Design and synthesis of Fe3O4@SiO2@KIT-6@DTZ-Pd0 as a new and efficient mesoporous magnetic catalyst in carbon–carbon cross-coupling reactions

In this paper, a new type of mesoporous material based on KIT-6 has been introduced. In this aim, magnetic Fe3O4 nanoparticles and mesoporous silica KIT-6 have been combined to obtain mesoporous MNPs. The prepared magnetic mesoporous catalyst has been applied in different carbon–carbon cross-coupling reactions including Mizoroki–Heck, Suzuki–Miyaura, and Stille reactions. This magnetic mesoporous compound is characterized by various techniques including FT-IR, BET, VSM, SEM, XRD, and TGA.

Synthesis of Magnetic Catalyst Derived from Oil Palm Empty Fruit Bunch for Esterification of Oleic Acid: An Optimization Study

Biomass, renewable, abundantly available and a good source of energy. The conversion of biomass waste into valuable products has received wide attention. In this study, an empty fruit bunch (oil palm EFB) supported magnetic acid catalyst for esterification reaction was successfully prepared via the one-step impregnation process. The new magnetic catalyst achieved a higher surface area of 188.87 m2/g with a total acidity of 2.4 mmol/g and identified iron oxide as g-Fe2O3. The magnetization value of 24.97 emu/g demonstrated that the superparamagnetic catalyst could be easily recovered and separated after the reaction using an external magnet. The catalytic performance of oil palm EFB supported magnetic acid catalyst was examined by esterification of oleic acid. Esterification process parameters were optimized via Response Surface Methodology (RSM) optimization tool with Box-Behnken design (BBD). The following optimum parameters were determined: an amount of 9 wt% catalyst, molar ratio of methanol to oleic acid of 12:1, reaction time of 2 h and reaction temperature of 60 °C with a maximum conversion of 94.91% was achieved. The catalyst can be recycled up to five cycles with minimal loss in its activity. The oil palm waste-based magnetic acid catalyst indicates its potential replacement to the existing solid catalysts that are economical and environmentally friendly for the esterification process in biofuel applications. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Glycerol Esterification for Triacetin Production using Fe3O4@SiO2@PO43- as Heterogeneous Magnetic Catalyst

To facilitate the magnetic separation, phosphate group is embedded onto silica-coated Fe3O4 magnetic nanoparticles to prepare Fe3O4@SiO2@PO43− solid catalyst for the glycerol esterification with acetic acid. The catalyst was characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating magnetic spectroscopy (VSM) and Fourier Transform Infrared (FTIR) spectroscopy. The Fe3O4@SiO2@PO43− magnetic catalyst during the glycerol esterification with acetic acid was found to demonstrate excellent glycerol conversion levels (97 %) while retaining 92 % triacetin selectivity. The plausible mechanism of glycerol esterification suggests the initiation of the reaction by the protonation of the acetic acid. The catalyst was recovered from the reaction mixture under the influence of external magnetic field and reused during 4 consecutive reaction cycles.

A new nanomagnetic Pd-Co bimetallic alloy as catalyst in the Mizoroki–Heck and Buchwald–Hartwig amination reactions in aqueous media

A Pd-Co bimetallic alloy encapsulated in melamine-based dendrimer supported on magnetic nanoparticles denoted as γ-Fe2O3@MBD/Pd-Co was synthesized by a facile co-complexation-reduction method and characterized sufficiently. The catalytic evaluation of γ-Fe2O3@MBD/Pd-Co showed promising results in the Mizoroki–Heck and Buchwald–Hartwig amination reactions of various iodo-, bromo- and challenging chloroarenes in aqueous media. The synergetic cooperative effect of both Pd and Co and dispersion of the catalyst in water due to the encapsulation of γ-Fe2O3 by melamine-based dendrimer lead to high catalytic performance compared with the monometallic counterparts. The dispersion of the magnetic catalyst also facilitates the recovery and reuse of the catalyst by ten consecutive extraction and final magnetic isolation with no loss of catalytic activity, keeping its structure unaltered.