Production of Xylenes from Heavy Reformate: Advances in Process Chemistry, Catalyst Design, and Kinetics

The production of xylenes from heavy reformates is increasingly becoming an essential process in integrated refinery-petrochemical complexes. This Review covers various aspects of the C9+ reformate conversion process, including process chemistry, reaction network, catalysis, and types of reactors used. Different classes of reactions and their significance in achieving desirable xylene product yields are discussed along with the impact of reformate feed composition on reaction outcomes. This Review highlights the role of zeolite catalysts in improving product selectivity, focusing on catalyst modifications and topologies. It evaluates the effects of process parameters, reaction kinetics, and thermodynamic constraints on conversion and product distribution for a comprehensive understanding of the process. Further, this review delves into the role of catalysts, emphasizing the significance of active sites in dictating the reaction mechanism and product selectivity. The effects of incorporating various metals into zeolite catalysts on the product selectivity and yield are also reported. Additionally, the challenges associated with catalyst deactivation and strategies for catalyst regeneration are explored. A perspective on the development of kinetic models for heavy reformate conversion to xylenes is presented by comparing various reported models, highlighting their strengths and limitations. The review concludes with an exploration of emerging sustainable technologies and advancements in catalyst design, reactor engineering, and process optimization.