Expansion of Si-SARA method utilising non-specialised instruments for multi-factorial asphaltene precipitation analysis

Analysis of bitumen chemistry is challenging due to the need for specialised equipment and laboratory facilities. A relatively newer method called ‘Si-SARA’ is being utilised for extracting bitumen chemical fractions in small quantities (commonly known as SARA fractionation). Key elements of Si-SARA procedure are (i) Polarity-based precipitation and syringe-filter-based filtration of asphaltene, and (ii) using prepackaged silica cartridges for fractionation of maltene. Refinement of original ‘Si-SARA’ method is one of the objectives, obtained through using a novel, less-expensive, and robust setup. Key features of the modified ‘Si-SARA’ setup (called c-Si-SARA) is that the filtration of asphaltene, chromatographic elution of maltene, drying of filtrated or eluted products are conducted in single hermetically closed metallic vessel. The second objective is to optimise the asphaltene filtration process regarding dissolution time, temperature, solvent as well as the use of reflux. The weights of SARA fractions from c-Si-SARA process are compared with Si-SARA results which show good agreement- confirming effectiveness of the process. It is also found that the asphaltene yield generally increases with time but can decrease due to prolonged dissolution. Dissolution at higher temperature, with or without reflux, has effect on dissolution rate but maximum yield of asphaltene is quite similar.