A Novel Method for the Growth of Silicalite Membranes on Stainless Steel Supports

Holmes, Stuart M.; Märkert, Christian; Plaisted, R.J.; Forrest, James O.; Agger, Jonathon R.; Anderson, Michael W.; Cundy, Colin S.; Dwyer, John

doi:10.1021/cm991087u

Cited by 52 publications

(27 citation statements)

References 26 publications

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“…It was interesting to note that the separation ℃ factor of membranes increased slightly after repeated calcination cycles, and this might be caused by the condensation of Si-OH on the crystal surfaces, which improved the hydrophobicity of silicalite-1 membranes. In order to avoid the formation of cracks during calcination, a lower calcination rate was applied by other researchers [15,16] . Work by Holmes et al [16] showed that the cracks would formed for membranes synthesized on stainless steel supports at a heating rate above 0.25 /min, so a lower calcin ℃ ation rate was performed.…”

Section: Thermal Stability Of Silicalite-1 Membranementioning

confidence: 99%

“…In order to avoid the formation of cracks during calcination, a lower calcination rate was applied by other researchers [15,16] . Work by Holmes et al [16] showed that the cracks would formed for membranes synthesized on stainless steel supports at a heating rate above 0.25 /min, so a lower calcin ℃ ation rate was performed.…”

Section: Thermal Stability Of Silicalite-1 Membranementioning

confidence: 99%

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Synthesis and separation performance of silicalite-1 membranes on silica tubes

Chen

Gong

et al. 2009

Sci. China Ser. B-Chem.

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High-performance silicalite-1 membranes were synthesized on silica tubes by in-situ hydrothermal synthesis. By using the "solution-filling (SF)" method, the average flux of membranes with the SF method was improved by about 25% compared to that of the membranes without using the SF method; the flux and the separation factor of the membranes prepared with the SF method for an ethanol/water mixture at 60 were 0.99 kg/(m ℃ 2 ·h) and 73, respectively. It was found that the membranes synthesized on silica tubes exhibited high thermal stability and high reproducibility, and the relatively standard deviations (R.S.D.) of the average flux and separation factor were only 9.6% and 5.6%, respectively, which suggests that the silica support is more suitable than other kinds of supports for preparing highperformance silicalite-1 membranes.silicalite-1 membrane, separation performance, pervaporation, silica tube Membrane pervaporation has advantages in separating azeotropes, closing-boiling mixtures, and thermally sensitive compounds, and in removing species present at low concentrations [1][2][3] . During the pervaporation process, only a fraction of the mixture can pass the membrane as vapor at lower temperature, and the energy consumption is lower than that of the conventional distillation or extraction. Polymeric membranes, have some drawbacks (such as swelling, low chemical resistance, and low thermal stability) which often limit their application, while zeolite membranes show a higher flux and a higher separation factor. Thus great interest has been focused on the preparation and characterization of zeolite membranes, and significant progress has been reported in recent years [4][5][6] . One important application of hydrophobic silicalite-1 membranes is to extract organics from low concentration aqueous solutions [7,8] , such as extracting ethanol from fermentation broth [9] . In order to protect the porous supports from the invasion of the synthesis solution during hydrothermal synthesis, Yan et al. [10] impregnated the support with a mixture of furfurylalcohol and tetraethylorthosilicate (TEOS), and the penetration depth of siliceous matter into the supports decreased from ca. 80 μm without pretreatment to ca. 55 μm with pretreatment.In 2002, Hedlund et al. [11] successfully prepared highflux MFI membranes by masking the porous supports with high-melting-point polyethylene wax, and the flux was one or two orders of magnitude higher than those in the literature, but the procedure was complex and not easy to be used for tubular supports.In order to synthesize high-performance silicalite-1 membranes, two factors should be considered: one is the dissolution of alumina supports during hydrothermal synthesis, which will result in less hydrophobic ZSM-5 membranes instead of the desired hydrophobic silicalite-1 membranes; the other is the different thermal expansion coefficients between supports and zeolite layers, which will result in the formation of cracks during

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Section: Thermal Stability Of Silicalite-1 Membranementioning

confidence: 99%

Section: Thermal Stability Of Silicalite-1 Membranementioning

confidence: 99%

Synthesis and separation performance of silicalite-1 membranes on silica tubes

Chen

Gong

et al. 2009

Sci. China Ser. B-Chem.

