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Pharmacosiderite Mo 4 P 3 O 16 (Pharma-MoPO) consists of [Mo 4 O 4 ] cubane unit and [PO 4 ] tetrahedral to form an open framework with a microporous structure similar to that of LTA-type zeolite. Although attractive applications are expected due to its microporous structure and redox-active components, its physicochemical properties have been poorly investigated due to the specificity of its synthesis, which requires a high hydrothermal synthesis temperature of 360 °C. In this study, we succeeded in synthesizing Pharma-MoPO by hydrothermal synthesis at 230 °C, which can be applied using a commercially available autoclave by changing the metal source. Through the study of the solids and liquids obtained after hydrothermal syntheses, the formation process of Pharma-MoPO under our studied synthesis conditions was proposed. Advanced characterizations provided detailed structural information on Pharma-MoPO, including the location site of a countercation NH 4 + . Pharma-MoPO could adsorb CO 2 with the amount close to the number of cages without removing NH 4 + . Pharma-MoPO exhibited stable catalytic activity for the hydrodesulfurization of thiophene while maintaining its crystal structure, except for the introduction of sulfide by replacing lattice oxygens. Pharmacosiderite Mo 4 P 3 O 16 was successfully obtained by hydrothermal synthesis at a moderate temperature, and its microporosity for CO 2 adsorption and catalytic properties for hydrodesulfurization were discovered.

Molybdenum oxides are widely used in various fields due to their electronic and structural characteristics. These materials can generate lattice oxygen defects by reduction treatments, which sometimes play central roles in various applications. However, little has been understood about their properties since it is difficult to increase the amount of lattice oxygen defects due to the crystal structure changes in most cases. Here, we report a new class of high-dimensionally structured Mo oxide (HDS-MoO x ) constructed by the random assembly of {Mo 6 O 21 } 6- pentagonal units (PUs). Since the PU is a stable structural unit, the structural network based on the PU hardly caused structural changes to make the lattice oxygen defects vanish. Consequently, HDS-MoO x could generate a substantial amount of lattice oxygen defects, and their amount was controllable, at least in the range of MoO 2.64 -MoO 3.00 . HDS-MoO x was more redox active than typical Mo oxide (α-MoO 3 ) and demonstrated an oxidation ability for gas-phase isopropanol oxidation under the reaction conditions, whereas α-MoO 3 affords no oxidation products.

Mo was successfully introduced into a vanadotungstate (VT-1), which is a crystalline microporous zeolitic transition-metal oxide based on cubane clusters [W 4 O 16 ] 8- and VO 2+ linkers (Mo x W 4- x . x : number of Mo in VT-1 unit cell determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES)). It was confirmed that W in the cubane units was substituted by Mo. The resulting materials showed higher microporosity compared with VT-1. The surface area and the micropore volume increased to 296 m 2 ·g -1 and 0.097 cm 3 ·g -1 , respectively, for Mo 0.6 W 3.4 compared with the those values for VT-1 (249 m 2 ·g -1 and 0.078 cm 3 ·g -1 , respectively). The introduction of Mo changed the acid properties including the acid amount (VT-1: 1.06 mmol g -1 , Mo 0.6 W 3.4 : 2.18 mmol·g -1 ) and its strength because of the changes of the chemical bonding in the framework structure. Mo x W 4- x showed substantial catalytic activity for the selective catalytic reduction of NO with NH 3 (NH 3 -selective catalytic reduction (SCR)) at a temperature as low as 150 °C.

High-dimensionally structured Mo-Fe oxide (HDS-MoFeO) was synthesized through an assembly of structural units supplied from Keplerate-type polyoxometalate, {Mo 72 Fe 30 }, under an appropriate hydrothermal condition. HDS-MoFeO showed excellent catalytic activity for the selective oxidation of methanol with slightly lower selectivity for formaldehyde than that of a conventional Mo-Fe oxide catalyst.

