Synthesis and Characterization of Ceramic Membranes (W-Type Zeolite Membranes) (original) (raw)

Ceramic-zeolite composite membranes and their application for separation of vapor/gas mixtures

Journal of Membrane Science, 1994

Ceramic-zeolite composite membranes were prepared by in-situ synthesis of a thin ( _ 10 pm) polycrystalline silicalite-1 layer on the inner surface of an alumina membrane tube. The inner surface is a y-alumina coating that has 5-nm diameter pores. X-ray diffraction verified the presence of a pure silicalite phase in the layer, and SEM showed that individual silicalite crystals had grown together to form a continuous silicalite-1 layer. The addition of silicalite to the alumina membrane decreased the Nz permeance by a factor of 5, but it decreased the n-C4Hu, permeance by a factor of 190, and n-C.,H10 appeared to adsorb on the membrane. At room temperature, the permeante ratio of n-C4H,,-,/i-C4Hlo was one for the alumina membrane, but it was 3 for the zeolite membrane. Methanol was separated from HZ and from CH4 at 373 K and pressures from 110 to 1100 kPa by preferentially permeating CH30H through the zeolite membrane. For some conditions the CH30H/H2 separation factor was greater than 1000, and the CHsOH/CH4 separation factor was 190. Apparently, CH30H adsorbs and blocks the pores for H2 or CH4 permeation.

Optimization of conditions for the preparation of zeolite HS membrane

Effects of synthesis parameters on the membrane structure and performance have been investigated for Nano pore Hydroxysodalite (HS) zeolite membranes grown onto seeded mullite supports. Molar composition of the starting gel of HS zeolite membranes was SiO2/Al2O3=1.0-5.0, Na2O/Al2O3=15-65, and H2O/Al2O3=500-1500. In addition, Effects of crystallization time and temperature on the membrane performance were studied. X-ray diffraction (XRD) patterns of the membranes exhibited peaks corresponding to the support and the zeolite. The crystal species were characterized by XRD and morphology of the supports subjected to crystallization was characterized by Scanning electron microscopy (SEM). Separation performance of HS zeolite membranes was studied for water-Ethanol mixtures using pervaporation (PV). The membranes showed good selectivity towards water in the water-Ethanol mixtures. Water permeates faster because of its preferential adsorption into the Nano-pores of the hydrophilic zeolite membrane. In PV of water-Ethanol mixtures, the membrane exhibits a hydrophilic behavior, with a high selectivity towards water and a good flux. The best Flux and separation factor of the membranes were 2.05 kg/m 2 .h and 10000, respectively. Effects of operation condition (temperature, rate and pressure) on the membrane performance have been investigated for HS zeolite membranes grown onto seeded mullite supports.

Zeolites: An Emerging Material for Gas Storage and Separation Applications

Zeolites - New Challenges, 2020

Zeolites are one of the amazing materials available in nature because of their structural pores. Interestingly, these god-gifted properties of zeolite can be used in gas separation and storage application. Actually, hydrogen separation and its storage are now a thrust research area. Hydrogen is considered as a 'clean energy,' which is indispensable for global affluence and alternative energy for future. But hydrogen is not accessible in its pure form during the industrial synthesis process and comes out with some other impurities like CO 2 (GHG) and other gases. So, the production of carbon-free hydrogen and its storage is so much vital. In conventional technologies, few concerns are always existed during gas separation and also in storage process. Recently, membrane-based separation process is a highly demanding technology in the industry and shows some advantages as compared to conventional process. Based on this concept, in this chapter, three different types of zeolites, that is, DDR, SAPO 34, and Bikitaite are highlighted. Here, we described the advanced synthesis process and the mechanism towards the development of high-quality nearly defect-free membranes on cheaper support. Finally, the evaluation of membranes is described through gas permeation and selectivity results of different single gas and mixture gas composition. In addition, storage capacity of H 2 by zeolite/surface-modified zeolites is included in this chapter.

