纳米Fe3O4催化剂在稠油水热裂解降黏中的应用

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

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Fe3O4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Fe3O4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 Fe3O4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Fe3O4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。

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.