The petrochemical industry plays a crucial role in the global economy, providing versatile products such as resins used in a wide range of quotidian applications. However, the complexity of multi-grade continuous production systems often results in significant operational inefficiencies, particularly in the form of "off-spec" or "non-prime" products during transitions between resin grades. This thesis addresses the challenge of optimizing sequencing and production planning for a polymer reactor within a second-generation petrochemical facility. A mixed-integer linear programming (MILP) model, introduced by the work of Abdullah, Shamayleh and Ndiaye, is implemented to minimize production and transition costs while satisfying customer demands. Real-world data from a leading Latin American petrochemical company are used to validate the model.