Research On Deep Removal Of Formaldehyde From Hydrogen By Adsorption

As a clean energy and secondary energy with great development potential,the development of hydrogen energy in the fuel cell sector has received extensive attention from various countries.The hydrogen used for fuel cells will contain a small amount of formaldehyde(HCHO)during the production process,especially in the process of reforming natural gas or methanol to hydrogen;its presence will poison the electrodes in the hydrogen fuel cell and affect the service life of the battery.In this paper,the preparation method and adsorption performance of the adsorbent for the deep removal of trace HCHO in hydrogen is mainly studied.Firstly,the removal performance of activated carbon(AC),13 X molecular sieve,and macroporous alumina for trace HCHO in hydrogen is compared.It is found that AC has the best effect on trace HCHO in hydrogen.After that,the adsorbent carrier was modified by different methods,and the adsorbent was characterized and analyzed by XRD,SEM,TEM,BET,Fourier Transforms Infrared,and Thermogravimetry.Finally,the dynamic adsorption evaluation of the adsorbent was carried out with hydrogen-containing trace HCHO as the feed gas.It was found that.The modification of AC surface loaded with metals(Ag,Mn,Cu,Zn,Ni)can not significantly improve the adsorption capacity of AC.Among them,the adsorption effect of AC loaded with Mn,Cu,and Ni on HCHO is reduced,while the removal rate of HCHO can be improved faster after loading with metals Zn and Ag.When Ag nanoparticles are loaded in AC,the adsorption capacity of the adsorbent is improved to a certain extent.Acid-base treatment of AC(nitric acid,oxalic acid,and ammonia)can effectively increase the specific surface area and pore volume of adsorbent,and then improve the adsorption capacity and removal rate of HCHO.Among them,the AC treated with ammonia has the best adsorption performance.Different organic functional groups were further modified on the surface of the acid-base modified adsorbent.It was found that the existence of functional groups containing N and O could effectively improve the chemical adsorption of HCHO,and the adsorbent modified by ethylenediamine after ammonia treatment had the best effect.The preparation method of the above ammonia / ethylenediamine AC adsorbent was further optimized.It was found that the adsorbent obtained by equal volume step-by-step impregnation with 0.5 mol/L ammonia and ethylenediamine(ratio: 1:1)had the highest adsorption capacity for HCHO,which could reach 61.9 mg/g,and the formaldehyde removal rate was 100% in about 30 hours.