The alteration of catalytic activity and selectivity of the cracking catalyst by porphyrinic metallic elements present in heavy crude oil fractions is a subject that requires serious attention. In this study, the effects of the two most deleterious of the metals (vanadium and nickel) and how they shift the product selectivity of the catalytic cracking are discussed, with a key focus on the catalytic behavior of the residual acidity consequent upon metal deactivation. Increasing loadings of vanadium and nickel were deposited on the FCC catalyst and subjected to a simulated FCC regeneration unit conditions. It is found that at loadings greater than 0.3 wt%, vanadium is 4–5 times as destructive as nickel on the crystalline structure of the catalyst. Catalytic evaluation results revealed correlations between residual surface acidity, catalyst activity and amount of coke formed on the catalyst at a constant catalyst-to-oil ratio (CTO). This result is in slight contrast with the widely reported enhanced coking activity of vanadium on FCC catalyst consequent upon dehydrogenation reaction. An alternative coke formation pathway based on the residual catalyst acidity is advanced for the observed coking behavior of high vanadium laden catalyst. In addition, a vanadium control measure relying on the acid-base chemistry and hydrothermal stability of a mixed-metal oxide is demonstrated as an effective method to limit the mobility of vanadium into the framework of the catalyst, the action that initiates vanadium deleterious effects. This study is expected to renew interest in the research on the coking behavior of metal poison catalysts.

存在于重质原油馏分中的卟啉金属元素对催化活性和裂化催化剂选择性的改变是需要认真研究的课题。在这项研究中，讨论了两种最有害的金属（钒和镍）的影响以及它们如何改变催化裂化的产物选择性，重点关注了金属失活后残留酸度的催化行为。越来越多的钒和镍负载沉积在FCC催化剂上，并经过模拟的FCC再生装置条件。发现在大于0.3 wt％的负载量下，钒在催化剂的晶体结构上的破坏性是镍的4-5倍。催化评估结果表明残留表面酸度之间存在相关性，催化剂活性和在恒定的催化剂与油比（CTO）下在催化剂上形成的焦炭量。该结果与广泛报道的脱氢反应后钒在FCC催化剂上增强的焦化活性略有不同。为观察高载钒催化剂的焦化行为，提出了基于残留催化剂酸度的另一种焦炭形成途径。另外，已经证明了依赖于酸碱化学和混合金属氧化物的水热稳定性的钒控制措施是限制钒迁移到催化剂骨架中的有效方法，该作用引发了钒的有害作用。预期该研究将重新引起对金属毒物催化剂的焦化行为研究的兴趣。