Fluid catalytic cracking (FCC) is one of the major conversion technologies in the oil refinery industry and produces the majority of the world’s gasoline. FCC Is conventionally performed in a circulating rising fluidized bed reactor, however, the usage of down-flow reactors offers several advantages such as less species back-mixing and more narrow residence time distributions. Experimental studies have shown that in both riser and downer reactors, catalyst particles tend to agglomerate forming clusters, predominantly in the near-wall region, leading to considerable heat and mass transfer limitations. Wall modifications such as dimples and other indentations can counter this agglomeration. To bring these reactors to a new level, an Euler-Lagrangian CFD framework in CFDEMcoupling will be constructed in which these different wall modifications are to be assessed. This model will accurately account for the hydrodynamic behavior and FCC chemistry in the first demonstration case. However, a general heterogeneous chemistry framework will be constructed allowing for micro-kinetic models to be implemented directly in the solver. The micro-kinetic model developed at the Laboratory for Chemical Technology (LCT) for catalytic conversion of plastic waste will serve as case study to demonstrate the solver’s flexibility. Additionally, the solver will be equipped with several different speed-up algorithms in order to reduce the computational cost such as in-situ adaptive tabulation (ISAT).