Pilot-scale Experiment And Process Design Of Biodiesel Via Reactive Distillation Technology From Soybean Oil Deodorizer Distillate

Implementing sustainable fuels is a crucial issue worldwide in the context of increasing energy demand the deteriorating ecological environment.Biodiesel is a biodegradable and renewable fuel,emerged as a viable alternative to petroleum diesel.In spite of the recent advances,the existing biodiesel processes still suffer from serious problems associated with the use of homogeneous catalysts and the limitations imposed by the chemical reaction equilibrium,thus leading to severe economic and environmental penalties(e.g.high operating costs,salt waste streams).The objective of the present work is to find a potential way for great decrease in biodiesel production energy requirement and CO2 emission from the aspects of reactor and process.In this paper,soybean oil deodorized distillate(SODD)was used as the main raw material for the preparation of biodiesel.Thecontinuous reactive distillation(RD)experiments of esterification of SODD and methanol to biodiesel were conducted using the cation exchange resin catalysts.The simulation model of RD process was established,and the design and operation parameters of the process were obtained through process simulation.Firstly,the esterification experiments of model compounds(oleic acid,linoleic acid,palmitic acid)and methanol were carried out in an intermittent reactor with the cation exchange resin KC105D as the catalyst,respectively.The effects of internal and external diffusion,acid-alcohol ratio,and temperature on fatty acid conversion rates were explored.A fitted homogeneous kinetic model was developed and kinetic parameters were calculated to obtain kinetic equations for each fatty acid methylation reaction.Secondly,the continuous reactive distillation experiments were operated under various operating conditions(MEOH/FFA feed molar ratio,FMR;reflux ratio,RR;feed position)using a reactive distillation column filled with seepage catalytic packing internals(SCPI)of soybean oil deodorized disillate and methanol as feedstock.The effects of various operating conditions were explored,with the highest conversion rate of free fatty acids reaching 66.23%.Finally,a rigorous model of the reaction distillation process for the production of biodiesel based on kinetic and thermodynamic methods was established by Aspen Plus 9.0,and the reliability of the model was verified by good agreement between simulation results and experimental data.The simulation model was then used for process design and optimization,including sensitivity analysis and global optimization,and the optimized process flow and operating parameters were:3NTSM for the distillation section and the stripping section respectively,and 18NTSM for the reaction section;SODD and methanol feed stream were fed from the21st and 4th stage,respectively;the FMR was set at 22.08;and the RR was set at 0.52.Compared with the traditional process,the free fatty acid conversion rate increased by57.9%,the product acid value decreased by 97.8%,CO₂ emissions decreased by 80.98%and TAC decreased by 53.41%.The results indicate that the reactive distillation process for biodiesel production proposed in this paper is commercially competitive in terms of energy savings and reduction of total annual costs.