LOW-TEMPERATURE CARBONIZATION OF ACTIVE CENTERS IS THE REASON OF Pd/C CATALYSTS DEACTIVATION

Physicochemical and catalytic properties of Pd/C catalysts before and after the deactivation as a result of a dimethylbenzylamine debenzylation–acylation reaction are compared. A comprehensive analysis conducted by a number of methods (chemisorption, X-ray photoelectron spectroscopy, electron microscopy, X-ray diffraction) showed that a tenfold loss of the catalyst activity in the reaction conducted in soft conditions (atmospheric H 2 pressure, 25 °C) is related to the formation of a nanoscale graphite phase. While this phenomenon is common for high temperature reactions, it is first discovered at low temperatures.