Yuichi Kamiya

Adsorption and Catalytic Properties of the Inner Nanospace of a Gigantic Ring-Shaped Polyoxometalate Cluster**

are of great interestbecause of their unique properties such as adsorption,separation, exchange, and catalysis, which are all associatedwith the presence of a functional nanospace. In this respect,polyoxometalate clusters, which are nanosized metal-oxidemacroanions built from molecular precursors with a range ofunique redox and acidic properties, are ideally suited for thedevelopment of functional nanospaces but have not yet beenthus explored.

Alkylation of 1,3,5-trimethylbenzene with γ-butyrolactone over heteropolyacid catalysts

Abstract A Friedel–Crafts-type reaction of 1,3,5-trimethylbenzene with γ-butyrolactone was conducted over various solid acid catalysts such as zeolites, polymer resins, and heteropolyacids. The alkylation to 4-(2,4,6-trimethylphenyl) butyric acid proceeded exclusively with these catalysts; no acylation to the ketone occurred. The heteropolyacids, such as H3PW12O40 and H4SiW12O40, were superior in activity to the other catalysts; they also accelerated the reaction of the product acid with γ-butyrolactone to the corresponding carboxylic acid. When the heteropolyacids were supported on silica, alkylation proceeded efficiently with high mass balance, suppressing further reaction. The reusability of the supported heteropolyacids also was confirmed.

Modification of Sn-Beta zeolite: characterization of acidic/basic properties and catalytic performance in Baeyer–Villiger oxidation

Sn-Beta was post-synthetically modified with various cations such as Li+, Na+, K+, Cs+, and NH4+. During the modification process, the ion-exchange of the cations with silanol groups occurred along with a reversible change between “closed” and “open” Sn sites through hydrolysis of the Si–O–Sn bonds. The IR study showed that Sn-Beta had weak Bronsted acid sites, which were passivated by the ion-exchange, in addition to the Lewis acid sites and that surprisingly, basic sites were formed on the modified zeolites. The ion-exchange with a small amount of Li+, Na+ and NH4+ was effective for suppressing side-reactions, leading to an improvement in selectivity to caprolactone in the Baeyer–Villiger oxidation of cyclohexanone with H2O2. The modification of Sn-Beta with such cations also effectively enhanced the catalytic activity in the Baeyer–Villiger oxidation of 2-adamantanone.

A Highly Water‐Tolerant Magnesium(II) Coordination Polymer Derived from a Flexible Layered Structure

A two-dimensional (2D) layered Mg(II) coordination polymer (CP) with a high tolerance for H2 O was designed, synthesised, and crystallographically characterised. The synthesis was achieved by the introduction of a flexible 2D layered structure composed of Mg(II) ions and isonicotinate N-oxide ligands. Owing to its high H2 O tolerance, the obtained 2D layered structure has the flexibility to repeatedly adsorb a large amount of H2 O associated with interlayer expansion and enable the removal of H2 O from a H2 O/2-propanol mixed vapour. These results indicate that the CP could be an excellent dehydrating agent.

Toward Green and Sustainable Chemical Glycosylation: Enhanced Lewis Acidity of Recyclable Solid Super Acid Catalyst, SO4/ZrO2 by CaCl2 Doping

The simple doping of calcium chloride allowed highly improved yields in the glycosylation promoted by sulfated zirconia (SZ) without calcination. It was revealed by means of per-O-benzylated galactose trichloroacetimidate as a model glycosyl donor that this effect depends greatly on the cationic ion radius of used metal chlorides. Temperature-programmed desorption of ammonia (NH3 TPD) and the pyridine IR method showed clearly that coordination of calcium ion provides the SZ surface with newly formed Lewis acidic sites while the Brønsted acid site disappeared, indicating that the enhanced catalytic potency of SZ is due to the increased Lewis acid sites by doping the optimal calcium ions. The present findings might give insight into the relationship between a catalytic mechanism and superacidity of SZ, which is crucial for the design of novel superacid–based catalysts and environmentally benign glycosylation processes.

