Understanding the roles of switchable-hydrophilicity tertiary amines in recovering heavy hydrocarbons from oil sands

Abstract

A kind of novel process aids, switchable-hydrophilicity tertiary amines (SHTAs, such as triethylamine, N,N-dimethylcyclohexylamine, N,N-dimethylbenzylamine) in their hydrophilic forms, have been synthesized and applied to enhancing heavy hydrocarbons recovery from oil sands ores in the solvent extraction. It is observed that the addition of SHTA solution increases the recovery of heavy hydrocarbons and improves the quality of bitumen product (less solids entrained) and residual solids (less solvents and chemicals attached). According to the surface characterizations by FT-IR, SEM–EDS, wettability test, zeta potential measurements and QCM-D (a surface material adsorption detection), it is found that the external addition of SHTAs solution plays an important role in modifying the bitumen and solids surfaces. The improved processability was mainly attributed to the absorption of cation ions (e.g., [Et3NH]+) of SHTAs on bitumen surface, forming ions pairs. The formation of ions pairs reduces the interactions between bitumen components (e.g., asphaltenes or other polar materials) and the solid surface, which significantly increases the wettability of solid surfaces. Consequently, the detachment of bitumen materials from the solid surfaces becomes much easier and more complete. In addition, the efficiency of the recycled SHTAs is found to be not influenced much even the SHTAs are recycled for 5 times, indicating a promising application of this kind of ‘green chemicals’ in unconventional petroleum production or soil remediation.