In this work, n-octane has been selected to represent the alkane content in the naphtha for the catalytic cracking over Mn-ZSM-5 and Fe-ZSM-5 catalysts. Various characterization techniques are applied to quantify the possible active sites. The introduction of transition metal cations does not influence the strength of BAS. Therefore, the change on kinetic behavior is the contribution from newly generated LAS. Upon the elucidation of their roles in different adsorption scenarios, it is found that the new LAS establishes new adsorption equilibrium with olefin molecule formed from the thermal cracking, making the remaining alkane molecules adsorb and react on the BAS with minimum coverage of olefin. It is therefore favorable for the enhancement of ethylene yield in the primary cracking products. Furthermore, the unfavorable energy requirement of the carbonium ion pathway is compensated by the boosted activation entropy via the pathway change, as suggested by the kinetic analysis.

在这项工作中，n-辛烷值已被选为代表石脑油中的烷烃含量，用于在 Mn-ZSM-5 和 Fe-ZSM-5 催化剂上进行催化裂化。应用各种表征技术来量化可能的活性位点。过渡金属阳离子的引入不影响BAS的强度。因此，动力学行为的变化是新生成的 LAS 的贡献。在阐明它们在不同吸附场景中的作用后，发现新的 LAS 与热裂解形成的烯烃分子建立了新的吸附平衡，使剩余的烷烃分子在 BAS 上吸附和反应，烯烃覆盖率最小。因此有利于提高初级裂解产物的乙烯收率。此外，