Operation range extension via hot-spot control for catalytic CO2 methanation reactors

Heterogeneous catalytic reactions are essential for future CO2-based process routes, but are, however, sensitive to dynamic perturbations. To incorporate these processes into existing production networks, increased flexibility under different operating loads is necessary. One prominent example of a CO2-based process is methanation using H2 as a basis of the Power-to-X production concept. However, this reaction is strongly exothermic creating a major bottleneck for dynamic operation due to the limited thermal resistance of the catalyst. Based on a detailed mathematical reactor model at the industrial-scale, we found that stabilizing control is a very promising yet unexploited heat management approach. We applied stabilizing control to moderate the reactive zone (hot spot) via adaptive coolant temperature variations and compared its performance to other well-established approaches such as intensified and recycle reactors. In this way, we attained unconventional operating points in regions of steady-state multiplicity that offer reduced catalyst temperatures (<500 °C) while maintaining elevated reactor performance. When considering these additional operating points, a broader and more flexible operation of industrial reactors becomes feasible. Systematic sensitivity studies regarding relevant reactor and operating parameters indicate that a robust technical implementation of these operating points is possible.