Enhancement of biodiesel production via sequential esterification/transesterification over solid superacidic and superbasic catalysts

Synthesis of Carbide Lime Waste Derived Base Catalyst (KF/CLW-Fe3O4) for Methyl Ester Production: An Optimization Study

In this paper, solid base catalyst KF/CLW-Fe3O4 was prepared from carbide lime waste, primarily calcium hydroxide with tiny amounts of carbonate and; the catalyst was used in the optimization study on the methyl ester production. The new strong base catalyst was synthesized by chemical impregnation. This catalyst was characterized by Hammett indicator analysis, Brunauer, Emmett, and Teller (BET), scanning electron microscope (SEM), X-ray diffraction (XRD) and temperature-programmed desorption (TPD) of carbon dioxide. The catalyst was further used to catalyzed the transesterification reaction to produce methyl ester. Taguchi method was used to assess the impact of catalyst at different intervals of reaction parameters, including reaction time, methanol to oil ratio, and catalyst loading. A mixed level of orthogonal array design with L9, analysis of variance (ANOVA) and signal to noise ratio were used to determine parameters that significantly impact the palm oil transesterification reaction. High methyl ester conversion was attained, and the catalyst can be easily separated and reused. KF/CLW-Fe3O4 has great potential to be used to produce methyl ester because of its high catalytic activity and environmental friendliness. 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). 

Synthesis of Magnetic Base Catalyst from Industrial Waste for Transesterification of Palm Oil

Industrial waste is produced in large amounts annually; without proper planning, the waste might cause a serious threat to the environment. Hence, an industrial waste-based heterogeneous magnetic catalyst was synthesized using carbide lime waste (CLW) as raw material for biodiesel production via transesterification of palm oil. The catalyst was successfully synthesized by the one-step impregnation method and calcination at 600 °C. The synthesized catalyst, C-CLW/g-Fe2O3, was characterized by temperature-programmed desorption of carbon dioxide (CO2-TPD), scanning electron microscopy (SEM), electron dispersive X-ray spectroscopy (EDX), X-ray Diffraction (XRD), Brunauer-Emmett-Teller (BET), vibrating sample magnetometer (VSM), and Fourier transform infrared spectroscopy (FT-IR). The catalyst has a specific surface area of 18.54 m2/g and high basicity of 3,637.20 µmol/g. The catalytic performance shows that the optimum reaction conditions are 6 wt% catalyst loading, 12:1 methanol to oil molar ratio with the reaction time of 3 h at 60 °C to produce 90.5% biodiesel yield. The catalyst exhibits good catalytic activity and magnetism, indicating that the CLW can be a potential raw material for catalyst preparation and application in the biodiesel industry. 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). 

Silica Coating of Metal-Loaded H-ZSM-22 to Form the Core-Shell Nanostructures: Characterization, Textural Properties, and Catalytic Potency in the Esterification of Oleic Acid

In this study, ZSM-22 was synthesized using N,N-diethylaniline as a template through a hydrothermal method. The proton and various metals such as zirconium, strontium, and iron were immobilized on the surface of obtained zeolites through the ion exchange method. The catalysts were studied by Fourier-Transform Infrared Spectroscopy (FT-IR), X-Ray Diffraction (XRD), Brunauer–Emmett–Teller (BET) adsorption isotherms, Transmission Electron Microscope (TEM), Scanning Electron Microscope (SEM), Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) elemental analysis, and Temperature-Programmed Desorption of ammonia (TPD-NH3) technique for determining the number of acid sites. In the esterification reaction of oleic acid, the operating conditions such as catalyst dosage, temperature, molar ratio of methanol to oil, and reaction time were optimized and adjusted at 11 wt%, 70°C, 10 : 1, and 48 h subsequently. The maximum yield% of 48.07% was achieved in the presence of Zr-H-ZSM-22 at optimum conditions. In order to improve the efficiency of three zeolites Zr-H-ZSM-22, Fe-H-ZSM-22, and Sr-H-ZSM-22, the core-shell structures with SiO2 coating were prepared. Zr-H-ZSM-22@SiO2 was less active than Zr-H-ZSM-22 due to the SiO2 coverage of Lewis active sites.

Biodiesel Production from Waste Cooking Oil Catalyzed by a Bifunctional Catalyst

The objective of this study was to prepare bifunctional catalysts based on iron and CaO and test them in the biodiesel production using waste cooking oil (WCO) as feedstock. Two iron precursors were studied, Fe₂O₃ and Fe(NO₃)₃·9H₂O. The identified crystalline phases were Ca₂Fe₂O₅ and CaFeO₃. Surface morphology and textural properties (distribution of active species, specific surface area, size, and pore volume) were also analyzed. Additionally, thermal stability was studied and 800 °C was established as the optimum calcination temperature. The density of both acidic and basic sites was higher with the catalyst prepared with Fe₂O₃ than with that prepared with Fe(NO₃)₃·9H₂O. The latter, however, leads to reach equilibrium in half of the time than with the former. This was ascribed to the ratio of acidic to basic sites, which is higher with the catalyst prepared with the precursor salt. This ratio not only affects the overall cost of the process by affecting the time at which equilibrium is reached but also by dictating the methanol/oil molar ratio at which the equilibrium is reached sooner. The prepared bifunctional catalyst allowed us to produce biodiesel with 90% of methyl ester content at atmospheric pressure, reaction temperature of 60 °C, reaction time of 2 h, with 12:1 M ratio of methanol/WCO, 10 wt % of Fe over CaO, and a catalyst loading of 5 wt %. This catalyst can be used at least 3 times. The so-obtained biodiesel met the European norm EN-14214 regarding viscosity and density.

SO4 2-/ZrO2 as a Solid Acid for the Esterification of Palmitic Acid with Methanol: Effects of the Calcination Time and Recycle Method

Two types of SO₄ ^2-/ZrO₂ solid acid catalysts with various calcination times were prepared via incipient wetness impregnation of (NH₄)₂SO₄ to hydrothermally synthesized ZrO₂ and subsequently employed to catalyze the esterification of palmitic acid with methanol. The resulting catalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and temperature-programmed oxidation (TPO) to elucidate their physicochemical properties, morphology, and deactivation mechanism. A calcination procedure is required to transform the amorphous ZrO₂ into the crystal form. Both chelating and bridged bidentate SO₄ ^2- coordinate with the ZrO₂ surface. The calcination at 600 °C could well eliminate the water in the catalyst and a further higher temperature would accelerate the loss of SO₄ ^2-. Long-time calcination also decreases the catalytic activity due to the transformation of monoclinic ZrO₂ into tetragonal one and the slow leaching of SO₄ ^2-. The catalytic activity increases with increasing catalyst loading amount, reaction temperature, and molar ratio of palmitic acid to methanol, while the heating temperature over 65 °C and excess methanol amount are unfavorable to the esterification reaction due to the low-boiling-point methanol and attenuation of the palmitic acid concentration. It appears that the reaction conditions of 65 °C, 6 wt % catalyst, 25:1 of methanol to palmitic acid, and 4 h reaction time are economically optimal under atmospheric pressure. The catalyst could not be well regenerated by the ultrasonic methanol washing method because of refractory organic residues. The catalyst activity could be well recovered without major activity loss by the calcination at 600 °C for 1 h. The catalyst deactivation is due to contamination by the refractory organic residues in the catalyst as well as by the leaching of SO₄ ^2-, and thus both the calcination temperature and time should be strictly controlled to achieve a better catalyst lifetime.