Influence of vacuum pressure on the vacuum pyrolysis of plant oil asphalt to pyrolytic biodiesel

Plant oil asphalt (POA) is a waste by-product in the biodiesel and fatty acid industry, especially in China. A novel vacuum pyrolysis method was developed obtaining diesel-like pyrolytic biodiesel from POA. This study was aimed at qualitatively analyzing components of POA and probing the influence of vacuum pressure on reaction selectivity, product composition and properties in POA vacuum pyrolysis. The POA was characterized by FT-IR, TGA, positive ion ESI FT-ICR MS, while the pyrolytic oil and pyrolytic biodiesel were analyzed by GC/MS. Pyrolytic biodiesel was tested for its properties such as density, viscosity, flash point, acid value, and cetane number according to the ASTM standard methods. At 400 °C, the pyrolytic biodiesel obtained at vacuum pressure range of 20-60 kPa achieved the ASTM standards of diesel fuel. An overall pathway of POA pyrolysis was proposed combining general pyrolysis changes and experimental data. The proposed POA components and their pyrolysis pathway reported are useful for the further study of POA utilization. © 2012 Elsevier B.V.