Optimization of supercritical dimethyl carbonate method for biodiesel production

Abstract

Biodiesel could be produced from triglycerides and dimethyl carbonate, instead of the conventional methanol, in this non-catalytic supercritical dimethyl carbonate method. It was demonstrated that, supercritical dimethyl carbonate method successfully converted triglycerides as well as fatty acids to fatty acid methyl esters (FAME) with glycerol carbonate, a higher value by-product compared to the conventional glycerol. The FAME are high in yield, comparable with supercritical methanol method, and satisfy the international standard for use as biodiesel fuel. In this study, therefore, optimization of supercritical dimethyl carbonate method was discussed to include all important key parameters such as reaction temperature, pressure, time, molar ratio of dimethyl carbonate to oil, the FAME yield, thermal decomposition, degree of denaturation, tocopherol content, oxidation stability and fuel properties. The optimum condition for supercritical dimethyl carbonate method was determined at 300ºC/20MPa/20min/42:1 molar ratio of dimethyl carbonate to oil to have satisfactory yield of FAME at 97.4wt%. Conclusively, this study showed the importance to address all those key parameters in order to produce high quality biodiesel from supercritical dimethyl carbonate method.

Optimization of catalyst-free production of biodiesel from Ceiba pentandra (kapok) oil with high free fatty acid contents

“…Actually, it can be seen that there is no definite trend or combination of the optimized reaction parameters toward FAME yield for supercritical transesterification process using different kinds of oil feedstocks. By comparing the statistical analysis results that incorporate four reaction parameters simultaneously between the present work and those obtained by Shin et al [39] and Ilham and Saka [40], the optimized pressure and temperature are both comparable. However, the optimized values of methanol to oil molar ratio and reaction time in this work are lower than those reported by Shin et al [39] and Ilham and Saka [40] for obtaining FAME yield higher than 90%.…”

Production of biodiesel with glycerol carbonate by non‐catalytic supercritical dimethyl carbonate

“…When the pressure was lower, they decomposed even more. It was apparent that the polyunsaturated FAME (methyl linoleate, 18:2; methyl linolenate, 18:3) were more vulnerable to thermal decomposition than the mono-unsaturated (methyl oleate, 18:1) and saturated esters (methyl palmitate, 16:0; methyl stearate 18:0) [5]. This is also in agreement with a previous study by Imahara et al [4].…”

“…In addition, it is crucial to monitor the temperature and pressure due to the marked effect of supercritical condition on the stability of dimethyl carbonate itself. If subjected to high temperature and high pressure beyond the real optimum supercritical condition, dimethyl carbonate decomposes to produce gaseous products with reduction in the yield of both FAME and value-added by-products [3,5].…”

Supercritical fluid technology in biodiesel production

“…Ilham and Saka [69] reached 97 wt% of FAME yield for the SCDMC at 300°C, 20 MPa, 20 min, and a 42:1 molar ratio of dimethyl carbonate to oil. This work also investigated the fuel properties of FAMEs to ensure that they are satisfactory as biodiesels.…”