Study On The Synthesis Of Phthalazinone-based Microporous Organic Polymers And Their CO₂ Capture/Separation Properties

The imperatives of global warming and ocean acidification,due to the escalation concentration of greenhouse gas CO2 for the extensive consumption of the fossil fuels,have attracted great attention and widespread public concerns over the last decades.However,trodational aqueous amine solution method exhibits the unavoided corrosion,volatility and also the high energy cost in desorption process for the chemical adsorption nature.Therefore,it seems that appropriate carbon capture and storage(CCS)technologies with low-cost,efficient,and durable performance are of great importance in both environmental and economic aspects.Those merits such as high specific surface areas,low skeletal densities,various structures,and porosity and functional flexibility for rational design endow microporous organic polymers(MOPs)excellent application potential in CCS field,accompany with energy efficiency advantage for their physical adsorption process.In this thesis,the original novel phthalazinone structure with rigid,twisted,asymmetric,and hetrocycle characters was selectied as the core unit.Then,various phthalazinone-based MOPs with superior gas adsorption and separation properties were developed and the influence toward the porosities and gas adsorption and separation properties were systermatically evaluated and investigated in term of the structure diversities of the building blocks.The main contents are exhibited as follows:Fisrt of all,two fully rigid dicyano building blocks containing phthalazinone structure,PHPZ-DN and THPZ-DND were designed and synthesized successfully.Following,new classes of phthalazinone core-based covalent triazine frameworks(PHCTF-1 and PHCTFF-2)were prepared by ionothermal reaction using the ZnCl2 catalyst and stepwise heating procedure in the high temperature and vaccum system.The impacts of the catalyst ratios and reaction temperatures on the the porosity and gas adsorption and separation properties were also considered.PHCTF-lc showed the highest surface area(1845 m2 g-1)constructed at 600 ?with the broad pore size distribution.Although PHCTF-2 materials showed the decreased surface areas for the smaller dihedral angle between the naphthyridine and thiophene of the building block THPZ-DN,they exhibited the smaller pore sizes locating in the ultramicropore region.This results reflect the consideration of regulating the porosities by the rational molecular design pathway.These materials illustrated very good CO2 adsorption and separation properties for the heterocycle chemical composite of the phthalazinone and triazine,also the microporosity,with the CO2 uptake up to 17.1 wt%at 273 K/1 bar.At the same time,PHCTF-2 exhibited above 13 wt%CO2 uptakes together with the superior CO2/N2 up to 52(intial slop method)because of enthanced molecular sieving effect.Next,a novel tricyano triphenylamine functional phthalazinone building block TPAHPZ-TN was easily synthesized by simple and low-cost aromatic nucleophilic substribution reaction to reduce the reactants cost and increase the CCS properties of PHCTFs.And the PHCTF-8s were prepared by the same ionothermal method at the different reaction temperature.The three functional groups increased the crosslinking density,further enhancing the surface areas in the range of 1188 to 1665 11m2 g-1.The centrosymmetric conformation of the building block molecular structure is in favor of maintaining the uniform pore size distributions,dominated the microporous distributions even in the high reaction temperatures,also the micropore volumes.The high specific surface areas,superior porosities,and electron-rich N-heterocycle skeleton feature are responsible for the high CO2 storage capacity of these materials up to 17.8 w%at 273 K/1 bar,furthermore the very competitive CO2 uptake up to 11.2 wt%at 298 K/l bar and a high capacity(5.7 wt%)at low pressures at 273 K/0.15 bar.Meanwhile,the materials also show the very good CO2 separation properties with CO2/N2 up t0 142(LAST).These results further indicate that MOPs with superior gas adsorption and separation properties can be obtaioned by the rational molecular design.Following,we drop the traditional thought that just the full rigid building blocks will be used to construct MOP materials,then the flexible molecules being taken into account.Based on this idea,PHCTF-3-7 materials were successfully prepared by five flexible dicyano building blocks,DHPZ-DN,MDHPZ-DN(single methyl),DMDHPZ-DN(double methyl),PHPZ-DN(single phenyl)and DPHPZ-DN(double phenyl),with different substituents.The surface area of PHCTF-3 material decrases to 676 m2 g-1,for the existence of the flexiblility of the building block.Then,the creative introduction of the substituents can effectively decrease the probility of the nework interpenetration from the longer struts and the inter-/intramolecular interaction from the increased degree of conformation freedom in the flexible ether linkage,which favors the formation of the high surface areas of PHCTF-4-7 in the range of 835?1270 m2 g-1.Furthermore,the size(methyl or phenyl group)and amount(one or two)of substituents affected the porosities and the gas adsorption and separation properties of the target polymer networks.These materials also show the good CO2 adsorption properties up to 10.3 wt%and separation performance,CO2/N2 uP t0 138(IAST)for theN,O-rich and microporous natures.These results can not only further expand the selection range of the building blocks,but also increase the designablility of the phthalazinone moiety and promote its application in the field of constructing MOP materials.Finally,considering the abovementioned crosslinked PHCTFs with not easy processing disadvantages,a series of linear soluble phthalazinone-based copolymers with intrinsic microporosity(PHPIMs)were synthesized from the a novel rigid and twisty tetrahydroxyl-phthalazinone building block TPHPZ.Apart from the very good solubility,these materials also exhibited the high surface areas in the range of 693 to 812 m2 g-1 with micropore distributions.Such copolymer membrane materials possess high gas pemeabilities and CO2 permeabilities locating in the range of 1850 to 4627 barrern PHPIMs membranes demonstrated an improvement in the gas ideal selectivities,while accompanying the decrease of the permeability for the increase of the phthalazinone content.The PHPIM061 and PHPIM041 membranes surpass the 2008 Robeson plot for the gas pair CO2/CH4 and approach the upper bound for gas pairs H2/N2 and O2/N2.Meanwhile,the cas of PHPIMs showed an uptrend with the increased phthalazinone content for the rich heteroatoms.Systematical investigation of the structure-property relationship of phthalazinone-based PHPIMs indicates that the twisted,non-coplanar and heterocyclic phthalazinone moiety can be used to tune the inter-chain spacing and molecular packing,and thus to adjust the separation parameters and performance of the intrinsic microporous polymer membranes to meet the requirement of gas separation.