Produção de ésteres metílicos de óleo de soja utilizando líquidos iônicos

Abstract

Ionic liquids have been studied to use as alternative catalysts in biodiesel production. Thus, the aim this work was produce methyl esters with high yields from soybean oil like precursor, using ionic liquids like catalysts. The ionic liquids triethylammonium hydrogen sulfate ([Et3NH]HSO4), triethylammonium dihydrogen phosphate ([Et3NH]H2PO4), triethylammonium sodium tetrafluoroborate [Et3NNa]BF4, triethylammonium aluminium chloride ([Et3NH]Cl-AlCl3), 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4), n-methyl-2-pyrrolidone methyl sulfonate ([NMP][CH3SO3]) e choline hydroxide (ChOH) was synthesized according the adapted methodology of articles founded in literature. Transesterification tests were evaluated in following conditions: 70 ºC of temperature, 1:12 molar ratio of oil:alcohol and 10% (w/w) of catalyst. The ionic liquids with the higher yields in reaction were done for new tests evaluating the effects of the following parameters: temperature, molar ratio of oil:alcohol and amount of catalyst. Finally, the reaction kinetic was determined in condition that have the higher yields. The ionic liquids [Et3NH]Cl-AlCl3, [NMP][CH3SO3] and ChOH obtained the higher yields in reaction obtaining the following conversion values: 94%, 93% and 94%, respectively. The better operational conditions happened in temperature of 70 ºC, 1:12 molar ratio of oil:alchool and 10% (w/w) of catalyst. The equilibrium time of ionic [Et3NH]Cl-AlCl3, [NMP][CH3SO3] and ChOH was next to 8 h, 6 h and 3 h, respectively. The catalysts [Et3NH]Cl-AlCl3, [NMP][CH3SO3] e ChOH were able to be reused for 5, 4 and 2 times, respectively. The ionic liquid [NMP][CH3SO3] was considered the more indicated to use as catalyst in biodiesel transesterification due its operation conditions as mild, intermediary kinetic and high reuse possibility.