Adsorptive　removal　of　hydrodesulfurization　inhibitors,　that　is,　nitrogen-containing　compounds　(N-compounds),　was　studied　using　model　fuel　which　contains　carbazole　and　dibenzothiophene　in　an　n-dodecane-toluene　mixture　over　ion-exchange　resins　(IXRs)　in　batch　and　in　fixed-bed　adsorption　systems.　The　adsorptive　capacity　and　selectivity　for　neutral　N-compounds　were　examined.　The　high　affinity　for　neutral　N-compounds　present　in　hydrocarbon　feed　was　explained　by　hydrogen　bonding　between　the　chloride　anion　(with　nonbonding　electrons)　and　the　neutral　N-compounds.　However,　the　presence　of　a　flat　charged　cation,　that　is,　N-alkylated　pyridinium,　is　essential　to　ensure　the　adsorption　of　neutral　N-compounds.　The　regeneration　of　the　sorbent　could　be　easily　performed　using　polar　organic　solvent　like　methanol.　Commercially　available　IXR　bearing　pyridinium　chloride　functionality　(HPQ)　was　further　evaluated　with　straight-run　fuel　oil.　The　N/S　selectivity　decreases,　but　analysis　of　the　adsorbed　compounds　by　gas　chromatography/mass　spectroscopy　(GC/MS)　shows　that　no　paraffin　and　no　monoaromatics　were　adsorbed.　The　results　obtained　provided　new　insight　into　the　fundamental　understanding　of　the　adsorption　mechanism　of　neutral　N-compounds　from　hydrocarbon　feed.　©　2010　American　Chemical　Society.