EVA/改性SiO2纳米复合降凝剂的制备及对含蜡模拟油降凝降黏的效果研究

摘要

利用纳米二氧化硅(SiO2)表面带有羟基的性质,使用硅烷偶联剂γ-氨丙基三乙氧基硅烷(KH550)和硬脂酸对其改性,得到有机纳米二氧化硅(YSiO2).采用溶液共混法制备了YSiO2与乙烯醋酸乙烯共聚物(EVA)降凝剂的复合产物EVA/YSiO2,以蜡质量分数20%的模拟油为研究对象,通过凝点和流变试验,从宏观上评价EVA/YSiO2对不同含蜡量模拟油的作用效果,并与EVA、EVA/未改性SiO2纳米复合降凝剂进行对比,利用偏光显微镜考察加剂前后不同模拟油蜡晶形貌的变化.结果表明:采用加剂量为500×10 -6的EVA/YSiO2纳米复合降凝剂,可使含蜡质量分数20%的模拟油凝点从33 ℃降至0 ℃,并大幅降低油样黏度.偏光显微试验结果表明:添加EVA/YSiO2能有效降低蜡晶尺寸,并促进蜡晶分散.%Taking advantage of the property that there is hydroxly group on the surface of SiO2, nanosilicon dioxide (SiO2) is modified by silane coupling agent γ-aminopropyltriethoxysilane(KH550) and stearic acid,and the organic nano-silica(YSiO2) is pre-pared. The complex EVA/YSiO2is prepared by YSiO2and pour point depressant ethylene vinyl acetate copolymer(EVA) through so-lution mixing technology. Taking simulated oil with 20% mass fraction of wax as study object,the effect of EVA/YSiO2on the simula-ted oil is evaluated by condensation point and rheological test,and the comparison is made among EVA and EVA/SiO2. The change of wax crystal morphology of different simulated oil before and after adding pour point depressant is investigated by polarizing microscope. The results show that using EVA/YSiO2pour point depressant with additive dosage of 500×10 -6,the condensation point of simulated oil can be reduced from 33 ℃ to 0 ℃,and the viscosity of oil is greatly reduced as well. The microscopy result indicates that EVA/YSiO2can decrease the wax crystal size and improve the dispersion of wax crystal.