The synthesis of pyridine from aldehydes and ammonia was performed over ZSM-5 catalyst. The catalytic activity in reaction was correlated with the acidity of the zeolite catalysts. A few of ZSM-5 (m(SiO2)/m(Al2O3)=120...The synthesis of pyridine from aldehydes and ammonia was performed over ZSM-5 catalyst. The catalytic activity in reaction was correlated with the acidity of the zeolite catalysts. A few of ZSM-5 (m(SiO2)/m(Al2O3)=120) were prepared and modified with Co2+, Fe3+. The surface acidity was determined by Py-IR technique. It was found that CoZSM-5 and FeZSM-5 have fewer Lewis acid sites than HZSM-5. The decrease of Lewis acid sites leads to decreasing the ability of NH3 adsorption, this phenomenon insures that there are adequate acid sites discovering and reacting with aldehydes. It is advantageous to the reaction. By using a CoZSM-5 catalyst, the yields of pyridine base can reach 78%. The study provides a theoretical base for preparing high activity and high selective catalyst for pyridine synthesis.展开更多
Oleoylchitosans (O-chitosans) with different degrees of substitution (DS) were synthesized by reacting chitosan with oleoyl chloride. The chemical structures of the products were characterized by 1H NMR and FT-IR. The...Oleoylchitosans (O-chitosans) with different degrees of substitution (DS) were synthesized by reacting chitosan with oleoyl chloride. The chemical structures of the products were characterized by 1H NMR and FT-IR. These results suggested the for- mation of an amide linkage between the amino groups of chitosan and the carboxyl groups of oleic acid. The viscosity of O-chitosan sharply increased with the increase of concentration, whereas that of unmodified chitosan rose only slightly. This increase became larger as the DS increased. All of the O-chitosans could reduce surface tension slightly. The critical aggregation concentration (CAC) of O-chitosans with DS 5%, 11%, and 27% were 79.43 mgL-1, 31.6 mgL-1, and 10 mgL-1, respectively. Nanoparticles were prepared using an O/W emulsification method. The mean diameters of the polymeric amphiphilic nanoparticles of O-chitosans with DS 5% and 11% were around 327.4 nm and 275.3 nm, respectively.展开更多
Membrane fouling seriously restricts applications of membrane technology. A novel strategy was applied in this study to retard membrane fouling by changing operating pressure with the pressure responsibility membrane....Membrane fouling seriously restricts applications of membrane technology. A novel strategy was applied in this study to retard membrane fouling by changing operating pressure with the pressure responsibility membrane. A polyurethane-based hollow fiber membrane was used to treat surface water for evaluating the effect of operating pressure on membrane fouling. Some bench-scale tests in dead-end mode were carried out. In the experiments without backwashing, as operating pressure increased, severe membrane fouling occurred on membrane surface, while the permeate quality was improved obviously, which is considered to be due to shrinkage deformation. The total resistance, irreversible resistance and reversible resistance under different backwash pressures were determined in filtration/backwashing test. With the increase of backwash pressure, the total resistance decreased, and more importantly, the irreversible resistance also decreased, which implies that small particles deposited inside membrane pores and cake layers on membrane surface are effectively removed. Similar results could be obtained in mass balance tests. The results of the present study indicate that the application of pressure responsibility membrane in surface water treatment may be an effective strategy for reducing membrane fouling.展开更多
The controlling step and the extraction reaction rate equation of zinc extraction from Zn（II）-NH3 solution by using a newly synthesized organic compound, 2-acetyl-3-oxo-dithiobutyric acid-myristyl ester as the zinc ...The controlling step and the extraction reaction rate equation of zinc extraction from Zn（II）-NH3 solution by using a newly synthesized organic compound, 2-acetyl-3-oxo-dithiobutyric acid-myristyl ester as the zinc extractant, were clarified. The effects of agitation speed, specific interfacial area, temperature, extractant concentration and Zn ion concentration on the extraction rate are studied in constant interfacial area cell. The results show that the extraction rate depends on interfacial chemical reaction and diffusion by using this new extraetant to extract zinc, and the apparent activation energy of this extraction reaction is measured as 28.2 kJ/mol, which demonstrates that the extraction reaction is controlled by the mixed-controlled reaction rate. The apparent reaction orders a and b are measured as 1 and 0.38, and the constant k0 is 138.70. So, when extraction conditions are controlled as [HR]=20%-50%, T=0-30℃, N=120-177 r/min and S=72.6-127.5 m-1, the solvent extraction reaction rate can be depicted as v/（mol . m-2 . s-1 ） = 138.7. exp（ - 28 206/8.314T ）. [Zn 2＋ ]r ·[HR ]o0.38.展开更多
文摘The synthesis of pyridine from aldehydes and ammonia was performed over ZSM-5 catalyst. The catalytic activity in reaction was correlated with the acidity of the zeolite catalysts. A few of ZSM-5 (m(SiO2)/m(Al2O3)=120) were prepared and modified with Co2+, Fe3+. The surface acidity was determined by Py-IR technique. It was found that CoZSM-5 and FeZSM-5 have fewer Lewis acid sites than HZSM-5. The decrease of Lewis acid sites leads to decreasing the ability of NH3 adsorption, this phenomenon insures that there are adequate acid sites discovering and reacting with aldehydes. It is advantageous to the reaction. By using a CoZSM-5 catalyst, the yields of pyridine base can reach 78%. The study provides a theoretical base for preparing high activity and high selective catalyst for pyridine synthesis.
