zeolite decreased with a continuously increasing La content. Afterwards, the La-ZSM-5 zeolite was used as the support of PtSnNa catalyst for propane dehydrogenation. The test results revealed that the utilization of La- ZSM-5 zeolite could achieve a high propene conversion, and effectively inhibit the coke formation on the catalyst surface. When the content of La was 0.16%, the catalytic activity and stability of the catalyst got the best of its performance. Besides, the PtSnNa/La （0.16%）-ZSM-5 catalyst is more stable than the conventional PtSnNaLal ZSM-5 catalysts.展开更多
Activated carbons （ACs） with different surface properties were prepared from different raw materials. N2 adsorption, pH value, Boehm titration, Temperature-programmed reduction （TPR） and FTIR were employed to char...Activated carbons （ACs） with different surface properties were prepared from different raw materials. N2 adsorption, pH value, Boehm titration, Temperature-programmed reduction （TPR） and FTIR were employed to characterize the pore structure and surface chemical properties of the ACs. The results show that AC from bituminous coal （AC-B） has more meso-pores, higher pH value, more carboxylic groups and basic site than ACs from coconut shell and hawthorn（AC-C, AC-H）. Oxygen in the mixture gas has great effect on S02 catalytic oxidation/oxidation ability of AC-B. In the absence of oxygen, the adsorbed SO2 on AC-B is 0.16 mmollg and the conversion ratio of adsorbed S02 to S03 is 22.07~; while in the presence of oxygen, the adsorbed amount of S02 is 0.42 retool/g, and all of the adsorbed S02 was totally converted to SO3. This feature of AC-B is consistent with its higher pH value, basic site and the reaction ability with H2 from TPR. The conversion ratios of S02 absorbed on both AC-C and AC-H were 100%, respectively.展开更多
The acidic properties of aluminum phosphate （A1PO4-5） solid acid catalyst were characterized by tem- perature programmed desorption （TPD） of ammonia （NH3）, n-propylamine （n-C3HTNH2）, iso-propylamine [（CH3）2C...The acidic properties of aluminum phosphate （A1PO4-5） solid acid catalyst were characterized by tem- perature programmed desorption （TPD） of ammonia （NH3）, n-propylamine （n-C3HTNH2）, iso-propylamine [（CH3）2CHNH2] and n-dipropylamine [（C3H7）2NH] separately, and its catalytic performance in benzene alkylation with long chain olefin was studied in a fixed-bed reactor. The characterized acid amount of catalyst increased with the basicity of adsorbates. With increase of the activation temperature of catalyst, the acid amount characterized by NHa-TPD decreased, however, it increased when characterized by TPD using three other adsorbates. The desorption kinetics of TPD process and the deactivation kinetics of catalyst were investigated. The acidity and catalytic per- formance of catalyst was also correlated. The results showed that the acid amount and strength are well correlated with the activity and stability using NH3 as adsorbate, respectively, which indicated NH3 was a better basic adsorbate. It was also found that the catalyst with higher acid amount and lower acid strength on the surface exhibited the better catalytic performance and stability.展开更多
Photocatalysis of 2-propanol on A-TiO2（101） has been investigated using a temperature programed desorption method with 266 nm laser light. A clear mechanism is proposed for photodissociation of 2-propanol on A-TiO2...Photocatalysis of 2-propanol on A-TiO2（101） has been investigated using a temperature programed desorption method with 266 nm laser light. A clear mechanism is proposed for photodissociation of 2-propanol on A-TiO2（101）. Acetone product on five coordinate Ti4＋ sites is formed in a stepwise manner in which the O-H dissociation proceeds first and then followed by secondary C-H dissociation of 2-propanol while H atoms are transferred to the adjacent bridge bond oxygen （BBO） sites. Low temperature water is formed in a thermally driven process via H-atom on BBO in exchange with isopropyl groups of molecule 2-propanol, while isopropyl radical desorbs at high temperature during the TPD process. The observation demonstrates the prospect of TiO2 as a photocatalyst for degradation of organics.展开更多
CO self-poisoning and slow surface kinetics pose major challenges to a CO oxidation catalyst that should work at ambient temperature.Furthermore,the presence of moisture would cause passivation of the catalyst A highl...CO self-poisoning and slow surface kinetics pose major challenges to a CO oxidation catalyst that should work at ambient temperature.Furthermore,the presence of moisture would cause passivation of the catalyst A highly active ceria promoted Pt catalyst（4%Pt-12%CeO_2/SiO_2;conversion≥99%at low（ 500 ppm） and high（ 2500 ppm） CO concentrations was developed for CO oxidation at ambient temperature in humid air.Catalyst preparation variables such as Pt and CeO_2 loading,ceria deposition method,drying and calcination conditions for the ceria and Pt precursors were optimized experimentally.The activity was correlated with surface properties using CO/H_2 chemisorption,O_2-H_2 titration,X-ray diffraction and BET surface area analysis.The method of CeO_2 deposition had a significant impact on the catalytic activity.CeO_2 deposition by impregnation resulted in a catalyst that was three times more active than that prepared by deposition precipitation or CeO_2grafting.O_2-H_2 titration results revealed that the close association of ceria and Pt in the case of CeO_2deposition by impregnation resulted in higher activity.The catalyst support used was also crucial as a silica supported catalyst was five times more active than an alumina supported catalyst.The particle size and pore structure of the catalyst support were also crucial as the reaction was diffusion controlled.The drying and calcination conditions of the ceria and Pt precursors also played a crucial role in determining the catalytic activity.The Pt-CeO_2/SiO_2 catalysts with Pt 2.5 wt%and CeO_2 15 wt%were highly active（TOF 0.02 s^（-1）） and stable（conversion 99%after 15 h） at ambient conditions.