Continuous and perfect single-layer B-Al-ZSM-5 zeolite membranes with c-axis orientation, self-transformation from B-containing porous gla ss disks w ith rough and uneven surfaces full of pits, have been in-situ prepa...Continuous and perfect single-layer B-Al-ZSM-5 zeolite membranes with c-axis orientation, self-transformation from B-containing porous gla ss disks w ith rough and uneven surfaces full of pits, have been in-situ prepared on the su bstrates surfaces in a mixed vapor of ethylenediamine, tri-n-propylamine a nd H 2O . The thickness of the membranes is ca. 60 μm. Under the conditions of 20 ℃ and 0.1 MPa pressure difference, the permeabilities of H 2, O 2 and N 2 thro ugh the calcined B-Al-ZSM-5 zeolite membranes are 2 298×10 -8 , 1 176 ×10 -8 and 1 368×10 -9 mol/(m 2·s·Pa), respectively. The calculated values of ideal se lectivities of H 2 an d O 2 over N 2 are 16 8 and 8 60, respectively. The data indicate that the c alcin ed zeolite membranes are non-pinhole, non-crack, continuous and perfect.展开更多
It was found that rare earth influenced per process of permeation layer forming, and that the tooth of layer was thinner, thicker, straighter and longer by observing permeation layers at different holding times.It was...It was found that rare earth influenced per process of permeation layer forming, and that the tooth of layer was thinner, thicker, straighter and longer by observing permeation layers at different holding times.It was so image, lifelike and audio-visual by computer kinetic simulation that the layer forming could be continuously observed. Because it con forms to reality, the computer kinetic simulation can forecast the layer thickness and it will offer a reasonable permeating technology.展开更多
It is indicated that the initial layer of RE-B-Al permeation is mainly composed of Fe2B by means of TEM and EDAX, and (RE0.65 Feo0.35) 23B6 is found after RE permeation for 4 h. (Fe0.8, RE0.2)6B is found in the layer...It is indicated that the initial layer of RE-B-Al permeation is mainly composed of Fe2B by means of TEM and EDAX, and (RE0.65 Feo0.35) 23B6 is found after RE permeation for 4 h. (Fe0.8, RE0.2)6B is found in the layer of RE-B-Al permeation and the distance of crystal face of α-Fe is enlarged. The mechanism of formation of boride was analyzed. Prevention of compounds, such as Al, C etc., on dislocation movement, strengthening of grain boundary, dislocation and solution are responsible for the properties in the permeation layer.展开更多
The B Al permeation layers of Steel 45 were studied by means of SEM, TEM and XRD. The formation and growth model of permeation layer was proposed. The layer formation, growth and the migration behaviors of B were disc...The B Al permeation layers of Steel 45 were studied by means of SEM, TEM and XRD. The formation and growth model of permeation layer was proposed. The layer formation, growth and the migration behaviors of B were discussed. It is suggested that the diffusion of Al is deferred when the surface was covered by borides and aluminize compounds are surrounded by borides with the further growing of borides.展开更多
Solid-state crystallization process and mechanism of B-Al-ZSM-5 zeolite from a dry gel of B2O3. A12O3 ? SiO2 in the mixture of ethylamine and water vapour were studied by11B,27Al,29Si,13C MAS NMR, XRD and IR. The extr...Solid-state crystallization process and mechanism of B-Al-ZSM-5 zeolite from a dry gel of B2O3. A12O3 ? SiO2 in the mixture of ethylamine and water vapour were studied by11B,27Al,29Si,13C MAS NMR, XRD and IR. The extranetwork trigonal BO3 units in the gel play an important role in the process of crystallization. The change of chemical environment around Al atoms is complicated in the process of crystallization. Octahedral Al-O groups existing in the intermediate products do not appear in both the initial gel and final product. Silicon is mainly present as hydroxyl compounds, and the extrastructural Si-O groups detected in the process of crystallization disappear after complete crystallization. Ethylamine plays the role of both template and reactant. It acts with the boron-, aluminum-, and silicon-hydroxyls through hydrogen bonding and promotes the crystallization process. The relative crystallinity of the final & A1-ZSM-5 product is about 93% as measured with11B MAS NMR and IR.展开更多
文摘Continuous and perfect single-layer B-Al-ZSM-5 zeolite membranes with c-axis orientation, self-transformation from B-containing porous gla ss disks w ith rough and uneven surfaces full of pits, have been in-situ prepared on the su bstrates surfaces in a mixed vapor of ethylenediamine, tri-n-propylamine a nd H 2O . The thickness of the membranes is ca. 60 μm. Under the conditions of 20 ℃ and 0.1 MPa pressure difference, the permeabilities of H 2, O 2 and N 2 thro ugh the calcined B-Al-ZSM-5 zeolite membranes are 2 298×10 -8 , 1 176 ×10 -8 and 1 368×10 -9 mol/(m 2·s·Pa), respectively. The calculated values of ideal se lectivities of H 2 an d O 2 over N 2 are 16 8 and 8 60, respectively. The data indicate that the c alcin ed zeolite membranes are non-pinhole, non-crack, continuous and perfect.
文摘It was found that rare earth influenced per process of permeation layer forming, and that the tooth of layer was thinner, thicker, straighter and longer by observing permeation layers at different holding times.It was so image, lifelike and audio-visual by computer kinetic simulation that the layer forming could be continuously observed. Because it con forms to reality, the computer kinetic simulation can forecast the layer thickness and it will offer a reasonable permeating technology.
文摘It is indicated that the initial layer of RE-B-Al permeation is mainly composed of Fe2B by means of TEM and EDAX, and (RE0.65 Feo0.35) 23B6 is found after RE permeation for 4 h. (Fe0.8, RE0.2)6B is found in the layer of RE-B-Al permeation and the distance of crystal face of α-Fe is enlarged. The mechanism of formation of boride was analyzed. Prevention of compounds, such as Al, C etc., on dislocation movement, strengthening of grain boundary, dislocation and solution are responsible for the properties in the permeation layer.
文摘The B Al permeation layers of Steel 45 were studied by means of SEM, TEM and XRD. The formation and growth model of permeation layer was proposed. The layer formation, growth and the migration behaviors of B were discussed. It is suggested that the diffusion of Al is deferred when the surface was covered by borides and aluminize compounds are surrounded by borides with the further growing of borides.
文摘Solid-state crystallization process and mechanism of B-Al-ZSM-5 zeolite from a dry gel of B2O3. A12O3 ? SiO2 in the mixture of ethylamine and water vapour were studied by11B,27Al,29Si,13C MAS NMR, XRD and IR. The extranetwork trigonal BO3 units in the gel play an important role in the process of crystallization. The change of chemical environment around Al atoms is complicated in the process of crystallization. Octahedral Al-O groups existing in the intermediate products do not appear in both the initial gel and final product. Silicon is mainly present as hydroxyl compounds, and the extrastructural Si-O groups detected in the process of crystallization disappear after complete crystallization. Ethylamine plays the role of both template and reactant. It acts with the boron-, aluminum-, and silicon-hydroxyls through hydrogen bonding and promotes the crystallization process. The relative crystallinity of the final & A1-ZSM-5 product is about 93% as measured with11B MAS NMR and IR.
