Editorial: Understanding the behavior of reactive solid materials in chemical processes

Reactions on solids is a rather complex, but very important area in the field of Chemical Reaction Engineering, as they are in the core of large-scale industrial sectors such as hydrometallurgy, and biomass valorization. The reactive solids behavior influences greatly the overall reaction kinetics and thus, process efficiency and economics and understanding the factors influencing this is the key for process development and fundamental understanding. Typically, the diffusion of material influences significantly the overall reactivity and the system is also dynamic, as the interacting solid particles may change in geometrical shape during the reaction–therefore the interpretation of kinetics need to be tackled by understanding advanced phenomena and models that describe the change in parameters including shape and surface area. In this special issue, many of the often-encountered scenarios dealing with solid-fluid reactions have been discussed from different angles and methods for overcoming the complexity of a solid-liquid or solid-gas system have been presented. In the perspective article by Salmi et al., the short historical endeavor of solid reaction theory is discussed, and the theory dealing with non-ideal surfaces in a solid-fluid system is thoroughly explained along with the governing mathematical expressions. The approach presented here can be used to describe kinetics of non-ideal solids having surface defects and ultimately the model approaches the model used for completely porous particles. The importance oif the shape factor is thoroughly discussed and emphasized that the main benefit of including non-ideality is to get better kinetic models. In the article by Julcour et al., it was demonstrated how Nickel Slag Carbonation in a Stirred Bead Mill, which is an attrition-leaching carbonation process, can be studied and different modeling approaches are explained in detail. They developed an original thermo-kinetic modelling approach, which combines equilibrium thermodynamic OPEN ACCESS