Fuel oil desulfurization with dual functionalized imidazolium based ionic liquids

[Display omitted] •36 new dual functionalized ionic liquids (ILs) for EDS studies were synthesised.•EDS of dibenzothiophenes: benzimidazolium ILs outperformed imidazolium ILs.•Benzimidazolium ILs: extraordinary EDS capacity (52%) for sterically hindered 4,6-DMDBT.•1H NMR: intermolecular benzimidazol...

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Bibliographic Details
Published in:Separation and purification technology 2020-10, Vol.248, p.116959, Article 116959
Main Authors: Butt, Hussain Shakeel, Lethesh, Kallidanthiyil Chellappan, Fiksdahl, Anne
Format: Article
Language:eng ; nor
Subjects:
Dibenzothiophenes
Dual functionalized ILs
Extractive desulfurization
Ionic liquids
NMR interaction studies
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Summary:[Display omitted] •36 new dual functionalized ionic liquids (ILs) for EDS studies were synthesised.•EDS of dibenzothiophenes: benzimidazolium ILs outperformed imidazolium ILs.•Benzimidazolium ILs: extraordinary EDS capacity (52%) for sterically hindered 4,6-DMDBT.•1H NMR: intermolecular benzimidazolium ILs/DBT π-π interactions important for efficient EDS. A series of 36 dual functionalized N-(poly)ethylen glycol N-allyl-/N-benzyl imidazolium and benzimidazolium ILs were synthesized for extractive desulfurization studies (EDS). The novel ILs were readily prepared from imidazole by a three-step dialkylation and anion exchange procedure and characterised (1H, 13C, 19F NMR; IR; HRMS positive/negative mode). The desulfurization studies were performed on a model oil with dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) in n-dodecane. The N-allyl benzimidazolium based ILs exhibited higher extraction efficiency than corresponding imidazolium-based ILs (69 vs 59% DBT; 52 vs 29% 4,6-DMDBT). The EDS efficiency of the prepared ILs varied with the N-ethylen glycol chains length and by N-allyl or N-benzyl substitution on the imidazolium ILs. The results indicated that desulfurization efficiency is mainly affected by variation of the IL cation, as the IL anions (NTf2; N(CN)2-, SCN-, BF4-) only had minor impact on the extraction capacity of sulfur compounds. 1H NMR studies of IL-DBT solutions illustrated different EDS mechanisms, and specific interactions could explain the higher desulfurization capacity of dual functionalized benzimidazolium than the corresponding imidazolium ILs. 1H NMR confirmed that stronger π-π interactions between the planar aromatic electron system of benzimidazolium ILs and aromatic dibenzothiophenes play a major role for the high EDS extraction efficiency.
ISSN:1383-5866
1873-3794
DOI:10.1016/j.seppur.2020.116959