Study On Pour Point Depressant Of Diesel Fuels

Diesel fuel pour point depressants (PPDs) is a kind of oil additives. When small amounts of PPDs are added into diesel fuel, wax crystallization in the diesel fuel and cold flow properties of diesel fuel are improved. PPDs have excellent effects in increasing the production of diesel fuels, saving kerosene oil, increasing flexibility and economic efficiency of refineries, and improving cold flow properties of diesel fuels. Therefore, it was used widely in the refining industry.In order to study more effective and economical diesel fuel pour point depressants. The major studies in this thesis are as follows:(1) Several0#diesel fuel was used as raw to evaluate the effect of different kinds of representative PPDs from mainstream companies. Then PPDs that have better effects were separated by freezing, the compositions and structures of PPDs and their solvents were analyzed. At last the content of n-paraffin and the thermodynamics of crystallization of different diesel fuel were analyzed by gas chromatography spectrometry and differential scanning calorimetry (DSC).(2) The properties of T1804and its interactions with solvents and dispersant are studied. Their performance were studied by differential scanning calorimetry (DSC).(3) The PPDs which have good effect were selected to combine, and the influence of PPDs on the growth of wax crystal and thermodynamics of crystallization were studied by Digital X-ray diffraction (XRD), micropolariscope and differential scanning calorimeter (DSC).The results show:Although various kinds of PPDs exist in the market, due to diesel fuel is a very complex composition, PPDs have a high selectivity to diesel fuel and majority of PPD only significantly reduces the solidifying point (SP), could not significantly reduces the cold filter plugging point (CFPP); PPDs with better effects are copolymers of ethylene-vinyl acetate, its effective solvent are Aromatic compounds; T1804mix with appropriate solvent or appropriate dispersant could improve its effects and convenient; Combination of polymethacrylate PPD (KT4) and polyethylene-viny acetate PPD have better effect, especially the ratio of1:1; XRD and micropolariscope results indicate that polymethacrylate PPD (KT4) have taken effect by adsorption, polyethylene-viny acetate PPD (AH-BSFH) have taken effect by co-crystallization. DSC results show when combination of polymethacrylate PPD (KT4) and polyethylene-viny acetate PPD help to synergism and might lower the energy of liquid-solid phase change.