Portuguese researchers study alternative biodiesel processes
Researchers from the University of Porto, Portugal, are looking at water-free methods to purify biodiesel.
The study involved heterogeneous transesterification using what the researchers say is a very active calcium glyceroxide catalyst followed by efforts to remove soaps through pretreating the crude biodiesel (methyl ester content of 90.2 to 91.2 percent by weight, and calcium content of 372 to 393 parts per million) with sodium carbonate (Na2CO3) and, afterward, running the fuel through ion exchange resins (6 percent by weight) or a ceramic membrane (0.1 μm).
The purification was effective using biodiesel produced from both soybean and used cooking oils, and resulting fuel quality was comparable to that of conventional water-washing.
While dry-washing biodiesel is not uncommon, the researchers say the effectiveness of this treatment could be explained by calcium elimination through precipitation as calcium carbonate (CaCO3) during pretreatment, and sodium soaps removal by absorption into the resin or filtration by the ceramic membrane, according to the micelle formation mechanism. The researchers say the process “presents a high potential to remove calcium soaps from biodiesel,” and “could provide significant economic and environmental benefits compared to other more energy intensive water-based production methods.”
“In some countries like Brazil, biofuels provide nearly a quarter of their road transport needs,” says David Brown, the Institution of Chemical Engineers chief executive. “In the European Union, negotiations are under way to increase biofuels for transport to 10 percent. And Indonesia—the world's largest producer of palm oil—has announced plans to increase biodiesel production to reduce its reliance on crude oil imports. Current production processes do not always deliver the full potential of biofuels to help reduce greenhouse gas emissions, however, and there are continuing challenges including economic and environmental. But demand for biofuels is clearly increasing and advancement in chemical engineering processes, such as the use of heterogeneous catalysis and water-free methods using membranes, are very welcome to consolidate biofuels as a globally accepted and sustainable source of renewable energy.”