Modeling analysis of membrane reactor for biodiesel production

Abstract

in Wiley Online Library (wileyonlinelibrary.com).Recently, membrane reactor technology was used to produce high-quality biodiesel because of its advantage of simultaneous transesterification and separation. As the transesterification reaction involves two immiscible phases of methanol (MeOH) and oil (TG), a thorough investigation on the membrane reactor for biodiesel production with the consideration of chemical phase equilibrium (CPE) via modeling analysis, was conducted in this study. A mathematical model was developed based on the modified Maxwell-Stefan model with the incorporation of CPE. The formation of TG rich micelles dispersed in the continuous phase of MeOH was the most important hypothesis in the model development. The preliminary experiment results show that the permeate compositions from the membrane reactor were closely related to CPE of the system, which was highly depending on the MeOH to TG molar ratio. TG free permeate can only be obtained if the continuous phase of MeOH was free from TG and the TG rich micelles were retained by the membrane. The model verification further confirmed the formation of micelles dispersed in the continuous MeOH phase within the feed side of the membrane reactor and the model was able to predict the performance of the membrane reactor for biodiesel production at an acceptable accuracy.Experimental conditions: varying catalyst concentrations of 0.05 wt % (run 1), 0.1 wt % (run 2) and 0.5 wt % (run 3) at constant MeOH to TG ratio of 12:1 for CPE; varyingMeOH to TG ratio of 6:1 (run 4), 18:1 (run 5) and 24:1 (run 6) at constant catalyst concentrations of 0.1 wt % for CPE; constant trans-membrane pressure of 0.8 Â 10 5 kPa at constant circulation rate of 0.018m 3 /s for membrane separation. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.] 266

Mini Review of Biodiesel by Integrated Membrane Separation Technologies That Enhanced Esterification/Transesterification

“…Chong et al and Oh et al , combined thermodynamics and reaction kinetics with a modified Stefan–Maxwell mass transfer model. On the basis of the research of chemical balance, phase equilibrium, and mass balance, they also established an esterification model that successfully predicted the phase separation of the reaction system and the concentration of each ingredient in the penetrating fluid.…”

Can process intensification change the future of biodiesel?

“…The membrane reactor for biodiesel production is not a new study in the literature [23]. Although the fouling is an intrinsic problem of the membrane operation, the effects of fouling on the membrane reactor in biodiesel production has not received adequate attentions.…”

“…The results show that reaction kinetics are not affected by the residence time while the increase of catalyst loading raises the reaction rate constants. Chong et al (2013) [23] reported the importance of MeOH:oil at the feed side so that methanol becomes the continuous phase and the failure of membrane operation in the event of phase inversion if TG becomes the continuous phase. The critical point of phase inversion is expressed in terms of volume fraction of methanol (MeOH), ФMeOH to TG, ФTG ratio [23]:…”

“…Thus, the most important process limitation to the membrane reactor is the MeOH to TG ratio which should be maintained at ФMeOH/ФTG > 0.44 to prevent phase inversion. With excessive amount, methanol is regarded as solvent and other components are regarded as solute [23]. Cheng et al (2010) [22] investigated the effects of the methanol to oil molar ratio and catalyst concentration on the reaction kinetics.…”

“…The work of Cheng et al (2010) [22] showed the effects of temperature, methanol-to-oil molar ratio and catalyst concentration on canola oil methanolysis and obtained reaction kinetics data of the membrane reactor. Chong et al (2013) [23] developed and analyzed a model of a membrane reactor with the integration of a chemical phase equilibrium (CPE). In addition to homogeneous catalysis, Gao et al (2017) [24], and Hapońska et al (2019) [25] reported the effects of heterogeneous catalyzed transesterification in membrane reactors.…”