基金financial support from the National Natural Science Foundation of China(No.30370344)the Scientist Encouragement Foundation of Shandong Province(2004BS7001).
文摘Oleoylchitosans (O-chitosans) with different degrees of substitution (DS) were synthesized by reacting chitosan with oleoyl chloride. The chemical structures of the products were characterized by 1H NMR and FT-IR. These results suggested the for- mation of an amide linkage between the amino groups of chitosan and the carboxyl groups of oleic acid. The viscosity of O-chitosan sharply increased with the increase of concentration, whereas that of unmodified chitosan rose only slightly. This increase became larger as the DS increased. All of the O-chitosans could reduce surface tension slightly. The critical aggregation concentration (CAC) of O-chitosans with DS 5%, 11%, and 27% were 79.43 mgL-1, 31.6 mgL-1, and 10 mgL-1, respectively. Nanoparticles were prepared using an O/W emulsification method. The mean diameters of the polymeric amphiphilic nanoparticles of O-chitosans with DS 5% and 11% were around 327.4 nm and 275.3 nm, respectively.
基金Supported by the National Natural Science Foundation of China(51078264,51108314,51108315,51138008)
文摘Membrane fouling seriously restricts applications of membrane technology. A novel strategy was applied in this study to retard membrane fouling by changing operating pressure with the pressure responsibility membrane. A polyurethane-based hollow fiber membrane was used to treat surface water for evaluating the effect of operating pressure on membrane fouling. Some bench-scale tests in dead-end mode were carried out. In the experiments without backwashing, as operating pressure increased, severe membrane fouling occurred on membrane surface, while the permeate quality was improved obviously, which is considered to be due to shrinkage deformation. The total resistance, irreversible resistance and reversible resistance under different backwash pressures were determined in filtration/backwashing test. With the increase of backwash pressure, the total resistance decreased, and more importantly, the irreversible resistance also decreased, which implies that small particles deposited inside membrane pores and cake layers on membrane surface are effectively removed. Similar results could be obtained in mass balance tests. The results of the present study indicate that the application of pressure responsibility membrane in surface water treatment may be an effective strategy for reducing membrane fouling.
基金Foundation item： Project（51174240） supported by the National Natural Science Foundation of China Project（2006BA02B04-4-2） supported by the National Eleventh Five-Year Research Program of China Project（20100908） supported by Scientific and Industrial Research Organisation of Guangdong Province, China
文摘The controlling step and the extraction reaction rate equation of zinc extraction from Zn（II）-NH3 solution by using a newly synthesized organic compound, 2-acetyl-3-oxo-dithiobutyric acid-myristyl ester as the zinc extractant, were clarified. The effects of agitation speed, specific interfacial area, temperature, extractant concentration and Zn ion concentration on the extraction rate are studied in constant interfacial area cell. The results show that the extraction rate depends on interfacial chemical reaction and diffusion by using this new extraetant to extract zinc, and the apparent activation energy of this extraction reaction is measured as 28.2 kJ/mol, which demonstrates that the extraction reaction is controlled by the mixed-controlled reaction rate. The apparent reaction orders a and b are measured as 1 and 0.38, and the constant k0 is 138.70. So, when extraction conditions are controlled as [HR]=20%-50%, T=0-30℃, N=120-177 r/min and S=72.6-127.5 m-1, the solvent extraction reaction rate can be depicted as v/（mol . m-2 . s-1 ） = 138.7. exp（ - 28 206/8.314T ）. [Zn 2＋ ]r ·[HR ]o0.38.
