Article pubs.acs.org/IC
Scandium-Triflate/Metal−Organic Frameworks: Remarkable Adsorbents for Desulfurization and Denitrogenation Nazmul Abedin Khan and Sung Hwa Jhung* Department of Chemistry and Green-Nano Materials Research Center, Kyungpook National University, Daegu 702-701, Republic of Korea S Supporting Information *
ABSTRACT: Scandium-triflate (Sc(OTf)3) was introduced for the first time on metal−organic frameworks (MOFs), to utilize acidic Sc(OTf)3 for adsorptive desulfurization and denitrogenation of fuel containing benzothiophene (BT), dibenzothiophene (DBT), quinoline (QUI), and indole (IND). A remarkable improvement in the adsorption capacity (about 65% based on the weight of adsorbents; 90% based on the surface area of the adsorbents) was observed with the Sc(OTf)3/MOFs as compared to the virgin MOFs for the adsorption of BT from liquid fuel. The basic QUI was also adsorbed preferentially onto the acidic Sc(OTf)3/MOFs. However, nonsupported Sc(OTf)3 showed negligible adsorption capacities. The improved adsorptive performance for BT, DBT, and QUI might be derived from acid−base interactions between the acidic Sc(OTf)3 and basic adsorbates. On the other hand, the Sc(OTf)3, loaded on MOFs, reduced the adsorption capacity for neutral IND due to lack of interaction between the neutral adsorbate and acidic adsorbent and the reduced porosities of the modified adsorbents. The reusability of the adsorbents was found satisfactory up to the fourth run. On the basis of the result, it is suggested that metal-triflates, such as Sc(OTf)3, can be prospective materials for adsorptive desulfurization/ denitrogenation of fuels when supported on porous materials such as MOFs.
1. INTRODUCTION Sulfur- or nitrogen-containing organic compounds (SCCs or NCCs) are commonly present in crude fuels at very low levels. Recently, there has been a considerable demand to reduce these organic compounds in commercial diesel or gasoline to extreamely low levels to prevent air pollution due to emission of sulfur or nitrogen oxides (SOx or NOx) and deactivation of various catalysts. In addition, for fuel cell applications, ultralow sulfur levels (
