Desulfuration processes in refinery and biorefinery: Insight into the role of catalyst protection by catalytic study in the o-xylene hydrogenation process

Due to increased environmental concern, the European Union introduced the "zero-sulphur" legislation which limits the sulphur content in gasoline and diesel less than 10 mg/kg, thus requiring the development of new process technologies and improved HDS catalysts for ULSD applications. Commercial hydrotreating catalysts, however, are affected by several drawbacks that limit their performance. In particular, the acidic properties of catalyst can promote undesired side reactions, leading to catalyst deactivation by coke formation. Despite intensive efforts devoted to study deactivation phenomena, the nature of acid sites and their role in deactivation by coking is still unclear . On this account, the present study aims to ascertain the influence of the acidity of HDS catalysts on the catalytic pathway in the o-xylene hydrogenation process, as model reaction, and to examine the kinetic mechanism of coking phenomena, aiming also to disclose the key factors governing the catalyst deactivation and to identify new route for catalyst protection.