The reaction rates of the hydrolysis of tetrafluoromethane (PFC-14) and hexafluoroethane (PFC-116) were measured using a catalyst consisting of tungsten oxide supported on alumina-zirconia prepared from gamma-alumina. The hydrolysis rate of PFC-14 did not change even over the supported tungsten oxide catalyst. Ammonia temperature-programmed desorption measurements showed that acidity of tungsten oxide increased if supported on alumina-zirconia, suggesting that the acidity was due to Br & oslash;nsted acid sites. The hydrolysis rate of PFC-116 increased over supported tungsten oxide catalyst almost linearly with the increase in the number of acid sites. Hydrolysis of isopropyl benzene was carried out to investigate the increase in the acid sites caused by the tungsten oxide support. The hydrolysis rate of isopropyl benzene increased almost linearly with the increase in the number of acid sites, suggesting that the newly emerged acid sites were Br & oslash;nsted acid sites in the presence of water vapor.
Interfacial charge transfer (IFCT) has emerged as a novel strategy for selective photoactivation of adsorbed molecules through inner-sphere type electron transfer. Most IFCT systems require electron-rich functional groups such as hydroxyl or amino groups to form IFCT surface complexes, limiting their application to the oxidation of these functional groups. Herein, we demonstrate that nitrogen atoms in aromatic rings can be used to form a surface complex through acid-base interactions, which gives rise to IFCT with photocatalysts, and to promote the photooxidation of an aromatic methyl group of heteroaromatics. We found that 9-methylacridine (9-MA)-adsorbed on TiO2 exhibited an IFCT absorption band in the visible light region (400-500 nm), which can be attributed to the IFCT transition from 9-MA to TiO2. Under irradiation with a blue LED (2=465 nm), photo-oxidation of 9-MA into 9-acridinecarboxaldehyde (9-ACAl) proceeded in toluene, with a maximum yield of 44 %, which was 2.6 times higher than that under UV light irradiation (2=365 nm). The higher yield under visible-light irradiation can be attributed to the absence of photogenerated holes in the photocatalyst, which oxidize toluene to strongly adsorbed intermediates such as benzaldehyde and benzoic acid, causing deactivation of the photocatalyst. The present study opens up new IFCT systems utilizing the interaction of heteroatoms in aromatic rings with the surface of photocatalysts.
The catalytic activity of solid acids and bases is strongly affected by local structural features such as edge sites, interlayer galleries, lattice strain, and hierarchical porosity, yet these critical motifs are often optimized empirically. This review introduces crystal-structure-guided design strategies for inorganic solid acid and base catalysts, illustrated through four approaches developed in our work. (i) Edge engineering in hexagonal boron nitride (BN): top-down ball milling exposes polar planes and introduces surface-OH/-NH2 groups, converting inert layered BN into a bifunctional acid-base catalyst for nitroaldol reaction and Knoevenagel reactions with high selectivity. (ii) Porogen-directed porosity in porous BN: pyrolysis with single or multiple nitrogen-containing porogens controls micro/mesoporosity; base-catalyzed activity scales with pore volume, while weak surface acidity enables efficient CO2-epoxide cycloaddition. (iii) Chemo-mechanical strain into TiO2 via spark plasma sintering: thermal-expansion mismatch with Au introduces three-dimensional tensile strain in rutile, expanding the unit cell and stabilizing Ti3+/Ti2+ species that correlate with enhanced Br & oslash;nsted-acid-type activity in furfural acetalization. (iv) interlayer acidity and selective intercalation in HNbMoO6: robust, water-tolerant Br & oslash;nsted acid sites and substrate gating govern saccharide hydrolysis, esterification, and polyol cyclodehydration. Solvent-free mechanochemistry further enables cellulose depolymerization to soluble sugars.
Reduction of the environmental burden associated with waste management is a critical challenge for achieving a sustainable society, and establishing a recycling-oriented economic system has become an urgent priority. Waste lubricants are often utilized as recycled fuels in heat recovery through incineration, but direct reuse as lubricants remains challenging. To promote the recycling of lubricants, innovative technologies are needed that can efficiently remove impurities and residual additives from waste lubricants. This study proposes a new method for extracting additives and degradation products from waste lubricants using a Type V deep eutectic solvent. Extraction was performed by adding a deep eutectic solvent to waste lubricants, and the results demonstrated a significant reductions in residual additives, oxides, and by-products. Additionally, the deep eutectic solvent was easily regenerated after use, and the regenerated solvent exhibited comparable extraction performance to the fresh solvent. This technology enables efficient regeneration of lubricants and is expected to contribute to the development of a resource-recycling society and reductions in the environmental impacts.
