Abstract
Asphaltenes are heavy petroleum crude oil components which limit the production of petroleum crude oil due to their aggregation and their stabilization for all petroleum crude oil water emulsions. The present study aimed to modify the chemical structures of isolated asphaltenes by converting them into amphiphilic polymers containing ionic liquid moieties (PILs) to demulsify the emulsion and replace the asphaltene layers surrounding the oil or water droplets in petroleum crude oil emulsions. The literature survey indicated that no modification occurred to produce the PILs from the asphaltenes. In this respect, the asphaltenes were modified via oxidation of the lower aliphatic chain through carboxylation followed by conversion to asphaltene acid chloride that reacted with ethoxylated N-alkyl pyridinium derivatives. Moreover, the carboxylation of asphaltenes was carried out through the Diels–Alder reaction with maleic anhydride that was linked with ethoxylated N-alkyl pyridinium derivatives to produce amphiphilic asphaltene PILs. The produced PILs from asphaltenes acid chloride and maleic anhydride were designated as AIL and AIL-2. The chemical structure and thermal stability of the polymeric asphaltene ionic liquids were evaluated. The modified structure of asphaltenes AIL and AIL-2 exhibited different thermal characteristics involving glass transition temperatures (Tg) at −68 °C and −45 °C, respectively. The new asphaltenes ionic liquids were adsorbed at the asphaltenes surfaces to demulsify the heavy petroleum crude emulsions. The demulsification data indicated that the mixing of AIL and AIL-2 100 at different ratios with ethoxylated N-alkyl pyridinium were demulsified with 100% of the water from different compositions of O:W emulsions 50:50, 90:10, and 10:90. The demulsification times for the 50:50, 90:10, and 10:90 O:W emulsions were 120, 120, and 60 min, respectively. The interaction of the PILs with asphaltene and mechanism of demulsification was also investigated.
Highlights
Asphaltenes are the heaviest fraction of unconventional petroleum components, showing a series of one single or many crosslinked polycyclic aromatic and aliphatic groups as building blocks embedded with a trace amount of metal (V, Ni, Fe and Cu) [1]
The polymer chemical structures that are used as oilfield chemicals and interacted with asphaltenes consist of two main parts: (i) organic backbones linked with polar functional groups, and (ii) hydrophobic aliphatic side chains that provide sufficient dispersion and solubility into crude oils having different carbon numbers [13]
Asphaltene chemical structures generally contain polycondensed aromatics, heterocycles, and aliphatic alkyl groups, and their molecular weights are dependent on the origin, source, and types of crude oils [29]
Summary
Asphaltenes are the heaviest fraction of unconventional petroleum components, showing a series of one single or many crosslinked polycyclic aromatic and aliphatic groups as building blocks embedded with a trace amount of metal (V, Ni, Fe and Cu) [1] They are contaminated as high molecular weight constituents Asphaltenes have been considered as amphiphilic components with the presence of hydrophobic interactions of aliphatic chains or hydrophilic interactions of polycondensed aromatics and heteroatoms through acid-base interactions (electron donor-acceptor and hydrogen bonding). This allows the interaction with other hydrophilic and hydrophobic crude oil components or oilfield chemicals, forming stable films at oil–water or air–water interfaces [3,4,5]. The phosphochlorinated-asphaltene reacted with polypropylene oxide to produce amphiphilic surfactants that act as asphaltenes dispersants for heavy crude oil [16]
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