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The potassium and proton mixed salt of mono-Nb substituted Keggin-type phosphomolybdate, KH3[PMo11NbO40], was isolated in a pure form by reacting Keggin-type phosphomolybdic acid (H3[PMo12O40]) and potassium hexaniobate (K8Nb6O19) in water, followed by freeze-drying. The all protonic form, H4[PMo11NbO40], was isolated via proton exchange with H-resin and subsequent freeze-drying. The most crucial factor to isolate KH3[PMo11NbO40] and H4[PMo11NbO40] in pure forms is the evaporation of water using the freeze-drying method. Using a similar procedure, the potassium salt of the di-Nb substituted compound K5[PMo10Nb2O40] was isolated. H4[PMo11NbO40] exhibited high catalytic activity for oxidizing isobutylaldehyde to methacrolein and moderate catalytic activity for the Wacker-type oxidation of allyl phenyl ether when combined with Pd(OAc)2. [ABSTRACT FROM AUTHOR]

High‐dimensionally structured (HDS) mixed oxides of vanadium with metals (M) (e. g., Nb, Mo, and W; denoted as HDS‐MVO) were constructed by {M6O21}12− pentagonal units and {MO6} (M=Nb, Mo, W, or V) octahedra as linkers. The materials were synthesized using a hydrothermal method and rod‐shaped solids. The random assembly of the pentagonal units and octahedra in the cross‐sectional plane of the rods facilitated the formation of micropore channels along the long axis of the rods. Micropore formation was directly observed in the cross‐section by HAADF‐STEM. These structural features are common to HDS‐NbVO, HDS‐MoVO, and HDS‐WVO. The catalytic activity of these three HDS‐MVOs with V/Mo ratios in the range 0.35–0.39 was tested for the oxidative dehydrogenation of ethane and propane. The reaction rates per surface area for ethane oxidation and propane oxidation over the HDS‐MoVO and HDS‐WVO catalysts were comparable, whereas the HDS‐NbVO catalyst showed an appreciable difference between the two reaction rates. Both HDS‐MoVO and HDS‐WVO exhibited higher selectivity for olefin formation during ethane oxidation than propane oxidation. Interestingly, the olefin selectivity over the HDS‐NbVO catalyst was found to be almost independent of the alkane substrate. These catalytic features were discussed on the basis of V−O−V or V−O−Mo redox coupling and pore structure effects in HDS‐MoVO and HDS‐WVO and also of isolated and valence stable surface V in HDS‐NbVO. [ABSTRACT FROM AUTHOR]

• High dimensionally structured W-V oxide (HDS-WVO) was synthesized by hydrothermal method. • Local catalyst structure in HDS-WVO was analyzed in atomic level by HAADF-STEM analysis. • HDS-WVO showed outstanding catalytic performance for selective oxidation of toluene. High dimensionally structured W-V-O catalysts (HDS-WVO) were synthesized by hydrothermal method and catalyst structures were investigated by HAADF-STEM analysis. HDS-WVO were rod-shaped crystals and the cross-sections were constituted by W 6 O 21 pentagonal units and MO 6 octahedra (M = V, W), forming heptagonal and hexagonal channels. HDS-WVO catalysts showed excellent catalytic performance for selective oxidation of toluene to benzoic acid, and the activity and the selectivity to benzoic acid were superior to those of state-of-the-art catalysts. After the ion exchange using Cs+, the catalytic activity over HDS-WVO was significantly decreased. Since HAADF-STEM analysis and N 2 adsorption revealed that Cs+ was located mainly at the heptagonal channel of HDS-WVO, it can be concluded that toluene oxidation takes place at the heptagonal channel site of HDS-WVO. [ABSTRACT FROM AUTHOR]

