Selective Adsorption for Removal of Nitrogen Compounds from Liquid Hydrocarbon Streams over Carbon- and Alumina-Based Adsorbents

Abstract

In order to explore the adsorptive denitrogenation of liquid hydrocarbon streams for producing ultraclean fuels, the adsorption performance of seven representative activated carbon samples and three activated alumina samples was evaluated in a batch adsorption system and a fixed-bed flow adsorption system for removing quinoline and indole from a model diesel fuel in the coexistence of sulfur compounds and aromatics. Different adsorbents show quite different selectivity toward basic and nonbasic nitrogen compounds (quinoline and indole) and sulfur compounds (dibenzothiophene and 4,6-dimethyldibenzothiophene). The activated carbons generally show higher capacity than activated alumina samples for removing the nitrogen compounds. The adsorption capacity and selectivity of the activated carbons for nitrogen compounds were further correlated with their textural properties and oxygen content. It was found that (1) the microporous surface area and micropore volume are not a key factor for removal of the nitrogen compounds in the tested activated carbons; (2) the oxygen functionality of the activated carbons may play a more important role in determining the adsorption capacity for the nitrogen compounds since the adsorption capacity for nitrogen compounds increases with increase in the oxygen concentration of the activated carbons; and (3) the type of the oxygen-functional groups may be crucial in determining their selectivity for various nitrogen or sulfur compounds. In addition, regeneration of the saturated adsorbents was conducted by the toluene washing followed by the heating to remove the remained toluene. The results show that the spent activated carbons can be regenerated to completely recover the adsorption capacity. The high capacity and selectivity of carbon-based adsorbents for the nitrogen compounds, along with their good regenerability, indicate that the activated carbons may be promising adsorbents for deep denitrogenation of liquid hydrocarbon streams.

Trace Analysis of Carbazole in Commercial Diesel by using Adsorption on Activated Biochar from Rice Husk Pyrolysis

“…ACs exhibit excellent adsorption performance in the process of nitrogen and sulfur removal from many different matrices and are the most used adsorbents [30,31]. Adsorptive denitrogenation and desulphurization is considered promising methodology when compared with the conventional hydrodenitrogenation and hydrodesulphurization process, because it can be run at ambient conditions without using hydrogen and catalysts [32].…”

Remarkable improvement in adsorptive denitrogenation of model fossil fuels with CuCl/activated carbon, prepared under ambient condition

“…In this process, SCCs are treated with hydrogen, and H 2 S gas is produced, which can be easily separated from the fuel feed. However, before removing the SCCs, NCCs should be removed first because NCCs in the fuel reduce the efficiency of the HDS process by competing to attack the catalytically active sites of the catalysts and hence block and deactivate the catalytic capability of the HDS process [6][7][8]. Currently, NCCs from fossil fuels are usually removed by a hydrodenitrogenation (HDN) technique.…”

“…For example, this process requires large amounts of expensive hydrogen and is carried out at high temperature and pressure and, therefore, is not cost effective. In addition, compared to HDS, HDN is a kinetically slow multistep process because hydrogenation of heterocyclic rings (containing nitrogen) is required [7][8][9]. At this point in time, development of an economically feasible and selective NCC removal method is crucially needed, and adsorptive denitrogenation (ADN) may be one of the options to serve this purpose.…”

Core–Shell Magnetic Molecularly Imprinted Polymer Prepared for Selectively Removed Indole from Fuel Oil

“…10,11 As an alternative method, adsorption appears to be a promising approach to ultradeep denitrogenating because it can be run at ambient temperature and atmospheric pressure. [12][13][14] The molecular imprinting technique (MIT) has attracted attention recently for its outstanding advantages, such as predetermined recognition ability, stability, and low cost of preparation. 15 It has been applied to a wide range of target molecules in the field of chromatography, solid phase extraction, controlled drug release, and sensor devices.…”