Atsushi Takagaki

5-Hydroxymethylfurfural (HMF), one of the most important intermediates derived from biomass, was directly produced from monosaccharides (fructose and glucose) and disaccharides (sucrose and cellobiose) by a simple one-pot reaction including hydrolysis, isomerization and dehydration using solid acid and base catalysts under mild conditions.

Two-dimensional metal oxide sheets in HTiNbO(5) and HSr(2)Nb(3)O(10), cation-exchangeable layered metal oxides, were examined as solid acid catalysts. Exfoliation of HTiNbO(5) and HSr(2)Nb(3)O(10) in aqueous solutions formed colloidal single-crystal TiNbO(5)(-) and Sr(2)Nb(3)O(10)(-) nanosheets, which precipitated under an acidic condition to form aggregates of HTiNbO(5) nanosheets and HSr(2)Nb(3)O(10) nanosheets. Although esterification of acetic acid, cracking of cumene, and dehydration of 2-p

2,5-Diformylfuran (DFF) was selectively synthesized from 5-hydroxymethylfurfural using a hydrotalcite-supported ruthenium catalyst (Ru/HT) by oxidation with molecular oxygen under mild reaction conditions. A combination of hydrotalcite, Amberlyst-15, and Ru/HT catalysts successfully afforded direct synthesis of DFF from hexoses such as fructose and glucose via isomerization, dehydration, and successive selective oxidation in one pot. Stepwise addition of catalyst improved DFF yield up to 49% fro

The layered transition-metal oxide HNbMoO(6) is demonstrated to exhibit remarkable catalytic performance for the hydrolysis of saccharides such as sucrose, cellobiose, starch, and cellulose, attributable to water tolerance and the facile accessibility of saccharides into the strong acidic interlayer gallery of the solid.

An uncalcined Mg–Al hydrotalcite catalyst involving hydromagnesite with a high surface area acted as a highly active base catalyst for glycerol carbonate synthesis from glycerol and dialkyl carbonates under moderate reaction conditions.

Solid acid catalysts offer the opportunity to reduce environmental impact owing to such advantages as ease of product separation and recyclability of the catalyst, which contribute considerably to green chemistry. Nanosheets, crystalline two-dimensional metal oxide sheets prepared from cation-exchangeable layered metal oxides through exfoliation and aggregation, are a novel class of potential solid acid catalysts for replacing liquid acids, such as sulfuric acid. This article reviews the acid st

An aggregate of exfoliated HNb3O8 nanosheets obtained by exfoliation of a layered metal oxide functions as a strong protonic solid acid, exhibiting much higher catalytic performance for esterification and hydrolysis than conventional niobic acid, Nb2O5·nH2O.

HTiNbO5, HTi2NbO7, and HTiTaO5 nanosheets obtained by exfoliation of protonated cation-exchangeable layered metal oxides are examined as solid acids. These nanosheets exhibit high catalytic activity for esterification of acetic acid and hydrolysis of ethyl acetate, competing with niobic acid, Nb2O5·nH2O. NH3 temperature-programmed desorption reveals that the acidity of the nanosheets corresponds to the density of strong acid sites of H−ZSM-5 or niobic acid. 1H magic-angle-spinning nuclear magnet

Aqueous-phase transformation of C3- and C6-sugars toward valuable intermediates such as lactic acid and 5-hydroxymethylfurfural (HMF) using boehmite, an abundant, inexpensive and simple aluminium oxide hydroxide γ-AlO(OH) was demonstrated. Pyridine-adsorbed Fourier transform infrared (FTIR) spectroscopy and trimethylphosphine oxide-adsorbed 31P magic angle spinning (MAS) nuclear magic resonance (NMR) revealed that boehmite had no Brønsted acid sites and a small amount of weak Lewis acid sites. T

Abstract An efficient furfural formation from xylose, a major pentose in hemicellulose of biomass, was demonstrated using a pair of solid acid and base in one-pot. High furfural yield was obtained in polar aprotic solvents including N,N-dimethylformamide using Amberlyst-15 and hydrotalcite under moderate conditions. This efficient production of furfural was performed via aldose–ketose isomerization of xylose to xylulose by solid base and successive dehydration of xylulose to furfural by solid ac

Abstract CoFe2O4-embedded silica nanoparticles containing sulfonic acid groups were found to be highly active solid acid catalysts for hydrolysis of disaccharides (sucrose and cellobiose) and polysaccharides (starch and cellulose) with facile magnetic separation.

Hexagonal boron nitride solid base catalysts were prepared by simple ball-milling at various rotation speeds of a commercial low-surface area boron nitride.