Articles written in Journal of Chemical Sciences

    • Synthesis of well-ordered MCM-41 containing highly-dispersed NiO nanoparticles and efficient catalytic epoxidation of styrene


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      Well-ordered MCM-41 materials with different loadings of NiO were prepared combining hydrothermal method using cetyltrimethylammonia bromide as the structure-directing agent in an ammonia aqueous solution with calcination. A series of characterization of the resulting samples revealed that the materialsmaintained ordered mesostructure of MCM-41 after loading NiO and NiO nanoparticles were highly dispersed in the mesoporous wall and on the external surface of MCM-41. Characterization results also unveiled that Ni2+ prefer to enter the pores that formed by silicone gel during the hydrothermal reaction and incorporated into the pore wall and then formed NiO during the calcination process. And the TEM images indicated that smaller size NiO nanoparticles are easier to be formed on the MCM-41 materials. Catalytic results revealed that NiO should be the catalytic active centers for the oxidation of styrene and Ni-based materials showed the efficient catalytic property.

    • One-pot synthesis of bimetal MOFs as highly efficient catalysts for selective oxidation of styrene


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      A series of novel bimetallic organic framework materials (Cux-Coy-MOF) have been successfully prepared by a simple one-pot synthetic method, and their characters were evaluated via means of various techniques. The tested data showed a series of Cux-Coy-MOFs displayed good crystallinity and the doping of Co in original Cu-based framework would not change the morphology of the MOF catalysts. The catalytic activity of prepared materials was tested in the catalytic oxidation of styrene in the presence of TBHP. The effects of reaction time, reaction temperature and other reaction conditions on catalytic performance were systematically studied. The results revealed that the introduction of Co can improve the selectivity to form epoxides and reduce the yield of benzaldehyde without affecting the conversion rate of catalytic oxidation reaction of styrene. Excitingly, the Cu0.25-Co0.75-MOF showed better catalytic performance than Cu-MOF and Co-MOF under the optimal reaction conditions, the conversion rate of styrene reached 97.81%, and styrene oxide selectivity reached 83.04%, which indicated a significant synergistic effect of the Cu/Co bimetallic MOF. Furthermore, the Cu0.25-Co0.75-MOF catalyst exhibited good reusability that could be reused at least four times without significant inactivation

    • Modification of ZnCoPBA by different organic ligands and its application in the cycloaddition of CO2 and epoxides


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      Double metal cyanide (DMC) structures of Zn3[Co(CN)6]2 were modified by different organicligands and tested for their catalytic activity in the cycloaddition of CO2 and epoxides. ZnCoPBAs show anface-centred cubic structure with a high density of Lewis acidic Co(II)/Zn(II) metal sites and basic –CN–groups. The high crystallinity and excellent textural properties of the prepared ZnCoPBAs materials were confirmed by XRD and the N2 adsorption-desorption. We found the morphology and structure of ZnCoPBAs are related to the polarity of organic ligands. Through the analysis of morphology, crystallinity, specific surface area and pore size, explored the influence of different organic ligands on the catalytic performance of ZnCoPBAs. ZnCoPBA-TBA exhibited higher catalytic activity than other catalysts (ZnCoPBA-DMF,ZnCoPBA-MT, ZnCoPBA-ET). For a given catalyst weight, ZnCoPBA-TBA showed the best catalytic performance among the tested ZnCoPBAs, and the conversion rate of propylene oxide higher than 95% under relatively qualitative reaction conditions (2.0 MPa, 353 K).

      ZnCoPBAs show a face-centred cubic structure with a high density of Lewis acidic Co (II) /Zn (II) metal sites and basic -CN- groups. We successfully modified ZnCoPBAs with different organic ligands and their application in the cycloaddition of CO2 and epoxides.

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