A novel approach to fabricate zeolite membranes for pervaporation processes

2015

The conventional methods used in preparing zeolite membranes, such as the secondary growth and in situ crystallization methods, involve long and complex procedures that require the preparation of the zeolite aluminosilicate gel prior to the fabrication process and often result in membranes which contain pin holes. Here we report a simple, cheap, and less time-consuming technique to fabricate zeolite A and mordenite membranes on a porous stainless steel support. In addition, the technique makes it possible to fabricate types of zeolite membranes that have been previously difficult to synthesise. A clinoptilolite membrane was fabricated to demonstrate the ability to manufacture a zeolite membrane from an existing crystalline zeolite (natural or synthetic). All three membranes were subjected to separation tests, (ethanol dehydration, ethanol-cyclohexane and phenol removal from water) to demonstrate the efficacy of membrane synthesis. The fluxes obtained and separation factors which were achieved are comparable with literature values but as with most zeolite membranes there is a trade-off between high flux and separation. Experimental Membrane preparation The overriding aim of the work is to produce a simple and repeatable method of producing zeolite membranes. The method which has been developed can be summarised as

STUDY OF PERMEATION OF GASES THROUGH CERAMIC SUPPORTED POLYMERIC AND ZEOLITE MEMBRANES

2 from various effluent gas mixtures. Membrane operations are recognized as feasible and economical operations over conventional technologies for gas separation due to a higher flexibility to tolerate fluctuations in feed composition and flow rate. In this present work Hydroxy Ethyl Cellulose (HEC) membrane prepared on Silicon carbide (SiC) tube and ZSM-5 membrane casted on α-Al 2 O 3 tube support is used to study the permeation characteristics of various gases. Pour and decanting technique is used to coat HEC membrane on SiC tube whereas seed growth hydrothermal technique is used to prepare ZSM-5 zeolite membrane. Scanning electron microscope (SEM) and X-ray diffraction techniques (XRD) are used to characterize the membranes. Single component permeation experiments are conducted for measurement of permeability coefficients which are essential for understanding and designing the membrane modules. Both the membranes have shown good permeation characteristics for all the gases. Ideal selectivity values are calculated from the pure component permeances.

Production and Characterization of Zeolite Membrane

2012

The use of bioethanol as an alternative fuel with a purity of more than 99.5% wt has prompted research on bioethanol purification. One of the promising methods used for bioethanol purification is pervaporation membrane. This research is aimed to prepare and characterize zeolite membranes for pervaporation membrane. The membrane preparation consisted of two stages, namely support preparation and zeolite deposition on the support. In support preparation, α alumina and kaolin with spesific composition (50:30; 40:40; 50:30) was mixed with additives and water. After pugging and aging process, the mixture became paste and extruded into tubular shape. The tube was then calcined at temperature of 1250 °C for 3 hours. After that, zeolite 4A is deposited on the tubes using clear solution made of 10 %wt zeolite and 90 %wt water and heated at temperature of 80 °C for 3 hours. Furthermore, the resulting zeolite membranes was washed with deionized water for 5 minutes and dried in oven at temperature of 100 °C for 24 hours. Characterization of zeolite membranes included mechanical strength test, XRD, and SEM. In the mechanical strength test, the membrane sample with alumina:kaolin = 50:30 (#membrane A#) has the highest mechanical strength of 46.65 N/mm 2. Result of XRD analysis for the membran A indicated that mullite and corundum phases were formed, which mullite phase was more dominant. Meanwhile the result of SEM analysis shows that zeolite crystals have been formed and covered the pores support, but the deposition of zeolite has not been optimal yet. The performance examination for bioethanol purification showed that the membrane could increase the purty of bioethanol from 95% to 98% wt.

Using of cheap materials for making of zeolite membranes with an innovative method

In this research, two new innovations have been made. The first innovation involves the synthesis of zeolite membranes from the source of kaolin. In the first step, the kaolin was calcined at 700 C to the metakaolinite phase. As a second step, the zeolitisation experiments have been carried out under hydrothermal conditions. The metakaolinite obtained has been reacted with NaOH solutions in autoclaves at 100C. The second innovation to membrane synthesis was based on Self-supported zeolite membranes. Synthesis of nano NaA zeolite membrane from tubular extruded of kaolin was investigated. In the first step, kaolin has been calcined at 500-850 C to the metakaolinite phase. As a second step, the zeolitisation experiments have been carried out under hydrothermal conditions. The metakaolinite obtained has been reacted with NaOH solutions in autoclaves at 100C. X-ray diffraction (XRD) patterns of the membranes exhibited peak corresponding to the zeolite. The morphology of the support and membrane subjected to crystallization was characterized by Scanning electron microscopy (SEM). Separation performance of the NaA membranes was evaluated using pervaporation (PV) of water–organic mixtures. The membranes showed high water selectivity in the water–organic mixtures.