5 research outputs found
CATALYTIC ACTIVITY AND COKING RESISTANCE ON HYDROXYAPATITE FOR THE OXIDATIVE DEHYDROGENATION OF ISOBUTANE
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
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