Study on the preparation and n-heptane isomerization performance of MoOx-Pd/Ce-MCM-48 catalyst

A Ce-MCM-48 molecular sieve was prepared by the hydrothermal synthesis method. Using Ce-MCM-48 as the support, a series of MoOx Pd/Ce-M catalysts were prepared by the impregnation method by introducing MoOx and Pd. XRD, N2 adsorption desorption, SEM, TEM, NH3-TPD, Py-IR, FT-IR, and ICP-MS were used to characterize the physicochemical properties. The performance of n-heptane isomerization in a micro fixed bed device was evaluated. The results showed that the synthesized Ce-MCM-48 was mesoporous, with a spherical particle morphology, a long-range ordered pore structure, weakly acidic sites on the surface, and an increase of B and L acids. The 2% MoOx-Pd/Ce-M catalyst was used for the probe reaction of n-heptane hydroisomerization; when the reduction temperature was 400 °C, the reduction time was 2 hours, the reaction temperature was 300 °C, the WHSV was 7.6 h-1, the conversion rate was 58.7%, the selectivity was 91.2%, and the maximum yield was 53.5%. The product distribution of multiple C7 isomers increased the selectivity of multi branched isoheptane. The addition of an appropriate amount of MoOx would improve the performance of n-heptane isomerization.

Polyoxometalate-based CuII/CoII complexes tuned using various metal–pyrazole loops: design, diverse architectures and catalytic activity toward the oxidation of thioether derivatives

Three new polyoxometalate-based complexes with unique metal–pyrazole loops were synthesized, showing various architectures and finally resulting in different catalysis performance.

Carbazole-based bis-imidazole ligand-involved synthesis of inorganic–organic hybrid polyoxometalates as electrochemical sensors for detecting bromate and efficient catalysts for selective oxidation of thioether

Considering the potential application on preparing electrode and catalyst materials of inorganic–organic hybrid polyoxometalates, a bis-imidazole ligand with carbazole as a connector, 3,6-di(1H-imidazol-1-yl)-9H-carbazole (L), was used for preparing inorganic–organic hybrid polyoxometalates. As a result, three complexes formulated by [NiL₂(Mo₂O₇)] (1), [Cu(H₂O)₂(HL)₂ (β-Mo₈O₂₆)]·H₂O (2) and [Ni₂(H₂O)₄L₂ (CrMo₆(OH)₅O₁₉)]·6H₂O (3) were obtained successfully. Structural analysis indicated that the different polyoxoanions and metal ions showed important influences on the formation of structures. In the presence of Ni²⁺ ions and heptamolybdate, a 2D network constructed from Ni²⁺ ions and L ligands was formed in complex 1, in which the [Mo₄O₁₄]⁴⁻ polyoxoanions were encapsulated. But the use of Cu²⁺ ions led to a 1D chain of complex 2, which was composed of [β-Mo₈O₂₆]⁴⁻ polyoxoanions and mononuclear {CuL₂} units. By utilizing [CrMo₆(OH)₅O₁₉]⁴⁻ as the inorganic building block, complex 3 showed a 2D (4, 4)-connected layer. Complexes 1–3 could be employed as electrode materials for sensing bromate with the limits of detection of 0.315 μM for 1, 0.098 μM for 2 and 0.551 μM for 3. Moreover, these complexes showed efficient catalytic activity for the selective oxidation of thioethers.

Three inorganic–organic hybrid polyoxometalates were prepared using a bis-imidazole ligand featuring carbazole as a connector, exhibiting not only diverse structures, but also good electrochemical sensing activities for bromate, as well as efficient catalytic performances for oxidation of thioether.

α-γ-Type [Mo8O26]4--Containing Metal-Organic Complex Possessing Efficient Catalytic Activity toward the Oxidation of Thioether Derivatives

In this work, a new α-γ-type [Mo₈O₂₆]^4- anion was first synthesized and characterized by single-crystal X-ray diffraction analysis and was obtained by introducing molybdate to the synthesis of metal-organic complex (MOC) under hydrothermal conditions. An octamolybdate-based MOC, namely, {[Cu₈(H₂O)₆](dpyh)₄(α-γ-Mo₈O₂₆) }·(β-Mo₈O₂₆)·8.5H₂O (H₂dpyh = N,N-bis(3-pyrazolamide)-1,2-hexahydrobenzene), was obtained. The α-γ-type [Mo₈O₂₆]^4- anion was composed of four MoO₆ octahedra and four MoO₅ trigonal bipyramids by sharing their edges and corners. The title complex exhibited a 1D structure in which an α-γ-type [Mo₈O₂₆]^4- anion was connected with [Cu₄(dpyh)₂] units in a staggered manner. Under optimized conditions, complex 1 as the catalyst can achieve a highly efficient conversion (more than 99%) of thioanisole within 30 min and above 99% selectivity toward sulfoxide. Furthermore, efficient catalytic oxidation of thioether derivatives was also performed with 1 as the catalyst. In addition, the stable electrochemical sensing performance and adsorption capacity toward organic dyes were tested.

