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1.
Qing Wang Liang Yu Hiroki Nagasawa Masakoto Kanezashi Toshinori Tsuru 《Journal of the American Ceramic Society》2020,103(8):4473-4488
Polytitanocarbosilane (TiPCS)-derived ceramic membranes were fabricated using a pre-ceramic polymer. Special attention was focused on a process of thermal-oxidative curing that was used to induce cross-linking and the effect of this process on the ceramic yield, thermal stability, oxidation resistance, and microstructure of TiPCS. The cross-linked TiPCS powders showed a ceramic yield and thermal stability that were higher than that from the non-cross-linked version. In addition, the cross-linked TiPCS with uniform micropores showed higher levels of N2 and CO2 adsorption capacity, BET surface area, and micropore volume than the non-cross-linked versions, and the cross-linking process enhanced the stability of the pore structure at high temperature. The cross-linked TiPCS membranes showed high H2 permeance (1.49 × 10−6 mol/(m2 s Pa)) with sub-nanopores (H2/SF6 selectivity: 12 000, H2/N2: 10), and in addition higher oxidation resistance than their non-cross-linked counterparts. Furthermore, the influence of the concentration of the TiPCS precursor coating solution was optimized and the hydrothermal stability of the membranes at high temperatures was also evaluated. The optimized membrane demonstrated great performance for the pervaporation removal of methanol in binary azeotropic systems of either MeOH/butyl acetate or MeOH/toluene, and it also showed high hydrothermal stability with excellent dehumidification performance under high temperatures. 相似文献
2.
Norihiro Moriyama Yuta Kawano Qing Wang Ryota Inoue Meng Guo Makoto Yokoji Hiroki Nagasawa Masakoto Kanezashi Toshinori Tsuru 《American Institute of Chemical Engineers》2021,67(7):e17223
Pervaporation (PV) is a membrane technology that holds great promise for industrial applications. To better understand the PV mechanism, PV dehydrations of various types of organic solvents (methanol, ethanol, iso-propanol, tert-butanol, and acetone) were performed on five types of organosilica and two types of silicon carbide-based membranes, all with different pore sizes. Water permeance was dependent on the types of organic aqueous solutions, which suggested that organic solvents penetrated the pores and hindered the permeation of water. In addition, water permeance of various types of membranes in PV was well correlated with hydrogen permeance in single-gas permeation. Furthermore, a clear correlation was obtained between the permeance ratio in PV and that in single-gas permeation, which was confirmed via the modified-gas translation model. These correlations make it possible to use single-gas permeation properties to predict PV performance. 相似文献
3.
Rong Xu Jinhui Wang Masakoto Kanezashi Tomohisa Yoshioka Toshinori Tsuru 《American Institute of Chemical Engineers》2013,59(4):1298-1307
Hybrid organosilica membranes were successfully prepared using bis(triethoxysilyl)ethane (BTESE) and applied to reverse osmosis (RO) desalination. The organosilica membrane calcined at 300°C almost completely rejected salts and neutral solutes with low‐molecular‐weight. Increasing the operating pressure led to an increase in water flux and salt rejection, while the flux and rejection decreased as salt concentration increased. The water permeation mechanism differed from the viscous flow mechanism. Observed activation energies for permeation were larger for membranes with a smaller pore size, and were considerably larger than the activation energy for water viscosity. The organosilica membranes exhibited exceptional hydrothermal stability in temperature cycles up to 90°C. The applicability of the generalized solution‐diffusion (SD) model to RO and pervaporation (PV) desalination processes were examined, and the quantitative differences in water permeance were accurately predicted by the application of generalized transport equations. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1298–1307, 2013 相似文献
4.
