Kinetic modeling, simulation and optimization of butylated urea formaldehyde resin synthesis

Butylated urea formaldehyde is widely used amino resin. Synthesis of BUF takes place in two steps: addition reactions forming methylol species and condensation reactions forming species with methylene linkages. The addition reaction model for BUF resin synthesis was developed by Amin et. al. [1]. Beside addition reactions, oligomer species with di-methylene ether linkage also form. Here the process of forming oligomers is termed as X condensation. In this work kinetic model for X condensation has been developed jointly with a research scholar, Ms. Shital Amin at IIT Gandhinagar. Dynamic simulations are performed using this kinetic model at various reactor temperatures and initial conditions. Furthermore, the dynamic simulation activity is extended to operate the reactor optimally. Optimization activities are performed in this work to obtain minimum free formaldehyde concentration and minimum butanol concentration at the end of the batch operation by obtaining the optimum temperature. The optimization problems are solved in presence of process dynamics constraints. Hence, such optimization problem is also referred as dynamic optimization. Two optimization criteria used in this work include (1) minimizing end point F concentration and (2), minimizing end point butanol concentration by optimizing the temporal trajectory of temperature during the batch operation. Control vector parameterization approach is used to obtain the optimum temperature trajectory for solving the dynamic optimization problem (DOP). It was further found that both these optimization criteria, namely minimization of end point free formaldehyde and butanol concentrations are mutually conflicting. Hence, a multi-objective optimization problem (MOOP) with these to criteria has also been solved. The result to these MOOP is in the form of pareto optimal solutions. Such optimization solutions can help the operator to choose the operating conditions for the desired product.