Adsorptive Removal Of Nitrogen-Containing Compounds From Fuel

With the increasingly stringent environmental regulations,the removal of nitrogen compounds from fuel has become a more and more important research subject.In order to meet more stringent fuel regulation,the traditional hydrodenitrogenation technology is facing serious challenge.Therefore,the economic and efficient non-hydrodenitrogenation technologies are researched world wide,such as extraction denitrogenation,adsorptive denitrogenation,oxidative denitrogenation.The adsorptive denitrogenation technology can remove nitrogen-containing compounds efficiently under mild conditions,so it can be applied widely.The feasibility of using microporous and mesoporous materials as the adsorbents to remove nitrogen-containing compounds(NCCs) in fuel oil,such as pyridine,quinoline,pyrrole, indole and so on,was explored.Several mesoporous molecular sieves were chosen as the adsorbents for the adsorptive denitrogenation in this paper.Effect of adsorption time, temperature and ratio of adsorbent to oil(A/O) on the removal of NCCs was investigated. Meanwhile,the adsorption isotherms and adsorption thermodynamics of NCCs over Ti-HMS were studied.The thermodynamic functions results show that the adsorption of NCCs on Ti-HMS is an exothermic,irregularity decreased,spontaneous and physical process. Furthermore,the adsorption process primarily occurs in the pores of Ti-HMS.Adsorptive denitrogenation of model fuel and commercial diesel over three typical adsorbents(Ti-HMS,HMS,and MCM-41) in a fixed-bed adsorption system was also studied at ambient pressure in this paper.The adsorptive capacity for the various compounds were examined and compared on the basis of the breakthrough curves.With the increasing of temperature and liquid hourly space velocity(LHSV),the time taken to reach the adsorption saturation grew shorter.Ti-HMS showed the better adsorptive performance than HMS and MCM-41 on the removal of NCCs.The adsorbent MCM-41 showed higher selectivity on neutral compounds especially for indole.This result well illustrated that different adsorption mechanism may be suitable for separating different nitrogen compounds over adsorbents.The employed adsorbents could recover adsorptive active sites after regeneration by ethanol washing.