Optimized Synthesis And Shaping Of Anion-pillared Ultramicroporous Materials With Pyrazine Linker For Gas Separation

As a kind of anion-functionalized metal organic frameworks,anion-pillared ultramicroporous materials have made significant achievements in separation for light hydrocarbons due to its excellent performance.SIFSIX-3-Ni(SIFSIX=SiF62-,3=Pyrazine)whose raw materials are inexpensive and easily obtained,has great hydrothermal stability,showing good prospect for industrial applications.Large-scale preparation and shaping are the key factors for industrialization.However,issues like low loading and degradation of adsorption performance are widespread in previous researches.Synthesis methods of SIFSIX-3-Ni was systematically optimized by this dissertation.Besides,a novel shaping method by using polyvinyl butyral(PVB)as binder for achieved high loading and maintaining adsorption performance,has been described,in order to provided basic data for potential applications of anion-pillared ultramicroporous materials.In this dissertation,five synthesis methods of SIFSIX-3-Ni were contrasted with reaction conditions,productivity and influence to environment and properties of products.The method which is most applicable to large-scale preparation was systematically optimized by investigating the affects to product structure,adsorption performance and productivity.Also,the recyclability of solvent was investigated to maximize the solvent utilization as well as reduce energy consumption and emissions.It was found that the optimal ratio of SiF62-,Ni2+and pyrazine was 1:1:2 and the average productivity was 82.2%.Products collected after 2 hours had complete structure and the reaction reached equilibrium after 48 hours.Besides,temperature had envident impact on crystallinity,states and productivity.Slurry was gained under 100? whereas powder with high crystallinity was collected at over 100?.The latter could be activated under 140?.Productivity was reduced with the temperature rising.The solvent could be reusable as solvent and the productivity of three recycles were 82.2%,80.1%and 83.5%respectively.For the first time,polyvinyl butyral(PVB)was employed to investigate the shaping of metal organic framework,especially for four anion-pillared ultramicroporous materials(SIFSIX-3-Ni?SIFSIX-2-Cu-i?GeFSIX-2-Cu-i(GeF62-=GeFSIX,2=4,4'-dipyridylacetylene)and TIFSIX-2-Cu-i(TiF62-=TIFSIX)).Adsorption performance,properties and microstructure were characterized before and after pelletilization.It was found that pellets with different sizes and loading as high as 95%could be shaped with PVB.For 90%-loading pellets,the uptake capacity of C2H2 per gram pure MOFs had a 0.56%-0.93%decrease whereas C2H4 uptake decreased by 5.0%-12.5%.Adsorption experiemnts demonstrated that PVB hardly affected the gas with strong adsorption but had relatively great impact on that with weak adsorption.It was observed in SEM images that pellet had compact surface as well as relatively imcompact inner sturcure.The reduced BET indicated that pores blocking might occur during the pelletization.What is more,the characteristic of high CO2 adsorption quantity was kept after pelletization for HKUST-1,Mg-MOF-74 and MIL-101-Cr.The results testify that this facile route is generally valid for different kinds of MOFs.Based on the IAST selectivity and breakthrough experiments,separation performace of pellets was evaluated.SO2 adsorption performance was determined by static adsorption experiments.It was found that all of four materials had an increase in selectivity after shaping,illustrating that pelletilization via PVB could help the separation of C2H2/C2H4(1:99,v/v).Flow rate was 2.5 mL/min during three cycles of breakthrough experiment.Breakthrough times of C2H2 ranged from 54 to 66 mins,whereas C2H4 was 6.5 mins.The obvious discrepancy between breakthrough times of C2H2 and C2H4 proved that SIFSIX-3-Ni@PVB could realize the highly efficient separation for C2H2/C2H4(1:99,v/v)and it had good recyclability.At SO2 partial pressure of 0.002 bar(2000ppm)and 298 K,the SO2 uptake of SIFSIX-3-Ni@PVB were 1.17 mmol/g(95%loding)and 1.03 mmol/g(90%loding),which decreased by 12.8%and 21.4%respectively compared to powder.Those of GeFSIX-2-Cu-i@PVB were 2.25 mmol/g(95%loding)and 1.96 mmol/g(90%loding),which decrease by 3.4%and 12.2%respectively compared to powder.The results proved that anion-pillared ultramicroporous material pellets can accomplish highly efficient removal of SO2 even if at extremely low SO2 concentration.