Information on vapor–liquid equilibria in the extremely dilute regions is necessary for developing high-grade purification processes. In this study, we examine the vapor–liquid equilibria (x–y–T–P) of liquids containing 1×10⁻⁶ to 1×10⁻² mole fractions of alcohols for four binary systems, i.e., methanol+water, ethanol+water, 2-propanol+water, and 2-methyl-2-propanol+water, at 101.325 kPa using two Rose–Williams stills with a special device for a sampling system. The infinite-dilution equilibrium ratios K₁^∞ were measured, and the infinite-dilution activity coefficients obtained from K₁^∞ were compared with the literature and predicted values using modified UNIFAC (Dortmund) and ASOG. The x–y–T–P data at the finite composition regions were then calculated using Wilson parameters obtained by the infinite-dilution activity coefficients.

The correlation between liquid-phase mass transfer coefficient (k_L) and gas–liquid interfacial area (A) was measured within a CO₂–tap water system. An audio speaker was used to control both the bubble generation frequency (f) and bubble diameter. The bubble diameter was varied between 0.4 mm and 9.8 mm, and f was set to 10, 30, or 60 Hz. The maximum standard deviation of the volume equivalent diameter of bubbles just after generation from the nozzle was approximately ≤1/10 of the average diameter. Depending on the bubble diameter, one of two different methods was used to measure the effect of bubble diameter on k_L. The results indicate that for bubbles with a diameter greater than 5 mm, k_L depends on f. For f=10 Hz, the relationship between k_L and the bubble diameter was similar to that of an empirical correlation of a pure system described in the literature (Clift et al., 1965). For bubbles with a diameter 0.58 mm or less, k_L decreased with decreasing bubble diameter. The mass transfer of CO₂ bubbles in this release method correlated with the conventional dimensionless equation based on the relationship between the Sherwood (Sh) and Reynolds (Re) numbers. Sh was proportional to Re^1/2 for 5<Re<60, and Sh was proportional to Re^3/4 for 300<Re<3300. The dependence of Re on Sh for a row of bubbles was revealed to be similar to that for single bubbles.

An inside baffle which was placed inside a vessel with a clearance between the baffle and the vessel wall has been developed to draw down the floating solids into the liquid effectively. The drawdown performance of floating solids into the liquid was investigated under four baffle conditions: no baffle condition, standard baffle condition, surface baffle on the wall condition, and inside surface baffle condition. The minimum impeller rotational speed for the complete suspension of floating solid N_JD was measured visually under all the baffle conditions. Particle image velocimetry (PIV) was conducted to measure the velocity field. The volumetric power consumption P_{V, JD} at N_JD, was measured. As a result, N_JD under the inside surface baffle condition was the lowest at an impeller position near the vessel bottom. Moreover, P_{V, JD} under the inside surface baffle condition was the lowest among all the baffle conditions at all impeller positions.

CHA-type zeolite SAPO-34 membranes were synthesized on a tubular porous α-alumina support using a secondary growth method and tested for the separation of water/acetic acid mixtures by vapor permeation. The effects of SiO₂ molar fraction in the preparation gel on the membrane formation process and the separation properties of SAPO-34 membranes were studied. The SiO₂ molar fraction in the synthesis gel substantially affected the separation properties of prepared membranes. The membrane synthesized using a gel with a composition of 1.0 Al₂O₃ : 0.9 H₃PO₄ : 0.6 SiO₂ : 0.8 TEAOH : 100 H₂O exhibited a high separation factor of 140 with the water permeance of 2.2×10⁻⁷ mol m⁻² s⁻¹ Pa⁻¹. SAPO-34 membranes prepared in this study also showed resistance against acetic acid.

We previously reported the permselectivities, microstructure, and permeation mechanisms of ionic silsesquioxane-based membranes, which are a class of chemically stabilized ionic liquid (IL) membranes, prepared from ionic trialkoxysilanes (i.e., silylated ILs (T-type)) via the sol–gel method. These membranes comprise dense IL regions and Si–O–Si network-derived micropores, and their permeation characteristics depended on the two permeation pathways. Establishing a method for control the permeation characteristics of silylated IL-derived membranes is important for application expansion. Therefore, in this study, an ionic dialkoxysilane (i.e., silylated IL (D-type))-derived membrane was developed, and the effects of the Si–O–Si network structure on its permeation characteristics are discussed. Attenuated total reflectance infrared spectroscopy, N₂ adsorption, and nanopermporometry characterizations revealed that the structure of the newly developed membrane was consistent with the Si–O–Si linear structures and Si–O–Si rings, but not the Si–O–Si network-derived micropores. Both membranes showed selective methanol permeation against H₂ at temperatures up to 473 K, but the calculation of the activation energy for methanol permeation clearly suggested that the IL-like properties of ionic dialkoxysilane-based membranes were better than those of the ionic silsesquioxane-based membranes with respect to methanol permeation.

The present study introduces microreactors that were developed to be able to mix two kinds of raw materials at a high flow rate ratio. They consist of two substrates made of white and black polyethylene for corrosion resistance, respectively. They have a sheath flow channel that holds one raw material with the other and the channel width and depth are 0.2 or 0.5 mm. The mixing performance was evaluated using the Villarmaux–Dushman reaction, in which the flow rate ratio of the two solutions was set to 1 : 1, 1 : 5, 1 : 10, or 1 : 20. For the channel width and depth of 0.5 mm, the developed microreactor provided the same or better mixing performance than the batch method at larger total flow rates than about 2×10⁻⁵ m³/min. At a flow rate ratio of 1 : 20, the mixing performance of a tee connector was almost the same as that of the batch method and worse than that of the developed microreactor. For the channel width and depth of 0.2 mm, the developed microreactor provided the same or better mixing performance than the batch method at larger total flow rates than about 1×10⁻⁶ m³/min. The mixing performance of a split-flow and interflow microreactor with four times pressure loss was worse than that of the batch method at a flow rate ratio of 1 : 20. A Y-shaped microreactor with an order of magnitude larger pressure loss provided better mixing performance than the batch method at larger total flow rates than about 4×10⁻⁷ m³/min at each flow rate ratio. Therefore, the developed microreactors allow for their application to mixing in a wide range of flow rate ratios under lower pressure loss than several tens of kPa. These microreactors made of polyethylene are expected to also be used as single-use reactors, which are required particularly in the manufacturing of biopharmaceuticals.