催化剂的扩散性能和本征反应特性对重油分子断裂转化的影响

Catalyst's Physical Representation for Hydrocarbon Diffusibility and Intrinsic-Reaction Interaction and Their Effects on Heavy Oil Decomposition

通过分析烃分子断裂过程的催化反应化学,研究了重油裂解反应网络及各本征反应之间的关系,提出催化剂的扩散性能和本征反应特性是影响烃分子断裂过程的两类重要性质。开展了重油裂解反应化学实验,构建了分别反映扩散性能和本征反应特性的2个催化剂物性变量特征因子,即活性中心可接近性因子(ACI)和酸性特征因子(AFI),并以此两因子为二维调控因素,创建了用于设计重油复杂分子断裂生成丙烯、乙烯反应催化剂的物理模型。该模型表明,在两因子可调控区间内,存在低碳烯烃产率最高值,单独调控某一因子无法达到该最高值,只有耦合调控才可实现,从而显著提高低碳烯烃产率。调控催化剂的ACI会显著影响碳数为40～50的重油分子向低碳烯烃转化的主反应深度,从而调控催化剂的AFI会改变重油分子芳构化、异构化、环化等副反应在反应网络中发生的概率,影响作为低碳烯烃前身物的直链烃类的数量,从而影响低碳烯烃产率。通过对催化剂ACI和AFI的耦合调控,有可能根据目的产物需求,实现催化剂的优化设计。

Based on the analysis of catalysis chemistry about hydrocarbon decomposition, the conversion reaction network and the properties of various intrinsic reactions were discussed. The diffusibility and intrinsic-reaction interaction of hydrocarbon were focused as two main factors that gain the majority in this process. By the investigation of such process in laboratory, the two type of catalyst physical description index, active-site accessibility index （ACI） and acid-site function index （AFI）, were figured out to represent the diffusibility and intrinsic-reaction interaction of hydrocarbon. In the two-dimension tuning region formed with these two indices, the physical model was built for designing catalyst for production of light olefins by heavy oil decomposition. The model showed that each light olefin had its own highest yield, which could not be fulfilled by adjusting one index, but could do by tuning both of those two indices coupled. Further research revealed the facts, that the progress of the desirable reactions, such as the heavy oil molecules （the carbon number was 40--50） converting to light olefins, could be affected by tuning ACI of catalyst, and the probabilities of the undesirable reactions, such as aromatization, isomerization, etc. , could be affected by tuning AFI of catalyst, resulting in the light olefin yield changed. By coupled adjusting ACI and AFI, the catalyst for heavy oil decomposition could be designed according to the production purpose.