Orthorhombic Mo-V oxide is one of the most active solid-state catalysts for selective oxidation of alkane, and revealing its detailed structure is important for understanding reaction mechanisms and for the design of better catalysts. We report the single-crystal X-ray structure analysis of orthorhombic Mo-V oxide heated under a N 2 flow; V is present in 6-membered rings with partial occupancy, similar to the structure reported by Trunschke's group for orthorhombic Mo-V oxide heated under an Ar flow (Trunschke, ACS Catal.2017, 7, 3061). Our previous paper (Ishikawa, J. Phys. Chem. C, 2015, 119, 7195) reported that V is not present in the 6-membered rings when orthorhombic Mo-V oxide is calcined in the presence of oxygen. Furthermore, Trunschke's paper reported that V in the 6-membered rings moves to the surface of the crystals under oxidation reaction conditions in the presence of H 2 O. Our present results provide additional evidence for V migration in the 6-membered rings during heat treatment. We also report the differences in the thermal behaviors, ultraviolet-visible absorptions, N 2 isotherms, and elemental analysis results of Mo-V oxide heated in air and under a N 2 flow. Furthermore, we report the solid-state transformation of orthorhombic Mo-V oxide to tetragonal Mo-V oxide by controlled heat treatment., Competing Interests: The authors declare no competing financial interest.

The development of cathode-active material of Li battery is important for the current emerging energy transferring and saving problems. A stable crystalline microporous complex metal oxide based on Mo, V, and Bi is an active and suitable material for Li battery. High capacity (380 Ah/kg) and stable cycle performance are achieved. X-ray absorption near-edge structure analyses demonstrate that the original Mo 6+ and V 4+ ions are reduced to Mo 4+ and V 3+ in the discharging process, respectively, which results in a 70-electron reduction per formula. The reduced metal ions can be reoxidized reversibly in the next charging process. Furthermore, extended X-ray absorption fine structure analyses reveal that the Mo-O bonds in the material are lengthened in the discharging process probably due to interaction with Li + without change of the basic structure.

We describe the preparation of ε-Keggin-type cobaltomolybdate-based 3D frameworks with sodium cations, NaH 9 [ε-Co II Mo V 8 Mo VI 4 O 40 Co II 2 ], and their characterization by high-resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and X-ray absorption fine structure (XAFS) spectroscopy. Atomic-scale HAADF-STEM images of ε-Keggin compounds were obtained for the first time, and positions of Mo and Co were confirmed. Furthermore, clear evidence of the presence of a CoO 4 tetrahedron was obtained by X-ray absorption near-edge structure (XANES) analysis. Their characterization clearly revealed that ε-Keggin-type cobaltomolybdate units, [ε-CoMo 12 O 40 ] n- , constructed by a central Co II O 4 tetrahedron and 12 surrounding MoO 6 octahedra, are linked with Co II to form 3D frameworks.

Two new ε-Keggin-type polyoxometalate-based 3D frameworks, Na1.5H11.4[ε-Zn(II)Mo(V)10.9Mo(VI)1.1O40{Zn(II)}2] and (NH4)2.1H7.5[ε-Mn(II)0.2Mo(V)6Mo(VI)6O40{Mn(II)}2], are prepared, and their structures are determined by powder X-ray diffraction, Fourier transform infrared, Raman spectroscopy, and elemental analysis. ε-Keggin-type polyoxomolybdate units, [ε-ZnMo12O40] and [ε-Mn0.2Mo12O40], are linked with Zn(2+) and Mn(2+), respectively, in a tetrahedral fashion to form 3D frameworks. They show zeolite-like ion-exchange properties and redox properties. The ε-Keggin-based 3D framework shows high chemical composition diversity and can incorporate different elements in the framework.

