Tungsten oxide supported on copper ferrite: a novel magnetic acid heterogeneous catalyst for biodiesel production from low quality feedstock

Catalytic conversion of residual raw material into biodiesel using a superior magnetic solid acid catalyst based on Zn-Fe ferrite: thermodynamic and kinetic studies

This study investigates the potential and applicability of a novel solid magnetic catalyst constructed by incorporating molybdenum oxide (MoO3) into zinc ferrite (ZnFe2O4) to biodiesel production using Waste Frying Oil (WFO) as the residual raw material. The molybdenum amounts (5, 15, 25, 35 and 45%) present in the catalyst were studied and the catalyst demonstrated great characteristics and high acid properties, as well as superior magnetic and catalytic attributes. The one variable at time (OVAT) optimization method revealed that the application of the MoO3/ZnFe2O4 catalyst resulted in obtaining a biodiesel with 97.6% ± 0.727 conversion to fatty acid methyl esters (FAME) under the following optimized reaction conditions: temperature of 165 °C, methanol : WFO molar ratio of 40 : 1, catalyst amount of 6 wt% and reaction time of 3 h. In addition, the catalyst showed high reusability after six reaction cycles, with conversion to esters above 90%. Besides, the activation energy (E a) calculated in the kinetic study was 25.3 kJ mol-1. Moreover, the properties of the synthesized biodiesel met the standards set by the ASTM D6751 and EN 14214, which indicates the high MoO3/ZnFe2O4 potential for industrial application with low energy consumption as well as minimal negative environmental impact.

Functionalized Biochar from the Amazonian Residual Biomass Murici Seed: An Effective and Low-Cost Basic Heterogeneous Catalyst for Biodiesel Synthesis

This study presents the synthesis of a basic heterogeneous catalyst based on sodium functionalized biochar. The murici biochar (BCAM) support used in the process was obtained through the pyrolysis of the murici seed (Byrsonimia crassifolia), followed by impregnation of the active phase in amounts that made it possible to obtain concentrations of 6, 9, 12, 15 and 18% of sodium in the final composition of the catalyst. The best-performing 15Na/BCAM catalyst was characterized by Elemental Composition (CHNS), Thermogravimetric Analysis (TG/DTG), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), and Energy Dispersion X-ray Spectroscopy (EDS). The catalyst 15Na/BCAM was applied under optimal reaction conditions: temperature of 75 °C, reaction time of 1.5 h, catalyst concentration of 5% (w/w) and MeOH:oil molar ratio of 20:1, resulting in a biodiesel with ester content of 97.20% ± 0.31 in the first reaction cycle, and maintenance of catalytic activity for five reaction cycles with ester content above 65%. Furthermore, the study demonstrated an effective catalyst regeneration process, with the synthesized biodiesels maintaining ester content above 75% for another five reaction cycles. Thus, the data indicate a promising alternative to low-cost residual raw materials for the synthesis of basic heterogeneous catalysts.

Preparation of core-shell catalyst for the tandem reaction of amino compounds with aldehydes

Heterogeneous noble metal-based catalysts with stable, precise structures and high catalytic performance are of great research interest for sustainable catalysis. In this article, we designed a novel core-shell catalyst, Pd@UiO-66-NH₂@mSiO₂, with Pd@UiO-66-NH₂ as the core and mesoporous SiO₂ (mSiO₂) as the shell. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) measurement results demonstrated that the obtained catalyst has an excellent core-shell structure. It can significantly prevent the aggregation of Pd nanoparticles (NPs), as well as the leaching of Pd NPs during the reaction process, owing to the protective effect of mSiO₂. During the tandem reaction of aniline and benzaldehyde to generate secondary amines, the prepared Pd@UiO-66-NH₂@mSiO₂ is highly efficient, due to the strong acid sites provided by UiO-66-NH₂ and the hydrogenation reduction sites provided by Pd NPs. Meanwhile, the Pd@UiO-66-NH₂@mSiO₂ with porous structure can also enhance the mass transfer of reactants to improve the reaction efficiency. Additionally, the prepared catalyst was used to catalyze the series reaction of amino compounds and aldehydes, and the results showed that just 5 mg of the catalyst can convert more than 99% of the reactants within 60 minutes in the presence of 1 atm H₂ at room temperature. Finally, the selectivity and stability of the as-prepared catalyst were also confirmed.