镁改性FCC催化剂抗镍污染性能和机理

以碱土元素镁为改性元素，采用原位加入方法制备了镁改性流化催化裂化(FCC)催化剂。着重考察并探究了镁改性FCC催化剂对重油催化裂化的抗镍污染性能和反应机理。催化剂理化性质表征结果表明，与常规FCC催化剂相比，镁改性对催化剂的比表面积、孔体积、磨损强度以及堆密度等理化性质没有明显影响。高级催化裂化评价装置(ACE)评价结果表明，相同镍污染条件下，与常规FCC催化剂相比，镁改性FCC催化剂的干气和焦炭产率分别下降了0.38和1.28百分点，而汽油和总液体收率则分别增加了1.38和1.49百分点，显示了优良的抗镍污染性能。抗镍污染机理分析结果表明:镁改性FCC催化剂一方面可以减少催化剂表面酸中心尤其是强酸中心数量，改善催化剂的干气和焦炭选择性，从而提高催化剂的容镍能力；另一方面，高温水热条件下，镁原子能够进入到氧化镍晶格中形成镁 镍固溶体，能够极大地提高氧化镍的还原温度，从而使得镁改性能够显著提高FCC催化剂的钝镍性能。

Anti-Nickel Contamination Performance and Mechanism of Magnesium Modified FCC Catalyst

Magnesium modified FCC catalyst (Mg-Cat) was prepared by in-situ addition method with MgCl₂ as Mg source, and its anti-nickel contamination performance and mechanism in heavy oil catalytic cracking were investigated. Characterization results indicate that, compared with conventional FCC catalyst (C-Cat), Mg-modification has no obvious influence on physicochemical properties such as surface area, pore volume, attrition index and bulk density of Mg-Cat. Advanced cracking evaluation unit (ACE) evaluation results suggest that, under the same Ni-contamination condition, compared with C-Cat, the dry gas yield and coke yield of Mg-Cat decreased by 0.38 and 1.28 percentage points respectively with gasoline yield and total liquid yield increasing by 1.38 and 1.49 percentage points, thus demonstrating excellent anti-nickel contamination performance. Anti-nickel contamination mechanism research suggests that Mg modification decreases the acid sites especially for strong acid sites, which improve the dry gas and coke selectivities and thus promote the Ni-tolerance ability of the FCC catalyst. On the other hand, under hydrothermal condition, Mg gets into the lattice of NiO and forms Mg-Ni solid solution, thus increasing the reduction temperature of NiO and improving the Ni-passivation performance of FCC catalyst.