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Production of biodiesel from acid soybean oil using lithium metasilicate and its mixtures with zeolite ABW as catalysts was studied. Lithium metasilicate (Li 2 SiO 3 ) and zeolite ABW were synthesized hydrothermally at 150 °C for one day by using diatomite and LiOH (aq) as starting materials. These solid catalysts were employed successfully to catalyze transesterification of acid soybean oil in excess methanol at 60 °C for biodiesel production. The soybean oil was spiked with oleic acid to obtain an acid value of 0.54 mg KOH/g oil, i.e. 3.6 times higher than the Taiwan's legal limit on the acid value of refined edible soybean oil (CNS 749). Consequently, the yields of biodiesel were above 95% in an hour by using lithium metasilicate catalysts. Furthermore, the spent catalysts of could be recycled and reused for at least for three consecutive cycles without significant deactivation observed in catalysis. With a decreasing loading of catalyst-to-oil to 30 wt%, the yield of biodiesel could still reach ca. 95% in one hour at 60 °C. [ABSTRACT FROM AUTHOR]

Biodiesel was produced from transesterification of triolein with excess methanol using NaOH-treated kaolin clay as an active catalyst. The natural kaolin was first transformed into an efficacious catalyst under the conditions as (1) calcined kaolin/NaOH (aq ) = 1/2 (w/w), and (2) hydrothermal aging for 24 h at 90 °C prior to calcination at 400 °C for 6 h. Coincidently, these NaOH-treated kaolin catalysts possess characteristics of zeolite LTA. Subsequently, the Box–Behnken experimental design was applied to optimize the transesterification process of triolein in methanol. The optimal conditions are found as follows: (1) 36.6 as the mass ratio of methanol-to-triolein in the initial feed, (2) at 62.9   °C as the reaction temperature, (3) 146 min for reaction time, and (4) a catalyst loading at 72 wt. % of triolein used. Under this optimal condition, the conversion efficiency of triolein to biodiesel is (92.8 ± 4.0)%. Furthermore, these as-synthesized zeolite LTA-kaolin catalysts could be reused at least for three consecutive reaction cycles. [ABSTRACT FROM AUTHOR]

Zeolite beta with a high Si/Al ratio as a heterogeneous catalyst in the transesterification of triolein for biodiesel production was synthesized hydrothermally in fluoride media. The prepared zeolite beta was subsequently treated with dilute NaOH solutions to render better catalysis in the transesterification reaction. Effects of heating procedures, namely reflux and microwave heating, to the reaction system and sizes of the zeolite beta particles on the conversion of triolein to biodiesel were investigated as well. A conversion efficiency over 90% could be attained within an hour of the reflux reaction. Moreover, these Na-treated zeolite catalysts still exhibit acceptable endurability and good catalysis in the transesterification reaction after nine consecutive cycles. It is inferred that sodium cations existing in the cages and the defect sites of the NaOH-treated zeolite beta can be supplied to the surface of the catalysts during the transesterification reaction and, thus, to enhance the catalysis. [ABSTRACT FROM AUTHOR]

In this work microwave and reflux-assisted transesterification of triolein in methanol was carried out with alkali-loaded low-Al Zeolite Beta as catalyst. The results show that the alkali-treated Zeolite Beta can effectively catalyze transesterification reaction of triglycerides to produce fatty acid ethyl esters (biodiesel), if Zeolite Beta has been properly modified with the alkali ion-exchange process. As a result, the final conversion yield over 90% could be obtained within an hour of reflux reaction. However, the durability of this Na-modified Zeolite Beta still has much room to be improved. In this work, this inferior catalytic durability is overcome by using the low-Al Zeolite Beta with a smaller particle size near 0.5 μm. Consequently, for at least eight cycles, cyclic tests of these zeolite catalysts do not result in any significant decrease in catalysis in transesterification reaction. It is inferred that alkali cations existing in defect-sites of low-Al Zeolite Beta can be supplied to the surface of the catalysts during transesterification and enhance the catalysis. [ABSTRACT FROM AUTHOR]

In this work, biodiesel production from catalyzed transesterification of triglycerides with excess methanol was studied by using ion-exchanged Zeolite Beta and MCM-22 as heterogeneous catalysts. Zeolite Beta and MCM-22 were synthesized with hydrothermal processes and, subsequently, modified by ion-exchanged with alkali ions. These as -obtained zeolite catalysts could yield a high conversion of triglycerides to biodiesel. The conversion efficiency was largely affected by crystallinity and frameworks of zeolite support, pH value of alkali ion-exchange solutions and alkali loadings onto the zeolite support. Furthermore, the effects of the duration of the sodium ion-exchange process on the final conversion efficiency of triolein to biodiesel, both the as-prepared Zeolite MCM-22 and Zeolite Beta catalysts were used. The effect of the duration of the sodium ion-exchange process is insignificant in transesterification using Na-ion-exchanged Zeolite MCM-22 catalysts from 0.5 to 4 h. In contrast, the conversion efficiency of triolein to biodiesel reached ca. 95% in 0.5 hours of transesterification using Zeolite Beta ion-exchanged with 3 mmol-eq. Na + /g cat for 0.5 hours. [ABSTRACT FROM AUTHOR]

