Improvements to the biodiesel process

Biodiesel (fatty acid methyl ester, FAME) is a renewable diesel fuel made from vegetable oil and methanol. The two main problems with the process are disposal of waste streams and product purity. This thesis studies biodiesel process improvements, especially glycerol conversion to hydrogen and improved mass transfer to increase ester yield. Experiments on steam reforming with glycerol and waste water over a platinum alumina catalyst were used to convert the combined waste product streams of a biodiesel plant. Mass spectroscopy with internal standard was chosen to measure reformer gas yield and conversion. The glycerol steam reforming was shown to depend on several reaction variables. Therefore a solid oxide fuel cell was used as a sensor to measure the effects. The results showed that good syngas yield, conversion and reformer life could be obtained using this process. The purity of the biodiesel product was examined using real-time optical microscopy and gas chromatography to fit the FAME standard EN14214. It was observed that droplet size had a major influence on reaction end point and that the reaction was mass-transfer limited. This observation was confirmed by developing a mass-transfer based reaction model using the data from the batch reactor which agreed with results from other researchers. The model predicted better conversion with more mixing intensity. Finally, on the basis of these results, a high mixing intensity continuous reactor was developed which achieved the 96.5% standard with high flow rate and short reactor length. The conclusion was that significant cost effective improvements could be made to the conventional FAME process