沥青质稳定性在渣油加氢过程中的变化规律

为考察固定床渣油加氢-催化裂化双向组合（RICP）技术中多环芳烃改善杂质脱除效果和抑制催化剂积炭的原因，建立了基于Flory-Huggins活度系数模型考察380 ℃、14.0 MPa条件下沥青质稳定性的方法。基于上述方法，建立了衡量渣油加氢反应中活性氢使用效率的参数A/B：A越大，活性氢用于杂质脱除的效率越高；B越小，活性氢用于沥青质加氢的效率越高。研究结果表明，经过加氢后，渣油轻质化程度增加，渣油溶氢量增加，沥青质与渣油（含溶解氢）溶解度参数之差增加，沥青质稳定性变差；在380 ℃、14.0 MPa条件下，采用RDM-32，RDM-53，RCS-31催化剂以体积比40：10：50级配时，沙轻常压渣油加氢过程的A/B值最大；在此基础上，引入高芳香性馏分有利于进一步提高加氢过程的A/B值。多环芳烃改善杂质脱除效果并抑制催化剂积炭的原因在于：多环芳烃优化了活性氢用于杂质脱除和沥青质加氢的效率。

CHANGES OF ASPHALTENE STABILITY DURING RESIDUE HYDROTREATING

The effects of polycyclic aromatic hydrocarbons on the removal of impurities and the inhibition of carbon accumulation on catalyst in the RICP technology were studied with an autoclave using Saudi Arab (light) atmospheric residue as raw material. A method based on Flory-Huggins activity coefficient model was established to investigate the stability of asphaltenes at 380 ℃ and 14.0 MPa. The parameter A/B ratio was calculated, where A represents the reactivity of active hydrogen for HDS, HDN, HDCCR, and B is the reactivity of active hydrogen for asphaltene hydrogenation. It shows the tendency of reactive hydrogen to focus on the reaction: larger A means the higher the efficiency of active hydrogen in removing impurities; while the smaller B is the more efficient active hydrogen in the hydrogenation of asphaltenes. The results showed that after hydrotreating, the solubility difference between asphaltene and residual oil (containing dissolved hydrogen) increased, and the stability of asphaltene became worse. When the catalysts RDM-32, RDM-53 and RCS-31 were graded at a ratio of 40:10:50, the value of A/B for Saudi Arab (light) residue reached the maximum at 380 ℃ and 14.0 MPa. It indicated that the introduction of high aromatic fraction is beneficial to further increase the value of A/B. The reason why PAHs improve the impurity removal and inhibit catalyst carbon accumulation is that PAHs optimize the efficiency of active hydrogen for impurity removal and asphaltene hydrogenation.