RESUMOO dióxido de estanho apresenta alta estabilidade química e baixo custo, sendo bastante citado na literatura para a síntese hidrotérmica associada a micro--ondas. A utilização de catalizadores heterogêneos, na síntese de biodiesel, vem se mostrando bastante promissor, com taxas de conversão acima de 80 %.
PALAVRAS--CHAVE:SnO 2 , método hidrotermal assistido por micro--ondas, catalisadores, biodiesel.
MICROWAVE--ASSISTED HYDROTHERMAL SYNTHESIS OF Ni--DOPED SnO 2 NANOPARTICLES AND THEIR USE AS CATALYSTS IN BIODIESEL PRODUCTION ABSTRACTThe high chemical stability and low cost of tin dioxide has been widely reported in the literature, as has its microwave--assisted hydrothermal synthesis. The use of heterogeneous catalysts in biodiesel synthesis has proved very promising, with conversion rates exceeding 80%. The purpose of this study was to synthesize Ni--doped SnO 2 for application as a heterogeneous catalyst in the transesterification of vegetable oils. The powders were characterized by X--ray diffraction, Raman spectroscopy, scanning electron microscopy and N 2 (g) adsorption/desorption using the Brunauer--Emmet--Teller (BET) method. The results revealed powders with nanometric agglomerates and high surface areas. Catalytic tests revealed an 80% retention factor and a decrease in the viscosity of babassu oil from 30.27 mm 2 s --1 to 6.91 mm 2 s --1 , indicating that the synthesized catalyst can be used in the transesterification of vegetable oils.