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“…In order to avoid the formation of cracks during calcination, the synthesized membranes were generally calcined at a low calcination rate because of different thermal expansion coefficients between supports and zeolite layers. For example, work by Holmes et al [15] showed that the cracks would be formed for membranes synthesized on stainless steel supports at a heating rate of above 0.25℃/min, so a lower calcination rate was performed. Increasing the calcination rate to 5 /min ℃ , both the flux and separation factor decreased, and the reason was not clear.…”

Section: Thermal Stability Of Silicalite-1 Membranementioning

confidence: 99%

Preparation and pervaporation performance of high-quality silicalite-1 membranes

Chen

Liu

et al. 2007

SCI CHINA SER B

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High-performance silicalite-1 membranes were successfully synthesized on novel porous silica tubes by two-step in-situ hydrothermal synthesis. The flux and separation factor towards ethanol/water mixture at 60℃ were 0.56 kg/(m 2 ·h) and 84, respectively. The as-synthesized silicalite-1 membranes were characterized by scanning electron microscopy (SEM). The influence of different synthesis conditions on the separation performance of the silicalite-1 membranes was investigated. It was found that the average flux of silicalite-1 membranes was improved by about 26% after filling the silica tubes with mixed solution containing glycerol and water. After calcinating at 400℃ for 5 h repeatedly, membrane synthesized on silica tube still showed high pervaporation performance towards ethanol/water mixture even at a calcination rate of 4℃/min, which suggested that silica support was more suitable for preparing high-performance silicalite-1 membranes. silica support, silicalite-1 membrane, mixed solution filling, pervaporationIn recent years, great interest has been focused on the synthesis of zeolite membranes on various supports [1][2][3][4][5][6] because of the potential applications of zeolite membranes in a wide range of industrial processes, and significant progress in preparation and characterization of zeolite membranes has been seen [7][8][9][10] . MFI membranes (silicalite-1 and ZSM-5) have been the subject of the majority of these studies, mainly because of their suitability for the separation of commercially important species, such as p-xylene from its isomers [11,12] . For silicalite-1 membrane, which is more hydrophobic than that of ZSM-5 membrane, another important application is to extract organics from low concentration aqueous solutions [2][3][4][5][6] , such as extracting ethanol from fermentation broth [2] . For the separation of alcohol/water mixtures, only alcohol and a small quantity of water can pass the silicalite-1 membrane, and energy consuming is lower than that of conventional separation including vacuum distillation, solution extraction, and gas stripping by CO 2 , which is in favor of solving the extraction problem of ethanol from fermentation broth.In order to prepare high-performance silicalite-1 membranes, the influence of different supports is important. The hydrophobicity of silicalite-1 membranes will decrease as a result of the dissolution of alumina supports during hydrothermal synthesis, so the alumina supports are unsuitable for preparing silicalite-1 membranes. Geus [13] found that improving the separation performance of zeolite membranes could be achieved by using the porous intermediate layers like silica between the ceramic or metal support and the zeolite layer, and the porous intermediate layers were recommended to be used for suppressing the influence of supports. In 2003, Lai et al. [14] reported that the presence of the silica layer eliminated the formation of stress-induced cracks during calcinations, and high-performance zeolite membranes were prepared. In the current work, ...

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“…Several reports have presented various preparation methods for zeolite nanoparticles coated onto diatomite. Anderson et al [35,36] proposed a process involving ultrasonically loading silicalite-1 seeds onto diatomite, followed by a hydrothermal growth process of the seeds. The obtained composite showed a low specific surface area (S BET , 29.2 m 2 /g) and micropore volume (V micropore , 0.01 cm 3 /g).…”

Section: Introductionmentioning

confidence: 99%