Cu–ZrO2 catalysts were synthesized by the methanothermal (Me) and oxalate gel precipitation (Og) methods. Detailed characterization of the catalysts synthesized by the Me method shows that these contain only Cu substituted into the tetragonal ZrO2 lattice. For catalysts prepared using the Og method Cu is found not only in the tetragonal ZrO2 lattice but also in the form of CuO particles on the zirconia surface. When these materials were tested for the hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) it was found that Me materials show no catalytic activity, whereas GVL was formed using Og catalysts. A reduction treatment of the Og catalysts prior to use resulted in a marked increase in the catalytic activity, however, no activity increase was observed when the Me material was exposed to a similar treatment before testing. Based on these results and characterization data, we conclude that the catalytically active component of Cu–ZrO2 catalysts for the hydrogenation of LA is reduced Cu particles dispersed on the catalyst surface with strong interaction with the Cu incorporated zirconia support, while the role of Cu in the zirconia lattice is to improve the adhesion of these particles and maintain their dispersion. [ABSTRACT FROM AUTHOR]

• Development of approach for effective CO 2 utilization via the reversible CO 2 -HCOOH cycle. • Pd-based alloys were screened for FA decomposition, and the PdNi alloy showed superior catalytic activity. • PdNi x alloy catalysts have superior selectivity for FA formation compared to Pd catalysts. A novel approach is required to achieve effective CO 2 utilization. This study demonstrates a new approach for the reversible reaction in the CO 2 -HCOOH cycle, that is, FA decomposition and CO 2 reduction, under ambient pressure using Pd-based alloy catalysts. First, Pd-based alloys (Pd-M; M = Co, Ni, and Zn) were screened for FA decomposition; the PdNi alloy showed superior catalytic activity compared to Pd and the other alloys. Second, Pd 3 Ni, PdNi, and PdNi 3 were prepared to understand the composition-dependent activity of the PdNi x series. DFT calculations provided insight into why the PdNi x alloys show higher catalytic activities for FA decomposition than Pd. Finally, the electrochemical CO 2 reduction reaction was investigated, and the PdNi x alloy catalysts showed superior selectivity for FA formation compared to Pd catalysts. Thus, this study provides a novel strategy for CO 2 utilization using bimetallic Pd-Ni heterogeneous catalysts. [ABSTRACT FROM AUTHOR]

The effects of several alkylammoniumcations on the synthesis oforthorhombic Mo3VO11.2complex oxides (MoVO)were investigated. First, we synthesized various alkylammonium isopolymolybdatesas precursors for the synthesis of MoVO. Methylammonium heptamolybdate,dimethylammonium trimolybdate, ethylammonium trimolybdate, and ethylenediammoniumtrimolybdate were obtained as pure materials in new crystalline structures.Orthorhombic MoVO complex oxides were synthesized under hydrothermalconditions when (CH3NH3)6Mo7O24and ((CH3)2NH2)2Mo3O10·H2O were used.It was found for the first case that methylammonium cations and dimethylammoniumcations were incorporated into the orthorhombic MoVO structure, formingcompounds of Mo32.3V7.7O112(CH3NH3)4.0·9.7H2O and Mo30.2V9.8O112((CH3)2NH2)2.5·8.5H2O, respectively.These alkylammonium cations play an important role as a stabilizerin the synthesis of MoVO and act as a structure-directing agent forthe orthorhombic phase. [ABSTRACT FROM AUTHOR]

(MeNH3)6Mo7O24 (I), (Me2NH2) 2Mo3O10·H2O (II), (Me3NH)2Mo3O10 (III), (Et-NH3)2Mo3O10 (IV), Pr-NH2(Pr-NH3)6Mo7O24 (V), (enH2)Mo3O10·H2O (VI), (NH3-CH2-CH (Me)-NH3)Mo3O10·H2O (VII), and (NH3- (CH2)3-NH3) Mo3O10·H2O (VIII) are obtained by evaporation of aqueous solutions containing MoO3 and the respective alkylamine. [ABSTRACT FROM AUTHOR]