Multinucleax solid-state NMR was employed to study the silicon-substitutedmolecular sieve Si-VPI-5. 29Si and 27Al NMR suggest that Si can be incorporated intothe framework of VPI-5 and the substitution of two silicon ...Multinucleax solid-state NMR was employed to study the silicon-substitutedmolecular sieve Si-VPI-5. 29Si and 27Al NMR suggest that Si can be incorporated intothe framework of VPI-5 and the substitution of two silicon atoms for an aluminium atomplus a phosphorus atom is predominant. Such substitution is limited in a certain domainof the crystal and "silicon rich" regions are thus generated. 1H MAS spectra reveal that asmall arnount of silicon atoms substitute phosphorus only and SiOHAl groups are formed,which provides the acidic source for the molecular sieves. Si-VPI-5 prepared with silicagel as the silicon source exhibits a higher content of SiOHAl groups than that preparedwith (EtO)4Si.展开更多
According to the NMR spectroscopy of fiulds satuxated in porous rocks, by using different pulse sequences and imaging parameters, high resolution NMR micro-images of lime stone and sand stone samples were obtained. Th...According to the NMR spectroscopy of fiulds satuxated in porous rocks, by using different pulse sequences and imaging parameters, high resolution NMR micro-images of lime stone and sand stone samples were obtained. The heterogeneous interconnection structure of the tested sandstone is visuallzed. The images can provide detailed discription of the distribution of the internal porosity of the rock samples.展开更多
According to the relations of pixel signal intensity with the repetition time TR and echo time TE in spin-echo single slice imaging pulse sequence, by combining the multi-exponential relaxation procedure of fluids sat...According to the relations of pixel signal intensity with the repetition time TR and echo time TE in spin-echo single slice imaging pulse sequence, by combining the multi-exponential relaxation procedure of fluids saturated in porous media, tlle information about pore structure of the tested rock is obtained with T1- and T2-weighted microimagings. The macro- and micro-pore regions can be distinguished with the information.展开更多
文摘Multinucleax solid-state NMR was employed to study the silicon-substitutedmolecular sieve Si-VPI-5. 29Si and 27Al NMR suggest that Si can be incorporated intothe framework of VPI-5 and the substitution of two silicon atoms for an aluminium atomplus a phosphorus atom is predominant. Such substitution is limited in a certain domainof the crystal and "silicon rich" regions are thus generated. 1H MAS spectra reveal that asmall arnount of silicon atoms substitute phosphorus only and SiOHAl groups are formed,which provides the acidic source for the molecular sieves. Si-VPI-5 prepared with silicagel as the silicon source exhibits a higher content of SiOHAl groups than that preparedwith (EtO)4Si.
文摘According to the NMR spectroscopy of fiulds satuxated in porous rocks, by using different pulse sequences and imaging parameters, high resolution NMR micro-images of lime stone and sand stone samples were obtained. The heterogeneous interconnection structure of the tested sandstone is visuallzed. The images can provide detailed discription of the distribution of the internal porosity of the rock samples.
文摘According to the relations of pixel signal intensity with the repetition time TR and echo time TE in spin-echo single slice imaging pulse sequence, by combining the multi-exponential relaxation procedure of fluids saturated in porous media, tlle information about pore structure of the tested rock is obtained with T1- and T2-weighted microimagings. The macro- and micro-pore regions can be distinguished with the information.
