Synthesis Of Porous Polymers Containing Metals And Their Application In Hydrogen Storage

Porous polymers not only have the characteristics of common polymers, including light skeletal density (usually only contain light weight elements, such as C, H, O, N etc) and high structure flexibility, but also have the unique high surface areas and pore structure, and have been applied in many areas, including gas storage and separation, catalyst support, drug delivery, microelectronics and biomedical devices, and templates. The transitional metals have unique advantages in catalysis and hydrogen combination. Thus, porous polymers containing metals have broad application prospect in hydrogen storage.In this thesis, we have focused on the synthesis and hydrogen storage properties of the porous polymers containing metals, in view of their preparation, porous structure and hydrogen adsorption.(1)Two kinds of hypercrosslinked porous polystyrenes containing different metal elements (Pt-HCLPS and Pd-HCLPS) were synthesized. The morphology of metal-doped porous polymers was determined by XRD, SEM, and TEM. TGA was used to study their thermal stability and metal content. The hydrogen storage capacities of metal-doped porous polystyrenes were discussed as well. We found that after doping metal nanoparticles, the porous polymers gave stronger interaction with the H2molecules and enhanced the hydrogen adsorption capacities. The morphology of porous polystyrenes was not changed after embedding Pt/Pd nanoparticles on outer surfaces and internal pore channels. Smaller and better dispersion metal nanoparticles can be obtained by spontaneous redox reaction with the aid of ultrasonication compared with polyol reduction under conventional heating. The BET surface areas and pore volumes were decreased after metal embedding, however, hydrogen adsorption capacities were increased. This was led by the "hydrogen spillover", in which H2molecules were dissociated on metal nanoparticles and subsequent migration of hydrogen atoms onto adjacent surfaces. The hydrogen storage capacities were affected by the metal content. The maximum hydrogen uptake of Pt-HCLPS and Pd-HCLPS were1.32wt%and1.46wt%, respectively (163K,0-3.1MPa). (2)Ferrocenyl porous polymers were prepared from bifunctional methyl chloride monomer (BCMBP) and dibenzylferrocene, based on the Friedel-Crafts alkylation reaction. The morphology and pore structure of ferrocenyl polymers could be tuned by simply change the mole ratio of the two monomers. With the content of dibenzylferrocene increased, the morphology of polymer surface gradually became rough. The porosity in the polymers was confirmed by N2adsoption/desorption isotherms and mesopores appeared with dibenzylferrocene increasing. The BET surface areas of ferrocenyl porous polymers were in the range of133.2-887.7m2/g, with the average micropore diameter in the range of1.44-1.55nm. Mesopores appeared in sample25-poly-(DBzy1Fc-co-BCMBP) and40-poly-(DBzy1Fc-co-BCMBP) with the average mesopre diameter of3.78nm and3.73nm, respectively. The maximum hydrogen uptakes of ferrocenyl porous polymers were3.94wt%at163K and3.56wt%at173K (0-3.1MPa).