Multifunctional photoelectric sensors and catalysts for CO2RR and Cr(vi) solution based on a series of POM-based materials

A series of POM-based materials can be used as photoelectric sensors and have high catalytic activities for CO₂RR and the reduction of Cr(vi) solution, which are significant for environmental protection and energy shortage.

Different Anderson-type polyoxometalate-based metal–organic complexes exhibiting –OH group-directed structures and electrochemical sensing performance

Four new Anderson-type polyoxometalate (POM)-based metal–organic complexes were hydrothermally synthesized and the –OH groups in POMs have significant effects on their structures and electrochemical performance.

Crystal structure of poly[bis(μ2-1,4-di(1H-imidazol-1-yl)benzene-κ2 N:N′)-(μ2-tetraoxidomolybdato(VI)-κ2 O:O′)cobalt(II)], C24H20N8O4MoCo

C24H20N8O4MoCo, monoclinic, C2/c (no. 15), a = 19.3535(7) Å, b = 10.0870(4) Å, c = 12.4174(5) Å, β = 97.3700(10)°, V = 2404.08(16) Å3, Z = 4, R gt(F) = 0.0218, wR ref(F 2) = 0.0577, T = 298(2) K.

Two rare {M2(MoO4)2} n chain-containing molybdate-based metal-organic complexes with a bis-pyrazole-bis-amide ligand: fluorescent sensing and photocatalysis performance

By introducing a bis-pyrazole-bis-amide ligand, N,N'-bis(1H-pyrazole-4-carboxamide)-1,4-benzene (L), two molybdate-based metal-organic complexes containing {M2(MoO4)2} n (M = Co, Zn), [Co2L2(MoO4)2]·H2O (1), [Zn2L2(MoO4)2]·H2O (2), have been prepared under hydrothermal/solvothermal conditions. X-ray diffraction analyses reveal that both 1 and 2 are isostructural. An interesting structural feature is that a kind of {M2(MoO4)2} n chain could be found in 1 and 2, although different raw materials [Mo7O24]6- and [PMo12O40]3- anions were utilized. Then these chains are further linked by L ligands into a two dimensional (2D) structure. The title complexes represent the first examples containing {MoO4} units and pyrazole-/or amide-derivative ligands. Complexes 1 and 2 exhibit distinct performances due to different metal centers, with 2 acting as a fluorescent sensor for Fe3+, MnO4 -, CrO4 2- and Cr2O7 2-, but 1 being a better photocatalyst towards degradation of cationic dyes methylene blue (MB) and neutral red (NR).

Solvent-Assisted Modification to Enhance Proton Conductivity and Water Stability in Metal Phosphonates

Although proton-conductive metal phosphonates with well-defined structure offer a favorable platform for exploring their structure-property relationship, investigating of the synergic effect of phosphonate groups and functional moieties on proton conduction is rare. In this work, we have synthesized two new copper phosphonates, [Cu(4-cppH)(4,4'-bipy)(H₂O)₃] (FJU-80) and [Cu(4-cppH)(4,4'-bipy)]·H₂O·DMF (FJU-81), by the method of solvent-assisted modification, giving a 1D metal coordination polymer and a 3D metal open framework, respectively. Single-crystal X-ray diffraction shows that FJU-80 is full of hydrogen-bonding sites contributed from the improved synergic effect of phosphonate groups, carboxylate groups, and coordinated water molecules, thereby facilitating continuous hydrogen-bonding networks, whereas FJU-81 only has discrete hydrogen-bonding fragments. Powder X-ray diffraction and impedance analyses confirm that FJU-80 possesses higher water stability as well as improved proton conductivity, indicating that solvent-assisted modification is effective in increasing the hydrogen-bonding sites from phosphonate groups and functional moieties and then realizing facile proton transfer.

Four octamolybdate complexes constructed from a quinoline–imidazole–monoamide ligand: structures and electrochemical, photocatalytic and magnetic properties

Four octamolybdate-based complexes synthesized by employing N-(quinoline-5-yl)-1H-imidazole-4-carboxamide as a ligand exhibit excellent electrocatalytic activities, photocatalytic properties and antiferromagnetic behavior.