Facile Preparation of Bimetallic MOF-derived Supported Tungstophosphoric Acid Composites for Biodiesel Production

In this work, the novel TPA@C-NiZr-MOF catalyst is synthesized by the impregnation of tungstophosphoric acid (TPA) on the NiZr-based metal-organic framework (NiZr-MOF) followed by calcination up to 300 °C. The as-prepared catalyst materials were structurally, morphologically, and texturally characterized by XRD, FTIR, temperature programmed desorption of NH3 ( TPD-NH3 ), N2 physisorption, SEM, TEM, and XPS. The prepared catalyst can be used as an efficient heterogeneous catalyst for biodiesel production from oleic acid (OA) with methanol. The results indicated that, in comparison to TPA@NiZr-MOF, the TPA@C-NiZr-MOF catalyst calcined at 300 °C exhibits excellent catalytic performance probably owing to the synergistic effect between TPA and metal oxide skeletons, high acidity, as well as larger surface area and pore size. Additionally, the TPA@C-NiZr-MOF catalyst can be reused in up to six cycles with an acceptable conversion. This study showed that the bimetallic MOF-derived composite materials can be used as an alternative potential heterogeneous catalyst toward biorefinery applications

Immobilizing Ni (II)-Exchanged Heteropolyacids on Silica as Catalysts for Acid-Catalyzed Esterification Reactions

Biodiesel was synthesized from oleic acid using Ni (II)-exchanged heteropolyacids immobilized on silica (Ni0.5H3SiW / SiO2 ) as a solid acid catalyst. Based on detailed analyses of FT-IR, XRD, TG and SEM, the structural, surface and thermal stability of Ni0.5H3SiW / SiO2 were investigated. Obtained results demonstrated that the Keggin structure was well in the immobilization process and possess a high thermal stability. Various esterification reaction conditions and reusability of catalyst were studied. High oleic acid conversion of 81.4 % was observed at a 1:22 mole ratio (oleic acid: methanol), 3 wt. % catalyst at 70 °C for 4 h. The Ni0.5H3SiW / SiO2 catalyst was reused for several times and presented relatively stable. More interestingly, the kinetic studies revealed the esterification process was compatible with the first order model, and a lower activation energy was obtained in this catalytic system

Bis(μ-4-amino-3,5-dimethyl-4H-1,2,4-triazole)bis­[diiodidozinc(II)]

In the title compound, [Zn2I4(C4H8N4)2], the ZnII atom is coordinated in a distorted tetra­hedral geometry by two N atoms from the triazole rings of two 4-amino-3,5-dimethyl-4H-1,2,4-triazole (admt) ligands and two iodide ligands. Doubly bridging admt ligands connect two ZnII atoms, forming a centrosymmetric dimer. Weak N—H⋯I and C—H⋯I hydrogen bonds play an important role in the inter­molecular packing

A dimeric zinc(II) complex: bis­[μ-1,2-bis­(1,2,4-triazol-4-yl)ethane-κ2 N 1:N 1′]bis­[dinitritozinc(II)]

The coordination geometry of the ZnII atom in the title complex, [Zn2(NO2)4(C6H8N6)2], is distorted octa­hedral, in which the ZnII atom is coordinated by two N atoms from the triazole rings of two symmetry-related 1,2-bis­(1,2,4-triazol-4-yl)ethane ligands and four O atoms from two nitrite ligands. Two ZnII atoms are bridged by two organic ligands, forming a centrosymmetric dimer. Weak C—H⋯N and C—H⋯O hydrogen bonds play an important role in the inter­molecular packing