Aluminosilicate zeolites as one of the most important catalytic materials are widely applied in industrial reactions,and understanding of their synthetic mechanism is one of key factors in this field.27Al and 29Si NMR...Aluminosilicate zeolites as one of the most important catalytic materials are widely applied in industrial reactions,and understanding of their synthetic mechanism is one of key factors in this field.27Al and 29Si NMR techniques are one of powerful tools for characterization of zeolite synthesis,but unfortunately the study on 27Al NMR spectra of aluminosilicate solutions is still argumentative,and the assignment of aluminosi-licate species in the solutions are challengeable.In this work,we have carefully compared 27Al NMR spectra of various aluminosilicate solutions,harmonizing the assignments reported previously.Furthermore,we assigned 29Si NMR spectra related to Al species.The peaks at δ:-75.1 and-82.5 in 29Si NMR spectrum are related to Q2 Al species,the peaks at δ:-84.5 and-90.8 are related to Q3 and Q4 Al species in aluminosilicate solutions,respectively.展开更多
Silica mesoporous materials were synthesized and used as the supporting materials for immobilization of enzyme.Penicillin G acylase,an enzyme which was used to produce 6-APA in pharmaceutical industry,was immobilized ...Silica mesoporous materials were synthesized and used as the supporting materials for immobilization of enzyme.Penicillin G acylase,an enzyme which was used to produce 6-APA in pharmaceutical industry,was immobilized in the mesoporous materials by the immersion method.The stabilities of the immobilized penicillin G acylase were studied.After incubation at 60 ℃ for 2 h,the activity of immobilized penicillin G acylase remained 80% in the best case.At higher or lower pH,the free enzyme was deactivated quickly,while the immobilized enzyme still retained active.The result of operational stability showed that the immobilized(enzyme) retained 70% of its initial activity after operating for 6 times.These results showed that the stabilities of immobilized penicillin G acylase,related to the pore size of mesoporous materials,were increased significantly compared with those of free enzyme.The improvement of stabilities of immobilized enzyme was significant when the pore size of the mesoporous materials matched the enzyme molecule size.展开更多
This paper mainly elaborated the recent developments of the studies on the new type zeohite molecular sieve host-nanoguest composite materials composing of molecular sieve chaimels or cages encapsulated nanoscale mate...This paper mainly elaborated the recent developments of the studies on the new type zeohite molecular sieve host-nanoguest composite materials composing of molecular sieve chaimels or cages encapsulated nanoscale materials from the point of nanochemistry and material science,and the trends of development in this field. As the research of the properties of this kind of materials are gomg on. it is possible that this kind of host-guest nanocomposite materials will be usd in some fields. such as science and high technology fields. as the new type of ptical. electrical and magnetic materials in the level of molecular assembly. This paper contains the following contents:hosts and guests; the sizes and shapes of guests; the optical, electrical and magnetic properties of the materials; the syntheses and characterizations of the materials; the applications of the materials and forecast.展开更多
Silica mesoporous material MCFs with 16.0 nm pore sizes was prepared by using non-ionic block copolymers and the swelling agents, and was used as the support for the immobilization of enzyme. Penicillin G acylase, an ...Silica mesoporous material MCFs with 16.0 nm pore sizes was prepared by using non-ionic block copolymers and the swelling agents, and was used as the support for the immobilization of enzyme. Penicillin G acylase, an enzyme, was assembled in the channel of MCFs by immersion method. The activity and stability of immobilized penicillin G acylase were studied. It was found that the activity and stability of the immobilized penicillin G acylase increased significantly compared to those of free enzyme. The optimum reaction temperature is 60 ℃. After incubation at 60 ℃ for 1 h, the activity of these immobilized penicillin G acylase remains 69%. These results showed that thermostability and durability on heating of the immobilized penicillin G acylase in MCFs was improved remarkably. The silica mesoporous material MCFs with 3-dimensional channel structure is a good support for the immobilization of enzyme.展开更多
文摘Aluminosilicate zeolites as one of the most important catalytic materials are widely applied in industrial reactions,and understanding of their synthetic mechanism is one of key factors in this field.27Al and 29Si NMR techniques are one of powerful tools for characterization of zeolite synthesis,but unfortunately the study on 27Al NMR spectra of aluminosilicate solutions is still argumentative,and the assignment of aluminosi-licate species in the solutions are challengeable.In this work,we have carefully compared 27Al NMR spectra of various aluminosilicate solutions,harmonizing the assignments reported previously.Furthermore,we assigned 29Si NMR spectra related to Al species.The peaks at δ:-75.1 and-82.5 in 29Si NMR spectrum are related to Q2 Al species,the peaks at δ:-84.5 and-90.8 are related to Q3 and Q4 Al species in aluminosilicate solutions,respectively.
文摘Silica mesoporous materials were synthesized and used as the supporting materials for immobilization of enzyme.Penicillin G acylase,an enzyme which was used to produce 6-APA in pharmaceutical industry,was immobilized in the mesoporous materials by the immersion method.The stabilities of the immobilized penicillin G acylase were studied.After incubation at 60 ℃ for 2 h,the activity of immobilized penicillin G acylase remained 80% in the best case.At higher or lower pH,the free enzyme was deactivated quickly,while the immobilized enzyme still retained active.The result of operational stability showed that the immobilized(enzyme) retained 70% of its initial activity after operating for 6 times.These results showed that the stabilities of immobilized penicillin G acylase,related to the pore size of mesoporous materials,were increased significantly compared with those of free enzyme.The improvement of stabilities of immobilized enzyme was significant when the pore size of the mesoporous materials matched the enzyme molecule size.
文摘This paper mainly elaborated the recent developments of the studies on the new type zeohite molecular sieve host-nanoguest composite materials composing of molecular sieve chaimels or cages encapsulated nanoscale materials from the point of nanochemistry and material science,and the trends of development in this field. As the research of the properties of this kind of materials are gomg on. it is possible that this kind of host-guest nanocomposite materials will be usd in some fields. such as science and high technology fields. as the new type of ptical. electrical and magnetic materials in the level of molecular assembly. This paper contains the following contents:hosts and guests; the sizes and shapes of guests; the optical, electrical and magnetic properties of the materials; the syntheses and characterizations of the materials; the applications of the materials and forecast.
文摘Silica mesoporous material MCFs with 16.0 nm pore sizes was prepared by using non-ionic block copolymers and the swelling agents, and was used as the support for the immobilization of enzyme. Penicillin G acylase, an enzyme, was assembled in the channel of MCFs by immersion method. The activity and stability of immobilized penicillin G acylase were studied. It was found that the activity and stability of the immobilized penicillin G acylase increased significantly compared to those of free enzyme. The optimum reaction temperature is 60 ℃. After incubation at 60 ℃ for 1 h, the activity of these immobilized penicillin G acylase remains 69%. These results showed that thermostability and durability on heating of the immobilized penicillin G acylase in MCFs was improved remarkably. The silica mesoporous material MCFs with 3-dimensional channel structure is a good support for the immobilization of enzyme.
