Yasutaka Kuwahara

Production of γ-valerolactone (GVL) from biomass-derived levulinic acid and its esters via a catalytic transfer hydrogenation (CTH) process over sulfonic acid-functionalized UiO-66, a microporous zirconium-based metal–organic framework (Zr-MOF), is reported herein. On the basis of comprehensive structural analyses by means of XRD, N2 physisorption, IR, TG, and Zr K-edge XAFS, we show that free sulfonic acid (−SO3H) groups can uniformly be tethered on a UiO-66 framework without affecting the coor

The CO(2) adsorption characteristics of prototypical poly(ethyleneimine)/silica composite adsorbents can be drastically enhanced by altering the acid/base properties of the oxide support via incorporation of Zr into the silica support. Introduction of an optimal amount of Zr resulted in a significant improvement in the CO(2) capacity and amine efficiency under dilute (simulated flue gas) and ultradilute (simulated ambient air) conditions. Adsorption experiments combined with detailed characteriz

Harvesting solar light to boost commercially important organic synthesis still remains a challenge. Coupling of conventional noble metal catalysts with plasmonic oxide materials which exhibit intense plasmon absorption in the visible light region is a promising option for efficient solar energy utilization in catalysis. Herein, we for the first time demonstrate that plasmonic hydrogen molybdenum bronze coupled with Pt nanoparticles (Pt/H _xMoO_{3- y}) shows a high catalytic per

Silica supported amine materials are promising compositions that can be used to effectively remove CO(2) from large stationary sources, such as flue gas generated from coal-fired power plants (ca. 10 % CO(2)) and potentially from ambient air (ca. 400 ppm CO(2)). The CO(2) adsorption characteristics of prototypical poly(ethyleneimine)-silica composite adsorbents can be significantly enhanced by altering the acid/base properties of the silica support by heteroatom incorporation into the silica mat

A yolk–shell nanostructured composite composed of Pd nanoparticles (NPs) and aminopolymers, poly(ethylenimine) (PEI), confined in hollow silica spheres which act as an efficient and stable heterogeneous catalyst for semihydrogenation of alkynes is reported herein. The yolk–shell nanostructured Pd-PEI-silica composite catalysts (Pd+PEI@HSS), consisting of Pd NPs core ca. 5–9 nm in diameter and a porous silica shell ca. 30–50 nm in shell thickness, are fabricated by a facile one-pot method using l

The main components of blast furnace slag (BFS) are CaO, SiO2, A12O3, MgO and slight amounts of transition metals such as Fe, Ti and Mn. We successfully synthesized a hydrotalcite-like compound from BFS via a convenient chemical process: acid-leaching and precipitation. After the HCl acid-leaching process, BFS was separated into hydrated silica with 92 wt% SiO2 content and leaching solution including other components, which afforded a hydrotalcite-like compound after subsequent NaOH addition in

Titanium dioxide (TiO2) is a promising photocatalyst for degradation of organic compounds ideally under environmentally benign conditions. This paper reviews recent developments in designing TiO2-sorbent hybrid photocatalysts, especially those supported on ordered nano-porous silica materials including zeolites and mesoporous silicas, with the objective of fabricating efficient photodegradation systems toward organic compounds diluted in water and air. This review also describes the basic featur

Hexagonal mesoporous silica (HMS) material, which is commonly used in catalysis and the nanostructural design field as an adsorbent or host material, was hydrophobically modified via a simple silylation process using a fluorine-containing silylation agent, triethoxyfluorosilane [TEFS or SiF(OEt)3]. Structural analyses performed by XRD and N2 adsorption−desorption suggested that the mesoporous structure and large surface area of the HMS were retained even after the modification. Surface chemical

A new class of heterogeneous catalytic systems utilizing cation-guest interactions was designed based on microporous titanosilicate molecular sieves. Introducing heavier alkali metal cations on ion-exchange sites of the framework resulted in a significant enhancement of the catalytic activity for oxidation of cyclohexene and styrene, whereas such an enhancement was not observed in oxidation of cyclohexane without π systems. Distinct relationships between the catalytic activities and intermolecul

Blast furnace slag (BFS), a high volume byproduct resulting from the iron manufacturing industry, was used as a low-cost and abundant precursor for preparing a high-surface-area calcium silicate hydrate. The synthesis of slag-made calcium silicate hydrate (slagCS) was achieved via a facile two-step dissolution–coprecipitation procedure using HCl and NaOH, respectively. The use of concentrated protonic acid facilitated an easy dissolution of BFS, and the subsequent addition of aqueous NaOH soluti

CO2 hydrogenation to formic acid, a renewable hydrogen storage compound, has been regarded as a key reaction to realize hydrogen energy cycles. However, the development of robust heterogeneous catalysts with high activity and stability has been a challenge. We herein report a synthesis of hollow nanostructured composite consisting of PdAg nanoparticles (NPs) and aminopolymers, poly(ethyleneimine) (PEI), confined in hollow mesoporous organosilica spheres (HMOSs), which act as an efficient and sta