Continuous synthesis of biodiesel and glycerol ether using homogeneous and heterogeneous catalysts

Abstract

In our study, a mixture of p-toluenesulfonic acid and sulfuric acid (TsOH-H2SO4) as a catalyst showed a good performance in transesterification of palm oil (PO) with methanol and etherification of biodiesel with isobutylene. For biodiesel production, the catalyst noticeably accelerated the reaction faster than TsOH and H2SO4 alone and also gave up to 99.8% of the conversion. Etherification of biodiesel with isobutylene in the etherification process using isobutylene/glycerol molar ratio 6:1 at 70°C, in the period of 5 h reaction time, gave high selectivity to produce DTBG and TTBG (81.4%). Furthermore, the catalyst can be reused for 6 cycles of continuous synthesis (transesterification and etherification). When using deep eutectic solvents (DESs) as catalyst, the highest conversion of biodiesel (99.8%) were obtained from the condition of 10%wt ChCl-TsOH (3:1 ratio), 10:1 methanol/PO ratio at 110°C and reaction time 4 h. In the etherification process for the next step of the etherification synthesis using ChCl-TsOH as catalyst, isobutylene/glycerol molar ratio 6:1, reaction temperature 100°C, and 5 h reaction time, it gave high selectivity to produce DTBG and TTBG (89.9%). Furthermore, the ChCl-TsOH catalyst could be reused for 4 cycles. In comparison of fuel properties between biodiesel and biodiesel blending with 10% the prepared tert-butyl glycerol ethers blend would enhance the biodiesel efficiency as follows; acid value, pour point and iodine value.