Synthesis of Morpholine-Based Ionic Liquids for Extractive Desulfurization of Diesel Fuel

Abstract

Extractive desulfurization with ionic liquids has attracted significant attention from a growing number of scientists due to the current environmental restrictions on fuel. Protic ionic liquids (PILs) were synthesized via equimolar neutralization of morpholine and formic-based compounds. The obtained PILs were characterized by Fourier transform infrared and 1 H NMR spectroscopy and used as a promoter for the room temperature deep desulfurization of model oil and commercial B0S500 diesel. Extractive desulfurization of the model oil in n-octane showed that the alkyl chain length of the ionic liquid [Nmorph] + [HCOO]does not enhance the efficiency of dibenzothiophene (DBT) removal. Regardless, the [Morph] + [HCOO]-IL is the most promising candidate for extractive desulfurization. The best results were obtained using multistage extraction (n = 3) and a 1:1 volume ratio, resulting in a 99.44% removal rate of sulfur compounds. For commercial B0S500 diesel, extraction time significantly influenced the removal of sulfur species. For samples with multistage extraction and a 1:1 volume ratio, [Morph] + [HCOO]removed approximately 47.48% of the sulfur-containing compounds. The recycling study of [Morph] + [HCOO]suggests that the IL remains active for up to three operating cycles without losing efficiency.

Structurally flexible pyrrolidinium- and morpholinium-based ionic liquid electrolytes

“…15,16 In addition, they are less toxic and more biodegradable than conventional ILs based on other cations. 17–19…”

“…15,16 In addition, they are less toxic and more biodegradable than conventional ILs based on other cations. [17][18][19] Turning to the design of IL anions, interest in alkyl phosphate-based anions is growing, not least due to safety concerns regarding energy storage devices, where the anions play a key role in the optimization of separator 20 and electrode materials, 21 and are used as electrolyte additives for overcharge protectors and redox mediators. 22,23 With respect to the latter, the most common flame retardants are organophosphorus organic compounds [24][25][26][27] or ILs; 28,29 the former compounds, however, are limited by their lower ESWs and thermal stabilities, which is why ILs with phosphate-based anions are promising.…”

Desulfurization of Diesel Using Ionic Liquids: Process Design and Optimization Using COSMO-Based Models and Aspen Plus

“…Increasing the length of the alkyl chain on the cation has been reported to cause an increase in the desulfurization efficiency. 38 On the other hand, Fonseca et al 39 noted that there was no improvement in sulfur recovery when the cation alkyl chain was increased using EDS. Despite the numerous desirable properties that ILs possess, their application still requires extensive research and development to enable the industrial scale-up of IL-based processes.…”