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In the present study, a highly efficient CaO-based catalyst was synthesized by using abalone shell as a precursor and ethanol as a modification agent for biodiesel production. The physico/chemical properties of the catalysts, which could be tailored by altering the ethanol-treatment temperature (room temperature, 100 °C and 160 °C), were monitored by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) analysis and Hammett indicator. Once treated with ethanol, the modified CaO (M-CaO) catalyst exhibited an increased catalytic activity mainly due to the high surface area, increased specific basicity and decreased crystalline size compared to the unmodified CaO (U-CaO) catalyst. Particularly, when the ethanol treatment temperature was 100 °C, the maximal yield of fatty acid methyl ester (FAME) for the M-CaO catalyst could reach 96.2% (87.5% for the U-CaO catalyst). Furthermore, the M-CaO catalyst exhibited good reusability, having a superior catalytic activity compared to the U-CaO catalyst after recycling for more than five cycles. [ABSTRACT FROM AUTHOR]

Objective: To avoid lipase deactivation by methanol in the enzymatic transesterification process, a two-step biocatalytic process for biodiesel production from unrefined jatropha oil was developed. Results: Unrefined jatropha oil was first hydrolyzed to free fatty acids (FFAs) by the commercial enzyme Candida rugosa lipase. The maximum yield achieved of FFAs 90.3 % at 40 °C, water/oil ratio 0.75:1 (v/v), lipase content 2 % (w/w) after 8 h reaction. After hydrolysis, the FFAs were separated and converted to biodiesel by using Rhizopus oryzae IFO4697 cells immobilized within biomass support particles as a whole-cell biocatalyst. Molecular sieves (3 Å) were added to the esterification reaction mixture to remove the byproduct water. The maximum fatty acid methyl ester yield reached 88.6 % at 35 °C, molar ratio of methanol to FFAs 1.2:1, molecular sieves (3 Å) content 60 % (w/w) after 42 h. In addition, both C. rugosa lipase and R. oryzae whole cell catalyst in the process showed excellent reusability, retaining 89 and 79 % yields, respectively, even after six batches of reactions. Conclusion: This novel process, combining the advantages of enzyme and whole cell catalysts, saved the consumption of commercial enzyme and avoid enzyme deactivation by methanol. [ABSTRACT FROM AUTHOR]

In the present study, rice husk ash (RHA, a solid waste from agriculture) was served as the support for loading calcined eggshell (another material derived from waste source) to prepare solid base catalyst. This catalyst was then applied for catalytically converting palm oil into biodiesel. The effects of catalyst preparation conditions (such as rice husk treatment temperature, the loading of calcined eggshell on the RHA, and the calcination temperature of eggshell-loaded RHA), reaction conditions (such as reaction time, methanol-to-oil molar ratio and catalyst loading) and the catalyst reusability were carefully studied. The experimental results revealed that 30% RHA 800 -800 exhibited the highest catalytic activity. More specifically, when the reaction was carried out with a reaction time of 4 h, methanol-to-oil molar ratio of 9:1, and catalyst loading of 7 wt.%, the biodiesel yield could reach 91.5%. Besides, after reused for more than 8 cycles, the catalyst could still possess a rather high biodiesel yield (above 80%). [ABSTRACT FROM AUTHOR]

Biodiesel production by immobilized Rhizopus oryzae lipase in magnetic chitosan microspheres (MCMs) was carried out using soybean oil and methanol in a magnetically-stabilized, fluidized bed reactor (MSFBR). The maximum content of methyl ester in the reaction mixture reached 91.3 (w/v) at a fluid flow rate of 25 ml/min and a magnetic field intensity of 150 Oe. In addition, the MCMs-immobilized lipase in the reactor showed excellent reusability, retaining 82 % productivity even after six batches, which was much better than that in a conventional fluidized bed reactor. These results suggested that a MSFRB using MCMs-immobilized lipase is a promising method for biodiesel production. [ABSTRACT FROM AUTHOR]