纳米Fe_3O_4催化剂在稠油水热裂解降黏中的应用

通过高温热解法和低温双相回流法制备了四种不同尺寸的纳米Fe_3O_4催化剂,并将其应用于辽河油田稠油水热裂解降黏实验中。结果表明,制备过程中加入重烷基苯磺酸钠(HABS)表面活性剂能够有效提高Fe_3O_4催化剂在稠油水热裂解体系中的分散性,以高温热解法制备出的HABS修饰的9 nm Fe_3O_4催化剂降黏效果最佳。当稠油量为250 g时,按m(稠油)∶m(催化剂)∶m(油层水)质量比为100∶0.3∶30加入催化剂和油层水,加入0.75 g正作为己烷供氢体,在240℃下反应24 h,辽河油田稠油黏度从86200 mPa·s下降到2065 mPa·s,降黏率高达到97.6%。反应机理分析显示,纳米Fe_3O_4催化剂攻击稠油长链上键能最低C-S键,使其断键,重组分转化为轻组分。

Application of nano-Fe3O4 catalyst in the viscosity reduction of heavy oil by hydrothermal cracking

Four nano-Fe₃O₄ catalysts with different particle sizes were prepared by high temperature pyrolysis and low temperature two-phase reflux method; their performance in the hydrothermal cracking and viscosity reduction of Liaohe oil-field heavy oil was investigated. The results indicate that the addition of sodium sulfonate (HABS) surfactant in the preparation process can effectively improve the dispersion of Fe₃O₄ catalyst in heavy oil for hydrothermal cracking; the HABS-modified 9 nm Fe₃O₄ catalyst prepared by high temperature pyrolysis exhibits the best viscosity reduction performance. In a reaction system with 250 g heavy oil and 0.75 g n-hexane as hydrogen donor, where the mass ratio of heavy oil:catalyst:reservoir water is 100:0.3:30, the viscosity of heavy oil can be reduced from 86200 to 2065 mPa·s after reaction at 240℃ for 24 h; the viscosity reduction rate is as high as 97.6%. Analysis on the reaction mechanism suggests that the nano-Fe₃O₄ catalyst attacks the C-S bond on the long-chain heavy oil, breaks the bond and converts the heavy component into light component.