Separation Of Vanillin And O-vanillin By Three-zone Asynchronous Simulated Moving Bed

Simulated Moving Bed is a novel preparative chromatography separation technology,has been widely applied in petrochemical,pharmacy and food industries in past several decades.Recently,the theory research of SMB process focuses on the numerical methods of solving the model equations,improvement of operation modes and optimal design of operating parameters,etc..In this study,following researches were developed to separate vanillin and o-vanillin by using three-zone asynchronous simulated moving bed technology.Firstly,a numerical algorithm based on the 4th-order compact difference scheme is developed and used to solve the model equations of SMB process in this study.Accuracy tests demonstrate that the algorithm does deliver the 4th-order accuracy.Then,the effects of model parameters on chromatogram are examined.Finally,the developed algorithm was used to simulate the SMB process for separation of glucose and fructose,accurate solutions and high computational efficiency are achieved.Secondly,Particle Swarm Optimization(PSO)algorithm is applied for optimal design of SMB and Varicol processes.The research shows that,compared with Standard PSO and Genetic algorithm(GA),Linear Decreasing Inertial Weight PSO(LDIWPSO)can give better optimization results.Distributing too many columns into the separation zone makes against the improvement of separation performances.The configuration has a great influence on the performance of SMB process.The consumption of desorbent and the number of columns in separation zone gradually increase with the increase of separation load.Finally,the separation of o-vanillin and its isomeride,vanillin,by 3-zone simulated moving bed is studied.In the first part of this research,the bed-porosity of preparative reversed-phase chromatography column is determined by the method named TPB(Total pore blocking).The competitive Langmuir adsorption isotherms are determined by fitting the adsorption data of one-component frontal analysis with the least square method.The diffusion coefficient and mass transfer coefficient are estimated by empirical equations obtained from literature.Based on these parameters,the mathematical models of synchronous and asynchronous SMB processes are built respectively.Five sets of operating parameters located in the complete separation region of Triangle Theory are selected.The results of simulation and experiment showed that the design based on Triangle Theory is not reliable while the diffusion and mass transfer resistence are not ignorable.Therefore,LDIWPSO is applied for optimal design of operating parameters to maximize the feed flowrate,with the flowrate of zone I fixed at 2.0 mL/min and the constraints of the two product purities higher than 99.5%.The maximum feed flowrate is obtained to be 0.481 mL/min in the synchronous mode with a column configuration of[1/1/2].The maximum feed flowrate is 0.551 mL/min in the asynchronous mode with an average column configuration of[1.10/1.27/1.63],which is 14.6%higher than that in the synchronous mode.The experimental purities of both products are higher than 99%on the two sets of operation conditions optimized.