Desulfurization of Biodiesel Produced from Low-Quality Feedstocks

As biodiesel production in the USA increases, bottlenecks in feedstock appear likely. Several companies have formed to investigate novel forms of conversion of lower cost feedstocks but all have found the same substantial hurdle, meeting the 15PPM sulfur specification of ASTM D6751. Numerous experiments have shown that low-cost fats, oils and greases may contain 300 - 500PPM sulfur and that no single technology with acceptable operating requirements is available for desulfurization of these feedstocks. After exhaustive experimentation we have discovered two "primary purification" technologies which remove unsaponifiables, color bodies and reduce sulfur to approximately 30 - 50PPM. To further reduce sulfur to below15PPM, we've identified the need for a polishing step or "secondary purification". Six effective adsorbents, each showing sulfur reductions of at least 30%, as well as an effective catalyzed method of removal have been identified as possible candidates for a production system.The goal of this SBIR is simple; to conduct a thorough comparison of two primary purification technologies, to compare six proven adsorbents and to optimize results with catalyzed sulfur reduction. The data will be assembled into a technoeconomic analysis which shows the estimated cost of operating the two stage desulfurization unit. Such a desulfurization unit will allow biodiesel producers to utilize a wider variety of feedstocks and possibly allow producers of these feedstocks to increase their values. It would increase the availability of US produced feedstock and aid in the ability of producers to meet the mandates in the 2007 Energy Independence and Security Act.