(555f) Conversion of Inexpensive Oils Into Biodiesel Using ZnO Nanoparticle Catalyst
Biodiesel is a mixture of fatty acid esters which can be produced from vegetable oils or animal fats with methanol. Recently, many researchers focus on using waste or unrefined oils as feedstock to decrease the production cost of biodiesel. A two-step method was reported, which firstly esterified free fatty acids (FFA) with methanol in the presence of H2SO4, then transesterified oil with methanol in the presence of NaOH. This production process is long and highly corrosive. In this study, a single-step method was developed using Zn-La mixtures as catalyst to convert crude soybean oil, crude coconut oil, crude palm oil, crude corn oil from DDGs, crude algae oil, waste cooking oil and the well-refined soybean oil with 3 % water and 5 % oleic acid additions into FAME. Oil transesterification and FFA esterification reactions simultaneously took place in one step. Effects of catalyst structure, metal oxide molar ratio, FFA and water contents in feedstock, reaction temperature and oil concentration on the yield of biodiesel were investigated. In a batch stir reactor, 42:1 molar ratio of methanol to oil, 2.3 (wt) % of catalyst, a high yield (95 %) of biodiesel was obtained within 3 hours using the above oils as feedstock. In a continuous reactor, 26:1 molar ratio of methanol to oil, 200 °C and 100 ~ 450 Psi, the yield of FAME maintained at 94 % for 49 days. This class of zinc and lanthanum mixture catalysts expands the oil feedstock for biodiesel production.