Removal Of Organochlorine From Naphtha By Modified Adsorbent

At present,due to the reduction of crude oil reserves,oil extraction has become very difficult.In order to increase the oil recovery rate,some chlorinated hydrocarbon-containing oil recovery auxiliaries were often added,resulting in a significant increase in the content of organic chlorine in naphtha.Some organic chlorides form a HCl by chemical reaction,which further accelerates the corrosion of the equipment.And organic chlorine can easily lead to permanent inactivation of the catalyst poisoning.Therefore,this paper mainly focuses on the removal of organic chlorine in naphtha.13X,ZSM-5,activated carbon?AC?,Al₂O₃,MCM-22,NaY were selected as carriers to carry out the experimental study on removal of organic chlorine.The experimental results show that the dechlorination ability of 13X and ZSM-5 molecular sieves was better than other carriers.Further research on the use of metal ions for molecular sieve modification,the preparation of some new modified adsorbents to improve the ability to remove chloride.The 13X and ZSM-5 molecular sieves were modified by impregnation method,and the modified metal ions were Mg²⁺and Fe³⁺,and the adsorbents modified by different metal ions were prepared.It was found through experiments that the dechlorination effect of the adsorbent modified by the two metal ions of Mg²⁺and Fe³⁺was the best.The prepared adsorbents were analyzed by XRD,N₂ adsorption-desorption,TD-DTA,XRF and other characterization techniques.The characterization results show that the two metal ions of Mg²⁺and Fe³⁺were successfully loaded on the surface of the molecular sieve.The structure of the modified molecular sieve was not destroyed,but the pore size,pore volume and specific surface area of the adsorbent were changed.By investigating the dechlorination experiment of naphtha by modified adsorbent,the optimal process conditions were obtained:the adsorbent was calcined at 550?for 4h,the adsorption reaction time was 2h,the naphtha dosage was 30mL,and the adsorbent was1mL.When the adsorption temperature was 60?,the dechlorination rate of naphtha was the highest,reaching 98.7%.The removal of different organic chlorides in the simulated oil by the modified adsorbent was investigated,which showed that the removal of CH₂Cl₂ was the best.After 5 times of using the modified adsorbent,the dechlorination effect can still reach more than75%.The first-and second-order adsorption kinetic models were fitted to the simulated oil dechlorination process respectively.The correlation coefficient of the first-order kinetics R²<0.85 indicates that the reliability of the fit was not high.The correlation coefficient of the fitted second-order adsorption kinetics was R²>0.99,indicating that the adsorption dechlorination process conforms to the second-order adsorption kinetics,and the activation energy of the adsorption reaction was less than 40kJ/mol.It can be seen from the activation energy that the modified adsorbent was mainly for physical adsorption,the comparison shows that the adsorption reaction was easier to carry out after the modification.