Preparation And Catalytic Performance Of Carbon Nanotube-Ni Foam Immobilized Enzyme Catalyst

Objective: A novel monolithic f CNTs-Ni foam immobilized lipase composite catalyst was prepared,by employing the 1-Pyrenebutyric acid(Py BA)modified carbon nanotubes(CNTs)-Ni foam(denoted as f CNTs-Ni foam)as catalyst support.This composite catalyst shows high catalytic performance in biocatalysis,such as the synthesis of cinnamate acetate.Methods:1.Preparation and characterization of f CNTs-Ni foam immobilized lipase composite catalyst.The CNTs-Ni foam support was modified by Py BA,then the novel f CNTs-Ni foam immobilized lipase composite catalyst was prepared through the chemical bonding between the carrier surface and lipase molecule.The structure,morphology and composition of immobilized lipase were also investigated by using FESEM,TEM,FTIR,XPS and EDS.2.Catalytic performance of fCNTs-Ni foam immobilized lipase composite catalyst.The catalytic performance evaluations of immobilized lipases were conducted both in batch reactor and continuous flow microreactor,by employing the hydrolysis of p-NPP as model reaction.3.The application of fCNTs-Ni foam immobilized lipase composite catalyst for cinnamyl acetate synthesis.The application of fCNTs-Ni foam immobilized lipase composite catalyst for cinnamyl acetate synthesis was conducted.The reaction conditions(reactant concentration,temperature,space velocity etc.)were optimized to establish a better immobilized lipase catalyst system.Results:1.FTIR spectra results indicated that much carboxyl groups were obtained on the surface of carbon nanotubes in CNTs-Ni foam carriers after Py BA treatment,and the lipases were immobilized on the surface of support through covalent bonds.SWCA tests showed that the hydrophilic properties of CNTs-Ni foam carriers were greatly improved by the introduction of carboxyl groups.FESEM,TEM,XPS and elemental analysis results showed that lipase could be immobilized and highly dispersed on the surface of carbon nanotubes in CNTs-Ni foam support.Further analysis by circular dichroism(CD)spectra indicated that immobilization of lipase on the surface of carrier modified by Py BA could better remain the original structures of enzyme.2.The catalytic activity of the immobilized enzyme was influenced by the support surface properties significantly.A great catalytic activity enhancement of immobilized lipase was found,by introducing the carboxyl on the surface of CNTs-f CNTs-Ni foam after Py BA treatment.The catalytic performance tests indicated that this immobilized lipase presented high catalytic activity,catalytic stability and good thermal stability in organic solvent.A higher catalytic performance was observed for f CNTs-Ni foam immobilized lipase in micro reactor system than that in traditional batch reactor system.3.The fCNTs-Ni foam immobilized lipase showed a good catalytic activity in biosynthesis of cinnamyl acetate.The high conversion of about 90 % for cinnamyl alcohol and excellent catalytic stability was observed.Conclusion: A novel monolithic f CNTs-Ni foam immobilized lipase composite catalyst was prepared.This composite catalyst showed an excellent catalytic performance(high catalytic efficiency and good stability)both in p-NPP hydrolysis and cinnamyl acetate synthesis,making it to be a promising candidate for biocatalysis in industrial application.