Study On Adsorption Of 1,2-dichlorobenzeneand Carbon Tetrachloride From Naphtha

Recent years,the organic chlorine in naphtha is excessive in many refineries.Excessive chloride can cause the clogging and corrosion of the piping of the catalytic reforming device.In this research,zeolites and modified were used as the adsorbent to adsorb the organic chlorine by the static adsorption method.The chlorine removal rate and the amount of equilibrium adsorption were measured,the adsorbent were characterized by XRD,BET,SEM,NH3-TPD and TGA.Determined the optimum conditions for the adsorbent and the adsorption process.The adsorption isotherm of 1,2-dichlorobenzene and carbon tetrachloride were measured and fitted and got the thermodynamic parameters.Used the kinetic models to fit the process to determine the adsorption kinetic parameters,preliminarily analyzed the mechanism of the adsorption process.The results showed that,in the process of the 1,2-dichlorobenzene adsorption,the pore structure of zeolites determined its dechlorination performance.The introduction of metal ions can greatly enhance the dechlorination performance of zeolites,Cu13X zeolite was the best adsorbent to adsorbed 1,2-dichlorobenzene.The chlorine removal rate was 87.95%and equilibrium adsorption capacity was 3.88mg/g under the optimal condition.The adsorption isotherm of Cu13X zeolites to adsorb 1,2-dichlorobenzene can be simulated by the Freundlich isotherm equation.The thermodynamic parameter were calculated,AH=-40.06 kJ/mol,AS=-80.56 J/(mol K)and AG<0.The pseudo second-order kinetic equation can describe the adsorption process,the adsorption activation energy was 18.059 kJ/mol according to the equation.In the process of the carbon tetrachloride adsorption,activated carbon and 13X have a better adsorption effect on carbon tetrachloride compared to other adsorbents,but the removal effect was also not good,the removal rate was 38%.The removal effect of 13X zeolite on carbon tetrachloride did not improve after modified metal ions.But the removal effect of the activated carbon on carbon tetrachloride improved significantly after modified by nitric acid solution with a mass fraction of 20%,the chlorine removal rate was 60.84%and equilibrium adsorption capacity was 6.13mg/g.The adsorption isotherm of modified activated carbon to adsorb carbon tetrachloride can be simulated by the Freundlich isotherm equation.The thermodynamic parameter were calculated,AH=-14.2 kJ/mol,?S=-42.68 J/(mol K)and ?G<0.The pseudo second-order kinetic equation can describe the adsorption process,the adsorption activation energy was 16.114 kJ/mol according to the equation.