5 research outputs found

    CATALYTIC ACTIVITY AND COKING RESISTANCE ON HYDROXYAPATITE FOR THE OXIDATIVE DEHYDROGENATION OF ISOBUTANE

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    Hydroxyapatite (HAp) samples were prepared from precursor solutions with different Ca/P molar ratios. The HAp samples were utilized as catalysts for the oxidative dehydrogenation (ODH) of isobutane. Also, the HAp samples were characterized by N2 and H2O adsorption-desorption measurements, X-ray diffraction, inductively coupled plasma optical emission spectrometry, thermogravimetry-differential thermal analyses, and temperature-programmed oxidation (TPO). The Ca/P molar ratio of the precursor solution had a major influence on the catalytic activity and coking resistance ability. The HAp catalyst prepared from the stoichiometric precursor solution [HAp (1.67)] showed the highest isobutene yield. Furthermore, the white color of HAp (1.67) remained unchanged during the ODH of isobutene, indicating the absence of coke on the surface of HAp (1.67) after the reaction and its higher coking resistance ability. The results of the TPO measurements showed that the HAp (1.67) catalyst possesses the strongest oxidation ability which is likely related to its higher coking resistance ability

    Immobilization of Cu Complex into Zr-Based MOF with Bipyridine Units for Heterogeneous Selective Oxidation

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    A catalytically competent Cu species has been immobilized within the framework of a Zr-based metal–organic framework with bipyridine units, Zr-MOF-bpy, by a simple postsynthetic modification method from CuBr<sub>2</sub> (Zr-MOF-bpy-CuBr<sub>2</sub>) and used for the selective oxidation of cyclooctene to cyclooctene oxide. Zr-MOF-bpy was synthesized by a simple solvothermal method and was shown to have a UiO-type structure. Diffuse reflectance UV–vis and XAFS measurements have revealed that the immobilized Cu species has a square-planar geometry of two N atoms and two Br atoms. Zr-MOF-bpy-CuBr<sub>2</sub> catalyzed the selective oxidation of cyclooctene to cyclooctene oxide with high activity and selectivity in the presence of <i>tert</i>-butyl hydroperoxide as an oxidant. In addition, the catalytic ability of Zr-MOF-bpy-CuBr<sub>2</sub> was demonstrated to be superior to that of the corresponding homogeneous catalyst ((bpy)­CuBr<sub>2</sub>). It was also confirmed that Zr-MOF-bpy-CuBr<sub>2</sub> can be reused as a heterogeneous catalyst without significant loss of its activity and selectivity
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