Hye Ryeon Lee Masakoto Kanezashi Yoshihiro Shimomura Tomohisa Yoshioka Toshinori Tsuru 《American Institute of Chemical Engineers》2011,57(10):2755-2765
Organic/inorganic hybrid silica membranes were prepared from 1,1,3,3‐tetraethoxy‐1,3‐dimethyl disiloxane (TEDMDS) by the sol‐gel technique with firing at 300–550°C in N2. TEDMDS‐derived silica membranes showed high H2 permeance (0.3–1.1 × 10?6 mol m?2 s?1 Pa?1) with low H2/N2 (~10) and high H2/SF6 (~1200) perm‐selectivity, confirming successful tuning of micropore sizes larger than TEOS‐derived silica membranes. TEDMDS‐derived silica membranes prepared at 550°C in N2 increased gas permeances as well as pore sizes after air exposure at 450°C. TEDMDS had an advantage in tuning pore size by the “template” and “spacer” techniques, due to the pyrolysis of methyl groups in air and Si? O? Si bonding, respectively. For pore size evaluation of microporous membranes, normalized Knudsen‐based permeance, which was proposed based on the gas translation model and verified with permeance of zeolite membranes, reveals that pore sizes of TEDMDS membranes were successfully tuned in the range of 0.6–1.0 nm. © 2011 American Institute of Chemical Engineers AIChE J, 2011 相似文献
5.
Meng Guo Masakoto Kanezashi Hiroki Nagasawa Liang Yu Kazuki Yamamoto Takahiro Gunji Toshinori Tsuru 《American Institute of Chemical Engineers》2020,66(4):e16850
Fine-tuned, molecular-composite, organosilica membranes were fabricated via the co-condensation of organosilica precursors bis(triethoxysilyl)acetylene (BTESA) and bis(triethoxysilyl)benzene (BTESB). Fourier transform infrared and UV–vis spectra confirmed the co-condensation behaviors of BTESA and BTESB. The evolution of the network structure indicated that the incorporated BTESB decreased the membrane pore size, which was determined by a modified gas translation model according to the steric effect of the phenyl groups. The incorporation of BTESB to BTESA finely tuned the membrane structure and endowed the resultant composite membrane with improved separation properties. The BTESAB 9:1 membrane (molar ratio of BTESA/BTESB was 9:1) exhibited high C3H6 permeance at 4.5 × 10−8 mol m−2 s−1 Pa−1 and a C3H6/C3H8 permeance ratio of 33 at 50°C. One of the most important developments of this study involved clearly defining the relationship between membrane pore size and C3H6/C3H8 separation performance for organosilica membranes in single and binary separation systems. 相似文献
6.
Methylcyclohexane dehydrogenation for hydrogen production via a bimodal catalytic membrane reactor 下载免费PDF全文
Lie Meng Xin Yu Takuya Niimi Hiroki Nagasawa Masakoto Kanezashi Tomohisa Yoshioka Toshinori Tsuru 《American Institute of Chemical Engineers》2015,61(5):1628-1638
The dehydrogenation of methylcyclohexane (MCH) to toluene (TOL) for hydrogen production was theoretically and experimentally investigated in a bimodal catalytic membrane reactor (CMR), that combined Pt/Al2O3 catalysts with a hydrogen‐selective organosilica membrane prepared via sol‐gel processing using bis(triethoxysilyl) ethane (BTESE). Effects of operating conditions on the membrane reactor performance were systematically investigated, and the experimental results were in good agreement with those calculated by a simulation model with a fitted catalyst loading. With H2 extraction from the reaction stream to the permeate stream, MCH conversion at 250°C was significantly increased beyond the equilibrium conversion of 0.44–0.86. Because of the high H2 selectivity and permeance of BTESE‐derived membranes, a H2 flow with purity higher than 99.8% was obtained in the permeate stream, and the H2 recovery ratio reached 0.99 in a pressurized reactor. A system that combined the CMR with a fixed‐bed prereactor was proposed for MCH dehydrogenation. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1628–1638, 2015 相似文献
7.
