Performance And Optimization Of Packing Surface Loading CALB

Green chemistry is the inevitable development direction of chemical industry,material and so on.Bioenzyme catalysis has the advantages of green environmental protection and good catalytic performance.To overcome the shortcomings of poor stability of free enzyme and difficulty of recovery,spraying method was used to immobilize the sol loaded with Candida antarctica B（CALB）on random packing（316L stainless steel mesh）to form enzyme-loaded packing for the esterification reaction of ethyl acetate with n-butanol.The long-lasting effect of immobilized enzyme on random packing is an important factor influencing the development of enzyme catalytic distillation.In order to improve the long-term effect of the enzyme-loaded packing,the formulation of the enzyme-loaded coating was further optimized.The coating of the enzyme-loaded packing after multiple reactions in the small distillation column was studied and its determination and characterization were carried out.Compared to the original immobilized enzyme,Fourier infrared spectroscopy showed that the peak caused by the NH₂ bending of CALB at 3420.77 cm^-1 almost disappeared,proving that the immobilized enzyme gel network was still present qualitatively,but the enzyme was almost completely lost.Energy spectrograms showed a decrease of 77.17%in the N element,which can prove that the enzyme shedding is serious.Poor enzyme stability becomes the primary problem to be solved.Five groups of formulations were prepared and compared by adding silane coupling agent 3-urea-propyltrimethoxysilane（UPS）to the sol formulation.It can be seen from the x-ray photoelectron spectroscopy that the UPS grafting on the sol produces new reaction sites for the NH₂ group.It can be observed from FT-IR,the N-H stretching vibration at3400 cm^-1 shifted to low wavelength due to the combination of amino and carboxyl groups.At 1556 cm^-1,the N-H stretching was more intense,indicating that the amino group bonded with CALB,and the electrostatic attraction between the charged active amino group and the lipase carboxyl group was the main reason for lipase immobilization.The ionic bond binding of UPS to the enzyme can improve the stability of the enzyme.The properties of modified enzyme-loaded coatings were studied.By means of scratch resistance test and solvent resistance test,the effect of UPS treatment on the performance of enzyme coating was studied.The anti-scratch experiment proved that the modification improved the adhesion of the carrier enzyme coating on the random packing and significantly improved the adhesion of the carrier enzyme coating.Finally,25%UPS was selected as the best proportion formula,and the repeatability experiment showed that the modification improved the repeatability of the loaded enzyme packing in the esterification reaction.The paper proposed a feasible method to immobilize the coating on random packing to form excellent surface properties by modification,which provides a promising approach for enzymatic catalytic reaction distillation and lays a foundation for green production.Kinetics of the modified immobilized enzyme CALB catalyzed the transesterification of ethyl acetate with n-butyl esters.The effect of stirring speed,catalyst dosage,alkyd molar ratio,reaction temperature and other reaction conditions on the reaction process were investigated in the batch stirred kettle reactor.The second-order pseudo-homogeneous dynamics model is established,and the kinetic equation is determined by using least square method to fit the kinetic data.