Synthesis of (VO)2P2O7 catalystsvia exfoliation-reduction of VOPO4·2H2O in butanol in the presence of ethanol

The exfoliation-reduction of VOPO4·2H2O in l-butanol oriso-butanol alone, and in a l-butanol/ethanol oriso-butanol/ethanol mixture, were conducted. Although all precursors were composed of a lamellar compound with intercalated alcohol molecules, VOHPO4·0.5H2O was formed when the exfoliation-reduction process was carried out in the mixed alcohol. All precursors transformed to a single phase of (VO)2P2O7 under the reaction conditions forn-butane oxidation, but the crystallinity of (VO)2P2O7 was different. The catalyst synthesized iniso-butanol/ethanol was well crystalline (VO)2P2O7, and exhibited higher selectivity to maleic anhydride than that synthesized iniso-butanol alone for then-butane oxidation.

Tin-palladium supported on alumina as a highly active and selective catalyst for hydrogenation of nitrate in actual groundwater polluted with nitrate

We developed Sn0.5Pd/Al2O3 showing high activity and high selectivity to gaseous products towards the hydrogenation of NO3− with H2 in aqueous NO3− solutions via precise control of the Sn/Pd molar ratio. For the catalyst with the optimum Sn/Pd molar ratio, the surface concentration of adsorbed nitrogen on the Pd sites is thought to be high and that of the adsorbed hydrogen on the Pd sites is thought to be low. This is due to the abundant supply of NO2− for the Pd sites and the prompt consumption of adsorbed H on the Pd sites for reduction of the oxidized Sn sites formed by the reduction of NO3−, respectively, leading to the high selectivity to gaseous products. Although the catalytic performance of Sn0.5Pd/Al2O3, like that of Cu0.5Pd/Al2O3, was lower in groundwater, the decrease for Sn0.5Pd/Al2O3 was less than that for Cu0.5Pd/Al2O3. Nitrate in the groundwater polluted with 0.4 mmol dm−3 (250 cm3) of NO3− was completely reduced at 298 K in 24 h with a selectivity for gaseous products of around 90% in the presence of 10 mg of Sn0.5Pd/Al2O3, whereas it took 60 h in the presence of Cu0.5Pd/Al2O3, and the selectivity for gaseous products was around 75%. However, both catalysts showed comparable high activity and high selectivity in aqueous NO3− solutions. When reactions were performed in aqueous NO3− solutions containing other anions (Cl−, SO42−, and SiOxn−) present in the groundwater, Cl− had the largest negative impact but it had a smaller impact in the presence of Sn0.5Pd/Al2O3 than it did in the presence of Cu0.5Pd/Al2O3. On the basis of adsorption isotherms for Cl− and kinetics analysis of the hydrogenation of NO3−, it was concluded that Sn0.5Pd/Al2O3 had less affinity for Cl− and a strong affinity for NO3− on the Sn sites, leading to its superior catalytic performance in groundwater.

Selective oxidation of n-butane over Fe-promoted vanadyl pyrophosphate prepared from modification of nano-sized interlayer of lamellar vanadyl benzylphosphate

A novel approach for the preparation of promoted vanadyl pyrophosphate in well-defined structure was examined. Lamellar vanadyl benzylphosphate (LVBP) was used as a host material and iron acetylacetonate as a guest. It was found that iron acetylacetonate was successfully inserted into the interlayer of LVBP by heating of LVBP and iron acetylacetonate in toluene solution. Calcination of this in tercalated material resulted in a well-crystallized vanadyl pyrophosphate phase with uniform dispersion of Fe in bulk and surface. The obtained Fe-promoted vanadyl pyrophosphate showed an enhancement in the activity for selective oxidation of n-butane, especially at high temperature and long contact time.