Although there has been big surge in biodiesel production recently, such fuels are not without problems of their own, such as low mileage, poor performance at lower temperatures, and adverse effects on engine components. Also, the production process for making biodiesel — the methyl esterification of fatty acids derived from vegetable oils (such as palm and rapeseed) — is relatively expensive and is creating a glut of glycol, a byproduct from biodiesel production. Such problems are avoided by using vegetable oil directly to increase the yield of conventional petroleum-based diesel fuels, in a process developed by Nippon Oil Corp. (Tokyo; edlinks.chemengonline.com/6519-537), in cooperation with Toyota Motor Corp. (Toyota, both Japan; edlinks.chemengonline.com/6519-538).
In the new process, palm oil is first mixed with a vacuum-gas-oil (VGO) component coming from the vacuum distillation of residue oil at a petroleum refinery. The mixture (about 20 vol.% palm oil) is then hydrocracked with hydrogen (100 bar) at 390–410°C. This adding of palm oil to VGO has the effect of increasing the yield of gas oil (diesel) by about 35–40% — without changing the rate — compared to the yield obtained from hydrocracking pure VGO, says Nippon Oil. The product shows similar properties as conventional gas oil, the firm says. The two companies plan to further develop and commercialize this technology in the near future.