We developed a membrane reactor integrating dimethoxydimethylsilane (DMDMS)-derived hydrogen-selective silica membranes with Rh/Al₂O₃ catalysts and produced high-purity hydrogen from simulated biogas by operating the reactor under pressure on the reaction side while maintaining ambient pressure and excluding sweep gas that has often been used on the permeate side. We investigated changes in the performance of the DMDMS-derived membrane when exposed to pressurized hydrothermal conditions. The results indicated that pressure had a nonnegligible effect on membrane performance and led to a more severe decline in hydrogen permeance compared with exposure under similar hydrothermal conditions but at 0.1 MPa pressure. Although the performance of the DMDMS-derived membrane decreased, we developed a membrane reactor and operated it for hydrogen production. For the various pressures (0.6–1.0 MPa) and temperatures (500–600°C) tested, the conversions exceeded those in the packed-bed reactor, and high hydrogen purity was achieved without the use of sweep gas. Specifically, 55% conversion with 94% hydrogen purity was achieved when the membrane reactor was operated at 0.6 MPa and 600°C.

Continual CO hydrogenation over a Ru/Fe/TiO₂ catalyst using a CO and H₂ mixed gas (H₂/CO=3) was investigated at 275°C and 0.6 MPa. Hydrogenation produced methane-rich gas as well as C₂–C₆ hydrocarbons. Moreover, the production of small amounts of higher aliphatic hydrocarbons (up to C43) was confirmed in after continual catalysis for 84 h. CO conversion decreased from 100 to 67% during this test, however, it recovered to 91% upon exposure of the deteriorated catalyst to H₂ treatment.

In this study, the effect of grafted dextran on the pore size of anion-exchange resins was investigated to optimize the accessible surface areas and mass transfer properties of protein chromatography. Three different methacrylate polymer-based anion exchangers of BioPro (BP) with different chain lengths of dextran (BP-0-Q, BP-60-Q, and BP-200-Q) were prepared. The mean pore radii of BP-0-Q, BP-60-Q, and BP-200-Q were 24.0, 10.6, and 6.2 nm, respectively, indicating that the penetration of proteins inside the pore was different depending on the chain length of the grafted dextran. Furthermore, the accessibility of human IgG antibodies to the surface inside the pore was the highest for BP-60-Q, suggesting that the dextran polymer of 60 kDa grafted on the pore maximized the accessible surface area of the resin. The static binding capacity of human IgG on BP-60-Q was 78 mg/cm³, which was 73% of the capacity of BP-200 Q and comparable to that of the conventional resins tested. According to the results of linear gradient elution experiments using human IgG, the values of the reduced height equivalent to a theoretical plate (h) of BP-60-Q were smaller than those of BP-200-Q as well as the conventional resins tested. The results indicate that BP-60-Q exhibited the highest performance for the chromatographic purification of human IgG with balanced binding capacity and mass transfer properties among the resins tested. Therefore, by changing the chain length of the grafted dextran, the pore radii of the resins were controlled, and thus, the binding capacity and mass transfer of the resin were optimized according to the target protein size.

The interaction between Al³⁺ and poly(acrylic acid) (PAA) which is a polyelectrolyte was investigated under various conditions. It was revealed that PAA has a strong binding ability with Al³⁺ not only in liquid phase but also in solid phase. Even when no hydrolysis of Al³⁺ occur at pH 3, the Al³⁺ was deposited together with PAA under various COOH/Al ratios and formed an insoluble Al–PAA complex. It was found that the hydrolysis of Al³⁺ was strongly retarded due to the complexation with PAA even under neutral and alkaline conditions. An excess amount of PAA in mixed solution retarded the precipitation of Al³⁺ at pH 4.5–8. The soluble Al–PAA complex suppressed the formation of the Al₁₃ polycation in solution. Moreover, an insoluble Al–PAA complex was also formed under COOH/Al ratio of 1. The molar ratio of COOH/Al in precipitates was dependent on the pH of the reaction solution. The type of chemical bond involved in the Al–PAA complex was affected by the Al³⁺ hydrolysis and dissociation of H⁺ from the carboxyl groups in PAA. At pH 3, one Al³⁺ combined with three carboxyl groups by substitution reaction with H⁺. Above pH 3, one Al(OH)²⁺ or one Al(OH)₂⁺ combined ionically with two or one COO⁻ groups, respectively. The results of this study can be potentially applied to formulate a method to remove Al³⁺ from various wastewater environments in a wide pH range.