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Membrane Technology—A Sustainable Approach for Environmental Protection
Published in Sundergopal Sridhar, Membrane Technology, 2018
Ranjana Das, Arijit Mondal, Chiranjib Bhattacharjee
Well-defined pore structure can be found in zeolites which are crystalline alumino silicates. A thin zeolite layer deposited on different types of support (porous α-alumina or stainless steel) constitutes a zeolite membrane which has numerous advantages in the field of gas separation compared to traditional polymeric membranes due to excellent thermal, mechanical and chemical stabilities. Gas separation through zeolite membranes is governed by molecular sieving accompanied by surface diffusion. For CO2 separation at low temperature, zeolite membranes are very useful due to their preferential adsorption (Shekhawat et al., 2003), which helps to get both high permeability and selectivity. At high temperatures, selectivity of zeolite membranes starts decreasing because the selective adsorption of CO2 decreases. Additionally, zeolite membranes are very expensive, and difficult to process and handle.
2 Permeation and Separation
Published in Zeinab Abbas Jawad, 2 Sequestration and Separation, 2019
Thiam Leng Chew, Tiffany Yit Siew Ng, Yin Fong Yeong
Selective CO2/N2 separation can be obtained due to the stronger electrostatic quadrupole of CO2 with the zeolite compared to N2. Several zeolite membranes were reported with CO2 permeation dominant in surface diffusion while N2 permeation via micropore diffusion (Bernal et al. 2004, Shin et al. 2005). High separation factor of CO2/N2 can be caused by the preferential adsorption of CO2 inhibits the N2 permeation. Table 8.3 illustrates the performance of different types of zeolite membrane in CO2/N2 separation system. Owing to its low Al content, MFI-type zeolite membrane is able to attract researchers’ attention and these membranes are synthesized with good reproducibility and chemical stability. For the separation and permeation of CO2/N2 using MFI zeolite membrane, in Table 3.2, the best performance is reported by Shin et al. (2005) with selectivity of 54.3 and CO2 permeance of ~ 3.6 × 10−8 mol/m2.s.Pa at 25°C using Na-ZSM-5 zeolite membrane. ETS-4 zeolite membrane is another type of zeolite membrane used to remove N2 from CO2 in which it favorably adsorbs N2 over CO2 (Guan et al. 2001). Hasegawa et al. (2002) synthesized NaX zeolite membrane and was able to obtain CO2/N2 selectivities as high as 78. Research works have been carried out on investigating the CO2/N2 permeation and separation performance using small pore zeolite membrane such as SAPO-34 and T-type zeolite membranes. In the research works reported by Cui et al. (2004), the synthesized T-type zeolite membrane displayed high CO2/N2 selectivity of 107 with CO2 permeance of 3.8 × 10−8 mol/m2.s.Pa at 35°C.
Zeolite Membrane for Gas Separation
Published in Stephen Gray, Toshinori Tsuru, Yoram Cohen, Woei-Jye Lau, Advanced Materials for Membrane Fabrication and Modification, 2018
Motomu Sakai, Kei Yoshihara, Masahiro Seshimo, Masahiko Matsukata
In addition, differences in the affinities between gas molecules and the zeolite membrane can be utilized for separation. Molecules that have a strong affinity for zeolite preferentially penetrate through the membrane. In this case, zeolite membranes can exhibit selectivity for larger molecules, which is different from separation by molecular sieving effects (Sawamura et al., 2009; Sandström et al., 2010).
Study on the effect of seed particle size toward the formation of NaX zeolite membranes via vacuum-assisted seeding technique
Published in Journal of Asian Ceramic Societies, 2021
Liyana Salwa Mohd Nazir, Yin Fong Yeong, Thiam Leng Chew
FAU-type zeolite membrane has received attention from researchers due to its unique performance in separation processes. NaY and NaX zeolite membranes which categorized under FAU type are low silica zeolites with 12 membered-ring and pore size of 7.4 Å. NaY and NaX zeolite membranes are highly CO2 selective due to their polar characteristic. Besides, these membranes showed high performance in CO2/CH4, CO2/N2, and CO2/H2 gases separation [15–19], and demonstrated promising performance in pervaporation process [20–24]. Nevertheless, FAU-type zeolite membrane does not exhibit molecular sieving property mainly attributed to its large pore size, as compared to zeolite membranes with smaller pore size such as CHA (~3.4 Å) and MFI-types (~5.6 Å). The separation property of FAU-type zeolite membrane is usually achieved by the difference in adsorption and diffusion mechanisms of the permeates. Even so, high permeation rate is one of the advantages demonstrated by FAU-type zeolite membrane, as compared to small pore zeolite membranes [16].
Methods and synthesis parameters affecting the formation of FAU type zeolite membrane and its separation performance: a review
Published in Journal of Asian Ceramic Societies, 2020
Liyana Salwa Mohd Nazir, Yin Fong Yeong, Thiam Leng Chew
Zeolite membrane has been gaining a lot of attention due to its robust properties as well as high separation performance. Zeolite membrane is a type of inorganic membrane which consists of a thin layer of polycrystalline zeolite film growth on the top of a substrate [1]. Zeolite membranes offer several advantages over organic membrane and other types of inorganic membrane due to their attractive characteristics such as adaptability to harsh environment, long-term stability at high temperature and pressure, molecular sieving, catalytic, and selective sorption properties [2]. Due to these properties, zeolite membranes can be used for various applications including gas separation, pervaporation, solvent dehydration, membrane reactors, coating materials, catalytic microreactors, gas sensor, and fuel cells [3–8]. Zeolite membrane was firstly prepared by Suzuki in 1987, where a continuous zeolite layer was prepared on a porous support [9]. Subsequently, in 1998, Mitsui Engineering and Shipbuilding Co. Ltd in Japan was the first company applied NaA zeolite membrane for pervaporation dehydration in industrial scale [10]. Then, the applications of zeolite membranes have been extensively explored and widely reported in the literature [6,7,11–13].