The Effect of Compositional Changes of Binary Mixtures of n-alkane solvents on the Precipitation of Heavy Organics from a Solution of Crude Oil Residue

The effect of precipitant compositional changes on the precipitation of heavy organics (ho) from a solution of crude oil residue using binary mixtures of n-alkane solvents was studied. heavy organic precipitates were generated using different ratios of c5:c6, c6:c7 and c5:c7 n-alkane solvents. the result obtained showed that for binary mixtures at 1:0, 3:1, 2:1, 1:1, 1:2, 1:3 and 0:1 ratios, the weight percentage precipitates of c5:c6 were 11.19±0.45, 8.56±0.80, 5.62±0.58, 8.53±0.80, 5.83±1.29, 5.45±0.57 and 5.24±0.32; c5:c7 were 11.19±0.90, 5.63±0.52, 2.12±0.25, 4.51±0.65, 2.11±0.37, 1.67±0.40 and 0.97±0.05; and c6:c7 were 5.24±0.32, 3.37±0.08, 1.94±0.03, 3.39±0.60, 1.48±0.03, 1.43±0.03 and 0.97±0.05 respectively. the results have shown that the quantity of ho precipitate decreases with increasing quantity of higher carbon number of n-alkane solvent to a minimum value at 2:1 ratio. from the minimum value, it rises to a maximum at 1:1 ratio as the proportion of cn+x to cn (where c is carbon atom, n and x represent the number of carbon atom) increases. the quantity of ho precipitate decreases again to a minimum at 1:2 ratio as the proportion of cn+x increases further, and finally to the lowest value at pure cn+x. the conclusion is that the components of the crude oil residue undergo a three-stage phase transition as the volume ratios of the n-alkane solvents vary. this study can lead to a better understanding of the phase behavior of heavy organics under compositional changes and hence the prediction of heavy organic precipitation