Loading...
2 results
Search Results
Now showing 1 - 2 of 2
- Biodiesel glycerin valorization into oxygenated fuel additivesPublication . Soares Dias, A. P.; Fonseca, Frederico G.; Catarino, Mónica; Gomes, Joãorequires costly purification before commercialization. Production of oxygenated fuel additives is a potential route for glycerin valorization. Glycerin acetylation was carried out over heterogeneous acid catalysts (15%, glycerol weight basis) using glacial acetic acid (molar ratio=9). The catalysts, containing different amounts of phosphate species (P/Si from 10 to 20 atomic ratio), were prepared by wet impregnation of commercial silica with aqueous solutions of diammonium phosphate and ortho-phosphoric acid. X-ray diffraction patterns of calcined solids presented amorphous patterns like raw silica. The prepared catalysts presented, at 120 degrees C, glycerol conversion higher than 89.5% after 1 h of reaction, been diacetin the major product, with triacetin selectivities lower than 26.1%. Diacetin selectivity was found to be almost invariant with catalyst acidity thus underlining the relevance of catalyst porosity due to the large acetins molecules sizes. The slow rate of triacetin diffusion in narrow pores of catalyst might be responsible for the relatively low yield obtained. Surface phosphate species showed a slow rate of leaching in the reaction medium showing high catalyst stability.
- Co-processing lard soybean oil over Ca-based catalysts to greener biodieselPublication . Soares Dias, A. P.; Catarino, Mónica; Gomes, JoãoFatty Acid Methyl Esters (FAME) were produced from lard/soybean oil (SBO) mixtures using a calcium-based heterogeneous catalyst. The green catalyst was prepared by scallop shell calcination at a relatively low temperature (800 degrees C) to minimize energy consumption. Images from Scanning Electron Microscopy showed agglomerates of a few tens micrometers with rhombohedral calcite crystallites studded with lime. X-ray diffractogram of fresh catalyst presented overlapped patterns of calcite and lime In tested conditions (methanol reflux temperature, 5% (fat mass basis), methanol fat = 12 molar ratio, and 150 min), the FAME yield reached 95% (mass) with SBO. However, only 75% FAME yield was obtained from pure lard since the active sites of the catalyst were partially neutralized by lard acidity. Co-processing lard/SBO mixtures attenuated the undesirable fat acidity drawback allowing FAME yields around 90% for mixtures containing less than 50% (mass) of lard. The low-grade fat content of the processed mixture showed no impact on the glycerin quality. Co-processing lard/SBO is a smart strategy to overcome the low-grade fats acidity in biodiesel production process thus providing a more sustainable biodiesel production route.