Study On Removal Of Organic Chlorine From Naphtha By Molecular Sieve Adsorption

The content of organic chlorine in naphtha is very small but it is harmful.Chloroform,cellon and chloroben are the highest and representative organic chlorine content in naphtha.The organic chlorine is difficult to be removed from the traditional method of electric desalting.The more mature technology in industry is to convert organic chlorine into inorganic chlorine and then remove it.This paper aims at the direct removal of organic chlorine.Using n-hexane as a simulant for naphtha,added three kinds of organic chlorine,chloroform,cellon and chloroben.Then a naphtha simulate oil containing a variety of organic chlorine is prepared.The experimental study of adsorption and dechlorination was carried out by using naphtha simulated oil as the base oil,and molecular sieves and different metal ions modified molecular sieves as adsorbents.The adsorption of organic chlorine by molecular sieve before and after modification was studied.The modification conditions and adsorption conditions of the modified molecular sieve were optimized.The adsorption kinetics and thermodynamics of the modified molecular sieves were studied and analyzed.The modified molecular sieve was analyzed by means of XRD,SEM,BET,NH3-TPD and so on.The effect of ion modification on the adsorption process was studied,and the adsorption mechanism of organic chlorine adsorbed by modified adsorbents was studied.It is found that the adsorption dechlorination ability of 13X molecular sieves is the strongest among the selected adsorbents of ZSM-5,NaY,13X,MCM-22 and activated carbon.The Zn2+,Co2+,Ni2+ and Ag+ metal ions were used to modify the 13X molecular sieve.The adsorption experiment showed that the removal of organic chlorine by 13X molecular sieve after Ag+ ion modification was the best.The molecular sieve modified by Ag+ ions reduces the activation energy required for the adsorption process.It is indicated that the addition of Ag+ has a similar effect to the catalyst,which makes the adsorption process easier to carry out.And the addition of Ag+ ions reduces the influence of temperature on adsorption during the adsorption process.The characterization results showed that the addition of Ag+ ions enhanced the polarity of the molecular sieves.And the whole adsorption process is very rapid and selective.The addition of low carbon organic molecules can promote the adsorption of organic chlorine by molecular sieve.