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Showing papers in "Journal of Chemical Engineering of Japan in 2018"


Journal ArticleDOI
TL;DR: In this article, a review of pure silica (SiO2) and organosilica membranes for use in molecular separation is presented, highlighting the great progress achieved in sol-gel and CVD processing.
Abstract: Over the past several decades, inorganic membranes composed of zeolite, silica, carbon, and metal/organic frameworks (MOF) have improved dramatically in terms of fabrication and application. Pure silica (SiO2) and organosilica membranes for use in molecular separation are the focus of this review. First, the fabrication of these silica-based membranes is outlined to highlight the great progress achieved in sol–gel and CVD processing. Then, applications in gasand liquid-phase separations and an evaluation of pore sizes are summarized and future perspectives are discussed.

54 citations






Journal ArticleDOI
TL;DR: In this paper, a silicon-based membrane was prepared using hexamethyldisiloxane (HMDSO) as a silicon precursor and annealed at 400°C in N2 and showed a high H2 permeance of 1.6×10−6 mol m−2 s−1 Pa−1 with H2/N2 and H 2/SF6 permeance ratios of 53 and 1,800, respectively, at 300°C.
Abstract: Silica-based membranes were prepared by atmospheric-pressure plasma-enhanced chemical vapor deposition. The e ects of membrane preparation parameters such as thermal annealing temperature and precursor on their gas permeation properties were investigated by assessing the temperature dependence of their gas permeances. Thermal annealing was e ective for the improvement of membrane performance owing to the formation of permselective pores via partial decomposition of organic components in the plasma-deposited layer. The membrane prepared using hexamethyldisiloxane (HMDSO) as a silicon precursor and annealed at 400°C in N2 showed a high H2 permeance of 1.6×10−6 mol m−2 s−1 Pa−1 with H2/N2 and H2/SF6 permeance ratios of 53 and 1,800, respectively, at 300°C. High carboncontent structures were obtained by plasma-deposition of HMDSO mixed with a second precursor (1,5-cyclooctadiene) or a carbon-rich silicon precursor (triethylsilane). Gas permeation measurements revealed that a higher the carbon content in the plasma-deposited layer leads to a higher activation energy of permeation.

12 citations









Journal ArticleDOI
TL;DR: In this paper, a micro-circulating fluidized bed was constructed by micro-machining channels of 1mm cross section in Perspex and PMMA and soda lime glass micro-particles were used as fluidised particles and tap water as the fluidising liquid.
Abstract: Solid-liquid micro-fluidised beds (FBs), i.e. fluidisation of micro-particles in sub-centimetre beds, hold promise of applications in the microfluidics and micro-process technology context. This is mainly due to fluidised particles providing enhancement of mixing, mass and heat transfer under the low Reynolds number flows that dominate in micro-devices. Albeit there are quite a few studies of solid-liquid micro-fluidised beds, we are presenting the first study of a micro-circulating fluidised bed. The present experimental research was performed in a micro-circulating fluidised bed which was made by micro-machining channels of 1mm cross section in Perspex. PMMA and soda lime glass micro-particles were used as the fluidised particles and tap water as the fluidising liquid to study flow regime transition for this micro-circulating fluidised bed. The results are in line with macroscopic observation that the critical transition velocity from fluidization to circulating regime is very dependent on solid inventory but once the inventory is high enough it is approximately equal to the particle terminal velocity. However, the transitional velocity is a weakly dependent on wall effect and surface forces confirming the importance of these two properties in a micro-fluidised bed systems. Similarly the transitional velocity to transporting regime is a strong function of surface forces. Finally, combining these results with our previous result on conventional fluidization indicated that map of solid-liquid fluidisation in a micro-circulating fluidised bed system is constructed showing conventional fluidisation, circulating fluidisation and a transport regime.



Journal ArticleDOI
TL;DR: In this article, the characteristics of three-phase (gas-liquid-solid) circulating uidized beds (TPCFBs) are discussed in order to visualize the unique features and advantages thereof due to the intrinsic flow and contacting behaviors of multi-phases, providing a better understanding of the state of art of TPCFB and their feasible applications as multi-phase reactors and contactors.
Abstract: The characteristics of three-phase (gas–liquid–solid) circulating uidized beds (TPCFBs) are discussed in order to visualize the unique features and advantages thereof due to the intrinsic ow and contacting behaviors of multi-phases, providing a better understanding of the state of art of TPCFBs and their feasible applications as multi-phase reactors and contactors. The hydrodynamics such as individual phase holdups, bubbling ow behaviors, bubble properties and liquid phase dispersions, and heat and mass transfer characteristics in the riser were examined based on the previous investigations. Although the information in the riser of various kinds of TPCFBs deviated from each other depending on the solid circulation modes and experimental conditions, they were summarized and consociated for the elucidation of the present states and views of the investigations. Rational guides to predict the hydrodynamics and heat and mass transfer phenomena in the riser of the TPCFB were possible by analyzing and synthesizing the results reported in the literatures presently available. Especially, the e ects of operating variables including gas (UG) and liquid (UL) velocities, properties of uidized solid particles and continuous liquid media, and solid circulation rate (Gs) on the hydrodynamic parameters and the heat and mass transfer characteristics such as heat transfer coe cient (h) and resistance, volumetric mass transfer coe cient (kLa), gas–liquid interfacial area (a) and liquid side mass transfer coe cient (kL) were determined. The information on the heat and mass transfer, however, were extremely limited comparing with those of hydrodynamics. Some correlations were suggested to predict the hydrodynamic parameters, and the values of h, kLa, a, and kL in the riser of the TPCFBs to provide insights for the present and future studies. The mechanism of heat and mass transfer and their modeling should be conducted for the better prediction of the performance of the TPCFB-reactors and contactors in the future.