展开更多
The vitrification characteristics of municipal solid waste incinerator (MSWI) fly ash were investigated. Effects of temperature on the binding efficiency of heavy metals, the change of chemical compositions and the we...The vitrification characteristics of municipal solid waste incinerator (MSWI) fly ash were investigated. Effects of temperature on the binding efficiency of heavy metals, the change of chemical compositions and the weight loss of fly ash in the range of 800-1350 ℃ were studied. Toxicity Characteristic Leaching Procedure (TCLP) of the United States was used to analyze the leaching characteristics of heavy metals in fly ash and molten slag. Results indicate that chemical compositions, the weight loss of fly ash and the binding efficiency of heavy metals in fly ash have a tremendous change in the range of 1150-1260 ℃. The percentage of CaO, SiO2 and Al2O3 increases with the increasing temperature, whereas it is contrary for SO3, K2O, Na2O and Cl; especially when the temperature is 1260 ℃, the percentage of these four elements decreases sharply from 43.72% to 0.71%. The weight loss occurs obviously in the range of 1150-1260 ℃. Heavy metals of Pb and Cd are almost vaporized above 1000 ℃. Cr is not volatile and its binding efficiency can reach 100% below 1000 ℃. Results of TCLP indicate that the heavy metal content of molten slag is beyond stipulated limit values.展开更多
The iso-conversion method to could calculate the kinetics parameters effectively, the present paper built an evaluation equation for iso-conversion methods according to the thermo kinetics integral equation and analys...The iso-conversion method to could calculate the kinetics parameters effectively, the present paper built an evaluation equation for iso-conversion methods according to the thermo kinetics integral equation and analyses the temperatures of the same degree of conversion for different heating rates by ideal TG （thermo-gravity） curve data. It is obtained that the temperatures of the same degree of conversion for different heating rates＇ TG curve have good linearity connection validating the correction of the evaluation equation for iso-conversion methods and the scope of linear slope for theratio between heating rates being 2 is 1.05 to 1.09.展开更多
基金the National Nature Science Foundation of China(50873026)the Science and Technology Support Program of Jiangsu Province (BE2008129)the"Six Talents Pinnacle Program"of Jiangsu Province(06-A-033) for financial supports
文摘The La-ZSM-5 zeolite with different contents of La was synthesized by the hydrothermal method. The physico-chemical properties of the materials were studied. The results of FT-IR analyses indicated that La might be incorporated into the framework of ZSM-5 zeolite. The NH3-TPD analyses showed that the amount of weak acid sites of the zeolite decreased with a continuously increasing La content. Afterwards, the La-ZSM-5 zeolite was used as the support of PtSnNa catalyst for propane dehydrogenation. The test results revealed that the utilization of La- ZSM-5 zeolite could achieve a high propene conversion, and effectively inhibit the coke formation on the catalyst surface. When the content of La was 0.16%, the catalytic activity and stability of the catalyst got the best of its performance. Besides, the PtSnNa/La （0.16%）-ZSM-5 catalyst is more stable than the conventional PtSnNaLal ZSM-5 catalysts.
基金support from the National Natural Science Foundation of China (No.50204011)
文摘Activated carbons （ACs） with different surface properties were prepared from different raw materials. N2 adsorption, pH value, Boehm titration, Temperature-programmed reduction （TPR） and FTIR were employed to characterize the pore structure and surface chemical properties of the ACs. The results show that AC from bituminous coal （AC-B） has more meso-pores, higher pH value, more carboxylic groups and basic site than ACs from coconut shell and hawthorn（AC-C, AC-H）. Oxygen in the mixture gas has great effect on S02 catalytic oxidation/oxidation ability of AC-B. In the absence of oxygen, the adsorbed SO2 on AC-B is 0.16 mmollg and the conversion ratio of adsorbed S02 to S03 is 22.07~; while in the presence of oxygen, the adsorbed amount of S02 is 0.42 retool/g, and all of the adsorbed S02 was totally converted to SO3. This feature of AC-B is consistent with its higher pH value, basic site and the reaction ability with H2 from TPR. The conversion ratios of S02 absorbed on both AC-C and AC-H were 100%, respectively.