Biodiesel production from transesterification of vegetable oils in excess methanol was performed by using as-prepared catalyst from low-cost kaolin clay. This effective heterogeneous catalyst was successfully prepared from natural kaolin firstly by dehydroxylation at 800°C for 10h and, subsequently, by NaOH-activation hydrothermally at 90°C for 24h and calcined again at 500°C for 6h. The as-obtained catalytic material was characterized with instruments, including FT-IR, XRD, SEM, and porosimeter (BET/BJH analysis). The as-prepared catalyst was advantageous not only for its easy preparation, but also for its cost-efficiency and superior catalysis in transesterification of vegetable oils in excess methanol to produce fatty acid methyl esters (FAMEs). Conversion efficiencies of soybean and palm oils to biodiesel over the as-prepared catalysts reached 97.0±3.0% and 95.4±3.7%, respectively, under optimal conditions. Activation energies of transesterification reactions of soybean and palm oils in excess methanol using these catalysts are 14.09kJ/mol and 48.87kJ/mol, respectively. [ABSTRACT FROM AUTHOR]

Abstract: A statistical strategy in experimental design is devised to predict the optimal conditions in esterification of palmitic acid with excess methanol over a solid acid catalyst, viz. Amberlite™ IR-120 (H) resin, at a temperature less than the boiling point of methanol. Combining the experimental data and the backward stepwise regression technique with a 25-1 fractional factorial design, the optimal condition is determined from the path of the steepest ascent and found as follows: (1) 8:1 in the molar feed ratio of methanol to palmitic acid, (2) 61.0°C set as reaction temperature, (3) 10.5h for reaction time, (4) catalyst loading at 10wt.% of palmitic acid, and (5) a stirring speed at 600rpm. Under this optimal condition, the conversion efficiency of palmitic acid to methyl palmitate could reach as high as 98.3±0.4%. [Copyright &y& Elsevier]

Abstract In this study, natural diatomaceous earth was utilized for the preparation of efficient lithium metasilicate (Li 2 SiO 3) catalyst for biodiesel production via the transesterification of soybean oil and waste cooking oil. Lithium metasilicate was successfully synthesized from the hydrothermal reaction of natural diatomite in LiOH solutions at 150 °C for 24 h and, subsequently, by calcination at 500 °C for 6 h. Both fresh and spent Li 2 SiO 3 catalysts were characterized by using XRD, 29Si NMR, BET, ICP-OES and acid-base titration. The acidity of the soybean oil and waste cooking oil used in this study was 0.54 mg KOH/g oil and 1.67 mg KOH/g oil, respectively. The yields of biodiesel from soybean oil reached ca. 80.3% in 1 h, respectively, in presence of catalyst at 3 wt% of oil used. Generally, more catalyst present would lead to a higher yield of biodiesel. With the mass loading of catalyst-to-oil at 0.05, the activation energy of the catalyzed transesterification using Li 2 SiO 3 catalyst was 61.65 kJ/mol. The durability test of the Li 2 SiO 3 catalysts was conducted in the same system. A high catalytic activity after being reused for 19 times was observed with a yield of biodiesel near ca. 85% after 4 h of the transesterification reaction at 60 °C. The deactivation mechanism of the Li 2 SiO 3 catalyst was mainly attributed to the loss of surface base sites coincident with more Q4 and less Q2 Si atoms in catalyst after reaction, as found by 29Si NMR. Graphical abstract Durability of Li 2 SiO 3 catalysts in the transesterification of soybean oil with an acid value as 0.54 mg KOH/g oil. Image 1 Highlights • Lithium metasilicate (Li 2 SiO 3) hydrothermally synthesized from diatomite and LiOH. • Biodiesel produced from Li 2 SiO 3 -catalyzed transesterification of acid oil. • A yield of biodiesel >97% was achieved with Li 2 SiO 3 in 2 h-reflux reaction. • A yield of biodiesel ∼86.4% from waste cooking oil was realized with Li 2 SiO 3. • Good durability of Li 2 SiO 3 in biodiesel production was attained. [ABSTRACT FROM AUTHOR]

Abstract: Optimization of sodium loading on zeolite HY for catalyzed transesterification of triolein in excess methanol to biodiesel was studied. Zeolite HY catalyst was activated by loading sodium ions to their surface via an ion-exchange method. The effects of ion-exchange process parameters, including the temperature, the process time, the pH value, as well as concentrations and sources of Na+ cations (NaOH, NaCl and Na2SO4), on the conversion yield of triolein to biodiesel were investigated. Most of these Na+-activated zeolite HY catalysts could really facilitate the catalyzed transesterification reaction of triolein to biodiesel at a lower temperature near 65°C. Consequently, a high conversion yield of triglycerides to biodiesel at 97.3% was obtained at 65°C. Moreover, the durability of zeolite catalysts was examined as well. Catalytic performance tests of these zeolite catalysts in transesterification did not show a significant decrease in catalysis at least for three batch cycles. [Copyright &y& Elsevier]

A new type of solid catalyst prepared from hydrothermal reaction of natural diatomaceous earth in NaOH solution was studied for biodiesel production through the transesterification of soybean and palm oil in excess methanol. Explicitly, the natural diatomite was transformed into efficacious catalysts, sequentially, by dispersion and activation in NaOH solutions for 30 min at 30 °C, followed by hydrothermal treatments at 180 °C or 220 °C for 12 h, and finally by calcination at 500 °C for 6 h. Coincidently, the physicochemical characteristics of these as -prepared catalysts were shown to bear a good resemblance with those of zeolite CAN. Under suitable conditions, the conversion efficiencies of soybean and palm oils to biodiesel in presence of these zeolite CAN catalysts at 63 °C and 70 °C could be obtained as high as 98.0% and 98.4%, respectively. Furthermore, the activation energies of the transesterification reactions of soybean and palm oils in excess methanol were found as 64.1 kJ/mol and 122.5 kJ/mol, respectively. [ABSTRACT FROM AUTHOR]