Application Of Solid Catalysts In Biodiesel Preparation From Jatropha Oil

Biodiesel, as one kind of environmental friendly and renewable energy, plays an important role in solving the problem of energy shortage and environmental pollution. At present, biodiesel was mainly prepared by transesterification with homogeneous catalyts. However, compared with the traditional homogeneous catalysis method, heterogenous catalysis has become the hot spot of the whole society because of its simple post-processing and environmental friendly properties. In this paper, we prepared a lot of solid acid and alkali catalysts by the method of coprecipitation and impregnation. And the application of solid catalysts in biodiesel preparation was systemly studied with Jatropha oil.Firstly, solid catalysts were prepared, screened and characterized. As the results show, solid acid Ti(SO4)2-Zr(SO4)2/Si O2 and solid alkali K2CO3/Mg O-Al2O3 show high catalytic activity. The optimal preparation condition of Ti(SO4)2-Zr(SO4)2/Si O2 is with Ti to Zr molar ratio of 3:1 and calcined temperature of 300°C. The optimal preparation condition of K2CO3/Mg O-Al2O3 is with Mg to Al molar ratio of 3:1, K2CO3 capactity of 25% and calcined temperature of 550°C. Characterization results of solid ac id show zirconium sulfate and titanium sulfate were loaded to the carrier by Si-O-Ti and Si-O-Zr key, and formed composite solid acid catalysts. Solid acid particles are regular and round, with the size of 200~400 nm. Characterization results of solid alka li show that the composite oxides K-Mg(Al)-O and K2 O can help to improve the catalytic activity. Solid alkali particles are lamellar, with the size of 200~500 nm.Secondly, the application of solid catalysts in biodiesel preparation with Jatropha oil was studied. Results show that two step catalytic method is suitable for Jatropha oil to prepare biodiesel. The optimal pre-esterification conditions catalyzed by solid acid catalyst are with catalyst amount of 2%, methanol to oil molar ratio of 12:1, temperature of 75°C, and time of 2 h, under the condition, the acid value can be reduced to 0.78 mg KOH/g and the esterification conversion is 92.73%. The optimal transesterification conditions catalyzed by solid alkali catalyst are with catalyst amount of 2%, methanol to oil molar ratio of 12:1, temperature of 65°C, time of 2 h, and the conversion is up to 95.98%.Finally, the reaction kinetics of transesterification was studied with the products of pre-esterification and the main properties of the products were determined. Results show that the reaction rate equation of 60°C, 65°C and 70°C are-rA=0.01512C0.7094,-rA=0.01785C0.7138 and-rA=0.02194C0.8253, respectively. The activation energy of the reaction is 35.35 KJ/mo l. The determination results of the products show that Jatropha oil was finally converted to biodiesel, and show good performance, which also conforms to the current biodiesel standard GB/T 20828-2014.