Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

OP-V-6TiO 2 /SiO 2 HETEROGENEOUS CATALYST FOR BIODIESELPRODUCTION: A KINETIC AND MODELLING STUDY AT HIGHTEMPERATURES AND PRESSURESM. Di Serio, R. Tesser, A. D’Angelo, L. Casale, E. Santacesaria (*)University of Naples «Federico II» – Department of Chemistry,Complesso Universitario Monte S. Angelo, Via Cintia 4, I-80126 Naples, Italy(*) E-mail: elio.santacesaria@unina.it - Phone: +39 081674027 - Fax: +39 081674026Biodiesel is a renewable diesel fuel obtained by transesterification of vegetable oils withmethanol. Nowadays, most biodiesel is obtained by transesterification of triglycerides ofrefined/edible oils with methanol, in the presence of an alkaline catalyst (NaOH, NaOMe) [1].The recent strong increase in biodiesel production is due to both environmental andtechnological advantages– i.e. reduction of overall CO 2 emissions; increase of the lubricatingproperties of modern ultra-low-sulphur diesel by the addition of low amounts of biodiesel (1-2%) [2], but, the greatest driving force is represented by the environmental laws favouringbiodiesel use through tax reductions. These incentives are necessary because the higher costof biodiesel with respect to diesel from petroleum. The main factor determining the cost ofbiodiesel is the price of the edible oil feedstock, which accounts for 88% of the total estimatedproduction costs. Therefore, great economic advantages could be achieved only by using lowprice feedstock such as waste or not edible oils [1, 3].With the conventional technology of transesterification, based on the use of batch plantsin which a basic homogeneous catalyst is used, these types of oils cannot directly be used.This is due to the presence of large amounts of free fatty acids (FFA>0.5% w/w) and water[4] that favour the formation of soaps. Soaps emulsify the reaction products(biodiesel+glycerol) and the separation of glycerol becomes difficult. Moreover, alkalinecatalyst must be neutralized with mineral acids and recovered glycerol, dirty of the formedsalts, is difficult to purify. Therefore, a preliminary stage for free fatty acid elimination isnecessary for this process [1,3,5,6,7]. However, the cost of biodiesel could certainly belowered by using an heterogeneous catalyst instead of an homogeneous one, resulting in ahigher quality esters and glycerol that can be obtained, that are more easily separated. It hasrecently been announced, in France, the construction of a new 160000 t/y biodiesel plantbased on the use of an heterogeneous catalyst (a zinc aluminate) developed by the FrenchInstitute of Petroleum (IFP) [8]. Unfortunately, this catalyst cannot be used in the presence ofmoisture and free fatty acids.177