In the present study, metal-organic framework Cu-BTC-supported Sn (II)-substituted Keggin heteropoly nanocomposite (Sn 1.5 PW/Cu-BTC) was successfully prepared by a simple impregnation method and applied as a novel nanocatalyst for producing biodiesel from oleic acid (OA) through esterification. The nanocatalyst was characterized by Fourier transform infrared spectrometry (FTIR), wide-angle X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption-desorption, thermogravimetrics (TG), and NH 3-temperature-programmed desorption (NH 3-TPD). Accordingly, the synthesized nanocatalyst with a Sn 1.5 PW/Cu-BTC weight ratio of 1 exhibited a relatively large specific surface area, appropriate pore size, and high acidity. Moreover, an OA conversion of 87.7% was achieved under optimum reaction conditions. The nanocatalyst was reused seven times, and the OA conversion remained at more than 80% after three uses. Kinetic study showed that the esterification reaction followed first-order kinetics, and the activation energy (E a) was calculated to be 38.3 kJ/mol.
The
influence of the packing size on the mean bubble diameter in a flooded
bed reactor packed with glass spheres of three different diameters
(1.9, 4.0, and 9.3 mm) was investigated. The gas saturation and interfacial
area were respectively measured by electrical capacitance tomography
and chemical absorption of oxygen. It is observed that the presence
of packing has greatly reduced the bubble diameter and increased the
gas saturation compared with a bubble column. To explore the underlying
relationship between the bubble diameter and packing size, the packing
size featured by the pore diameter was utilized as a reference. It
shows that the bubble diameter is 2–3 times the pore for the
1.9 and 4.0 mm packings, while they are approached for the packing
of 9.3 mm. An empirical correlation was proposed for the mean bubble
diameter prediction with a discrepancy of less than 25% from the measurements.
AbstractNickel salts of Keggin-type heteropolyacid on Zr(IV)-based metal-organic frameworks (UiO-66) has been synthesized via ion-exchange followed by a facile one-pot hydrothermal method. The synthesized catalysts underwent FT-IR, N2 adsorption-desorption, powder XRD, SEM and TEM analysis. The NiHSiW/UiO-66 catalyst was used as a new and effective solid acid in the catalytic transfer free fatty acid to biodiesel with an optimum conversion of 86.7%. The excellent activity of the NiHSiW/UiO-66 nanocatalyst was closely related to its high specific surface area, nano-sized catalyst, and the synergistic effects of NiHSiW salts and UiO-66 matrix. Importantly, a relatively stable catalytic performance was achieved for 8 repeated cycles. Finally, kinetics of the esterification reaction have been assumed to be of pseudo first order.
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