Masakoto Kanezashi Akira Yamamoto Tomohisa Yoshioka Toshinori Tsuru 《American Institute of Chemical Engineers》2010,56(5):1204-1212
A sol–gel method was applied for the preparation of silica membranes with different average pore sizes. Ammonia (NH3) permeation/separation characteristics of the silica membranes were examined in a wide temperature range (50–400°C) by measurement of both single and binary component separation. The order of gas permeance through the silica membranes, which was independent of membrane average pore size, was as follows: He > H2 > NH3 > N2. These results suggest that, for permeation through silica membranes, the molecular size of NH3 is larger than that of H2, despite previous reports that the kinetic diameter of NH3 is smaller than that of H2. At high temperatures, there was no effect of NH3 adsorption on H2 permeation characteristics, and silica membranes were highly stable in NH3 at 400°C (i.e., gas permeance remained unchanged). On the other hand, at 50°C NH3 molecules adsorbed on the silica improved NH3‐permselectivity by blocking permeation of H2 molecules without decreasing NH3 permeance. The maximal NH3/H2 permeance ratio obtained during binary component separation was ~30 with an NH3 permeance of ~10?7 mol m?2 s?1 Pa?1 at an H2 permeation activation energy of ~6 kJ mol?1. © 2009 American Institute of Chemical Engineers AIChE J, 2010 相似文献
8.
Gang Li Masakoto KanezashiHye Ryeon Lee Makoto MaedaTomohisa Yoshioka Toshinori Tsuru 《International Journal of Hydrogen Energy》2012
A novel bimodal catalytic membrane reactor (BCMR) consisting of a Ru/γ-Al2O3/α-Al2O3 bimodal catalytic support and a silica separation layer was proposed. The catalytic activity of the support was successfully improved due to enhanced Ru dispersion by the increased specific surface area for the γ-Al2O3/α-Al2O3 bimodal structure. The silica separation layer was prepared via a sol–gel process, showing a H2 permeance of 2.6 × 10−7 mol Pa−1 m−2 s−1, with H2/NH3 and H2/N2 permeance ratios of 120 and 180 at 500 °C. The BCMR was applied to NH3 decomposition for COx-free hydrogen production. When the reaction was carried out with a NH3 feed flow rate of 40 ml min−1 at 450 °C and the reaction pressure was increased from 0.1 to 0.3 MPa, NH3 conversion decreased from 50.8 to 35.5% without H2 extraction mainly due to the increased H2 inhibition effect. With H2 extraction, however, NH3 conversion increased from 68.8 to 74.4% due to the enhanced driving force for H2 permeation through the membrane. 相似文献
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10.
Xin Yu Lie Meng Hiroki Nagasawa Masakoto Kanezashi Masato Machida Toshinori Tsuru 《Journal of the American Ceramic Society》2019,102(11):6946-6956
The decomposition of sulfur trioxide to produce sulfur dioxide and oxygen using a catalytic membrane reactor is technology that promises to improve the economic viability of the thermochemical water-splitting Iodine-Sulfur (IS) process for large-scale CO2-free hydrogen production. The chemical stability of membrane materials under SO3, however, is a significant challenge for this strategy. In this study, microporous membranes with a layered structure that consisted of a membrane support prepared from α-Al2O3, an intermediate layer prepared from silica-zirconia, and a top layer prepared from bis (triethoxysilyl)ethane-derived organosilica sols, were examined for stability under SO3 and for use in SO3/O2 separation. An α-Al2O3 support that features SiO2–ZrO2 intermediate layers with large pore sizes and a high Si/Zr molar ratio showed excellent resistance to SO3, which was confirmed by N2 adsorption, Energy Dispersive X-ray Spectroscopy (EDS), and Scanning Electron Microscopy (SEM). These membranes also demonstrated a negligible change in gas permeance before and after SO3 exposure. Subsequently, in binary-component gas separation at 550°C, microporous organosilica-derived membranes achieved an O2/SO3 selectivity of 10 (much higher than the Knudsen selectivity of 1.6) while maintaining a high O2 permeance of 2.5 × 10−8 mol m–2 s–1 Pa–1. 相似文献