Alkane monooxygenases and proton-exchanged zeolites are catalysts that have cavities within their molecular structure and a catalytic site for n-alkane conversion in the cavity. The effect of the spatial volume of the cavity in the catalysts and the molecular volume of the reacting molecules on the product selectivity in catalytic reactions was evaluated by analysis of the product selectivity in the oxidation of C₄-C₈ n-alkanes to alcohols by alkane monooxygenases, and in the cracking of n-pentane by proton-exchanged zeolites. The selectivity for production of the 2-hydroxyalkane enantiomer from n-alkanes depended on the cavity volume of the substrate binding site in the alkane monooxygenases. Further, the selectivity for ethane and propene in n-pentane cracking by proton-exchanged zeolite also depended on the cavity volume of the zeolite. From these dependencies, we propose that product selectivity is expressed if the molecular volume of the reacting molecules or reaction intermediates is almost identical to the volume of the cavity in which the catalytic reactions proceed.

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The relationships between the morphologies and dispersion of supported Mo sulfide catalysts and their catalytic functions evaluated by model test reactions are reviewed. The catalyst support had large effects on the morphologies through the electronic interaction and geometrical relationship between the catalyst and the support surface. High hydrogenation activities were obtained for Al₂O₃ supported catalysts due to high dispersion, whereas high hydrogenolysis activities were obtained for TiO₂-supported catalysts due to the electronic interaction. Relatively large single-layered MoS₂ structures were formed on the {110} γ-Al₂O₃ surface, whereas microclusters and multi-layered MoS₂ structures were more favorably formed on the {111} and {100} γ-Al₂O₃ surfaces. Multi-layered MoS₂ structures had the edge-bonding orientation on anatase-TiO₂ with an epitaxial relationship by sulfidation in H₂S/N₂. Single-layered MoS₂ catalysts exhibited relatively hydrogenation-oriented function, whereas multi-layered MoS₂ catalysts had relatively hydrogenolysis-oriented function. Steric hindrance affected the catalytic functions, particularly in hydrogenation that required η⁶ adsorption of aromatic rings. Long-term uses in hydrotreating caused growth of the MoS₂ structures in the lateral direction, which decreased the number of active sites. Simultaneously, the aging caused deep sulfiding of the catalysts, which weakened the interaction with the support and increased the intrinsic activities of the catalysts.

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Cellulose is a key material for the production of ethanol, which can be used for internal combustion. However, cellulose contains rigid crystalline regions that are not readily hydrolysable by cellulase, so methods for increasing the accessibility of cellulase to cellulose are needed. Our research aim involves high speed production of glucose from cellulose. Therefore, we established a method for highly efficient glucose recovery using hydrothermal dissolution. The amounts of decomposition products after hydrothermal dissolution were analyzed. Even with high levels of decomposition product, the sample showed the highest glucose concentration. Rapid enzymatic hydrolysis using dissolved cellulose generated by hydrothermal dissolution was successfully demonstrated. The optimal conditions of temperature and elution time for effective production of glucose were determined.

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The catalytic performance of unsupported Ni catalyst covered by a silica thin layer with core-shell structure for selective CO methanation was investigated. The thin silica layer prepared with a silane coupling agent as the silica source effectively suppressed Ni-sintering even at quite low Si/Ni ratio. Due to the low Si/Ni ratio, the Ni surface area of the catalyst was increased by 20 % compared to the conventional unsupported Ni catalyst and outlet CO concentration reached less than 10 ppm even at low temperature (155 °C). The durability test revealed that outlet CO concentration was maintained at less than 10 ppm during operation for 3000 h over the developed catalyst even under severe conditions (SV 4800 h^–1, inlet CO concentration 0.5 %). Further improvement of the catalyst selectivity is necessary because the operating window for the developed catalyst, in which outlet CO concentration is less than 10 ppm and CH₄ formation is less than 1 %, was almost the same as that for the conventional catalyst.

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