The soft-templating approach with the self-assembly of amphiphilic organic molecules is introduced as our methodology for synthesizing mesoporous metal oxides, e.g., alumina (Al₂O₃) and titania (TiO₂). Our efficient optimization of the synthetic conditions based on the common spin-coating process leading to fast evaporation of solvents has generalized a smart synthetic method combined with a temperature-controllable scalable spray-drying process for recovering porous metal oxide powders with high specific surface area. To illustrate the use of mesoporous metal oxides as catalyst supports, the chemical composition of nanocomposite catalysts was surveyed for synthesizing gaseous ammonia (NH₃) through the hydrogenation of solid-state nitrogen oxides (NO_x). The porous metal oxide based nanocomposite catalysts were prepared by one-pot doping of noble metal catalyst and subsequent impregnation of additional component for the storage of NO_x. The reaction process was designed for the selective synthesis of NH₃ by an alternate gas-switching operation between storage of NO_x and reduction by H₂.

Photothermal dry reforming of methane (PT-DRM) is an effective catalytic approach for CO₂ utilization into valuable synthesis gas (mixture of CO and H₂) using solar energy for the catalyst heating. Nickel is one of the most active catalytic components for thermal DRM reactions, and various Ni-based catalysts have been developed for PT-DRM. The oxidation state of Ni is considered to change depending on the reaction conditions such as gas atmosphere and temperature; however, the changes in the oxidation state in the rapid heating and cooling conditions induced by light irradiation have not been studied so far. In the present study, we investigated the chemical state and structure of nickel species in a Ni/Al₂O₃ catalyst during PT-DRM under visible and near-infrared light by operando X-ray absorption spectroscopy (XAS). We found that the spectral shape changed in response to the light on/off, and the origin was discussed based on the extracted information by analyzing the XANES and EXAFS spectra.

In the present study, we conducted the conversion of monosaccharides to aromatic compounds over a charcoal-supported platinum catalyst in high-temperature water and investigated the effects of the reaction conditions and monosaccharide type on the yields of aromatic compounds. Conversion of glucose (C6), xylose (C5), and glyceraldehyde (C3) at 573 K gave total yields of aromatic compounds of glucose (3.1 %) > xylose (2.4 %) > glyceraldehyde (2.1 %) in order of decreasing carbon number. We concluded that these low yields were the result of slow carbon–carbon bond formation, which is required for formation of aromatic compounds from these monosaccharides. In contrast, conversion of the monosaccharides at 673 K gave comparable yields of aromatic compounds at around 4 %, indicating that carbon number had no effect at higher temperature. To investigate the reaction pathway from monosaccharides to aromatic compounds, we also converted various monosaccharide derivatives. The yields of aromatic compounds from sugar alcohols, which do not have formyl groups, were much lower than those from the parent monosaccharides, indicating that the formyl groups in the monosaccharides are essential for the formation of aromatic compounds.

Recent advancements in tandem reactions, specifically the single step of conversion of CO₂ to methanol and subsequent hydrocarbon synthesis from methanol (MTH), have attracted attention. This study presents such tandem reactions over various spinel oxides and SSZ-13 catalysts. The catalytic performance of 26 different spinel oxides was tested with SSZ-13 zeolite. Zn-based spinel oxide tandem catalysts (ZnAl₂O₄, ZnCr₂O₄, ZnFe₂O₄, ZnGa₂O₄) exhibited high hydrocarbon yields at 653 K and 1.0 MPa. Furthermore, amorphous Zn–Al–O and SSZ-13 tandem catalyst yielded 3.1 % of hydrocarbon while the tandem catalyst of spinel Zn–Al–O and SSZ-13 tandem catalyst yielded 7.2 %, indicating that the spinel structure is essential for the first step of the tandem reaction, methanol synthesis. ZnFe₂O₄ was found to have a high hydrocarbon yield per surface area in the tandem reaction at 653-673 K, more than 100 K higher than conventional methanol synthesis.

Catalytic conversion of LDPE (low-density polyethylene) pyrolysis gas into valuable products was investigated to promote recycling of plastics. LDPE pyrolysis and catalytic conversion using a tandem reactor showed the potential for selective recovery of aromatics. LDPE was rapidly pyrolyzed at high temperatures in the first reactor, yielding uniform product in the pyrolysis. The zeolite catalyst in the second reactor of the LDPE pyrolysis effectively decomposed heavy hydrocarbons and formed aromatics. In particular, Beta-type zeolite and MFI-type zeolite showed relatively high aromatics yields, whereas Na-exchanged zeolite did not show decomposition activity. The results indicated the importance of strong Brønsted acid sites for aromatics production. Furthermore, LDPE pyrolysis within the system required higher temperatures than the decomposition temperature of LDPE, highlighting the necessity for rapid pyrolysis to achieve effective catalytic conversion into aromatics. The tandem system consistently showed stable aromatics yields across multiple tests.