| The widely distributed oil sands is an unconventional petroleum.The currently commercial process for minable ores is the water-based extraction(WBE)process which has caused high energy and water consumption.However the solvent extraction process also caused solvent residue problems and the recycling of the externally added functional chemicals(ionic liquids etc.)was found to be one of the most challenges which impeded the scaling-up of these hybrid processes.Therefore,searching for efficient and recyclable “green chemical additives” is an important research direction related to unconventional petroleum production.Switchable solvents which has been widely concerned due to its green and intelligence can change its physicochemical properties according to the practical application needs.Based on the analysis of basic physicochemical properties of oil sands and the properties of switchable-hydrophilicity tertiary amines(SHTAs)in their hydrophilic forms which can be recycled by hydrophilicity switching,SHTAs have been synthesized and applied to enhancing heavy hydrocarbons recovery from oil sands ores in the solvent extraction.In this paper,we researched on the synthesis of SHTAs,the extraction of oil sand in the laboratory scale,the mechanism of SHTAs-assisted solvent extraction and the properties of emulsion in turn.By condition optimization,we found tertiary amines' pKa values and reaction temperature are the main factors which influenced the reaction rate and process of tertiary amine salt synthetic.Will tertiary amine salt solution is applied in solvent extraction,when toluene was used as extracting agent,the bitumen recovery improved to 97.9% while the ratio of toluene to SHTA solution to oil sands was 4:3:1 at 35?;when using compound solvent(ethyl acetate / n-heptane)in extraction,the bitumen recovery increased to 87.6% while the ratio of compound solvent(30% ethyl acetate)to SHTA solution to oil sands was 4:1:1 at room temperature.At the same time,the addition of tertiary amine salt solution can effectively reduce the residual sand in bitumen and solvent in the sand.According to the surface characterizations by FT-IR,SEM-EDS,wettability test,zeta potential measurements,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 interfaces.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 reduced the interactions between bitumen components(e.g.,asphaltenes or other polar materials)and the solid surface,which changed the properties of the solid surfaces(significant increase in solids wettability).Consequently,the detachment of bitumen materials from the solid surfaces became much easier and more complete.Through the research on emulsion in the process of SHTAs-assisted solvent extraction,we found that the increasing asphaltene content in solvents is the main cause of serious emulsification. |
PDF Full Text Request