Enthalpy vs. friction: heat flow modelling of unexpected temperature profiles in mechanochemistry of metal–organic frameworks

Abstract

Numerical simulations for precise temperature profiles of milling reactions revealed dominant contribution of frictional heating, while reaction enthalpy remained negligible.

In situ monitoring of mechanochemical synthesis of calcium urea phosphate fertilizer cocrystal reveals highly effective water-based autocatalysis

“…The presented results further our understanding of fundamental principles and mechanisms of mechanochemistry, an area that has recently attracted signicant interest. [32][33][34][35][36][37][38][39][40][41][42] While chemical autocatalysis is not the only potential reason for appearance of sigmoidal kinetics in a mechanochemical reaction, ‡ this study provides direct evidence that such a model is relevant for mechanochemical reactions and, in principle, may be broadly applicable to water-forming acid-base milling reactions. The enhancement of mechanochemical reactions in liquid-assisted grinding can sometimes be explained by a purely physical effects of dissolution and having a liquid phase present.…”

Investigations of Thermally-Controlled Mechanochemical Milling Reactions

“…30 G on the equipment ( Figure S7) and the internal heating may vary throughout time considerably when the composition of reaction mixture changes. 28 These changes usually occur due to the formation of new material with different elastic properties, but also due to the changes in the rheology of the sample and possible sticking of the material to one side of the jar, resulting in the direct impact of milling media with reactor walls and a change in heating regime. 28 PID controller system used herein (SI, Section 4) ensured rapid adaptation and corrections in the heating regime during the milling, continuously lowering the deviation from the target temperature as milling continued.…”

“…18 Mechanochemistry is dubbed Chemistry 2.0, 19 as it opened a pathway towards numerous compounds not attainable by any other synthetic procedures. 20 Despite recent advances 21,22,23,24,25 in understanding the impact of milling media on bulk reaction mixture 26,27 and the energetics derived from kinetic and thermal energy in milling processes, 28,29,30,31,32 fundamental knowledge about these basic reaction parameters is still largely lacking. 9 The need for temperature control in the milling process has been emphasized as a central issue for mechanochemistry in several recent reviews, 12,33 expecting it to overcome the activation energy barrier for some reactions and thus open a way towards a new level of chemical reactivity.…”

Unconventional Approaches to Hydrogen Sorption Reactions: Non‐Thermal and Non‐Straightforward Thermally Driven Methods

“…Despite the important advantages mechanochemical activation offers in the area of hydrogen storage, the physico‐chemical mechanisms laying behind this phenomenon and in particular the associated tribological activation effects remained poorly understood. Recently, several experimental techniques have been developed, which allow for in situ and real‐time monitoring the mechanochemical transformations during milling that bridges the gap in the mechanistic understanding of these complex processes . Tribological activation correspond to the sliding of one surface against another .…”