Improving Biodiesel Production Efficiency via Methyl Ester Recovery

Technology No. 20180117

Methyl Ester Recovery via Microwave-Assisted Pyrolysis

Microwave-assisted pyrolysis (MAP) maximizes yields by recovering methyl ester from biodiesel vacuum distillation bottoms (VDBs). The technology is a MAP reactor with a fixed-bed heat susceptor silicon carbide (SiC) catalyst that absorbs microwave radiation and quickly achieves a high temperature. The process rapidly heats VDBs, thus avoiding further dimerization and derivatization. After distillation microwave-assisted pyrolysis (dMAP), 85.9% wt/wt of the VDBs were recovered as a transparent bio-oil composed mostly of methyl esters. This bio-oil can be blended back into B100 biodiesel and certified for sale using ASTM D67514. Blending dMAP bio-oil (10% wt/wt) with B100 biodiesel meets all certification requirements and demonstrates that MAP processing could be a significant yield improvement technology for any commercial biodiesel producer.

Solves Biodiesel Waste Formation Problems and Increases Yield

Vacuum distillation in commercial-grade biodiesel production is a reliable post-treatment method for removing multiple impurities. However, biodiesel distillation, the most significant and primary purification process, produces a waste stream of VDBs that represents approximately 5-15% of the crude biodiesel. VDBs must either be disposed of or sold as low-grade heating oil for use in boilers or ocean shipping. This new MAP technology recovers valuable methyl esters from VDBs, solving the waste formation problem by recovering a significant amount (approximately 85% wt/wt) of the VDBs as a transparent bio-oil composed mostly of methyl esters. Testing shows the bio-oil can be blended back into the initial distillate stream and that it passes all ASTM D6751 tests required for commercial biodiesel. The process is easily integrated into existing biodiesel processes and can increase biodiesel yield, resulting in more biodiesel sold than low grade heating fuel.


  • Up to 10% increase in biodiesel yields for any commercial biodiesel producer
  • Decreases waste stream from biodiesel production
  • Recovers valuable methyl ester from biodiesel vacuum distillation bottoms (VDBs)
  • Employs energy efficient microwave-assisted pyrolysis (MAP)
  • Robust, cost effective, fixed-bed heat susceptor silicon carbide (SiC) catalyst
  • Minimizes dimerization and derivatization; rapid heating maximizes yield
  • Produces biodiesel that passes ASTM D6751 tests when blended into conventional bio-diesel
  • High temperatures required for biofuel distillation can be sustained


  • Biodiesel production and purification

Phase of Development - Proof of Concept

Roger Ruan, PhD
Professor, Bioproducts and Biosystems Engineering
External Link (
Erik Anderson, PhD
Post-Doctoral Associate, Bioproducts & Biosystems Engineering
External Link (

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