Improving methods of CaO transesterification activity

Sunflower oil methanolysis over modified CaO catalysts

Oil methanolysis over modified CaO catalysts was studied to assess the catalytic performance and to define an appropriate kinetic model. CaO was modified by commercial glycerol and a deep eutectic solvent (DES), choline chloride : glycerol (ChCl : Gly), to obtain catalytically active complexes of CaO and glycerol. The main goal was to investigate the effect of the obtained complexes on the reaction rate and fatty acid methyl ester (FAME) content and to describe the variation of the triacylglycerol (TAG) conversion degree during the reaction time. Fourier transform infrared spectroscopy (FTIR) was applied to confirm the formation of CaO complexes with glycerol or the glycerol-based DES. Different catalyst loadings (0.5, 1, and 5 % of oil weight) and methanol-to-oil molar ratios (6 : 1 and 12 : 1) were applied for investigation of the sunflower oil methanolysis at 60 oC. Two kinetic models were employed yielding the kinetic parameters, which depended on the catalyst loading and the methanol-to-oil molar ratio. Both models showed valid applicability for describing the kinetics of the reactions catalyzed by both complexes (the mean relative percent deviation was lower than 10 %).

Catalytic efficiency of the eggshell calcined and enriched with glycerin in the synthesis of biodiesel from frying residual oil

Currently, there are several studies using calcium oxide, calcium alkoxide, and calcium hydroxide for biodiesel production. However, there is still a lack of studies highlighting the use of calcium diglyceroxide (calcium oxide enriched with glycerin in the presence of methanol) as a catalyst in the transesterification process. Therefore, the present work aimed to investigate the catalytic efficiency and reutilization of the eggshell calcined and enriched with glycerin and methanol (ECEG), in the synthesis of methylic esters from frying residual oil. As a result, thermochemically modified eggshells showed catalytic efficiency during methylic transesterification of residual oils in mass concentrations of 15%, 5%, 3%, and 1% due to the presence of a high level of esters (97.39, 96.97, 97.75, and 92.96%, respectively). The initial concentration of the enriched eggshell used in methanolysis had a direct effect on the final ester mixture. A 15% increase in the water content of the frying oil contributed to an increase in the ester content. The ECEG was reactive and efficient for four reaction cycles (without reactivation of the catalytic sites) due to the evidence of a high ester content (97.85%, 98.67%, 98.89%, 98.46%), reaching the standard quality of worldwide biodiesel regulations. Graphical abstract.

Effect of the Formation of Diglycerides/Monoglycerides on the Kinetic Curve in Oil Transesterification with Methanol Catalyzed by Calcium Oxide

Many researchers reported that a sigmoid kinetic curve was obtained in oil transesterification with methanol catalyzed by CaO and gave different explanations for this formation. In this paper, heterogeneously catalyzed transesterification of soybean oil with methanol using CaO has been investigated. The solid catalyst and the liquid reaction mixture under different reaction time periods were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and high-performance liquid chromatography (HPLC) to reveal the formation of an S-shape kinetic curve. The appearance of calcium hydroxide, calcium methoxide, calcium glyceroxide, fatty acid calcium, diglycerides, and monoglycerides and their contributions to the kinetic curve have been discussed. The low reaction rate in the induction period can be attributed to mass transfer in this three-phase system. However, the formation of surfactants, diglycerides and monoglycerides, promotes the emulsification of the reaction mixture and numerous emulsion reactors are generated. These emulsion reactors can improve the contact of the solid catalyst with the reactants and thus accelerate the reaction.

Waste cooking oil and waste chicken eggshells derived solid base catalyst for the biodiesel production: Optimization and kinetics

Waste chicken eggshells were used to derive two catalysts labeled in this study as Eggshell-CaO_C-H-D and Eggshell-CaDG. Both these catalysts were characterized by FTIR, XRD, BET, SEM, and basic strength was determined by the Hammett indicator method. The transesterification of waste cooking oil was carried out to compare the catalytic activity of Eggshell-CaDG and Eggshell-CaO_C-H-D. The effect of various reaction parameters-methanol molar ratio, temperature, speed of agitation, and catalyst loading on the progress of the reaction was also tested to produce higher biodiesel yield. Eggshell-CaDG catalyzed reaction produced 96.07% biodiesel under the optimized reaction conditions of methanol molar ratio 10:1, catalyst loading 1.50 wt%, temperature 60 °C and speed of agitation 300 rpm with a reaction time of 50 min. Whereas, Eggshell-CaO_C-H-D was yielded 93.10% biodiesel for the optimized operating parameters-methanol molar ratio 12:1, 400 rpm, 65 °C, catalyst loading of 3 wt% in the reaction time of 90 min. The reusability for both the catalysts was tested up to five cycles and found that biodiesel yield was decreased with successive cycles. The activation energies of the Eggshell-CaDG and Eggshell-CaO_C-H-D were found to be 31.39 and 54.05 kJ mol^-1, respectively. The physicochemical properties of the biodiesel were also found as per the ASTM standard range.

Optimization of Biodiesel Production over Chicken Eggshell-Derived CaO Catalyst in a Continuous Centrifugal Contactor Separator

Solid calcium oxide (CaO) catalyst was prepared via the calcination of chicken eggshells as an environmentally friendly waste resource and incorporated in a continuous centrifugal contactor separator (CCCS) for intensified biodiesel synthesis. Biodiesel or fatty acid methyl esters (FAME) were produced via the transesterification of sunflower oil (containing 5 wt % tetrahydrofuran as a cosolvent) with methanol under 60 °C and separated from the glycerol and catalyst phases continuously in the CCCS. The influence of reaction parameters on biodiesel production was well modeled by response surface methodology. At an oil flow rate of 9 mL/min, an alcohol to oil molar ratio of 11:1, and a weight hourly space time (defined as the catalyst weight over the oil mass flow rate) of 0.050 h, an optimized FAME yield of 83.2% with a productivity of 638 kg_FAME/(m³ _reactor·h) was achieved. CaO catalyst was reused without significant activity loss for at least four cycles.

Recent advances in the field of selective epoxidation of vegetable oils and their derivatives: a review and perspective

The present critical review reports the recent progress of the last 15 years in the selective epoxidation of vegetable oils and their derivatives, in particular unsaturated fatty acids (UFAs) and fatty acid methyl esters (FAMEs).

Economical and green biodiesel production process using river snail shells-derived heterogeneous catalyst and co-solvent method

River snail shells-derived CaO was used as a heterogeneous catalyst to synthesize biodiesel via transesterification of palm oil with methanol. The shell materials were calcined in air at 600-1000°C for 3h. Physicochemical properties of the resulting catalysts were characterized by TGA-DTG, XRD, SEM, BET, XRF, FT-IR and TPD. CaO catalyzed transesterification mechanism of palm oil into biodiesel was verified. The effects of adding a co-solvent on kinetic of the reaction and %FAME yield were investigated. %FAME yield of 98.5%±1.5 was achieved under the optimal conditions of catalyst/oil ratio of 5wt.%; methanol/oil molar ratio of 12:1; reaction temperature of 65°C; 10%v/v of THF in methanol and reaction time of 90min. The results ascertained that river snail shells is a novel raw material for preparation of CaO catalyst and the co-solvent method successfully decreases the reaction time and biodiesel production cost.