Investigation of Heavy Organics Precipitation from Nigerian Crude Oil Residue Using Binary Mixture of n-Alkane Solvents

Abstract

The effects of mixing two n-alkane solvents on the precipitation of heavy organics in crude oil were carried out. The crude oil sample sourced from a major operative in Nigeria was distilled at 240^oC and used for the precipitation experiment. The binary mixture of n-alkane solvents (C₆: C₁₀, C₆: C₁₆, C₁₀: C₁₄, C₁₀: C₁₆, C₁₄: C₁₆) was carried out in the solvent ratio of 0:1, 1:2, 1:1, 2:1, and 1:0 respectively. From the results, C6: C10 mixture shows an abrupt decrease in heavy organics precipitated from 1:0 volume ratio of C₆: C₁₀ to 2:1 volume ratio of C₆: C₁₀ and a further steady decrease were observed. The percentage volume increment of C6 in the mixture of C₆: C₁₆, also shows steady and an abrupt decrease in heavy organics precipitated, which indicates phase transitions occurring at 1:1 and 2:1 volume ratio points. The additions of C₁₀ to C₁₄ and C₁₀ to C₁₆ results to decrease in the weight percentage of heavy organics precipitated. While a slight decrease in weight percentage of heavy organics occurs during the addition of C₁₄ to C₁₆. Precipitation experiment carried out using binary mixture shows a three-stage phase transition: solid-liquid, liquid-solid and solid-liquid in C₆: C₁₆ at different volume ratios of the mixtures. 

Keywords: Binary mixture, heavy organics, crude oil residue, n-alkane solvents, precipitates