Optimization Modeling for Advanced Syngas to Olefin Reactive Systems

Reactor designs with mixed catalysts play an important role in transforming a multiple reactor system to single-shot reactors. In addition to savings in capital and ease of implementation, single-shot reactors are useful to break equilibrium limitations, thereby increasing the yield and selectivity of desired product as shown in previous studies. However, the nonlinear and highly exothermic nature of mixed-catalyst systems makes it difficult for commercial process simulation and optimization tools to optimize these systems. This study describes the development and application of optimization strategies for mixed-catalyst, single-shot reactors for syngas to olefin (STO) processes. Finding the optimal catalyst distribution is challenging and requires advanced solution strategies for singular optimal control problems, which are poorly conditioned and often lead to flat response surfaces. The graded bed and partial-moving finite-element approaches are used to find the optimal catalyst distribution that maximizes the olefins yield. A 1.3% increase in the yield is observed from one zone to three zones. The yield further improves from three zones to the exact infinite dimensional solution by 0.2%. This improvement can be realized in practice by changing only the catalyst distribution, without any extra investment. Finally, the results suggest that a mixed-catalyst single shot reactor bed can be applied to other reaction mechanisms to increase reactor performance.

Automated summary

This study presents the development and application of optimization strategies for mixed-catalyst, single-shot reactors in syngas to olefin (STO) processes. Finding the optimal catalyst distribution is challenging due to poorly conditioned singular optimal control problems. The graded bed and partial-moving finite-element approaches were used to maximize the olefins yield. An increase of 1.3% in yield was achieved from one zone to three zones, and further improved by 0.2% to the infinite dimensional solution. These improvements can be implemented without additional investment. The results suggest the potential application of mixed-catalyst single shot reactor beds for enhancing reactor performance in other reaction mechanisms.