文摘The acidic properties of aluminum phosphate （A1PO4-5） solid acid catalyst were characterized by tem- perature programmed desorption （TPD） of ammonia （NH3）, n-propylamine （n-C3HTNH2）, iso-propylamine [（CH3）2CHNH2] and n-dipropylamine [（C3H7）2NH] separately, and its catalytic performance in benzene alkylation with long chain olefin was studied in a fixed-bed reactor. The characterized acid amount of catalyst increased with the basicity of adsorbates. With increase of the activation temperature of catalyst, the acid amount characterized by NHa-TPD decreased, however, it increased when characterized by TPD using three other adsorbates. The desorption kinetics of TPD process and the deactivation kinetics of catalyst were investigated. The acidity and catalytic per- formance of catalyst was also correlated. The results showed that the acid amount and strength are well correlated with the activity and stability using NH3 as adsorbate, respectively, which indicated NH3 was a better basic adsorbate. It was also found that the catalyst with higher acid amount and lower acid strength on the surface exhibited the better catalytic performance and stability.
基金This work was supported by the Chinese Academy of Sciences, the National Natural Science Foundation of China （No.21403224）, the Chinese Ministry of Science and Technology （No.2013CB834605）, the Youth Innovation Promotion Association CAS, and the Key Research Program of the Chinese Academy of Sciences.
文摘Photocatalysis of 2-propanol on A-TiO2（101） has been investigated using a temperature programed desorption method with 266 nm laser light. A clear mechanism is proposed for photodissociation of 2-propanol on A-TiO2（101）. Acetone product on five coordinate Ti4＋ sites is formed in a stepwise manner in which the O-H dissociation proceeds first and then followed by secondary C-H dissociation of 2-propanol while H atoms are transferred to the adjacent bridge bond oxygen （BBO） sites. Low temperature water is formed in a thermally driven process via H-atom on BBO in exchange with isopropyl groups of molecule 2-propanol, while isopropyl radical desorbs at high temperature during the TPD process. The observation demonstrates the prospect of TiO2 as a photocatalyst for degradation of organics.
基金supported by US Army contract(W56HZV-05-C0686) at Auburn University administered through TARDEC
文摘CO self-poisoning and slow surface kinetics pose major challenges to a CO oxidation catalyst that should work at ambient temperature.Furthermore,the presence of moisture would cause passivation of the catalyst A highly active ceria promoted Pt catalyst（4%Pt-12%CeO_2/SiO_2;conversion≥99%at low（ 500 ppm） and high（ 2500 ppm） CO concentrations was developed for CO oxidation at ambient temperature in humid air.Catalyst preparation variables such as Pt and CeO_2 loading,ceria deposition method,drying and calcination conditions for the ceria and Pt precursors were optimized experimentally.The activity was correlated with surface properties using CO/H_2 chemisorption,O_2-H_2 titration,X-ray diffraction and BET surface area analysis.The method of CeO_2 deposition had a significant impact on the catalytic activity.CeO_2 deposition by impregnation resulted in a catalyst that was three times more active than that prepared by deposition precipitation or CeO_2grafting.O_2-H_2 titration results revealed that the close association of ceria and Pt in the case of CeO_2deposition by impregnation resulted in higher activity.The catalyst support used was also crucial as a silica supported catalyst was five times more active than an alumina supported catalyst.The particle size and pore structure of the catalyst support were also crucial as the reaction was diffusion controlled.The drying and calcination conditions of the ceria and Pt precursors also played a crucial role in determining the catalytic activity.The Pt-CeO_2/SiO_2 catalysts with Pt 2.5 wt%and CeO_2 15 wt%were highly active（TOF 0.02 s^（-1）） and stable（conversion 99%after 15 h） at ambient conditions.
基金Sponsored by the Chinese Postdoctoral Fund(Grant No.023205030)National Natural Science Foundation of China(Grant No.20577047)
文摘The vitrification characteristics of municipal solid waste incinerator (MSWI) fly ash were investigated. Effects of temperature on the binding efficiency of heavy metals, the change of chemical compositions and the weight loss of fly ash in the range of 800-1350 ℃ were studied. Toxicity Characteristic Leaching Procedure (TCLP) of the United States was used to analyze the leaching characteristics of heavy metals in fly ash and molten slag. Results indicate that chemical compositions, the weight loss of fly ash and the binding efficiency of heavy metals in fly ash have a tremendous change in the range of 1150-1260 ℃. The percentage of CaO, SiO2 and Al2O3 increases with the increasing temperature, whereas it is contrary for SO3, K2O, Na2O and Cl; especially when the temperature is 1260 ℃, the percentage of these four elements decreases sharply from 43.72% to 0.71%. The weight loss occurs obviously in the range of 1150-1260 ℃. Heavy metals of Pb and Cd are almost vaporized above 1000 ℃. Cr is not volatile and its binding efficiency can reach 100% below 1000 ℃. Results of TCLP indicate that the heavy metal content of molten slag is beyond stipulated limit values.
文摘The iso-conversion method to could calculate the kinetics parameters effectively, the present paper built an evaluation equation for iso-conversion methods according to the thermo kinetics integral equation and analyses the temperatures of the same degree of conversion for different heating rates by ideal TG （thermo-gravity） curve data. It is obtained that the temperatures of the same degree of conversion for different heating rates＇ TG curve have good linearity connection validating the correction of the evaluation equation for iso-conversion methods and the scope of linear slope for theratio between heating rates being 2 is 1.05 to 1.09.