A new type of polyoxometalate-based porous material was successfully synthesized. The new material is the first fully inorganic Keggin-type polyoxometalate-based microporous material with intrinsically ordered open micropores and is the third member of the small family of octahedral molecular sieves (OMSs). Twelve MoO6 or VO6 octahedra surround a central VO4 tetrahedron to form ε-Keggin polyoxometalate building blocks (ε-VMo9.4V2.6O40) that are linked by Bi(III) ions to form crystalline Mo-V-Bi oxide with a diamondoid topology. The presence of a tetrahedral shape of the ε-Keggin polyoxometalate building block results in arrangement of microporosity in a tetrahedral fashion which is new in OMSs. Owing to its microporosity, this Mo-V-Bi oxide shows zeolitic-like properties such as ion-exchange and molecule adsorption.

We demonstrate that the glass-transition temperature (T(g)) of a polymer sphere template is a crucial factor in the production of three-dimensionally ordered macroporous (3DOM) materials. Metal nitrate dissolved in ethylene glycol-methanol was infiltrated into the void of a face-centered, close-packed colloidal crystal of poly(methyl methacrylate) (PMMA)-based spheres. The metal nitrate reacts with EG to form a metal oxalate (or metal glycoxylate) solid (nitrate oxidation) in the void of the template when the metal nitrate-EG-PMMA composite is heated. Further heating converts metal oxalate to metal oxide and removes PMMA to form 3DOM materials. We investigated the effect of T(g) of PMMA templates and obtained clear evidence that the solidification temperature of the metal precursor solution (i.e., nitration oxidation temperature) should be lower than the T(g) of the polymer spheres to obtain a well-ordered 3DOM structure.

CH3OH temperature programmed surface reaction (TPSR) spectroscopy was employed to determine the chemical nature of active surface sites for bulk mixed metal oxide catalysts. The CH3OH-TPSR spectra peak temperature, Tp, for model supported metal oxides and bulk, pure metal oxides was found to be sensitive to the specific surface metal oxide as well as its oxidation state. The catalytic activity of the surface metal oxide sites was found to decrease upon reduction of these sites and the most active surface sites were the fully oxidized surface cations. The surface V5+ sites were found to be more active than the surface Mo6+ sites, which in turn were significantly more active than the surface Nb5+ and Te4+ sites. Furthermore, the reaction products formed also reflected the chemical nature of surface active sites. Surface redox sites are able to liberate oxygen and yield H2CO, while surface acidic sites are not able to liberate oxygen, contain either H+ or oxygen vacancies, and produce CH3OCH3. Surface V5+, Mo6+, and Te4+ sites behave as redox sites, and surface Nb5+ sites are Lewis acid sites. This experimental information was used to determine the chemical nature of the different surface cations in bulk Mo-V-Te-Nb-Ox mixed oxide catalysts (Mo(0.6)V(1.5)Ox, Mo(1.0)V(0.5)Te(0.16)Ox, Mo(1.0)V(0.3)Te(0.16)Nb(0.12)Ox). The bulk Mo(0.6)V(1.5)Ox and Mo(1.0)V(0.5)Te(0.16)Ox mixed oxide catalytic characteristics were dominated by the catalytic properties of the surface V5+ redox sites. The surface enrichment of these bulk mixed oxide by surface V5+ is related to its high mobility, V5+ possesses the lowest Tammann temperature among the different oxide cations, and the lower surface free energy associated with the surface termination of V=O bonds. The quaternary bulk Mo(1.0)V(0.3)Te(0.16)Nb(0.12)Ox mixed oxide possessed both surface redox and acidic sites. The surface redox sites reflect the characteristics of surface V5+ and the surface acidic sites reflect the properties normally associated with supported Mo6+. The major roles of Nb5+ and Te4+ appear to be that of ligand promoters for the more active surface V and Mo sites. These reactivity trends for CH3OH ODH parallel the reactivity trends of propane ODH because of their similar rate-determining step involving cleavage of a C-H bond. This novel CH3OH-TPSR spectroscopic method is a universal method that has also been successfully applied to other bulk mixed metal oxide systems to determine the chemical nature of the active surface sites.