Abstract: Combination of solidification point depressants is one of the effective means to improve low temperature properties of diesel fuel. In this paper, three kinds of solidification point depressants and their combinations with different ratios were used to investigate the effect on the reduction of solidification point of 0# diesel fuel from the refinery of Jilin Petrochemical Company. Cold Filter Plugging Point (CFPP) and differential scanning calorimeter (DSC) were used to evaluate the solidification point reduction effect and clarify the mechanism of wax crystallization at low temperature. The results indicate that there is a better synergistic effect in the combination use of di-n-alkyl fumarate-vinyl acetate copolymer (PFVA) and polyethylene-vinyl acetate (EVA) and paraffin crystal dispersant 2-(hydrogenated tallow) phthalic acid amide (Tab). The CFPP can be reduced by 19 ℃ at the sum dose of 500 ug/g with the ratio of PFVA 46%: EVA 46%: Tab 8%. Both of the peak temperature for wax crystal precipitation and the absolute value of wax crystal phase change heat ΔH is reduced. The combinations of solidification point depressants can delay the wax crystal precipitation, thus improves the low temperature fluidity of diesel fuel.

Key words: diesel fuel, cold flow improver, cold filter plugging point