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摘要
Biodiesel production from lipids (vegetable oils and animal fats) with non-catalytic supercritical methanol (SCM) has several advantages over that of homogeneous catalytic process, including a high production efficiency, environmentally friendliness and a wide range of possible feedstocks. This article reviews the effect of the operating parameters on the lipid conversion to biodiesel with SCM, such as the temperature, pressure, methanol to oil molar ratio, and reaction time, for both batch and continuous systems, including the effect of the mixing intensity and dispersion in tubular reactors. The operating temperature is the key parameter to control either extent of reaction or other parameters. Studies on evaluating the chemical kinetics, phase behavior, binary vapor-liquid equilibrium (VLE) of lipid conversion in SCM are summarized. The pseudo-first order model is suitable to simplify the system at high methanol to oil molar ratios, but it is inadequate at a low methanol concentration which instead requires the second order model. Transition temperatures of reaction mixture depend on the critical point of reaction mixture which is assigned by methanol to oil molar ratio and amount of co-solvents in the system. For binary VLE studies, no single thermodynamic model for the overall process is available, probably because of the differences in the polarity between the initial and the final state of the reaction system. Since traditional operating parameters of the lipid conversion in SCM involve elevated temperatures and pressures, techniques for allowing milder operating conditions that employ the addition of co-solvents or catalysts are discussed. The ongoing and more extensive research on co-solvents, heterogeneous catalysts, phase behavior and multicomponent VLE of lipid conversion to biodiesel with SCM should provide a better understanding and achieve the goal of green biodiesel production technology in the near future.
- 出版日期2010-11
