Preparation Of MOF Materials By Microchannel Reactor And Its Properties

Metal-organic frameworks（MOFs）are new porous materials with structural diversity,high porosity,large specific surface area,adjustable unsaturated metal sites and good design.Therefore,it is widely used in gas adsorption and separation,sensors,catalysis and energy storage fields.At present,the main preparation methods of MOFs materials include direct mixing method,solvothermal method,microwave method and ultrasonic method.However,these methods are intermittent and time-consuming,which greatly increases the production time and cost of MOFs synthesis.At the same time,the synthesis of MOFs generally requires a large number of organic solvents,which will cause serious pollution to the environment.Therefore,reducing the use of organic solvents will make the synthesis of MOFs more green and environmentally friendly.In this thesis,using highly efficient continuous microchannel reactor in different solvent to synthesize a series of MOFs materials,and by reducing the proportion of organic solvents were used to study the influences of solvent for MOFs synthesis,further synthesis of MOFs materials used in different fields are studied,at the same time using the density functional theory calculations for the related mechanism is verified.The related research contents are as follows:（1）Enhanced oxygen reduction reaction performance of Co@N-C derived from metal-organic frameworks ZIF-67 via a continuous microchannel reactor.In this work,microchannel reactor is used to prepare MOFs-derived zeolite-imidazole material via flash nanoprecipitation to form ZIF-67+PEI（FNP）,which reduces the MOF synthesis time down to millisecond time interval while keeping the synthesized ZIF-67+PEI（FNP）highly dispersed.Electrochemical tests show that the Co@N-C（FNP）catalyst prepared by this method has excellent oxygen reduction performance,good methanol resistance and high stability.Moreover,the performance of Zn-air battery assembled using Co@N-C（FNP）catalyst is superior to Pt/C.Density functional theory（DFT）calculations confirm that the Co（2 2 0）crystal plane present in Co@N-C（FNP）have stronger adsorption energy than that of Co（1 1 1）crystal plane in Co@N-C（DM）,leading to better electrocatalytic performance of the former.（2）Facile synthesis of metal organic framework ZIF-67 via a multi-inlet vortex mixer using various solvents:Me OH,Et OH,H₂O and Baijiu.In this work use the multi-inlet mortex mixer（MIVM）with Me OH,Et OH,H₂O,Baijiu,respectively,were synthesized by Co-MOF.MOFs materials were synthesized by using Baijiu as solvent for the first time.Using Baijiu as solvent reduced the synthetic conditions of MOF materials.The catalyst Co@N-C-FNP-Baijiu prepared by carbonization of ZIF-67-FNP-Baijiu with Baijiu as the solvent has a onset potential of 0.93 V_RHE and a half-wave potential of 0.82 V_RHE.Moreover,the performance of Zn-air battery assembled using Co@N-C（FNP）catalyst is superior to Pt/C.（3）Preparation of ZIFs with low proportion organic solvent in a microchannel reactor for CO₂adsorption and its first principle study.In this work,a series of different types of ZIFs were synthesized using a microchannel reactor with different proportions of methanol and water as solvents.Compared with the direct mixing method,the microchannel reactor can synthesize ZIFs structure in any proportion of mixed solvents,and it is found that different solvents have a great influence on the morphology of ZIFs.DFT calculation results show that three-dimensional structure is easier to be formed in methanol solvent.In aqueous solvents it’s two-dimensional.However,in aqueous solvent,the growth stops due to the sudden increase of free energy in the coordination process,so the two-dimensional structure appears in aqueous solution.Finally,CO₂ adsorption study on the synthesized ZIFs showed that ZIFs with more mesoporous structures had better adsorption performance.