(142d) Sulfur Level Changes in Brown Grease Conversions with Sulfuric Acid and Heterogeneous Zirconia-Supported Metaloxides Catalysts
Brown grease recovered from waste water is less expensive lipids and would make biodiesel much more competitive with petroleum-based fuels. Brown grease has been converted with homogeneous sulfuric acid and metaloxides (ZnO2, ZnO2-La2O3, ZnO2-Al2O3 and ZnO2-NiO) supported ZrO2 catalysts in batch reactors. The supported catalysts were prepared via impregnation and sol-gel method. The metaloxides loading on the supports were analyzed with SEM-EDS. Sulfur and metal concentrations in both reactant and product were measured with an inductively coupled plasma spectrometry. Total acid numbers of the brown grease and products were determined according to ASTM D 664. Composition of glycerides in brown grease was measured with a HPLC. The yields of fatty acid methyl esters in the samples were quantified using a GC-MS. Amounts of free fatty acids and macromolecules (bp>240°C) were 87.5% and 15±5%, respectively. Maximum FAME yield was detected in the range of 78~85%. Sulfur content in brown grease was very high as 640 ppm. The sulfur levels in the converted FAME phases decreased to 300~330 ppm by the methanolysis. About a half of the sulfur in the brown grease removed by methanolysis can be regarded as ester-bonded sulfates. The other half of the sulfur can be regarded as sulfonates, sulfones and reduced sulfurs. These sulfurs were difficult to be removed by methanolysis.